Nice job sir ! Im so happy to see the FIRST person on YT smart enough to use Victron! and even beter a MPPT + a Quattro , Now all I can hope for that you used "domestic" panels and not that camper junk.
Personally, I'd have fused each cell to the bank buzz bar - attaching a BMS to each parallel bank will not give individual cell protection - having seen the carnivorous nature of good cells into a damaged cell it all happens very fast
I actually considered that - I think it is a decent idea. The one problem (other than the cost of course) is putting in that many fuses would have introduced more resistance into the system. I also considered that when the battery came out of the leaf - it was not fused in this manner.
EXPANDED METAL ON THOSE BATTERY RACKS WOULD AFFORD MUCH MORE COOLING THAN THAT WOOD, AND EXPANDED METAL WONT CATCH FIRE IF THERE IS A PROBLEM WITH THE BATTERIES.
Expanded metal would have probably been a better choice. We have an air conditioner in that bay dedicated to cooling off the batteries, inverter, charge controller. We also have a BMS system that monitors the temperature of the batteries and shuts everything down if they exceed 150 degrees F. If there is a problem where the wood catches on fire we have much bigger problems than what these batteries are resting on ... the entire floor of the bus is of plywood.
if I am seeing how you bussed out the bank, You actually did a 7 parallel then then seriesed the 7 banks. And I am trying to understand that you are not going to be using BMS on all cells as should be but just on your larger groups. Will that really manage all the modules correctly
I Scott - I did connect the batteries in parallel before I connected them in series. The reason is for the BMS. Parallel batteries (especially Lithium batteries because they have such a low internal resistance) will naturally balance themselves. This essentially makes the first 7 modules (which is actually 14 "cells") behave like one giant cell. The final configuration of the battery is 14p14s. If I had tied them in series first I would have had to buy a BMS for each "battery" (7 in my case). Of course, the advantage of this is that If there was a problem you could (at least in theory) disconnect the offending "battery" and still have the capacity of the other "batteries". The big disadvantage is cost. The BMS I went with (REC-BMS) cost me about $1000 all together. It didn't make economic sense to have $7000 worth of BMS to monitor $2500 worth of batteries. So how did it work out with 7 in parallel first? So far it has worked out really great - the BMS solution I have balances the cells to keep them as close to each other as possible. The voltages are usually within 0.005V of each other regardless of load or state of charge. The question I get quite often is "what if a module goes bad"? Since the BMS I use tracks the voltage and health (internal resistance) of each cell - If a cell was dying what I would notice is that there would be one cell that is always "lagging" behind or reporting "full" too quickly (and thus needing to be discharged). I have a blog post where I go into the BMS and how it functions: beginningfromthismorning.com/bms/
Well almost 3 years later the battery is working fantastic - it easily powers our bus 100% of grid while we finish up the build on some land with no power or water. Battery has been extremely well behaved.
Could you answer a question for me... and just generally: I’ve been contemplating a similar design as yours for a camper. I’ll have the payload for 1000lbs of batteries; could you generally say that I could run a typical 13k btu AC unit for 50-60 hrs continuous run on that battery capacity? I won’t have the solar capacity that you do but plan to charge as I drive with 440amp onboard alternators? I would really appreciate your thoughts, Thank you 👍🏽
Hi Ken, Air conditioners are power hogs - I did some rough "back of the napkin" type math: your 13K BTU A/C if it is a rooftop unit probably pulls about 15 amps @ 120 Volts meaning it uses about 1800 Watts. If you run the A/C Straight for an hour you would use 1800 Watt Hours or 1.8 kWh of power. The battery itself is rated for 24 kWh but assuming 80% capacity (to stay safe) we get 19.2 kWh of usable energy. If we assume 10% efficiency loss through the inverter we arrive at roughly 17.3 kWh after the power is inverted. We arrive at about 9.6 hours. This, of course, assumes a 100% duty cycle - which would never happen - so if we change that to say 50% duty cycle we arrive at 19.2 hours. So if you wanted 60hrs of continuous operation @ 50% duty cycle you would need 3 Nissan Leaf battery modules or about 72 kWh of power. I hope that helps.
I wondered the same thing a while ago and ran the math.... your calculations are pretty close.... I came up with the same numbers, I don't think running an air conditioner from a battery bank is really practical, I will use the A/C from an inverter while traveling as the alternator on the engine is plenty large enough to keep up.... when I got my 120v welder I didn't know you had to change polarity when switching from gas to flux core wire.... I didn't read the instructions.... I'm a guy... :-)
Awesome way to go guys! That bay and the equipment is tighter than I'd thought you be. Alot of cool gear for sure.
Thanks, Cory! Yes, it is a TIGHT fit!
Wow an AC
That's seriously amazing!!
Keep up the good work, sir!
10 thumbs up on the whole series buddy... great job!
Thanks Ken I really appreciate that
You two are a great team !!!
Thank you!
Nice job, but a good tip. Oil the drill when drilling into metal do you will mess up the drill bit. WD40 works great too.
I saw that and immediately thought, that bit is toast.
Dude your wife is a keeper . Mine would have complained the entire time
Nice job sir ! Im so happy to see the FIRST person on YT smart enough to use Victron! and even beter a MPPT + a Quattro , Now all I can hope for that you used "domestic" panels and not that camper junk.
We went a step further and bought some "commercial" panels :) . Thank you for the encouragement and kind words.
