Battery pack build.

[beachcruiserbuild]

Hello, I'm building a battery for an Ebike project. I have minimal experience with electrical engineering and no experience with battery building. I ordered 68 18650 cells from Ebay, from all the research I've done this seems to be the best method(using 18650 cells). The only problem I'm having is finding the correct layout for my cells. I need them to end up as a 48V battery, but I'm not 100% sure on how to do the proper wiring. I plan on soldering a copper wire across the top of each battery pack to link them, but like I said before, I'm not positive on the correct configuration to make everything work properly Does anybody have any advice/tips on battery builds? Maybe a source for more detailed information.... Thank you for the help in advance!

 

[marty]

Look here.
Battery F.A.Q - Compilation of good stuff !
http://endless-sphere.com/forums/viewtopic.php?f=14&t=26621#p384360

Parallel groups first. Series second.

 

[TheBeastie]

Can you provide a URL of your eBay cells?
I want to get an idea of what kind of cells you have bought...

 

[beachcruiserbuild]

http://www.ebay.com/itm/Lot-of-36-18650-Li-ion-battery-cells-laptop-recycled/231605905182?_trksid=p2050601.c100085.m2372&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D32144%26meid%3D497b42aade8341faa3c5b464bf9c795a%26pid%3D100085%26rk%3D3%26rkt%3D4%26sd%3D281608645956%26clkid%3D7334433248660930907&_qi=RTM2067269 That is the Ebay seller. They are Samsung ICR18650-26D cells. Let me know what you think!

 

[dogman dan]

You need about 30 ah of those, to run a wimpy 15 ah controller. Those are not EM3ev's cells.

 

[marty]

Charge every cell. Measure voltage. Discharge and measure capacity and internal resistance.

You only want good cells to build your battery.

RC Charger is a good tool to have.

Read here.
Konion Makita LiMn battery care and feeding by Doctorbass

 

[beachcruiserbuild]

Hey guys, thanks a lot for the advice! As far as the batteries themselves go, I have the option to return them right now as they haven't shipped yet. I'm wondering what the disadvantages of a cell like this is. I got them for what I think is a cheap price, $111 shipped, so I'm not sure whether it would be better to buy different cells to work with or just use those. I'm gonna (try to) make them into a 48V (yet to be determined)AH battery pack.

 

[999zip999]

The battery is the heart of an ebike. Not an after thought. You need a cell made to take up a hill. So cells are just for a flashlight. Big difference. If not suitable start with a proper cell. Or buy a plug and play battery matched to your controller or you will be wasting time and money. Money.

 

[marty]

Power tool batteries usually have a higher C rate then laptop batteries.

 

[beachcruiserbuild]

I'm currently cancelling the order... I should have come here first to see what people who know what their talking about think... I would still like to build my own battery to save some money, but as Ive never done anything close to this I'm wondering if you guys might know some good play and play batteries that would be a better alternative to building one. It has to be 48V and I would like at least 11+AH. Anybody have any recommendations?

 

[Ykick]

Have you seen these? http://endless-sphere.com/forums/viewtopic.php?f=31&t=70812

Stateside, dunno if you are or not...