Hey people, first post! I picked up a broken Eagle HD power wheelchair for a mere $120. It was missing the batteries and had a smashed motor, but that repair is for another post. It seemed like a strong, well designed and high quality machine suitable for rough terrain, so I was willing to spend on repairs. This post shows how I bypassed the unreasonably expensive custom batteries and modified it for standard batteries, after a few false starts. As it was made it was a nice system but the batteries were completely specific to this wheelchair (and the Electra 7):
The original batteries slid inside the gaping holes down into the square frames, it was two of the 24 volt batteries wired in parallel.
I made a battery holder from hardware store aluminum bars hung from below the seat, this allows the wheelchair to be folded up as designed:
I used shrink-tube with internal hot-melt glue for a resilient and grippy wrapper over the smooth aluminum. In this setup I use two of the 12 volt batteries wired in series. NOTE: Not an ideal arrangement unless you have some understanding of lithium batteries. The use of 2 12v batteries gave me more options for use of available space, since the wheelchair needs to fold up, and available 24 volt batteries are larger in every dimension. 12v also allows me to charge them directly from my van's auxiliary 12v system, and also to use the wheelchair batteries for van power in a pinch. I would simply need to change the plug-in wiring adapter shown in the next picture.
Here is how I wired 2 12v batteries in series for 24v using the Anderson Powerpole connectors:
The red 180º bent wire runs diagonally across the four-ganged connector for the series wiring, and likewise the black negative wires goes diagonal. Strangely enough, I found no instructions anywhere on the internet explaining how to do this. The downside is that running this way for several charge/discharge cycles, while charging with a 24v charger, will result in a charge state imbalance. However charging the batteries in parallel at 12v keeps them equalized. A slight inconvenience I am willing to tolerate for the advantage of versatile 12v batteries.
The batteries are two of the 12v Bioenno LiFePO4 battery BLF-1212A size 8.5x2.2x3.1", laid down on the short side. I bought them and the wiring supplies from Powerwerx.com.
I searched the internet but found no information on how to do this mod. I hope this instructional helps someone as these wheelchairs get older and the original batteries get hard to find.