Installing the charging port: E-Bike Blog #19
- Tim Ellsworth
- Aug 5, 2017
- 3 min read
The Charger
I ordered this charger off of Amazon recently as it seemed like the best option from some of my research on Youtube and other sources. It is the aluminum case type with a cooling fan. I originally ordered the LiFePO4 which I didn't realize until it arrived with a large sticker on it saying "LiFePO4". I needed to contact the seller to specify the type of battery chemistry. I talked to the seller and they were very helpful. Aside form the cost of shipping I was able to swap out the charger for the correct one based on the type of battery that I built. They even called me to confirm.
The Battery Connection
When I first installed the battery into the re-purposed ammo box that I got, I used automotive style crimped electrical connections. This made the wiring a little messy and forced me to tape them down to the battery. I realized that I did not have enough room on the side of the box to add in the charger connector which is an XLR style. I needed to add the connector to the lid of the box and split off of the master positive lead to connect the charger. This would have been too much wiring to tape to the battery. I decided to move everything to a terminal strip that would allow me to unscrew the wires when I want to remove the battery. Although the wires would connect to the lid they could all be grouped together in a bundle.
The XLR Connector:
I installed the XLR connection to the lid. I bought this one on Amazon. I used a Dremel with a small drill bit to cut out a hole. For the time being I used #6 wood screws to attach the XLR connector but I plan on switching out to machine style with nuts. The location of the connector is over the BMS area in the box which will allow the most room for the wires attached to the back. Below is a picture of the mounted XLR connector.
The Terminal Strip:
To connect all of the wires together in an organized fashion I decided to use a terminal strip. I wanted to mount the strip to the underside of the lid but there was not enough room. I had to cut a section of the reinforcement ribs out with a razor blade to make room. I then drilled holes for the attachment points and bolted it on with 10-32 screws. I will probably change them out to something smaller later because the large nuts do not allow me to place the terminal cover over the contacts. I then created a 3 prong jumper from the red jumper strip that came with the terminals trip. This allowed me to split the positive lead to the power output and the charger input.
The Wiring:
I found the correct size prong style crimper connections for the terminal strip at Lowes and crimped the positive lead and the charger lead. I needed to extend the charger lead and the positive output lead for them to reach the terminal strip. To do this I just soldered on extensions. I thought that this would be better than crimped connections. I used heat shrink to seal the connections. Below is the result from the inside as well as the outside. Later I covered the terminal strip with Kapton tape to prevent shorting.
The Charger
Below is the correct charger that I received after returning the first one. It is labeled as a Manganese charger. Pin 1 on the XLR connector is positive, pin 2 is nothing and Pin 3 is negative. The initial battery charge when the battery was at its minimum voltage of about 34.5 volts took 3.5 hours. The temperature of the battery increased about 10 degrees Fahrenheit. The BMS temperature increased about 25 degrees Fahrenheit. The charging voltage maxed out at 41.8 volts.