2.4 Kwh Lithium Battery pack

[John in Santa Cruz]

Originally Posted by Anthonysherwood

What would you charge me to build one for me phone number 662-380-0655 Tony

you can buy 200AH (2.4KWh) lithium battteries off the shelf that have integral charge controllers, designed to be connected to a lead acid system. for example: https://www.lithiumion-batteries.com...on-battery.php

[gordon2]

Originally Posted by John in Santa Cruz

you can buy 200AH (2.4KWh) lithium battteries off the shelf that have integral charge controllers, designed to be connected to a lead acid system. for example: https://www.lithiumion-batteries.com...on-battery.php

But before you do, you might want to read this recent thread:
http://www.fiberglassrv.com/forums/f...ium-89668.html

[Friz]

How about a battery pack from a wrecked hybrid car? They are probably 100 volts or more and would need an inverter.

[John in Santa Cruz]

a lot of hybrids are NiMH, not LiIon.

2nd gen prius are 200VDC. a tesla is liion, and about 375 volts.

[Sparky0]

Originally Posted by Anthonysherwood

What would you charge me to build one for me phone number 662-380-0655 Tony

The cost was 2,000 for parts, and 2 weeks of evenings for assembly. I don't think you'd want to pay what I'd need to charge. I will however give you a list of parts and guide you through assembly.



Also I don't know that i would want to accept any liability for misuse of a lithium pack of that size. I'd be ruined if something bad happened. Financially and emotionally.


Also I don't think I can get a fully assembled 2.4 KWH lithium pack through customs to the States.



Any help or guidance you need in building your own I would gladly offer.

[John in Santa Cruz]

two of these in parallel, much much simpler, same capacity. should fit in place of dual GC batteries, although will require different wiring because parallel rather than serial...

https://battlebornbatteries.com/shop...cycle-battery/

no fancy li specific charger required, designed to drop into lead-acid environments.

actually one of those, you can use all 100AH, whereas the dual GC battery setup thats 220AH, you can really only use 110AH before you start taking a hit out of the life of the batteries.

[Sparky0]

Originally Posted by John in Santa Cruz

two of these in parallel, much much simpler, same capacity. should fit in place of dual GC batteries, although will require different wiring because parallel rather than serial...

https://battlebornbatteries.com/shop...cycle-battery/

no fancy li specific charger required, designed to drop into lead-acid environments.

actually one of those, you can use all 100AH, whereas the dual GC battery setup thats 220AH, you can really only use 110AH before you start taking a hit out of the life of the batteries.

Those are a good deal, Only a few hundred more than I paid (for two of them) and no inventing or work involved. Just drop in and go. Not a portable pack, but certainly easier to set up on the trailer.

[Defenestrator]

Originally Posted by Friz

How about a battery pack from a wrecked hybrid car? They are probably 100 volts or more and would need an inverter.

You can usually break those down into smaller modules. I've seen a few people use Tesla modules for their RV. The main problem is that the hybrid cars tend to use a more energetic lithium chemistry like NMC or NCA rather than LiFePo4. They're cheaper, smaller, and lighter for the same capacity compared to LiFePo4 batteries, but they have a much more "energetic" failure mode that I wouldn't want very close to the place that I sleep.

[mikhailmol]

Finally someone did it. I've been searching this forum to see if anyone used 18650 batteries for this purpose and couldn't find anyone. All I could find to be as close to this were the guys who used LiFePo4 batteries. I don't want to use those and want to have a battery pack based on 18650. I have exactly the same reasons as the OP and I think they are a much better choice. In addition to that it's possible to source them out either completely free or for a very low price - but they will probably be lower watts batteries as they would be used and would take some time to get them all around the same capacity in the quantities that is needed for such a pack. I get them from used laptop batteries for free. I test them, mark their capacity so that I could get around 200 of them that are relatively the same and then I would build a battery pack out of them. So far I got around 80 batteries, when testing them I find some that are either in very low capacity or are completely dead. I would say that probably about 20-30% of the batteries from those laptop batteries are "no good". The ones that are still good are about 1700-2100 mAh. This is a very doable project and my only expenses would be the case, BMS, battery holders and whatever goes into that pelican case. Sure I won't get the capacity that the brand new 2600 mAh 18650 batteries would give me but if I can get them for free - why not.