I think you can get a bluetooth dongle for that Victron mppt, to monitor your solar cells
The controller we ended up with is the "smart" MPPT controller with the bluetooth dongle built in!
Personally, I'd have fused each cell to the bank buzz bar - attaching a BMS to each parallel bank will not give individual cell protection - having seen the carnivorous nature of good cells into a damaged cell it all happens very fast
I actually considered that - I think it is a decent idea. The one problem (other than the cost of course) is putting in that many fuses would have introduced more resistance into the system. I also considered that when the battery came out of the leaf - it was not fused in this manner.
🎉❤
EXPANDED METAL ON THOSE BATTERY RACKS WOULD AFFORD MUCH MORE COOLING THAN THAT WOOD, AND EXPANDED METAL WONT CATCH FIRE IF THERE IS A PROBLEM WITH THE BATTERIES.
Expanded metal would have probably been a better choice. We have an air conditioner in that bay dedicated to cooling off the batteries, inverter, charge controller. We also have a BMS system that monitors the temperature of the batteries and shuts everything down if they exceed 150 degrees F. If there is a problem where the wood catches on fire we have much bigger problems than what these batteries are resting on ... the entire floor of the bus is of plywood.
if I am seeing how you bussed out the bank, You actually did a 7 parallel then then seriesed the 7 banks. And I am trying to understand that you are not going to be using BMS on all cells as should be but just on your larger groups. Will that really manage all the modules correctly
I Scott - I did connect the batteries in parallel before I connected them in series. The reason is for the BMS. Parallel batteries (especially Lithium batteries because they have such a low internal resistance) will naturally balance themselves. This essentially makes the first 7 modules (which is actually 14 "cells") behave like one giant cell. The final configuration of the battery is 14p14s. If I had tied them in series first I would have had to buy a BMS for each "battery" (7 in my case). Of course, the advantage of this is that If there was a problem you could (at least in theory) disconnect the offending "battery" and still have the capacity of the other "batteries". The big disadvantage is cost. The BMS I went with (REC-BMS) cost me about $1000 all together. It didn't make economic sense to have $7000 worth of BMS to monitor $2500 worth of batteries. So how did it work out with 7 in parallel first? So far it has worked out really great - the BMS solution I have balances the cells to keep them as close to each other as possible. The voltages are usually within 0.005V of each other regardless of load or state of charge. The question I get quite often is "what if a module goes bad"? Since the BMS I use tracks the voltage and health (internal resistance) of each cell - If a cell was dying what I would notice is that there would be one cell that is always "lagging" behind or reporting "full" too quickly (and thus needing to be discharged). I have a blog post where I go into the BMS and how it functions: beginningfromthismorning.com/bms/
Curious if you have a idea what all that weighs? just an estimate fine. 100 lbs 200lbs?
The cage itself does not weigh much - maybe 20lbs. The entire battery weighs just over 400 lbs.
Know update on the bus in a wild
Well almost 3 years later the battery is working fantastic - it easily powers our bus 100% of grid while we finish up the build on some land with no power or water. Battery has been extremely well behaved.
Could you answer a question for me... and just generally:
I’ve been contemplating a similar design as yours for a camper. I’ll have the payload for 1000lbs of batteries; could you generally say that I could run a typical 13k btu AC unit for 50-60 hrs continuous run on that battery capacity? I won’t have the solar capacity that you do but plan to charge as I drive with 440amp onboard alternators?
I would really appreciate your thoughts,
Thank you 👍🏽
Hi Ken, Air conditioners are power hogs - I did some rough "back of the napkin" type math: your 13K BTU A/C if it is a rooftop unit probably pulls about 15 amps @ 120 Volts meaning it uses about 1800 Watts. If you run the A/C Straight for an hour you would use 1800 Watt Hours or 1.8 kWh of power. The battery itself is rated for 24 kWh but assuming 80% capacity (to stay safe) we get 19.2 kWh of usable energy. If we assume 10% efficiency loss through the inverter we arrive at roughly 17.3 kWh after the power is inverted. We arrive at about 9.6 hours. This, of course, assumes a 100% duty cycle - which would never happen - so if we change that to say 50% duty cycle we arrive at 19.2 hours. So if you wanted 60hrs of continuous operation @ 50% duty cycle you would need 3 Nissan Leaf battery modules or about 72 kWh of power. I hope that helps.
I wondered the same thing a while ago and ran the math.... your calculations are pretty close.... I came up with the same numbers, I don't think running an air conditioner from a battery bank is really practical, I will use the A/C from an inverter while traveling as the alternator on the engine is plenty large enough to keep up.... when I got my 120v welder I didn't know you had to change polarity when switching from gas to flux core wire.... I didn't read the instructions.... I'm a guy... :-)
Did you seriously just build a 200 pound battery box?
HAHAHAHA omg
It was more like 40 or 50 lbs :)
Borrow someone engine hoist to install the battery's. ...
Excellent suggestion Harry. The irony is that we have been "downsizing" in preparation to go fulltime and we sold the engine hoist I had!
Lol...always happen .you sell it and u end up needing itq
If you have a Tractor Supply (TSC) near you hardware is sold by the pound. You could have got that bag for like $5.
+j jones we do have one - I have never been in there ... I'll have to check it out
Went to the Tractor Supply - LOVED IT ... thanks for the suggestion
Yes sir! That's what's great about youtube is sharing!
I am not liking the layout so much - I may have a better idea but it ain’t timely😂