Battery pack

[sock2828]

I want to make a lead acid battery pack but don't know how to wire it I do have basic soldering skills

[OneEye]

Take (3) 12V batteries and solder them in series:

| +   - | | +  - | | +  - |

myelectric bike is recommending 14ga or 16ga wire for the connections.  Wire the outstanding ends to the + and - of the controller.

I was wrong on the wire gage size, see myelectricbike's comment below

[sock2828]

K thanks thats what I thought but I wasn't sure

[myelectricbike]

Actually the controller uses a 16 AWG equivalent for the power leads to the motor and 12 AWG equivalent for the power supply leads going to the battery. (Go figure!) At 700 watts peak you will also need a fuse that can handle 700 watts at 36 volts, i.e., 20 amps at 36 volts. The difference in wire size to the motor is that power per motor power lead is less per lead     ...can you say that again?

[OneEye]

Thanks for the wire gage correction.  Don't want anyone melting through their battery leads.

-Mike

[myelectricbike]

No problem. I've heard but have not confirmed that some of the original kits used 14 and 12 in the same lead. There are all kinds of tricks used in electronics such as a solder bridge used as an internal fuse or splicing in a higher guage to protect windings in place of an internal fuse. Even if your controller is wired with 10 AWG going to the battery pack the math is what you should rely upon since on that day at the factory they may have simply used up the last spool of 12.

[sock2828]

so wait I need to use fuse

[myelectricbike]

Yep.

[sock2828]

where?

[OneEye]

I think it should be ~30A fuse on the Red (+) lead from battery pack to controller.  The motor is unlikely to be fed much more than ~20 amps (720W) before the controller's protection logic shuts it down.  The controller has self protection built in.  The 30A fuse should give you room to spare, yet still blow before melting down the wires, creating a fire hazard, or harming the battery.

[sock2828]

should I just solder it to the wires directly or is there a socket for it or something


and to be clear I use 12AWG wire for the battery pack?

[Dalecv]

You should use 12AWG or larger wire. If you use connectors they should be sized large enough to handle the current that the wire can handle. Connectors will allow you to disconnect the batteries much easier in the future.

Dale

[sock2828]

I meant the fuse.

[myelectricbike]

I use pigtail fuse holders with the pigtails soldered inline. As an added precaution I do not twist the ends to be soldered together but rather overlay them for about 3/4 of an inch and then slide up the piece of shrinkwrap I did not forget to put on the wire before soldering when I'm done.

[sock2828]

on the instructable that tells you how to put one of these things together he uses a male computer power plug thing does the kit come with this and if so does it come with a female one ?

oh and ime not familiar with the term pigtail in electronics