Thanks for the troubleshooting guide on e-bike batteries. I was in a real jam when after finishing a ride and suddenly my battery wouldn't take a charge for the next ride. After scouring a dozen videos on youTube I found yours. followed your troubleshooting guide step by step until discovering it was the BMS. I have a new one installed now and my 52v 17.5AH is sailing along like new.
Thank you so much for this information. I had two issues with my battery pack and I would like to share them with others. The first one was the power get disconnected especially after increasing motor speed, and it was due to defected battery groups. It seems the BMS disconnects the power to protected cells. I found the defect ones after connecting a resistor as a load (with 1A discharge current) on each group and monitor voltage decrease, then replace the one which is either short or has a low voltage. The second issue was the BMS is not charging. After checking with a multimeter I found an open SMD resister (value is 471) and replaced it. The BMS was able to charge again. Thanks again.
Thank you for giving me the confidence to attempt to build my own battery pack. I want to convert a recumbent trike and go for one last adventure, Solar powered trip across Australia (I may be gone for a while).
awesome tutorial, i was looking for why my BMS lights wont go on. I understand now. some times on or the other light up but very rare to see them lighting up.
Thanks for you comment. I back tracked my wiring with the balance leads and 1 was out there for the last 6 leads were also out. That explains the high voltage.
Hello! after 1.5 years of usage, my lifepo4 battery stopped charging (light on charger is off), and also DC voltage between + - terminals shows 0. On the other hand when I opened up the battery case and checked the NEGATIVE wires like in your video (on 7:35) - it shows 13.95V - which is a perfect condition voltage (if came from + -terminals).... what does it mean?
Thank you for great educational video. I have a battery where the charging port wires got shorted and I noticed that battery is not charging adnd voltage is not as it should be when full. Battery is Lithium ion 13SP6 48V 4.2V/cell (54.6V when full). I measured voltages between cells and I got all cell channels on 4.2V except 2 channels. 5th channel is 3.17V and 8th channel is 2.76V. I was wondering is it possible to disconect bms balancing plug and plug 1S charger to channels 5 and 8 separately to charge thoose batterys to 4.2V or should I dissasemble the whole battery pack? Also when Im measuring output voltage at the discharge port C- I get 47.7V (both charging and discharging wires are soldered to C-, P- is left free and I dont know why) and voltage at the B- 52V. Measuring voltage between B- and C- = 4.38V. Do you have any advice as what to do next? Thank you.
The video I made is for LiFePO4 batteries. While the same concepts apply, the voltages are different as are the battery chemistry. Be VERY careful while troubleshooting!!! Lithium ion batteries are not as fire-safe as LiFePO4 are. Never leave a battery charging unattended, don’t charge it inside your house(a yard or garage is better), and DO keep a fire extinguisher handy. Having said that, Sounds like either some of the cells are damaged or the BMS is damaged. Your plan of charging the 5th and 8th channels separately is a good one. If both channels take a charge and hold 4.2vdc, then it’s probably the BMS that is damaged. If those channels will not hold a charge, then the cells could be damaged. The other option is just to buy a new BMS and see if it is able to charge the 2 channels that are low better than the one you suspect is damaged. If it works, great. If not then some cells are damaged.
@@charleswerbick2154 Thank you very much for your fast reply. I will be as careful as I can. I will try to charge thoose 2 channels, and I already placed the order for new BMS for any case. Best regards.
Mr. charles I got the dc voltage reading between those 3 negative terminals in BMS when my battery power switch is turn off but if I turn on the power switch I don’t have dc voltage reading what does it means? my battery is li-ion 48v 14.5ah LG cells battery 2yrs of usage but not in everyday use. and my problem is the battery is not charging because the battery charger led indicators is not lighting up but I tested the battery charger thru multimeter and it’s working properly supplied the right amount of voltage for the battery
I've just gambled on an older IZIP Metro with 36V Lithium Ion System which came without a charger, and looks to have been out of service for quite while (dusty etc). It uncharacteristically has a 4-pin plug for the charger. I succeeded in removing the battery pack from its fat downtube housing and disconnected the charging plug. That plug had the typical 3 pins, not four and I was able to check continuity to each from the charging port. Is the forth pin connection at that port just Curry's way of making me buy their charger or does it conceivably play some part in the system? Lastly, the battery registered only 4.9 volts when tested: is this in itself a death certificate, at least of a cell? The original charger is very expensive and rated at 4 amps. I put my charger from a Ping 36v battery on the connections and its fan didin't even begin running. Very grateful for any input on this.
Not familiar with any 4 pin Currie charger. The ones I have seen are 3 pin XLR (Like a microphone). They use that connector because it is polarity-protected and can't be plugged in backwards. If the battery is only reading 5 volts, then the cells are certainly damaged. (You ideally want to see 3V per cell on even a dead battery.) If there is no corrosion or water damage on the battery circuitry, then you may be able to rebuild the battery & replace the individual cells. Battery stores can also do this for you too, esp. if the cells are welded together. The other option is just to get a new battery. BTW - You are probably lucky that your charger did nothing. (Damaged cells can catch fire when charged.)
