I have been running a 24v system for over two years and never had the problem you are describing. I am using 100 AH Redodo batteries in series and charging with Victron charge controller they stay the same voltage, and I have never had one shutdown for over or under voltage. I feel you may have a bad battery there. I would pull them out of that system, charge them and run capacity test on teach one. I am running 6 batteries in 3 series strings. No issues at all.
For what it's worth, I had problems with 100AH batteries in parallel that would only discharge 50AH before the inverter would shut down. I was on the verge of returning them when it was suggested that my cables to the 12 volt inverter was too light, despite using the cables that came with the inverter, and all indications were that they were adequate. I replaced them with 2/0 welding cables, then tested each battery individually. They both supplied over 100AH per battery before shutting down. I had previously used lead-acid with the supplied cables & never thought heavier cables would be needed in this case. Apparently the BMS systems like the lower resistance.
I see a few comments about using 24v batteries for a 24v system. While it is preferred, it isn't required, but limit two, meaning, don't use 4 X 12v to make a 48v system, but 2 X 24. That said, when it comes to the bms's in lithiums, some are not designed for serial connection, for the reason that you discovered. For example, the Victron Super Pack Lithiums, can NOT be series connected(but no limit to the number in parallel), but their Smart Lithium's(max 20 batteries), and the even newer 'NG's'(max 50 batteries), can be series connected. Another example would be Li-Time Lithiums, which clearly state that they can be configured in up to a 4p4s system(max 16 batteries). While you can hack your way around your issue, you really should either use 24v batteries, or, choose a brand that allows for(is designed and engineered for) serial connections.
Victron makes a battery balancer specifically designed to prevent this problem, but your solution will work too. Also, make sure that none of your charge controllers are set to "equalize the batteries" so high voltage won't be sent to the batteries for desulphating them. Only needed for lead acid.
You have over-complicated a simple issue, just set to 24v system and set controller to float just below shut off voltage, problem solved.
Месяц назад+1
I am wondering if those 12v packs have a Bluetooth access control screen?? Some of them allow for a setting if you have them in series or parallel to tweak the controllers to compensate for the imbalance.. I have also seen people crack them open and install a stand alone active balancer that has 8 leads for the 8 cells which can pull power from the higher cells and put it in the lower ones.. One day a battery manufacturer might offer a way to do this without cracking open the batteries by having a balance connector available so you could just plug and play with 2-3 or 4 12v batteries..
Looks like you got some decent answers but in summary... * You need a whole-battery balancer if you connect two LiFePO4 batteries in series. It is far better to get the appropriate native-voltage LiFePO4 battery instead of stringing lesser voltage lithium batteries in series. Far more robust using a native-voltage battery. * Do not circuit the separate 12V batteries in the 24V series bank to individual devices (except the balancer itself), for any reason. That will take them out of balance and change the ground reference on some of the related devices which can be extremely dangerous if you forget later on while messing with things. e.g. Those charge controllers really should only be wired to the "24V" bank, not to individual 12.8V batteries. In particular, the ground-reference for one of the charge controllers will be sitting at +12.8V instead of GND relative to the system and if you ever try to connect other comm cables or such to that charger controller, or mess with the solar array outside thinking that the black wire is GND, you might be in for a very nasty shock, smoke, or fire. * 24V native voltage batteries should not be more expensive or too much more expensive than individual 12V batteries. In terms of capacity, 2 x 50Ah 12.8V batteries = 1 x 50Ah 25.6V battery. -Matt
@@junkerzn7312 Thank you for the advice. I didn’t consider the issues you mentioned. I only paid $170 for both batteries combined. The 24v battery was $300. I thought I would take the cheaper way out,, but I guess it’s really not if I have to buy more equipment like balancers. I might just revert back to my 12v setup and save up for the proper battery. Maybe I could take these batteries apart and combine the cells in a 24v configuration with a BMS from amazon.
