How Do You Wire the Batteries in a 24V e-Bike?

[Tim Mc]

I have a Lee Iacocca 24-volt Mini e-Bike that was working until the batteries no longer took a charge.
When I bought new batteries, the fellow at the shop disconnected them from the battery pack without noting the connections.
The first time I tried to reconnect the new batteries I melted a wire. Hence, I am looking for expert guidance. (See attached image.) There is a ganged black wire connector, a blue wire with a fuse, and a ganged red wire connection. (Unsure if the red wires were originally connected.) Greatly appreciate any help!

 

[E-HP]

What wire did you melt?

 

[Tim Mc]

The wire that melted was a black wire that connected to a cylindrical component in the upper left corner of the batter box labeled "4700 micro farad 35V ..." The other end of that black wire was joined to the other two black wires that terminated at the spade connector.

 

[E-HP]

I can't see the red connector you referenced in your first post. Regardless, if you are trying to get 24V from two 12V lead acid batteries, they would need to be connected in series. Based on your description, and what I can see in the pics, the blue fused wire would join the two batteries in series, but connecting one end to the positive (red) terminal of one battery, to the negative (black) terminal of the second battery. Once that is done, then the remaining positive terminal and black terminals will provide 24V. At that point, the positive terminal of the series pack, should be connected to the red wire (that I can't see the connector for), and the black wire to the black connector of the series pack.

It's hard to tell by what you describe how you connected to pack that led to the wire melting, or whether you damaged the capacitor (cylindrical component), in the process. Better pictures of the main black lead and the main red lead would be helpful, as well as a more close up and well lit picture of the capacitor wiring.

Was the fellow at the shop someone who knows about what you were trying to accomplish, or just someone that sells batteries? Also, you shouldn't be doing this blindly. At minimum you should have a cheap volt/multi meter to measure the voltages and diagnose issues. When you connect two batteries in series, it's important to keep them "balanced", so both are at the same charge level, which starts with charging each battery to equal capacity and voltage.

 

[Tim Mc]

Thanks for the quick reply.

The fellow who disconnected everything was just a battery sales guy.
The attached image shows a better view of the red wires that are ganged together to the spade connector.

 

[E-HP]

Thanks for the quick reply.

The fellow who disconnected everything was just a battery sales guy.
The attached image shows a better view of the red wires that are ganged together to the spade connector.

The melting black wire is unusual, unless there was a short. Perhaps when the battery sales guy pulled it apart, he pulled the wire enough to short the leads for the capacitor. It's odd that the cap is in the battery box, unless it's there so suppress electrical noise or something like that.
Assuming that there's no short, and the cap isn't damaged, then you should be able to connect the batteries as I had described, with the red and black spade connectors go to the red and black battery terminals, respectively, from the series connected batteries.

 

[Tim Mc]

I will equalize the charge for both batteries and give it a try.

Thank you!!