Yes this bike has a 4 pin XLR, w the pins arranged in a trapezoidal configuration....so I wonder what purpose a 4 wire (if it exists) might serve. The Curry charger is a 4 amp. My Ping charger is much less. Overnight the voltage has risen to 5.2. There is not sign of anything getting warm except the charger's normal warming. Thanks for the input: greatly appreciated!
i have a battery pack that got wet and i had to replace 5 of the cell in one of the series. when checking across the balance connector i get 4.19 - 4.20. i have even removed the connector and checked voltages, in which i get the same. i have checked from the battery negative to the negative terminal on the balance port. i get 4.19 i have continuity across the negative terminals (0v) the issue comes when i put a positive and negative connection in the connection that goes to the controller. i get either 0 voltage, or the voltage goes to 18v and then disappears. i have no idea if it is the bms that is still faulty?...
Yes, If the BMS got wet while plugged into the battery then I'd suspect it has been damaged. If your lipo cells are testing at or near 4.2 each cell then it sounds like the cells might be ok (damaged cells will probably not hold 4.2v each.) However if ANY of the cells in the series drop below discharge cutoff voltage (3.3V or so), then the BMS is designed to cut off the load. That's to protect the cells. So you MUST rule that out before concluding the BMS is faulty.
I have a question. I checked voltage in each battery cell on a 36v 500w e-bike battery, they were 4.3v in each cell, accepted 5 cells. Cells say they are 3.6v, 2500 mAh, 9.0Watts. 5 batteries read 1.2 volts when still in the pack. I figured they were bad, so I removed them. Then I checked them again out of the pack and got crazy numbers. Here are the numbers, Why? 5.6v, 1.9v 5.6v 1.3v 13.1v HELP PLEASE!
3.6v cells are li-ion. If they are reading under 2volts it over 4.4 volts per cell then they have probably suffered internal damage. Note - Be careful!!! This is a safety issue. Unlike LiFePO4 cells, lipo cells can catch fire when they fail. You will want to either want to have the bad cells replaced or get a new battery.
Hi first of all thanks for this great video, very clear and very instructive! In my case I have a 10S5P 36V LiPo battery where I had to change the old BMS. I followed your suggestions, tested B-, C- and DS- and verified that there is NO voltage amongst those, so this is fine. Then I have also tested on the balance plug from B0 (the negative) and B10 (the positive of the 10th cell), I see 39,6V: this means that wiring on the balangc plug is OK. Unfortunately when I test against DS+ and DS- I see 18V, where between B+ (directly on the battery) and B- I have 39,6V. Same thing, when I test against C+ (directly on the battery) and C- I have 18V. I guess that the BMS is faulty, what would you think? thanks a lot!
Hi Charles, your explanation is very good. I have a problem with my PCM, I suspect it needs a replacement. The 10s 4p battery will not charge or discharge. When the button is pressed to switch the battery on the LED's showing state of charge light up for 3 seconds, the voltage at the pack output terminals goes from 20.4 to 40.3 and then voltage goes back to 20.4.... voltage at terminals B- and B- (output) is zero and voltage between B- and C- is 40.3 and voltage between B- (output) and C- is 20.4. what would you recommend?
It's possible that the module is bad. Or you could have a bad cell in your battery pack. (The first is more likely as a 4p battery should be pretty robust...) I'd check each cell's voltage. If all of the cells are above 3.3V (3.0V for lipo), then your charge controller is probably toast.
please help , i have 7 Bosch EBIKE Powerpack battery 36v all the BMS board are defect , how and where i can find new BMS board to replacement , thank you
Thank thee :-) However I do have a question. I have the voltages for a LiFePO4 cell listed as: minimal 2.500 volts nominal 3.200 volts maximum 3.650 volts Should not a fully charged battery have cells at somewhere near the maximum ?
Hi can I have the bms part number or link for that same bms I have the same battery and I can find a bms that conect to the exact connections I will really appreciate
Hi. Very well explained video. I am following through some of these steps because by pack got wet and now charges to full but then cuts off after riding for a while. When I check the voltage across all the points , I am getting just under 4 on then all and approx58 for them all but when checking the voltage across them it seems to start smoking?? Any thoughts
I'm sorry to hear your pack got wet. Smoke is generally an indication of thermal damage. Testing the BMS and battery should not cause smoke. Multimeters have high internal resistance. But you do want to be careful not to short any connections on the board with the test leads. To find your fault you may need to load the battery until it fails, then test it.(without removing from the load. You may find that one of the BMS circuits is faulting or perhaps one of the cells in you battery was damaged by water and is dropping in voltage before the others...
Thanks for the quick reply. Your second idea makes most sense- the pack is attached at a 45 degree angle so the pack at the bottom was sitting in the water!! I assumed because it charges to the full approx 58v that it was probably ok but I guess that is not necessarily true?
Hi. So I changed out to packs of 5 cells in my battery pack and it still cuts out after a few minutes of load. Plus the new packs didn’t charge up to 4.1 just stayed at 3.5. I’m guessing that is because the other packs all are at 4.3 or 4.4 so the total reaches 58 and then cuts out without getting a chance to charge the new packs. I think that means I need to get the other packs down to 3.5 so all packs can charge and get balanced. I’m going to do that but over riding the bms- does that make sense?
