Turning 48v 30ah into 12v 120ah bms? charger? solar

[camperman1000]

Hi everyone,

Hopefully I have posted this in the right section. As the title says I need to convert this battery to 12v output and make it a 12v charge as well. I will use a 200w panel and charge controller. This is the battery https://www.goldenmotor.bike/product/48v30ah-lifepo4-battery-in-a-stainless-steel-case/?currency=CAD.

I opened it up and it appears to be wired as 3s16p. Am I correct in thinking that I need to separate it into 4 separate 3s4p packs then hook those 4 in parallel to get the 12v 120ah ?

So far I think I need 4 separate 12v4s BMS modules one for each pack... and the 12v coming in from the charge controller will be sent to all 4 of them.

If im on the right track here... can someone point me to a decent BMS I should be looking into on fleabay or amazon?

Also, here is the solar panel and controller I am currently thinking of ordering. https://www.amazon.ca/ECO-WORTHY-Mo...00w+panel&qid=1556646885&s=lawn-garden&sr=1-9

Thank you!

 

[eee291]

You only nee one 3S BMS unless you wish to make multiple 3S1P packs. Those 4 Cells are connected in parallel and act as one cell and a total of 3 in series.

Pretty much any eBay BMS would work as you can't rely on them for anything except undercharge protection and some ''meh'' balancing.
Since you don't want to let your Battery suffer by fully dis/charging it every time.
It would be a good idea to only charge them to 4.1V/Cell and discharge them to 3.3V/Cell if you want your pack to live long.
I would also advise against using that charge controller since the min. charge voltage is something like 14V!
A charge controller that works with lithium or is programmable is a must!

Something else to keep in mind is that a lot of cheap BMS's overstate their current so if you want 50A cont. output look for a 100-150A model.

I recently bought this Lifepo4 BMS for 8€ and the over-dis/charge protection features actually work!
It even has a decent balancing accuracy so I can't complain.

If you want to go Cheap: https://www.ebay.ca/sch/i.html?_odkw=3S+bms&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR4.TRC2.A0.H1.X3S+bms+100A.TRS0&_nkw=3S+bms+100A&_sacat=0

Personally I really like these:
https://www.aliexpress.com/item/3S-11-1V-12-6V-80A-60A-40A-20A-Li-ion-Lithium-smart-bms-battery-protection/32960304360.html?spm=2114.search0104.3.27.68d46701rnJ5Dp&ws_ab_test=searchweb0_0,searchweb201602_9_10065_10068_10547_319_317_10548_10696_10084_453_10083_454_10618_10304_10307_10820_10821_537_10302_536_10059_10884_10887_321_322_10103,searchweb201603_52,ppcSwitch_0&algo_expid=beb1a06a-cbae-4c1b-b03e-98931967ab62-4&algo_pvid=beb1a06a-cbae-4c1b-b03e-98931967ab62

 

[999zip999]

This is lfepo4 ? So 4s for 12v. Or 3.6 volts tines 4 = 14.4v. The best best chemistry for 12v sla Exchange.. Put as many as you need in parallel for your needs. Always do more in parallel then needed.

 

[999zip999]

Does the battery really just bolred togethere ? If so ez. But be very careful as there is a lot of stored energy. And when bolting together make sure each cell is of same voltage. How old is the battery and how many ah ?