@@Checkitfirst whole battery balancers are very cheap so definitely start by wiring one up. That should solve 90% of your problems. Though it might take a bunch of cycles for it to rebalance the batteries, it will keep them in balance from that point onward. The remaining 10% of the problem space is dealing with low-voltage battery disconnects. If you run the system all the way down to the BMS disconnect, then in a series configuration it is possible for one battery to disconnect and prevent the charge controllers from reactivating the bank when the sun comes up the next day. The usual solution for this case is to ensure that the inverter shuts off on low-voltage before the batteries do. If the batteries disconnect at 10.0Vx2 = 20.0V, then being able to program the inverter to shutoff at, say, 22.0V would prevent the battery BMSs from disconnecting. That inverter probably isn't programmable in that way, but it's the usual solution. If the inverter has a remote-control relay input you can program a smart relay to tell it to shutdown earlier based on the DC side voltage. If the inverter does not have a remote-control relay input, then you are kinda stuck in that regard. -Matt
This is the prime reason you buy 24v batteries for a 24v system. In lithium using the wrong voltage batteries has the problem you’re having. I would stick to 24v batteries and skip the old lead acid mentality
Why the skinny ass wires? You need to charge them independently, then put them back in series. Maybe one of them has a bad BMS? (my self experience). Great looking equipment layout on the wall.
Sounds like they are cheap for a reason, I'm guessing you have one crapped out cell that is killing the whole thing. 40% difference is way too much, see if you can get it replaced under warranty.
I'm in UK.....I'm seeing more and more of these batteries and stacks failures..... And basically it's down to cell balance, Alot of them aren't top balancing the cells before manufacturing.. I took me 4weeks to sort a set of cells out... pulled out of a 48v rack......now 6 weeks on getting full capacity.
@@marcobrian1619 What would you think if I took those two batteries apart and reconfigured the cells in them for a 24 V system and bought a BMS to manage it. Would you think that would be better than trying to run two separate batteries. Thinking of building a 24 V battery with the cells I have available to me in these two batteries.
@Checkitfirst you could do that....then just one BMS would monitor the battery. Or strip the packs you have , top balance all cells together for one battery and then again for other then rebuild it back up. Both ways will work,
Did you parell the batteries for a day or 2 before connecting in series? I belive that is the key ( i my opinion). I never had any of my different systems wandering off in different charge level.. 🤔
@@BeeBeorn Yes, in the beginning, I had them in parallel and I was using my 12 V system. I only had one battery to start with so I was using my 12 V inverter to play around with it when I got my second battery I ran them in parallel to make 100 amp hour system . When I got done playing with it,, I left it on the Solar charger until the batteries quit taking a charge. I ran them in series. After about a month, I noticed one of the batteries was not at the proper charge level as the other one was. Figured it was a balancing issue between the two batteries.
You would be better off with a 24-volt battery the BMS is made inside the work that way. If you do two more of those batteries you have there now you still just need to other small chargers the way you have it you don't need four more. Because it's a series parallel setup. The things in parallel will use the same charger
@@Checkitfirst balancer would be ideal...again not for me as my set up is used off and on. mostly off. only choice will be balancer with on/off switch when not in use.
The 24 V lithium was quite expensive and I figured I could go 24 V this way or I could resort back to a 12 V system if my power inverter went out. It’s just little thoughts like that I was thinking of. I know it’s not a perfectly correct way to do everything, but I was hoping I could make it work.
@@RomansSeven7 I have 500 W going to the 3215 BN in the center for the 24 V system. I have a separate 300 W system. I’m using for the other two controllers for the balancing.
@@Checkitfirst yes i understand the 24v .its the two 12v on one panel im confused about. so 300w panels connected to the two controllers? or each controller has a 300w panei? what we want to know is can multiple controllers be connected the the same panel/panels? the two wires from panels connect to two charge controllers.
@ Yes,, you can connect more than one controller to the same panel string. If you had 10,000 watts of solar,, you could connect 10 1000 watt controllers to the panels to charge a large battery bank. In the beginning,, I had 2 100 watt controllers connected to a 400 watt panel setup. It worked great
@@Checkitfirst I would be concern about the charge profile for lithium vs lead acid. You have a great idea and I may even steal it for my shed. Please consider changing the controllers. thanks and good luck.
@ I’m not really sure if it matters because I can take a bench power supply and charge lithium batteries with it as long as you’re at the right voltage it doesn’t matter what you use Voltage is voltage the only issue is that it would not put out enough amperage to actually make a difference
Why not just quit the playing around and get a 100ah 24v lifepo4 I have 2 of them in my antique electric car. It runs 24v and 48v at higher speeds. They are not that expensive and you will be much happier. If not then the wattcycle 12v 100ah are available thru Amazon for 150 and the ones with Bluetooth are 199.
