what batteris are these?

[hoserrb]

so i have a couple battery packs that are used in electric pallet carts. look alot like this one https://globallifttruck.ca/product/powered-plus-pallet-jack-3000lbs-spt3p-m/

label reads 24v 20ah, pretty sure its lithium altho doesnt say that on the label
so i was thinking of using them in an ebike project hooked in series for 48v and wanted to make sure it had a proper bms, took it apart to see.
(bms say a bunch of Chinese and 30A, figure that means max discharge. so thats ok)
i was expecting to find ~50ish 18650 cells hooked together. instead there are 8 of these big cells. measures 26.4v so guessing each is 3.3?
i cant figure out what they are. labels ae Chinese. second pic gives a rough idea of size.
im pretty green at this stuff. any help here?
thanks

 

[amberwolf]

They look like Headway cells. There are a number of versions; you might use whatever info is on the barcode labels to figure out which ones.

Some threads

Search results for query: headway

endless-sphere.com

there's more wihtuot headway in teh title so not in that list.

note that if you series the packs the BMS have to be designed to handle the full voltage of *both packs togehter*, because if one turns off the entire pack voltage will be across it's FETs. If they can't take that they'll fail. Most commonly they fail shorted, or stuck on, so the pack that tried 5to turn off now can't, and you won't know anything has happened, so you'll keep discharging it and it may damage the cells by overdiscahrge, etc.

They may smoke and open circuit, which means all power will cut like it should, but you won't be able to use the pack again utnil the BMS is repalced.

If the BMS do fail and you need to replace one, I'd take the opportunity to replace both with one that is made for the full pack as a hwole instead of two separate ones.

 

[hoserrb]

ok thanks so much for those links, that was a couple hour rabbit-hole and i learned lots and got some more confused too.
my take is that these cells can be finicky to keep balanced and perhaps this isnt the best idea for what im planning, especially if i am tryng to run 2 packs in series with separate bms. so the search for proper battery begins...
thanks again

 

[amberwolf]

depends on what you need the battery to do for you--what job does it have? you'll need to define the job it has to do, how much current, for how long, at what voltage, in order to find a suitable battery.

if this is for an ebike, then you will want to list for yourself all the riding conditions and usage you will have for it, so ou can figure out the worst-case conditions and then determine power usage of the bike from those. that then lets you make sure you get a motor and ocntroller that can handle that, and a battery that can supply all the power those will need. the motor simulator at ebikes.ca is very helpful in doing this.



if it says they are 24v 20ah, then since the biggest headway cells i know of are 10ah, it must be 2p in each pack, and since the headway are lifepo4 they're 3.2v nominal, so 8s to get 24v. so each pack must have 16 cells in it. if they have less cells, they are either lower voltage (less series cells) or lower ah (less parallel cells). i only see 8 cells, so unless there are twice as many cells as are visible in the pictures, they are either only 12v or they are only 10ah.