First battery build questions galore

destro23

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Edit: Scroll to bottom for update and more questions.

OK, so i picked up a small box of dell laptop batteries and they are all sony SF US18650GR G7 https://secondlifestorage.com/t-Sony-US18650GR-G7-Cell-SpecificationsUsing liito-kala 500 charger i've tested every cell and have put any low voltage/dead cells or ones that got to hot to the side and won't be used.

I also just received in the mail a diy spot welder from https://malectrics.eu/ and it's working GREAT so far! the test spot welds that i've done have been very good (considering i don't know what i'm doing lol)

i'd like to build a 48v pack. most of the cells rate from 2000 to 2300 mah. My question is what is the discharge amp rate per cell? Am i missing something in the above link?

i'm going to pair this battery with a magic pie v5 . and i've read everything i could i think i'm just missing something on the math side of pack amp discharge rate and magic pie controller math to make a better paired battery.

also what gauge wire for charger, and what gauge wire for power to motor?
what type of wire do you use?
and what connectors are you using? xt60 for charger and xt90's for power to motor?

i bought 2 cheap 48V 35A 13S BMS off ebay (where do you guys trust 48v bms boards from? )

also i'm going to have about 40 cells in the 1000-1500 range(they weren't high capacity to begin with). is it wrong that i think i'd like to make a 13s2p battery for practice? and also hook up a bms as well for practice on spotwelding and bms ?


thanks for any help suggestions on my first battery build would be great

Thanks!
 
I have bought bms from this seller and am happy.

http://s.aliexpress.com/QnMryQvu?fromSns=Copy to Clipboard

I'd say go ahead and make a 13s2p battery but I wouldn't use it on your bike.
Being laptop cells you will need quite a few in parallel as they won't be high drain cells.
I usually don't ask more than 1-2 amp max per laptop cell.
Hope that helps
 
I agree go make a test 2p battery then buy some cells and make 6p battery with good new cells of ebike quality. This battery is pulling you up a hill and not laying flat on a table top.
 
I buy the silicon 1,000 strain 10ga from hobby king or 8ga. If needed. I found IMR in Texas has good prices on cells. I have not used them. There has been a lot of research on high-density versus high discharge cells and you should be able to find. One to fit your needs. I go with a higher power cell vs higher-capacity thinking the higher power cell will have less stress and last longer.
 
I don't use a BMS I just build a good size battery mine is 20 ah with sense wires for checking and balancing. It would be harder to do the smaller the battery gets. I think the magic Pie has a 25 amp to 30 amp controller inside. So build a battery for a 40amp controller as not to stress battery. It does not hurt to have a bms . I did on my first two batteries. But find an extra set of sense for checking with a cellog is quick and ez check of state of charge. Check out Dr angle's threadshttps://endless-sphere.com/forums/viewtopic.php?f=2&t=47924&start=125&hilit=Toolbox+bargains
 
Yes but 5amp cell at 5amp may be warm. Warm ok . Hot no good. Just check with your ambient temperature regulator God given. Your hand. If it's cooking marshmallows it's too hot.
 
P.S. this ambient temperature regulator can also be used for your controller and Motor if you can't touch it stop doing what you're doing. Hills the two chicks on the back rack or ect. Flavor.
P.S. 2 keep your wire short and fat as opposed to skinny and long.
 
battery was finally built and paired with a Golden Motor Black pie v5. Using mostly Sony Laptop cells, I went overboard and went 8p13s for about 17aH i think those cells are 5a discharge. I've been riding the pack around and really haven't measured the true pack capacity yet. Golden motor just released an iPhone app so i'll try and go for a long ride and figure that out after a full charge.

So i have a few questions on my next battery build.

My Black Pie v5 has a 25amp controller for up to 1500 watts of power depending on batter voltage.

If i bought samsung 30Q cells that are 15a discharge what BMS would be best to match the v5?

Basically what are the safe ratios needed for battery / BMS / Controller/hub?
if controller is 25amp then the battery should be _____ amps (30Q 4-5p = 60a/75a) ? then what should BMS be capable of in order to be safe?

thanks! Love this stuff just wish i had more time to do it!

So Samsung 30Q 3000mAh - 15a
Or SanyoNCR 18650GA 3450mAh - 10a
 

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