I just watched you’re video. I just build a battery pack with a brand new bms but did wrong balance wiring, I try to do it right but now my bms show 7volt between C- and B- and 0,25 between P- and B- and ofcourse it wouldn’t charge. I’m wondering if I burned bms when I put to balance wires on the same battery?
Hi there, thanks for a great video. i am only new to this but ive been building ebike batteries for about 6 months, now,and have had some trouble wondering what trouble shooting i can do. im building a 48volt 13amp hailong battery pack. your video explains that if there is any voltage between C- and P- is saying 176.3volts dc and the same from P- to C- is the same 176.3 volt dc. .and from B- to P- its 4.7 Volts , what does this mean. ? i am using 3200mah lg cells and a 15 amp bms.? and how do i trouble shoot from here.?i will note that i have built about 6 to 8 of these the same way and no problem . so not sure what ive done wrong, have replaced bms and the same result i have got, does this mean the bms is not working at all ??
If you are building a 48V battery you should NOT be seeing 176.3V anywhere in your setup. Sounds like you have severely miswired your cells. (and probably completely hosed your BMS). You say you are building a 13 Amp battery from 3200mah lg LiPo cells? So that would suggest that you are trying to build a '12S4P' cell. But instead of wiring each of those 4 cells in parallel it sounds like you wired them in series. (and then wired all of those in series) So my guess is you accidentally made a 48S1P pack! I could be wrong. (I haven't looked at your set-up) But thats the only way I can think of you'd get those voltages... For more information on battery pack configurations read this - batteryuniversity.com/learn/article/serial_and_parallel_battery_configurations Hope that helps!
Charles thank you for getting back to me so quickly. I think I can replace the 5 batteries. They were in the last row, easy to get to. I'm going to get a new bms also. Will a new one plug right in? My bms as no temp. sensor all the new ones do. I'm getting a small spot welder too, are they any good? Thanks again, Rick
@@charleswerbick2154 I have 2 wires going to my switch from my bms. how do I find a bms with those 2 wires? I see bms with thermocouple but no switch wires.
Hey man. I got a question: I touched 2 wires together by accident and shorted the lifepo4 battery I have. Now it reports as around 32v out of full 48v. I ordered 2 BMS from china on ebay. Do you think replacing the BMS would fix it? it's a brand new battery.
I honestly don't know. You may be able to measure the voltage of each series cell to try to gauge whether the battery was damaged. (In a functioning, balanced battery each cell will float at close to the same voltages.)
@@charleswerbick2154 wow ok. I dont see why a new battery with short would cause damage to battery? Must be BMS that is dead? Nobody knows at all. weird.
@@canadianmonkey1954I'm not trying to tell you your battery is hosed. But I'm also not going to tell you that it isn't. the BMS is designed to protect the battery. But with a short it is possible to exceed the discharge rate the cells can handle or overheat them (both of which can damage the cells). You can replace the BMS and see if the battery takes and holds a charge.(with appropriate precautions) If it was the BMS the voltage should come all the way back up after charging. Good Luck!
@@charleswerbick2154 Hello Thanks for reply. My guesswork is that since it won't charge for more than 2 minutes or so that it would be the BMS. What else could it be? I don't understand how BMS works I suspect.
I have a question though. is it possible to just rip the BMS out and have your battery work w/o it? seems to me that it's not necessary except for balancing cells that don't really need balancing. Thank you for very good informative video
Hello and sorry for the delayed response. This is a topic of heated debate in eBike circles. There are competing viewpoints and evidence on both sides. (Any response I give will likely be flamebait for someone.) I will say that aside from balancing the cells during charge the BMS does perform ONE other important function- It disables the entire battery during discharge if any bank drops to ~ 2.8V. This helps protect the cells in the battery from being damaged by being run down too far. I would not criticize someone either way. But I would encourage you to do your research and make an informed decision.
Fantastic video !!! I have a 48v LiFePO4 battery pack. I charged it up until charger turned green indicating battery charged and I checked voltage at the battery connector with it connected to the motor controller and I’m getting 58v after riding it around under light throttle for a few mins it dropped to around 53-54v . My problem is when I accelerate hard the scooter cuts out I lose all power... i check voltage at the battery connector with fault present and I’m now getting 4v I unplug battery connector and check battery voltage and voltage comes back to 54v I then plug battery back into motor controller and I still have 54v and can ride around under light throttle for a bit as long as I don’t accelerate hard. If I hard throttle issue comes back I unplug and reconnect battery and I can go again under light throttle Do I go after battery??? Or motor controller??? I’m leaning towards battery/BMS
Sounds like the under voltage protection is kicking in. You may be pulling too much current for the battery capacity or the battery may just be worn. What is the capacity of the battery and how many watts is your motor? (Also, how old is the battery?)
