New to Custom Battery packs.

[Harlequin Hawk]

Hello

I am very new to building a custom battery pack and was hoping for advise. After reading the stickies and posts here i have a general idea of "how to", but still not confident.

So After looking through ebay i came across these batteries 8pcs 18650 3.7V 9800mAh Yellow Li-ion Rechargeable Battery Cell For Torch and wondered if they would be applicable to run a 70amp motor on the E-board i am trying to make. I figured if i bought 2 sets, Serialized each set of 8 than paralleled the 2 sets, id get 29.6v At 19600mah. Is that correct? or did i fub up the math? Considering if i did the math right will it work without issue with the motor?

 

[Peter.bp]

Do you really believe that it is possible to put almost 10Ah into 18650 case???
My advice: forget any Ultrafire cells.

 

[cody196]

I bought those same exact batteries from china, so it took a long time to get to where i live. Then coming to find out that they were piece of shit batteries, the yellow paper-like casing peels off too easily, wired them wrong caused them to heat up severely.

 

[Harlequin Hawk]

So those batteries are fakes? good to know before i buy. Thanks guys!

I will continue to look for cost friendly alternatives, if anyone has suggestions i am open to hear them

 

[Syonyk]

They're not "fake." A "fake" would be a cell claiming to be a Samsung 3500mAh cell, while in fact being recycled garbage.

UltraFire is just comedy at this point. They've figured out that the number they print doesn't have anything to do with reality, so just go big or go home.

Anything claiming to be more than about 3600mAh in an 18650, at this point, without serious external testing, is a lie.

 

[dogman dan]

Agreed, 980 mha more like it, and a very low discharge rate. You did not flub the math, but they sure did. Run Forest,, Run!

 

[amberwolf]

wired them wrong caused them to heat up severely.

Wired wrong? My guess is you were lucky they were just *fire cells...if those crappy cells heated up "severely", then if they'd been good ones you might have had a real fire.


As for any cells that have *fire in the name, they're garbage (probably literally) wrapped with whatever marketing lies they felt like putting on them at the time.

 

[Harlequin Hawk]

Thanks for all the great advise guys!

As i have been reading these forums and checking around the web i have come to the conclusion that "You get what you pay for". I really like Another No Solder/Weld 18650 Build (Updated 03/09/2014) forum post, but that many 18650's is gonna be expensive. I'll probably settle for a cheapish battery from Hobbyking or somthing (if anyone here has any suggestions, by all means =D )so that i can do initial test runs etc on the E-Board and than save up for a better battery pack.

Thanks again everyone!

 

[999zip999]

First where do you live. Second what ampage does the controller use and voltage and motor are you trying to run.

 

[Harlequin Hawk]

999zip999

First where do you live. Second what ampage does the controller use and voltage and motor are you trying to run.

i live in so cal , City of Industry, there are hilly areas and flat areas a good mix.

For a motor I am getting the Turnigy Aerodrive SK3 - 6374-149kv 70 amp Brushless Outrunner Motor. I read that lower KV = higher Torque. so ill use this with a gear ratio of 3:1 for some speed.

I dont have an ESC yet im still looking, ive just read that this sk3 motor has 12 poles, and im in the middle of figuring out what that means, how it effects the ESC and thereby which ESC i should get XD. did i mention this is my first E-board project lol.