Instructables: "How to make a lithium battery"

"How to make a lithium battery for an electric bicycle"
http://www.instructables.com/id/How-to-Make-a-Lithium-Battery-for-an-Electric-Bicy/?ALLSTEPS

... by Instructables Member name "mlt34". (Ya here on ES?)


Seems like lots of + [C]omments there. Anything ES can improve/clarify/disprove?

... stuff like "All lithium-ion cells are 3.7V" [cough cough]

is it really that simple? lol

still looks like a good amount of work. any dangers to the usage of a spot welder?

1KW said:

is it really that simple? lol

still looks like a good amount of work.

Click to expand...

It really is just as easy as it looks. The hardest part is trimming balancing wires, cutting the heat shrink for them, arranging then soldering them. It does make it much easier when you use cell holders and dual row nickel strips. You can get the dual row nickel strips for batteries without cell holders too.

Check out my battery build using a homemade spot welder (also see further down the page when I've tidied up my balance wires). If my spot welder had 100% duty cycle I could probably finish a battery build in less than 30 minutes.

1KW said:

any dangers to the usage of a spot welder?

Click to expand...

Not really. The output is only around 2V or so and isolated from the mains. The main danger is a bad connection or slipping while welding the battery which will make some big sparks fly. You can use some safety glasses if you want. The only other thing is you might get a small burn if you touch the weld during or immediately after it's been welded.

Just realized. He didn't mention one crucial item. Gotta have a can/bottle handy.










(To drink lots of coffee, silly. [Burp])

also, wouldnt it be alot simpler to not use a bms and just use a good RC charger? Seems like it would cut down on almost half of the wiring. I grasp the whole concept, except the grouping of cells the way he did it. Im used to parallel then serial.

1KW said:

also, wouldnt it be alot simpler to not use a bms and just use a good RC charger? Seems like it would cut down on almost half of the wiring. I grasp the whole concept, except the grouping of cells the way he did it. Im used to parallel then serial.

Click to expand...

Most RC chargers only support up to 6S (series cells). The BMS will provide undervoltage, overcurrent and short protection. The BMS will allow using a much cheaper charger which also allows you to get a faster one. Most RC chargers are not that fast.

The way the cells are grouped are basically the same as my battery or most other ones. Each group of nickel plates covers six batteries. Three are the positive terminals of one parallel group and the other three are the negative terminals of the next parallel group, in series.