I tried trouble shooting your way and nothing showed up. My charger works because i used it on another 42v 10s battery but when i tried to charge my other battery with a 10s bms it doesnt charge. It only charges for a few seconds when i discharge it for a couple of seconds. Each cell is at 4v making it have a total voltage of 40v and it just doesnt charge. I know it isnt that the charger is stopping because of the voltage on the battery reaching 40v because it is a 42v charger. My bms is a 45a 10s 42v bms
i've tryed to upgrade a ridgid's battery pack by 2200mah to about 6700mah 18650 panasonic ncr18650, (2 pair for 5 in series), when i started to use a brushless drill i've had no problem when tryed a brushed tools the same battery pack stopped to work. To enable the battery i insert into owner charger and all back like before, what i have to think bms problem with the brushed tool Thank you vey much
Good video very informative subscribed. Any tips on an issue with a 1 year old 36v 10s 13ah samsung battery pack which will no longer charge (charger stays green not red). charger is outputing 42v no issue with charger connections . samsung cells are ok checked between balance wires and B- Wondering what is likely to be the issue which is preventing charging. Bike is otherwise operating fine.
I don't have the foggiest idea of what you're talking about but could I send you my lithium battery it's a 48 volt 1200mah and I will pay you to fix it all I can tell you is it got wet through rain while I was riding it and when I stopped I noticed my LED would not light up anymore it won't charge on my charger it's only 3 months old I've only charged it 10 times
Hello everyone and especially Charles! I have a friend who has i lifepo4 48v 12ah and he dint use it for 6 mionths because he had an accidrnt. He is now trying to reuse the bike and the battery last very little time. I told hime let it charge again all night and try tommorrow again hoping that the battery needs some charge cycles the get in full performance of old time. Was my advice good? Has anyone has any other ideas? Thank you in advance!
Hello Jamzra, It really depends upon what state the battery was in when it was stored and the type of BMS installed. LiFePO4 batteries last the longest when charged halfway. If the battery was all of the way dead when stored then it the cells may have been damaged. Charging the battery all of the way up before storage can also cause damage to the cells. AFA the BMS, old BMS boards pull their operating voltage from the first 4 series groups of cells. Newer BMS boards pull their operating voltage equally from all 16 groups of series cells. So if he has a bettery with the old style BMS then the first 4 groups of cells were likely drained all the way down while the battery was stored. If it was the new style then the cells were drained equally during storage. I would test the voltage at each series bank both fully charged fully discharged. If the 4 banks of batteries nearest the negative battery lead show a lower voltage when discharged, then they have been worn more than the rest of the battery. If they show a lower voltage when fully charged then they were DEFINITELY damaged. If any of the battery banks read below 2.8V then damage to the cells has occurred. To try to recover the existing battery as much as possible I would leave the battery on the charger for a long time (a week maybe?) without using it rather than charge and discharge it. The BMS will prevent the cells that are OK from being overcharged and the trickle charge the damaged cells receive over a longer period of time will do more for them than charging and discharging the damaged cells repeatedly. Hope that helps!!! P.S. for those planning on storing their LiFePO4 battery I recommend charging the battery to approx. 60%, then unplug the BMS from the battery cells before storage (i.e. unplug the big plug with a bunch of wires from the BMS board). This will prevent the BMS from discharging the cells during storage.
Thank you a lot about your help! I will try to leave the battery in chargingand i will let you know about the results! Ihave the saame battery on my bike and i use it for 4 years and i know that is a good one
it seems the battery is back again! thank you very much! Although now i have a problem with my motor. Ithink it is hall sensor problem. This is the motor i have encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQQe-AIJE7fDrBGCEGcQgExSfEm_VC_oKmJbLtH4aPOZaYYbuzQEQ How is it possible to find suitable sensors for this motor? Thank you for any help in advance!
Most of these use 3x SS41 sensors on a board together. If one has failed I would recommend just replacing all 3 while you have the hub apart... They are not very expensive. (If you look on ebay or google for 'SS41 hall sensor' you will find them readily.) The trick with those is to make sure that you solder them in the correct orientation and that they are positioned correctly. Look carefully at the old ones and take some pictures with your phone to make sure the new ones go in the exact same way as the old ones were.
Just opened the motor and found these tiny devils! I see that they are ss41! I already ordered them in a local electronics store! Now i got to find someone with good skills in soldering! Thank you very much for your help!!
I'm having problems with my 48v 30Ah battery. It is shutting off at around 50v on my bike, cant ride even at 300W. I have a post on Endless Sphere if anyone is interested to help me out. endless-sphere.com/forums/viewtopic.php?f=2&t=108215
Thanks for the troubleshooting guide on e-bike batteries. I was in a real jam when after finishing a ride and suddenly my battery wouldn't take a charge for the next ride. After scouring a dozen videos on youTube I found yours. followed your troubleshooting guide step by step until discovering it was the BMS. I have a new one installed now and my 52v 17.5AH is sailing along like new.
Thanks for this. Easily the best video I've seen on the subject. Has answered a few questions I had after pulling my battery apart yesterday.
Thank you so much for this information.
I had two issues with my battery pack and I would like to share them with others.
The first one was the power get disconnected especially after increasing motor speed, and it was due to defected battery groups. It seems the BMS disconnects the power to protected cells. I found the defect ones after connecting a resistor as a load (with 1A discharge current) on each group and monitor voltage decrease, then replace the one which is either short or has a low voltage.
The second issue was the BMS is not charging. After checking with a multimeter I found an open SMD resister (value is 471) and replaced it. The BMS was able to charge again.
Thanks again.
Best troubleshooting video I’ve seen! Answered every question I had. Thank you for your concise and clear style, Charles.