@@solosailingboatlife7203 They were a little more expensive at the time that I didn’t wanna spend the money ,,better yet I didn’t have the money. My lead acid batteries completely died on me and this battery was on sale so I bought one to play around with it to see if I liked it or what the benefit was of having a single battery. It worked so great I bought another one figuring I would run them in series Like I did my lead acid batteries. Coming to find out this has been problematic for me so I was hoping I could use these two batteries that I have and make it work and then at some point in my life when I make money and not be a loser, I can buy a decent 24 V battery.
@@kussemeinkont I do agree with you. I bought a 24 V power inverter about two years ago thinking it would be more efficient, but the batteries have been quite the challenge running anything in series whether it be lead acid or these lithium ones.
@@kussemeinkont It uses half the current over 12 v. On a 12 v system,, for every one amp your device uses that you plug into your inverter on a 12v system it draws right at 10 amps from your battery. On a 24 v system,, it would only use 5 amps.
I think he had his original charge controler connected improperly but, I agree with the 24 volt battery. I have a 48 and a 24 volt system and buy batteries at those voltages and same amp/hr.
I have been running a 24v system for over two years and never had the problem you are describing. I am using 100 AH Redodo batteries in series and charging with Victron charge controller they stay the same voltage, and I have never had one shutdown for over or under voltage. I feel you may have a bad battery there. I would pull them out of that system, charge them and run capacity test on teach one. I am running 6 batteries in 3 series strings. No issues at all.
For what it's worth, I had problems with 100AH batteries in parallel that would only discharge 50AH before the inverter would shut down. I was on the verge of returning them when it was suggested that my cables to the 12 volt inverter was too light, despite using the cables that came with the inverter, and all indications were that they were adequate. I replaced them with 2/0 welding cables, then tested each battery individually. They both supplied over 100AH per battery before shutting down. I had previously used lead-acid with the supplied cables & never thought heavier cables would be needed in this case. Apparently the BMS systems like the lower resistance.
I see a few comments about using 24v batteries for a 24v system. While it is preferred, it isn't required, but limit two, meaning, don't use 4 X 12v to make a 48v system, but 2 X 24.
That said, when it comes to the bms's in lithiums, some are not designed for serial connection, for the reason that you discovered. For example, the Victron Super Pack Lithiums, can NOT be series connected(but no limit to the number in parallel), but their Smart Lithium's(max 20 batteries), and the even newer 'NG's'(max 50 batteries), can be series connected.
Another example would be Li-Time Lithiums, which clearly state that they can be configured in up to a 4p4s system(max 16 batteries).
While you can hack your way around your issue, you really should either use 24v batteries, or, choose a brand that allows for(is designed and engineered for) serial connections.
Victron makes a battery balancer specifically designed to prevent this problem, but your solution will work too. Also, make sure that none of your charge controllers are set to "equalize the batteries" so high voltage won't be sent to the batteries for desulphating them. Only needed for lead acid.
You have over-complicated a simple issue, just set to 24v system and set controller to float just below shut off voltage, problem solved.
I am wondering if those 12v packs have a Bluetooth access control screen?? Some of them allow for a setting if you have them in series or parallel to tweak the controllers to compensate for the imbalance.. I have also seen people crack them open and install a stand alone active balancer that has 8 leads for the 8 cells which can pull power from the higher cells and put it in the lower ones.. One day a battery manufacturer might offer a way to do this without cracking open the batteries by having a balance connector available so you could just plug and play with 2-3 or 4 12v batteries..
Looks like you got some decent answers but in summary...
* You need a whole-battery balancer if you connect two LiFePO4 batteries in series. It is far better to get the appropriate native-voltage LiFePO4 battery instead of stringing lesser voltage lithium batteries in series. Far more robust using a native-voltage battery.
* Do not circuit the separate 12V batteries in the 24V series bank to individual devices (except the balancer itself), for any reason. That will take them out of balance and change the ground reference on some of the related devices which can be extremely dangerous if you forget later on while messing with things.
e.g. Those charge controllers really should only be wired to the "24V" bank, not to individual 12.8V batteries. In particular, the ground-reference for one of the charge controllers will be sitting at +12.8V instead of GND relative to the system and if you ever try to connect other comm cables or such to that charger controller, or mess with the solar array outside thinking that the black wire is GND, you might be in for a very nasty shock, smoke, or fire.
