Davidericrosenberg said:
while the battery is a 14ah (36v) that can safely charge at 5A.
Do you have a link to the specifications for the battery that show this? Just to be certain that it really is capable and you won't be damaging the cells, wiring, or BMS, causing a future possibility of dangerous failure modes.
The battery connector is a funky configuration that I have never seen before called a Stellar 3 Pin.
I've never seen that one either. A search on that name doesn't find anything like it. An image search might, with a picture from the right angle to match any pics that might exist of one. If you want a spare connector that's your best bet, short of contacting the charger manufacturer directly.
The 3rd pin is probable some sort of data pin for high temp or safety shutdown.
What do you measure with a voltmeter, relative to battery negative, on that pin during charging, at start of charging and various stages during charging?
Anybody have any suggestions for how I can best circumvent the charger and utilize my variable power supply for charging at 5 amps?
You'd need to verify which pin is battery positive, which is battery negative, and either find a matching connector, move the existing one over to your PSU, change the connector on the battery to match what you use on the PSU, or use a likely more dangerous temporary connection method.
If the third pin does measure something on it during charging in the testing done above, you'd need to figure out what that something means, to be able to use it as a safety feature (if that is what it is intended for, and not just an OEM charger interlock).
If it is actually (one or) two way communications and the battery won't charge without receiving the correct data from the charger, you'd have to at least record the data during an actual charge cycle and play it back to the battery as needed to emulate the OEM charger, or reverse engineer the data/protocol, or else replace the BMS with a non-OEM-locked one to allow universal charging.