Great vid! Best explanation of all that is BMS I have ever seen. You really know your stuff. Keep up the great work :)
Thank you for giving me the confidence to attempt to build my own battery pack. I want to convert a recumbent trike and go for one last adventure, Solar powered trip across Australia (I may be gone for a while).
Hope you are living that dream now.
awesome tutorial, i was looking for why my BMS lights wont go on. I understand now. some times on or the other light up but very rare to see them lighting up.
Thanks for you comment. I back tracked my wiring with the balance leads and 1 was out there for the last 6 leads were also out. That explains the high voltage.
Hello! after 1.5 years of usage, my lifepo4 battery stopped charging (light on charger is off), and also DC voltage between + - terminals shows 0.
On the other hand when I opened up the battery case and checked the NEGATIVE wires like in your video (on 7:35) - it shows 13.95V - which is a perfect condition voltage (if came from + -terminals).... what does it mean?
Great vid. I learned a bit more from it. The whispery voice was annoying to me but w/e. lol. thanks.
Thank you for great educational video. I have a battery where the charging port wires got shorted and I noticed that battery is not charging adnd voltage is not as it should be when full. Battery is Lithium ion 13SP6 48V 4.2V/cell (54.6V when full). I measured voltages between cells and I got all cell channels on 4.2V except 2 channels. 5th channel is 3.17V and 8th channel is 2.76V. I was wondering is it possible to disconect bms balancing plug and plug 1S charger to channels 5 and 8 separately to charge thoose batterys to 4.2V or should I dissasemble the whole battery pack? Also when Im measuring output voltage at the discharge port C- I get 47.7V (both charging and discharging wires are soldered to C-, P- is left free and I dont know why) and voltage at the B- 52V. Measuring voltage between B- and C- = 4.38V. Do you have any advice as what to do next? Thank you.
The video I made is for LiFePO4 batteries. While the same concepts apply, the voltages are different as are the battery chemistry. Be VERY careful while troubleshooting!!! Lithium ion batteries are not as fire-safe as LiFePO4 are.
Never leave a battery charging unattended, don’t charge it inside your house(a yard or garage is better), and DO keep a fire extinguisher handy.
Having said that, Sounds like either some of the cells are damaged or the BMS is damaged. Your plan of charging the 5th and 8th channels separately is a good one. If both channels take a charge and hold 4.2vdc, then it’s probably the BMS that is damaged. If those channels will not hold a charge, then the cells could be damaged.
The other option is just to buy a new BMS and see if it is able to charge the 2 channels that are low better than the one you suspect is damaged. If it works, great. If not then some cells are damaged.
@@charleswerbick2154 Thank you very much for your fast reply. I will be as careful as I can. I will try to charge thoose 2 channels, and I already placed the order for new BMS for any case. Best regards.
my bms allow some element to reach 3.7V while the others are still at 3.3 , is it faulty?
Mr. charles I got the dc voltage reading between those 3 negative terminals in BMS when my battery power switch is turn off but if I turn on the power switch I don’t have dc voltage reading what does it means? my battery is li-ion 48v 14.5ah LG cells battery 2yrs of usage but not in everyday use. and my problem is the battery is not charging because the battery charger led indicators is not lighting up but I tested the battery charger thru multimeter and it’s working properly supplied the right amount of voltage for the battery
I've just gambled on an older IZIP Metro with 36V Lithium Ion System which came without a charger, and looks to have been out of service for quite while (dusty etc). It uncharacteristically has a 4-pin plug for the charger. I succeeded in removing the battery pack from its fat downtube housing and disconnected the charging plug. That plug had the typical 3 pins, not four and I was able to check continuity to each from the charging port. Is the forth pin connection at that port just Curry's way of making me buy their charger or does it conceivably play some part in the system? Lastly, the battery registered only 4.9 volts when tested: is this in itself a death certificate, at least of a cell? The original charger is very expensive and rated at 4 amps. I put my charger from a Ping 36v battery on the connections and its fan didin't even begin running. Very grateful for any input on this.
Not familiar with any 4 pin Currie charger. The ones I have seen are 3 pin XLR (Like a microphone). They use that connector because it is polarity-protected and can't be plugged in backwards. If the battery is only reading 5 volts, then the cells are certainly damaged. (You ideally want to see 3V per cell on even a dead battery.) If there is no corrosion or water damage on the battery circuitry, then you may be able to rebuild the battery & replace the individual cells. Battery stores can also do this for you too, esp. if the cells are welded together. The other option is just to get a new battery.
BTW - You are probably lucky that your charger did nothing. (Damaged cells can catch fire when charged.)
Yes this bike has a 4 pin XLR, w the pins arranged in a trapezoidal configuration....so I wonder what purpose a 4 wire (if it exists) might serve. The Curry charger is a 4 amp. My Ping charger is much less. Overnight the voltage has risen to 5.2. There is not sign of anything getting warm except the charger's normal warming. Thanks for the input: greatly appreciated!
i have a battery pack that got wet and i had to replace 5 of the cell in one of the series. when checking across the balance connector i get 4.19 - 4.20. i have even removed the connector and checked voltages, in which i get the same.
i have checked from the battery negative to the negative terminal on the balance port. i get 4.19
i have continuity across the negative terminals (0v)
the issue comes when i put a positive and negative connection in the connection that goes to the controller. i get either 0 voltage, or the voltage goes to 18v and then disappears. i have no idea if it is the bms that is still faulty?...