* 24V native voltage batteries should not be more expensive or too much more expensive than individual 12V batteries. In terms of capacity, 2 x 50Ah 12.8V batteries = 1 x 50Ah 25.6V battery.
-Matt
@@junkerzn7312
Thank you for the advice. I didn’t consider the issues you mentioned.
I only paid $170 for both batteries combined. The 24v battery was $300. I thought I would take the cheaper way out,, but I guess it’s really not if I have to buy more equipment like balancers. I might just revert back to my 12v setup and save up for the proper battery. Maybe I could take these batteries apart and combine the cells in a 24v configuration with a BMS from amazon.
@@Checkitfirst whole battery balancers are very cheap so definitely start by wiring one up. That should solve 90% of your problems. Though it might take a bunch of cycles for it to rebalance the batteries, it will keep them in balance from that point onward.
The remaining 10% of the problem space is dealing with low-voltage battery disconnects. If you run the system all the way down to the BMS disconnect, then in a series configuration it is possible for one battery to disconnect and prevent the charge controllers from reactivating the bank when the sun comes up the next day.
The usual solution for this case is to ensure that the inverter shuts off on low-voltage before the batteries do. If the batteries disconnect at 10.0Vx2 = 20.0V, then being able to program the inverter to shutoff at, say, 22.0V would prevent the battery BMSs from disconnecting.
That inverter probably isn't programmable in that way, but it's the usual solution. If the inverter has a remote-control relay input you can program a smart relay to tell it to shutdown earlier based on the DC side voltage. If the inverter does not have a remote-control relay input, then you are kinda stuck in that regard.
-Matt
This is the prime reason you buy 24v batteries for a 24v system. In lithium using the wrong voltage batteries has the problem you’re having.
I would stick to 24v batteries and skip the old lead acid mentality
Why the skinny ass wires? You need to charge them independently, then put them back in series. Maybe one of them has a bad BMS? (my self experience). Great looking equipment layout on the wall.
Sounds like they are cheap for a reason, I'm guessing you have one crapped out cell that is killing the whole thing. 40% difference is way too much, see if you can get it replaced under warranty.
I'm in UK.....I'm seeing more and more of these batteries and stacks failures.....
And basically it's down to cell balance,
Alot of them aren't top balancing the cells before manufacturing..
I took me 4weeks to sort a set of cells out... pulled out of a 48v rack......now 6 weeks on getting full capacity.
@@marcobrian1619
What would you think if I took those two batteries apart and reconfigured the cells in them for a 24 V system and bought a BMS to manage it. Would you think that would be better than trying to run two separate batteries. Thinking of building a 24 V battery with the cells I have available to me in these two batteries.
@Checkitfirst you could do that....then just one BMS would monitor the battery.
Or strip the packs you have , top balance all cells together for one battery and then again for other then rebuild it back up.
Both ways will work,
interesting video, however I can't quite see how the two PWM controllers get their "panel inputs" ; to they have their own panel each? Thanks
Did you parell the batteries for a day or 2 before connecting in series? I belive that is the key ( i my opinion). I never had any of my different systems wandering off in different charge level.. 🤔
@@BeeBeorn
Yes, in the beginning, I had them in parallel and I was using my 12 V system. I only had one battery to start with so I was using my 12 V inverter to play around with it when I got my second battery I ran them in parallel to make 100 amp hour system . When I got done playing with it,, I left it on the Solar charger until the batteries quit taking a charge. I ran them in series. After about a month, I noticed one of the batteries was not at the proper charge level as the other one was. Figured it was a balancing issue between the two batteries.
You would be better off with a 24-volt battery the BMS is made inside the work that way. If you do two more of those batteries you have there now you still just need to other small chargers the way you have it you don't need four more. Because it's a series parallel setup. The things in parallel will use the same charger
Man you have a lot of antiques in your system but hey it works they do make balancers for 12 volt batteries in series.
@@offgridwanabe
I didn’t know that. I will look into it. Thank you
@@offgridwanabe
Are these balancers available on Amazon and if so, how do I look them up?
just one thing...balancers have constant draw of power, small but constant and if this system is not used daily charged daily it can deplete battery.
@
It’s used daily and at night. Basically it’s a 24 hour running system.
@@Checkitfirst balancer would be ideal...again not for me as my set up is used off and on. mostly off. only choice will be balancer with on/off switch when not in use.
Maybe you could try charging the batteries in 12 volt parallel. Then use a 12 volt to 24 volt booster with rated Amp.
