Looking for Help with a Free Sondors E-Bike

I got this for free from a (now great) friend of mine yesterday as a broken future project. I use "broken" lightly- despite sitting for the last 2 years it still has something of a charge, and the motor still spins up perfectly fine. The 'problem', however, is that the motor doesn't like to stop running, and it lacks any clutch on the pedals- so when you engage the motor the things start mashing your legs.

I was thinking of starting with trying to get some charge readings on a voltimeter, then doing a slow charge for a few hours and rechecking. What else should I do? All the E-bike books I've bought never really went into electricity or teaching it, and I doubt i'm gonna keep the tiny 350w hub motor in the back when Endless Sphere (and THIS THREAD) say to start off with 1000w.

These things use pulse width modulation to control speed. That requires a signal from the throttle. Usually 0-5v if i remember right. Anyways id be curious to see if the signal is coming from the throttle “sticking” or if its something on the PWM board. We had some boards at work that when a component, maybe resistor went bad, the signal ramped up and pump ran away. Cut it off, restart and it would be fine again, until it wasnt. 

Edit: Do you think the throttle is sticking or are you just saying it wont freewheel and coast?

PWM eh? I'll look that up.

I'm not *too* sure if it's even a problem. Per my friend, the reasons he got rid of it were:

1. Bike can only measure charge values in 33% increments.
2. The aforementioned lack of a clutch for the pedals.
3. Motor does not slow despite letting off the throttle. <----What you're talking about.

I'm not certian it's a *problem* to be honest, as his issue with the charge value is really one of lacking software. Pick up the rear end and give it throttle, the rear tire will spin up but continues spinning at it's rate, and it feels like it tried to fight against the brake when you begin to stop.

I don't know about Sondors specifically, but I've never heard of an ebike that doesn't have a standard bicycle freewheel on it.  You should be able to throttle and ride without moving your legs at all.  (If this is what you mean by "clutch on pedals")

If the motor is forcing the pedals to move, the freewheel might be frozen.  They are a very cheap part at any bike shop.  However it can be difficult to remove the old freewheel....