Yes, If the BMS got wet while plugged into the battery then I'd suspect it has been damaged.
If your lipo cells are testing at or near 4.2 each cell then it sounds like the cells might be ok (damaged cells will probably not hold 4.2v each.)
However if ANY of the cells in the series drop below discharge cutoff voltage (3.3V or so), then the BMS is designed to cut off the load. That's to protect the cells.
So you MUST rule that out before concluding the BMS is faulty.
I have a question. I checked voltage in each battery cell on a 36v 500w e-bike battery, they were 4.3v in each cell, accepted 5 cells. Cells say they are 3.6v, 2500 mAh, 9.0Watts. 5 batteries read 1.2 volts when still in the pack. I figured they were bad, so I removed them. Then I checked them again out of the pack and got crazy numbers. Here are the numbers, Why? 5.6v, 1.9v 5.6v 1.3v 13.1v HELP PLEASE!
3.6v cells are li-ion. If they are reading under 2volts it over 4.4 volts per cell then they have probably suffered internal damage.
Note - Be careful!!! This is a safety issue. Unlike LiFePO4 cells, lipo cells can catch fire when they fail. You will want to either want to have the bad cells replaced or get a new battery.
Hi first of all thanks for this great video, very clear and very instructive!
In my case I have a 10S5P 36V LiPo battery where I had to change the old BMS.
I followed your suggestions, tested B-, C- and DS- and verified that there is NO voltage amongst those, so this is fine.
Then I have also tested on the balance plug from B0 (the negative) and B10 (the positive of the 10th cell), I see 39,6V: this means that wiring on the balangc plug is OK.
Unfortunately when I test against DS+ and DS- I see 18V, where between B+ (directly on the battery) and B- I have 39,6V.
Same thing, when I test against C+ (directly on the battery) and C- I have 18V.
I guess that the BMS is faulty, what would you think?
thanks a lot!
urgent !! may I ask if 14s (white cables),can use to 12S? (bms not change)
Hi Charles, your explanation is very good. I have a problem with my PCM, I suspect it needs a replacement. The 10s 4p battery will not charge or discharge. When the button is pressed to switch the battery on the LED's showing state of charge light up for 3 seconds, the voltage at the pack output terminals goes from 20.4 to 40.3 and then voltage goes back to 20.4.... voltage at terminals B- and B- (output) is zero and voltage between B- and C- is 40.3 and voltage between B- (output) and C- is 20.4. what would you recommend?
It's possible that the module is bad. Or you could have a bad cell in your battery pack. (The first is more likely as a 4p battery should be pretty robust...)
I'd check each cell's voltage. If all of the cells are above 3.3V (3.0V for lipo), then your charge controller is probably toast.
please help , i have 7 Bosch EBIKE Powerpack battery 36v all the BMS board are defect , how and where i can find new BMS board to replacement , thank you
Thank thee :-)
However I do have a question. I have the voltages for a LiFePO4 cell listed as:
minimal 2.500 volts
nominal 3.200 volts
maximum 3.650 volts
Should not a fully charged battery have cells at somewhere near the maximum ?
Fully charged LiFePO4 cells are about 3.6V.
Hi can I have the bms part number or link for that same bms I have the same battery and I can find a bms that conect to the exact connections I will really appreciate
Great video Charles. My balance connector warms up a bit when plugged in which I believe is OK?
Hi. Very well explained video. I am following through some of these steps because by pack got wet and now charges to full but then cuts off after riding for a while. When I check the voltage across all the points , I am getting just under 4 on then all and approx58 for them all but when checking the voltage across them it seems to start smoking?? Any thoughts
I'm sorry to hear your pack got wet. Smoke is generally an indication of thermal damage. Testing the BMS and battery should not cause smoke. Multimeters have high internal resistance. But you do want to be careful not to short any connections on the board with the test leads.
To find your fault you may need to load the battery until it fails, then test it.(without removing from the load. You may find that one of the BMS circuits is faulting or perhaps one of the cells in you battery was damaged by water and is dropping in voltage before the others...
Thanks for the quick reply. Your second idea makes most sense- the pack is attached at a 45 degree angle so the pack at the bottom was sitting in the water!! I assumed because it charges to the full approx 58v that it was probably ok but I guess that is not necessarily true?
Hi. So I changed out to packs of 5 cells in my battery pack and it still cuts out after a few minutes of load. Plus the new packs didn’t charge up to 4.1 just stayed at 3.5. I’m guessing that is because the other packs all are at 4.3 or 4.4 so the total reaches 58 and then cuts out without getting a chance to charge the new packs. I think that means I need to get the other packs down to 3.5 so all packs can charge and get balanced. I’m going to do that but over riding the bms- does that make sense?
I just watched you’re video. I just build a battery pack with a brand new bms but did wrong balance wiring, I try to do it right but now my bms show 7volt between C- and B- and 0,25 between P- and B- and ofcourse it wouldn’t charge. I’m wondering if I burned bms when I put to balance wires on the same battery?
