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Battery Pack Ideas
#1
Currently looking at battery ideas to build something in the region of 22kwh, 48v 

Currently I'm thinking Aliexpress is one of the better options, but I'm wondering what sort of secondhand EV batteries etc are currently available. Don't mind left field suggestions, just trying to see what I can do to trim a little cost etc.


The project will be in Bulgaria, so looking for European options, or stuff worth the hassle of imports\duties etc..
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#2
You ment 22kWh of capacity?

Start to scout local places and onlineshops that handle 2nd hand cars and see what you can find.

nkon.nl could perhaps be an option as well but then not in same country. I would not do Aliexpress if you want genuine stuff and not have to hassle around.
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#3
(09-13-2020, 03:27 PM)daromer Wrote: You ment 22kWh of capacity?

Start to scout local places and onlineshops that handle 2nd hand cars and see what you can find.

nkon.nl could perhaps be an option as well but then not in same country. I would not do Aliexpress if you want genuine stuff and not have to hassle around.


Yes sorry 22kwh, I've corrected the original post.

There are very few EVs here in BG so the SH market is pretty much non existent, I've had some pretty good CALB cells from Aliexpress in the past, think you just have to have your eyes open, read the reviews, and look at the feedback etc.

I'll look at nkon.nl, thank
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#4
Calb cells are great if you find a reliable source with proper cells that arent 2nd hand Smile
NOTE! My links supplied in this message may be affiliated with Ebay and by clicking on them you agree on the terms.
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 100kWh LiFePo4 | 20kWh 14s 18650 |  66*260W Poly | ABB S3 and S5 Trip breakers
Upcoming: 14S 18650~30kWh
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#5
Progressing this slightly, how easy is it to mix cells of different configurations?? Unless I buy brand new cells, I think it is unlikely to find 22kwh of cells of the same time, so if I say got 5kwh of nissan leaf cells, then later on got 5kwh of bmw i3 cells, etc, their characteristics would obviously be completely different. Naturally each would run on thier own BMS, but what else needs to be done?
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#6
(09-15-2020, 05:36 PM)dragonfly Wrote: Progressing this slightly, how easy is it to mix cells of different configurations?? Unless I buy brand new cells, I think it is unlikely to find 22kwh of cells of the same time, so if I say got 5kwh of nissan leaf cells, then later on got 5kwh of bmw i3 cells, etc, their characteristics would obviously be completely different. Naturally each would run on thier own BMS, but what else needs to be done?
If the types are similar voltage range (like lithium-ion) you can arrange the different types of cells into separate batteries of the same total ah - and then parallel them.   

If you mix fundamentally different types such as 16s LifePo4 and 14s 18650 lithium-ion..   if you put LifePo4 into 1 battery at 16s and 18650 in the other at 14s, with the same ah, you should be able to parallel them if you operate them at a common DOD range with separate BMSs.
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#7
(09-15-2020, 05:41 PM)OffGridInTheCity Wrote:
(09-15-2020, 05:36 PM)dragonfly Wrote: Progressing this slightly, how easy is it to mix cells of different configurations?? Unless I buy brand new cells, I think it is unlikely to find 22kwh of cells of the same time, so if I say got 5kwh of nissan leaf cells, then later on got 5kwh of bmw i3 cells, etc, their characteristics would obviously be completely different. Naturally each would run on thier own BMS, but what else needs to be done?
If the types are similar voltage range (like lithium-ion) you can arrange the different types of cells into separate batteries of the same total ah - and then parallel them.   

If you mix fundamentally different types such as 16s LifePo4 and 14s 18650 lithium-ion..   if you put LifePo4 into 1 battery at 16s and 18650 in the other at 14s, with the same ah, you should be able to parallel them if you operate them at a common DOD range with separate BMSs.

That makes sense, is their anything more complicated than normal in paralleling them? Just make sure your cables are big enough, and the polarity is right?
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#8
(09-15-2020, 06:49 PM)dragonfly Wrote:
(09-15-2020, 05:41 PM)OffGridInTheCity Wrote:
(09-15-2020, 05:36 PM)dragonfly Wrote: Progressing this slightly, how easy is it to mix cells of different configurations?? Unless I buy brand new cells, I think it is unlikely to find 22kwh of cells of the same time, so if I say got 5kwh of nissan leaf cells, then later on got 5kwh of bmw i3 cells, etc, their characteristics would obviously be completely different. Naturally each would run on thier own BMS, but what else needs to be done?
If the types are similar voltage range (like lithium-ion) you can arrange the different types of cells into separate batteries of the same total ah - and then parallel them.   

If you mix fundamentally different types such as 16s LifePo4 and 14s 18650 lithium-ion..   if you put LifePo4 into 1 battery at 16s and 18650 in the other at 14s, with the same ah, you should be able to parallel them if you operate them at a common DOD range with separate BMSs.

That makes sense, is their anything more complicated than normal in paralleling them? Just make sure your cables are big enough, and the polarity is right?
Yes sir,  + to + and - to - is highly recommended Smile
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