[Sparky0]

Originally Posted by mikhailmol

Finally someone did it. I've been searching this forum to see if anyone used 18650 batteries for this purpose and couldn't find anyone. All I could find to be as close to this were the guys who used LiFePo4 batteries. I don't want to use those and want to have a battery pack based on 18650. I have exactly the same reasons as the OP and I think they are a much better choice. In addition to that it's possible to source them out either completely free or for a very low price - but they will probably be lower watts batteries as they would be used and would take some time to get them all around the same capacity in the quantities that is needed for such a pack. I get them from used laptop batteries for free. I test them, mark their capacity so that I could get around 200 of them that are relatively the same and then I would build a battery pack out of them. So far I got around 80 batteries, when testing them I find some that are either in very low capacity or are completely dead. I would say that probably about 20-30% of the batteries from those laptop batteries are "no good". The ones that are still good are about 1700-2100 mAh. This is a very doable project and my only expenses would be the case, BMS, battery holders and whatever goes into that pelican case. Sure I won't get the capacity that the brand new 2600 mAh 18650 batteries would give me but if I can get them for free - why not.

If you followed the same config as mine... 30 parallel and 7 series using 2000mah cells you would still get slightly more than the equivalent of 2 trojan t-105's and come in at 40 lbs.


I used new LG F1L 3350 mah cells, but if you can get free batteries you'd have a fairly cheap lithium pack. the balancer, bms, step down unit and misc was about $700. I had the pelican case just laying around but you can find a nice 510 Protector Pelican for cheap on Kijiji or ebay.


Charge the cells to 4.1v (28.7v total) and the pack should last a good while.


Active balancer: https://www.aliexpress.com/item/3284...aa604c4dHnABsU


Bms 45A: https://www.aliexpress.com/item/3298...aa604c4dHnABsU


Charger: https://www.aliexpress.com/item/3285...aa604c4dHnABsU


Step down to 13.8v: https://www.aliexpress.com/item/3284...aa604c4dHnABsU


Solar charging: https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1


Plug for umbilical to trailer: https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1

[mikhailmol]

Originally Posted by Sparky0

If you followed the same config as mine... 30 parallel and 7 series using 2000mah cells you would still get slightly more than the equivalent of 2 trojan t-105's and come in at 40 lbs.


I used new LG F1L 3350 mah cells, but if you can get free batteries you'd have a fairly cheap lithium pack. the balancer, bms, step down unit and misc was about $700. I had the pelican case just laying around but you can find a nice 510 Protector Pelican for cheap on Kijiji or ebay.


Charge the cells to 4.1v (28.7v total) and the pack should last a good while.


Active balancer: https://www.aliexpress.com/item/3284...aa604c4dHnABsU


Bms 45A: https://www.aliexpress.com/item/3298...aa604c4dHnABsU


Charger: https://www.aliexpress.com/item/3285...aa604c4dHnABsU


Step down to 13.8v: https://www.aliexpress.com/item/3284...aa604c4dHnABsU


Solar charging: https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1


Plug for umbilical to trailer: https://www.amazon.ca/gp/product/B01...?ie=UTF8&psc=1

Thanks so much for the links. I really appreciate that. Is one BMS enough for a whole pack? I have seen some packs where they put in several BMSes, like one per maybe 40 cells. I am new to this so haven't looked much into this yet other than watching some videos and following some groups on facebook, is there an advantage of say putting 7 small BMSes - one for each of your 7 series?

[mikhailmol]

Some more questions I have that maybe you have the answers for:

1) about balancers - it's easy enough to get each cell connected to be balanced when the cells are big like LiPoFe4 cells as there would be much less cells in a pack but when there are 200 of cells are used - I doubt anybody would put 200 balancers. So I assume one balancer would balance series of cells, not each individual cell, is that correct? Also can that possibly cause overcharge of one individual cell in a series when it's the whole series that are being balanced and not each cell?

2) temperature cut off - can you cut off charging when the temperature goes down too much or goes up too much? I looked at the BMS you used and it has a temperature protection as "Needs additional customazation" but doesn't show anything other than that. I didn't see any ports for a temperature sensor or anything else on the BMS to do that. What I would want is to charge only between a min and max temperature and cut off charging if the temperature is above certain temperature and and possibly to turn on a heating pad if the temperature is below certain temperature - is that doable? Is there another BMS that would allow that?

