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Add different Cells into a 10S2P Pack?

battery
18650

#1

Hi, I have a 10S2P Light weight Pack/Board and i love it! I want to extend the range a bit (Around 15km now). All 20 cells are the same, 18650 Sasung 22P.
I collected over 30 Cells from old laptop batterys and many are still full charged but i have no chance to fully test them because i have no Imax or other Special charger. Just 3 10s Charger…
Do you guys think its the risk worth and just add the best branded into the pack or should i wait and get a Imax?


#2

The concern here is cell balance.

Do the cells discharge safely at the same rates?

Are some cells going to be used more than others/uneven wear leading to increased internal resistance in deader batteries (fire hazard)?

Etc.

Frankly, I wouldn’t. Too unpredictable and requires a lot of LOL (labor of love). You should check the cells ever week or so with a multimeter to be safe.


#3

Hm okay fire hazard does not sound nice :smiley:
I thought about it and i will wait for a charger to check them.


#4

I also think you should do some battery testing, especially if you go without using bms.

I think no bms can be used for new, unused cells. For used cells a lot of things can happen, so bms would be a ‘‘safe net’’ in case something goes a drift. Of course, this is only speculation as I have not had a mixed battery pack and have not done such tests / experiments… it just seems common sense from what to expect from varying aged / used batteries :slight_smile:


#5

Don’t go there Monte, laptop batteries are more likely to be junk than not.
Your pack is made of some of the highest quality cells available.
If you want to add to your pack, best to buy cells that are identical to whats in there now.


#6

@Okami Yeah i have bms for it. I use bms in every of my packs. It just feels more safer. :slight_smile:

@Namasaki But, if i have a chance to test the laptop batteries, and then check the 10S2P battery how good it is, i could only add identical cells. (I hope you get what i mean, english is my second language^^)


#7

contact @barajabali or @chaka. I think we need experts here to tell what exactly happens… what is the worst case scenario?

**The good batteries gets overs discharged?
**The bad (laptop) batteries receives or tries to push way too big current
**For the bad cells thermal runaway happen, they release a little bit of gas and they die…


Open for discussion!


#8

did you say your getting 15 km now if so dont change anything your doing fine ;-)))))
Or add all the new battery’s you’ve got, the bad ones wont give you much, the good ones will do all they can and you will have a great and longer ride.


#9

This is a bad idea and I hope it’s not employed. Unless you test every single cell and then use fuse wires to build the pack for when something goes wrong. You would mitigate risk at least. Ideally you build battery packs with new cells that are of the same lot number.


#10

@smurf nono like i said, i will buy a cell tester before i do that.


#11

Don’t do it. It’s a bad idea. This kind of thing would be a painful process even if you had the right tools. Also do you know what the discharge rate of those batteries are, continuous or max? If you really want to extend your range you are better off buying 10 new Samsung batteries. You can get them at reasonable prices these days.