Hi there, thanks for a great video.
i am only new to this but ive been building ebike batteries for about 6 months, now,and have had some trouble wondering what trouble shooting i can do. im building a 48volt 13amp hailong battery pack. your video explains that if there is any voltage between C- and P- is saying 176.3volts dc and the same from P- to C- is the same 176.3 volt dc. .and from B- to P- its 4.7 Volts , what does this mean. ? i am using 3200mah lg cells and a 15 amp bms.? and how do i trouble shoot from here.?i will note that i have built about 6 to 8 of these the same way and no problem . so not sure what ive done wrong, have replaced bms and the same result i have got, does this mean the bms is not working at all ??
If you are building a 48V battery you should NOT be seeing 176.3V anywhere in your setup. Sounds like you have severely miswired your cells. (and probably completely hosed your BMS).
You say you are building a 13 Amp battery from 3200mah lg LiPo cells? So that would suggest that you are trying to build a '12S4P' cell. But instead of wiring each of those 4 cells in parallel it sounds like you wired them in series. (and then wired all of those in series) So my guess is you accidentally made a 48S1P pack!
I could be wrong. (I haven't looked at your set-up) But thats the only way I can think of you'd get those voltages...
For more information on battery pack configurations read this - batteryuniversity.com/learn/article/serial_and_parallel_battery_configurations
Hope that helps!
Charles thank you for getting back to me so quickly. I think I can replace the 5 batteries. They were in the last row, easy to get to. I'm going to get a new bms also. Will a new one plug right in? My bms as no temp. sensor all the new ones do. I'm getting a small spot welder too, are they any good? Thanks again, Rick
Usually the BMS will connect easily. Just make sure you get a Li-Ion BMS and not a LiFePO4 one. The charge voltages are different.
@@charleswerbick2154 I have 2 wires going to my switch from my bms. how do I find a bms with those 2 wires? I see bms with thermocouple but no switch wires.
@@rickdag1 - some BMS have a connector for a switch, some do not. If in doubt, ask the vendor from which you purchased the BMS for a wiring guide.
@@charleswerbick2154 I was using Amazon to find a bms. it's really hard to contact a vender on Amzon. Any suggestions on a place to buy a bms. thanks!
@@rickdag1 - i would recommend looking on eBay and Banggood.com for ebike parts.
Misty any ebay seller will answer questions prior to purchase.
Hey man. I got a question: I touched 2 wires together by accident and shorted the lifepo4 battery I have. Now it reports as around 32v out of full 48v. I ordered 2 BMS from china on ebay. Do you think replacing the BMS would fix it? it's a brand new battery.
I honestly don't know. You may be able to measure the voltage of each series cell to try to gauge whether the battery was damaged. (In a functioning, balanced battery each cell will float at close to the same voltages.)
@@charleswerbick2154 wow ok. I dont see why a new battery with short would cause damage to battery? Must be BMS that is dead? Nobody knows at all. weird.
@@canadianmonkey1954I'm not trying to tell you your battery is hosed. But I'm also not going to tell you that it isn't. the BMS is designed to protect the battery. But with a short it is possible to exceed the discharge rate the cells can handle or overheat them (both of which can damage the cells). You can replace the BMS and see if the battery takes and holds a charge.(with appropriate precautions) If it was the BMS the voltage should come all the way back up after charging.
Good Luck!
@@charleswerbick2154 Hello Thanks for reply. My guesswork is that since it won't charge for more than 2 minutes or so that it would be the BMS. What else could it be? I don't understand how BMS works I suspect.
Guy just sprayed his knowledge all over me
I have a question though. is it possible to just rip the BMS out and have your battery work w/o it? seems to me that it's not necessary except for balancing cells that don't really need balancing.
Thank you for very good informative video
Hello and sorry for the delayed response. This is a topic of heated debate in eBike circles. There are competing viewpoints and evidence on both sides. (Any response I give will likely be flamebait for someone.) I will say that aside from balancing the cells during charge the BMS does perform ONE other important function- It disables the entire battery during discharge if any bank drops to ~ 2.8V. This helps protect the cells in the battery from being damaged by being run down too far.
I would not criticize someone either way. But I would encourage you to do your research and make an informed decision.
Fantastic video !!! I have a 48v LiFePO4 battery pack. I charged it up until charger turned green indicating battery charged and I checked voltage at the battery connector with it connected to the motor controller and I’m getting 58v after riding it around under light throttle for a few mins it dropped to around 53-54v . My problem is when I accelerate hard the scooter cuts out I lose all power... i check voltage at the battery connector with fault present and I’m now getting 4v I unplug battery connector and check battery voltage and voltage comes back to 54v I then plug battery back into motor controller and I still have 54v and can ride around under light throttle for a bit as long as I don’t accelerate hard. If I hard throttle issue comes back I unplug and reconnect battery and I can go again under light throttle Do I go after battery??? Or motor controller??? I’m leaning towards battery/BMS
Sounds like the under voltage protection is kicking in. You may be pulling too much current for the battery capacity or the battery may just be worn. What is the capacity of the battery and how many watts is your motor? (Also, how old is the battery?)
