Need help diagnosing controller

I have a Schwinn Stealth 1000. Everything is stock other than I'm running 12s 10ah Lipo (50.4v max) instead of the factory 36v 12ah SLA's. I ran in this configuration last year with zero issues. Stock 1000w motor did great and top speed was around 20-25mph. I had it down over the winter and ended up replacing one of my lipo packs. This time around when I hooked it all up I added an aftermarket throttle with integrated voltmeter and key switch (ebay special). Now when I run it I'm only seeing about 15mph.

So I'm only seeing 3.4v being supplied from the controller to the throttle which if I understand correctly should be more like 5v. As a result I'm seeing signal wire voltage of .8v at rest, motor begins spinning once I get to 1.1v with throttle and wide open throttle is only 2.6v signal going back to controller. Consequently the maximum voltage I'm seeing at the motor is 36.6v.

So what could be causing this low voltage supply from the controller to the throttle?

Of course in the end I'm open to replacing the factory controller with a high quality one more suitable to my setup but if I go that route what should I look into and do I want a controller designed for 36v or one designed for 48v applications knowing that my safe operating range is between 38v-50v?

Thanks for any help you can give!

Too hard to say from.a distance? Corrosion? It sat around all winter. Did you replace e batteries because of this?

The controller I was going to point you toward appears to be no more. The Currie controller is about as big as you'll find for those brushed mtors, right? But 48v at 1000w or more can be found, it's just we don't necessarily know anything about them.

https://www.monsterscooterparts.com/48vo12unscco.html

I haven't opened up the controller to poke around yet but it was stored in my garage the entire winter so I doubt corrosion is an issue. I replaced one of the lipo packs because I discharged it too low at the end of last season and lost one cell that won't take a charge now.

Disconnect the throttle 5v line from the controller, and see what you get for controller 5v at that point.

If you get 5v (or 4.something) then something is wrong with the throttle itself, loading down the line too much.

If it's voltmeter is powered by the 5v, then it could be that (but usually they're powered only by the battery voltage line).

If you get the low voltage even with throttle 5v line disconnected, then something may be wrong with the controller.

Find all the other places the 5v line goes to (hall sensors, etc) and disconnect from those, too, one at a time, and measure the voltage after each disconnection. if it goes bakc to normal, you've found the loading problem.

Very helpful thanks amberwolf!

Sure enough. Pulled the connector for the throttle and I get 5v on the nose coming out of controller but only 3.4v when its plugged in. Dug in and found some damage to the wiring/insulation on the throttle harness.

Well perhaps I spoke too soon. I swapped the throttle for a brand new one (originally ordered two of them) and I get the same exact scenario. Tomorrow I'll swap the stock throttle back on and see if I get my speed back. Curious . . .

I picked up something called a Brushless Motor & Controller Tester from a site called electricscooterparts.com. It really does take the guess work out of troubleshooting your rig. Pretty cheap, about 20$ and I got it in 4 days. Also, I have used it on a variety of brands and it's worked for each of them.
https://ibb.co/QjkYJV2

https://endless-sphere.com/forums/viewtopic.php?t=47258

https://endless-sphere.com/forums/viewtopic.php?f=31&t=20413

https://endless-sphere.com/forums/download/file.php?id=87595