[Sparky0]

Originally Posted by mikhailmol

Some more questions I have that maybe you have the answers for:

1) about balancers - it's easy enough to get each cell connected to be balanced when the cells are big like LiPoFe4 cells as there would be much less cells in a pack but when there are 200 of cells are used - I doubt anybody would put 200 balancers. So I assume one balancer would balance series of cells, not each individual cell, is that correct? Also can that possibly cause overcharge of one individual cell in a series when it's the whole series that are being balanced and not each cell?

2) temperature cut off - can you cut off charging when the temperature goes down too much or goes up too much? I looked at the BMS you used and it has a temperature protection as "Needs additional customazation" but doesn't show anything other than that. I didn't see any ports for a temperature sensor or anything else on the BMS to do that. What I would want is to charge only between a min and max temperature and cut off charging if the temperature is above certain temperature and and possibly to turn on a heating pad if the temperature is below certain temperature - is that doable? Is there another BMS that would allow that?

Balancers: All parallel cells (30) balance with each other. You just need to balance the 7 groups of 30... so 7s balancer. The balancer keeps the 7 packs close to balanced, the bms will cut off charging or discharging if one pack gets higher than 4.2 or lower than 2.8. Balancing will not over charge a cell, as it takes energy from the highest pack and delivers it to the lowest.



Temp Cutoff: I charge with a 25 amp charger, divide that by 30 parallel and it means each cell is charging at .83 amps. The cells don't get noticeably warm. As far as environmental temp cut off.... just don't charge them when temps are below zero. If the pack is portable you can take it inside. There are BMS units that monitor external temps. This one doesn't.

[mikhailmol]

Originally Posted by Sparky0

Balancers: All parallel cells (30) balance with each other. You just need to balance the 7 groups of 30... so 7s balancer. The balancer keeps the 7 packs close to balanced, the bms will cut off charging or discharging if one pack gets higher than 4.2 or lower than 2.8. Balancing will not over charge a cell, as it takes energy from the highest pack and delivers it to the lowest.



Temp Cutoff: I charge with a 25 amp charger, divide that by 30 parallel and it means each cell is charging at .83 amps. The cells don't get noticeably warm. As far as environmental temp cut off.... just don't charge them when temps are below zero. If the pack is portable you can take it inside. There are BMS units that monitor external temps. This one doesn't.

Do you know of any bms or charge controller that would cut off charging and output from the pack if it's out of a set temperature range? I just tried to search for something like that and can't find anything. Would love that kind of a safety feature with multiple probes spread out through the battery pack.

[Sparky0]

Originally Posted by mikhailmol

Do you know of any bms or charge controller that would cut off charging and output from the pack if it's out of a set temperature range? I just tried to search for something like that and can't find anything. Would love that kind of a safety feature with multiple probes spread out through the battery pack.

I haven't been able to find anything. A temp probe with a switch, hooked to a relay that controls input from the charger might work fine.

[Jon Vermilye]

Originally Posted by mikhailmol

Do you know of any bms or charge controller that would cut off charging and output from the pack if it's out of a set temperature range? I just tried to search for something like that and can't find anything. Would love that kind of a safety feature with multiple probes spread out through the battery pack.

They do exist. Battleborn uses both high & low temperature cutoffs in their batteries.

[John in Santa Cruz]

I stumbled onto this power pack...

https://www.aliexpress.com/item/Wate...884143681.html

caveat emptor, I know nothing other than what that page says. way cheaper than any other 100AH LiFePo I've seen.

[Defenestrator]

Originally Posted by John in Santa Cruz

I stumbled onto this power pack...

https://www.aliexpress.com/item/Wate...884143681.html

caveat emptor, I know nothing other than what that page says. way cheaper than any other 100AH LiFePo I've seen.

Half the price and about 30% lighter to boot!

With a bit of poking around, the low price and weight are because it's actually a 60Ah battery (or less... cells may be used rather than new). Doesn't seem to have any short-circuit protection either, which isn't ideal.

I'd definitely steer clear.

[k corbin]

you could get a 3" screw out deck plate. That would give you an opening for a fan that can be sealed up water tight when needed.

[Gompka]

Much easier diy project, still has some diy, but not quite as time/labor intensive.

https://www.youtube.com/watch?v=RAO5qARz6FA&t=72s