Charles Werbick it is a 1500w BLDC motor the battery is 48v 20ah Lifepo4 60a output battery is a couple years old only used a few times
Had this issue when battery was “new” just never addressed it
I tried trouble shooting your way and nothing showed up. My charger works because i used it on another 42v 10s battery but when i tried to charge my other battery with a 10s bms it doesnt charge. It only charges for a few seconds when i discharge it for a couple of seconds. Each cell is at 4v making it have a total voltage of 40v and it just doesnt charge. I know it isnt that the charger is stopping because of the voltage on the battery reaching 40v because it is a 42v charger. My bms is a 45a 10s 42v bms
i've tryed to upgrade a ridgid's battery pack by 2200mah to about 6700mah 18650 panasonic ncr18650, (2 pair for 5 in series), when i started to use a brushless drill i've
had no problem when tryed a brushed tools the same battery pack stopped to work. To enable the battery i insert into owner charger and all back like before, what i have to think bms problem with the brushed tool
Thank you vey much
Good video very informative subscribed. Any tips on an issue with a 1 year old 36v 10s 13ah samsung battery pack which will no longer charge (charger stays green not red). charger is outputing 42v no issue with charger connections . samsung cells are ok checked between balance wires and B- Wondering what is likely to be the issue which is preventing charging. Bike is otherwise operating fine.
Did you ever figure this out? I’m having the same issue
@@Scrachdc Yes issue due to faulty BMS. BMS replaced. now ok.
I don't have the foggiest idea of what you're talking about but could I send you my lithium battery it's a 48 volt 1200mah and I will pay you to fix it all I can tell you is it got wet through rain while I was riding it and when I stopped I noticed my LED would not light up anymore it won't charge on my charger it's only 3 months old I've only charged it 10 times
Hello everyone and especially Charles! I have a friend who has i lifepo4 48v 12ah and he dint use it for 6 mionths because he had an accidrnt. He is now trying to reuse the bike and the battery last very little time. I told hime let it charge again all night and try tommorrow again hoping that the battery needs some charge cycles the get in full performance of old time. Was my advice good? Has anyone has any other ideas? Thank you in advance!
Hello Jamzra,
It really depends upon what state the battery was in when it was stored and the type of BMS installed. LiFePO4 batteries last the longest when charged halfway. If the battery was all of the way dead when stored then it the cells may have been damaged. Charging the battery all of the way up before storage can also cause damage to the cells.
AFA the BMS, old BMS boards pull their operating voltage from the first 4 series groups of cells. Newer BMS boards pull their operating voltage equally from all 16 groups of series cells. So if he has a bettery with the old style BMS then the first 4 groups of cells were likely drained all the way down while the battery was stored. If it was the new style then the cells were drained equally during storage.
I would test the voltage at each series bank both fully charged fully discharged. If the 4 banks of batteries nearest the negative battery lead show a lower voltage when discharged, then they have been worn more than the rest of the battery. If they show a lower voltage when fully charged then they were DEFINITELY damaged. If any of the battery banks read below 2.8V then damage to the cells has occurred.
To try to recover the existing battery as much as possible I would leave the battery on the charger for a long time (a week maybe?) without using it rather than charge and discharge it. The BMS will prevent the cells that are OK from being overcharged and the trickle charge the damaged cells receive over a longer period of time will do more for them than charging and discharging the damaged cells repeatedly.
Hope that helps!!!
P.S. for those planning on storing their LiFePO4 battery I recommend charging the battery to approx. 60%, then unplug the BMS from the battery cells before storage (i.e. unplug the big plug with a bunch of wires from the BMS board). This will prevent the BMS from discharging the cells during storage.
Thank you a lot about your help! I will try to leave the battery in chargingand i will let you know about the results! Ihave the saame battery on my bike and i use it for 4 years and i know that is a good one
it seems the battery is back again! thank you very much! Although now i have a problem with my motor. Ithink it is hall sensor problem. This is the motor i have encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQQe-AIJE7fDrBGCEGcQgExSfEm_VC_oKmJbLtH4aPOZaYYbuzQEQ How is it possible to find suitable sensors for this motor? Thank you for any help in advance!
Most of these use 3x SS41 sensors on a board together. If one has failed I would recommend just replacing all 3 while you have the hub apart... They are not very expensive. (If you look on ebay or google for 'SS41 hall sensor' you will find them readily.) The trick with those is to make sure that you solder them in the correct orientation and that they are positioned correctly. Look carefully at the old ones and take some pictures with your phone to make sure the new ones go in the exact same way as the old ones were.
Just opened the motor and found these tiny devils! I see that they are ss41! I already ordered them in a local electronics store! Now i got to find someone with good skills in soldering! Thank you very much for your help!!
thanks bro :-) .....my bike (48v) shows 52v but "cuts off" with ANY load,...so,...I gotta learn how to fix it,...
Thnak you!!!
thank you sooooooo much
A lot of chinese bms are faulty
I'm having problems with my 48v 30Ah battery. It is shutting off at around 50v on my bike, cant ride even at 300W.
I have a post on Endless Sphere if anyone is interested to help me out. endless-sphere.com/forums/viewtopic.php?f=2&t=108215
Why are you whispering, I would think you would want us to hear you. That was the purpose of this video right? Speak up!