The 24 V lithium was quite expensive and I figured I could go 24 V this way or I could resort back to a 12 V system if my power inverter went out. It’s just little thoughts like that I was thinking of. I know it’s not a perfectly correct way to do everything, but I was hoping I could make it work.
Have you tried switching the batteries around?
It does look like a battery balancing nightmare 😨
you need a balancer between these two batteries if you put them in series
@
No
@
Someone just commented the same thing. I wasn’t aware that this was an option. I will have to look into it
thats cool but how are your pannels attached to the charge controllers? individual panels each controller?
I believe he is running 3 separate systems, a main 24v and 2x smaller12v which is more complex than a single but ingenious to solve this problem..
@@RomansSeven7 I have 500 W going to the 3215 BN in the center for the 24 V system. I have a separate 300 W system. I’m using for the other two controllers for the balancing.
@@Checkitfirst yes i understand the 24v .its the two 12v on one panel im confused about. so 300w panels connected to the two controllers? or each controller has a 300w panei?
what we want to know is can multiple controllers be connected the the same panel/panels? the two wires from panels connect to two charge controllers.
@
Yes,, you can connect more than one controller to the same panel string.
If you had 10,000 watts of solar,, you could connect 10 1000 watt controllers to the panels to charge a large battery bank. In the beginning,, I had 2 100 watt controllers connected to a 400 watt panel setup. It worked great
@@Checkitfirst ok cool, thank you
i love those harbor freight charge controllers, so hard to find
Are you using separate panels for the additional chargers? are all chargers connected to same panels.
@@HR-rt9nh
The EP ever 24 V charger in the center is connected to a 500 W solar array. The other two chargers are on a separate 300 W solar array.
@@Checkitfirst thats what i figured, another set of panels, and that wont do for me.. it was a thought though. thanks.
Are the HF controllers for lipo4 batteries?
@@tlnelson7598
They supply 14.2 volts. I figure that should be fine. It’s probably not though. It seems to be doing fine
@@Checkitfirst I would be concern about the charge profile for lithium vs lead acid. You have a great idea and I may even steal it for my shed. Please consider changing the controllers. thanks and good luck.
@
I’m not really sure if it matters because I can take a bench power supply and charge lithium batteries with it as long as you’re at the right voltage it doesn’t matter what you use Voltage is voltage the only issue is that it would not put out enough amperage to actually make a difference
Why not just quit the playing around and get a 100ah 24v lifepo4 I have 2 of them in my antique electric car. It runs 24v and 48v at higher speeds. They are not that expensive and you will be much happier.
If not then the wattcycle 12v 100ah are available thru Amazon for 150 and the ones with Bluetooth are 199.
@@solosailingboatlife7203
They were a little more expensive at the time that I didn’t wanna spend the money ,,better yet I didn’t have the money. My lead acid batteries completely died on me and this battery was on sale so I bought one to play around with it to see if I liked it or what the benefit was of having a single battery. It worked so great
I bought another one figuring I would run them in series Like I did my lead acid batteries. Coming to find out this has been problematic for me so I was hoping I could use these two batteries that I have and make it work and then at some point in my life when I make money and not be a loser, I can buy a decent 24 V battery.
batteries work much better in parallel, no advantage to 24v system
@@kussemeinkont
I do agree with you. I bought a 24 V power inverter about two years ago thinking it would be more efficient, but the batteries have been quite the challenge running anything in series whether it be lead acid or these lithium ones.
@@kussemeinkont
It uses half the current over 12 v.
On a 12 v system,, for every one amp your device uses that you plug into your inverter on a 12v system it draws right at 10 amps from your battery. On a 24 v system,, it would only use 5 amps.
Thanks for sharing.
Thank you
Balancer
may not cope with the amps, but good idea
That's why you don't use 2x 12v 😅
Dedicated 24 volt lithium and stop wasting your time
Also use a docent brand 😅
I think he had his original charge controler connected improperly but, I agree with the 24 volt battery. I have a 48 and a 24 volt system and buy batteries at those voltages and same amp/hr.
You get what you pay for.
I love your solution.
get a balancer simple
@@chuksobi593
I didn’t know this was an option. You’re the 3rd person to mention this. I will definitely look into it
Put 4 on 😊
@@petersimms4982
It’s in the works. I have three just waiting on the fourth one.