[Unlimited2002q]

Hello to All from a new EV back-yarder. I have a Group Herrington Electric Junior Car that does not run. A local battery store tried to sort it but failed. They also failed to return the charger that it had with it. I took the car to Canada Electric Vehicles to check out the problem and they reported back that the only item that checked out was the motors. I think that they are dual wheelchair motors but CANEV thought they might be E-Bike motors.

What I wish to accomplish is to understand the present original system and then find an updated Go-Kart electrics to replace it. I am unable to understand the two electronic boards that it has.Hopefully I can make a simpler car for my Granddaughter to drive.
Here are some pics and random thoughts of what we may have......... thanks for your patience.

System has dual electric motors on fixed rear axle. Band brakes at each side at rear. 2 controllers into a mainboard. A pedal throttle up front into a speed control interface? Batteries are long gone as is the original charger. Was a 3 X12V
system 36V motors? 250 wt controllers X2 and key switch 2 position off/on. 12V power to headlamps and horn. Hand operated lever rear brakes. Car weighs in with out batteries at 90KGs (200 lb) I seem to remember from somewhere that top speed was around 20 kmh (13 mph) but not sure on that. What are those boards doing?

 

[brian_]

Interesting
So those are hub motors (with brakes) with 250 W controllers. Using two separate motors avoids the need for a differential, and the motors look like the big drum brakes of a car of the Bugatti's vintage.

The motors and controllers are e-bike stuff, so one of the e-bike enthusiasts here might recognize the components.

When two separate motors are used to drive left and right wheels, the controllers need some sort of coordination. In the Curtis controllers one operates as a master, getting the accelerator pedal signal and telling the slave controller what to do; the master even looks at the steering angle so it knows how much faster the wheel on the outside should be turning than the one on the inside of the turn. The custom electronics in this case presumably provide some form of coordination of the two controller/motor sets.

In some cases a dedicated 12 V battery is used to provide 12 V for the lights, etc., separate from the batteries for the motors, and I have seen listings of this model of Harrington as having two (not three) batteries. In this case, it does look like all three batteries are likely used to provide 36 V (nominally) to the motors, and the transformer on one of the boards might be part of a 36 V to 12 V converter.

 

[Unlimited2002q]

Thanks Brian, that helps break some of it down. I think that it runs 2 batteries behind the seat and 1 just ahead of the smaller board. I have not looked for any steering sensor stuff but will do. So the board with the controller boxes unifies the running (speed) of the two motors as dictated by the throttle and possibly the steering. I will also look to see where the charger port goes to.

 

[Unlimited2002q]

Well, the throttle goes to the main (rear) board and in fact, the two boards do not seem connected to each other. The wiring going up front looks to be for the horn. I am unable to see about the steering but I am doubtful until I can get under the front end to be sure. The charger port has a 3 wire plug going to the main board with the controllers on it.
Two shots of the throttle, doesn't seem to have a ground but the car is fiberglass.