Electric Scooter Dies Quickly - Power Drain

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koco

10 mW
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Jul 13, 2016
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25
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California
On this 52v electric scooter the key switch LED voltmeter displays 57.4v
After holding the power button on, it turns on but the LCD shows the voltage decreasing rapidly until it shuts down.

It is a Nanrobot D4 dual motor scooter and has 2 different voltmeters...the LCD meter is on the key switch and the other one is on the throttle/mode/odometer/power button.

The battery cell groups measure 4.1v each, all 14 of them. Also, if the BMS was faulty, the LCD voltage would decrease along with the voltage on the LED.

It seems like there is a big power drain within one of the speed controllers (it has 2 controllers and 2 motors)

If any of you have a better idea about this maybe you can chime in. Thanks.
 
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E-HP said:
what voltage is the battery after it shuts down?
Click to expand...

The battery itself is still above 57v when measured with a voltmeter or on the LCD display that is connected directly to the battery. So it doesn't actually drain the entire battery. The LED computer readout drops rapidly down below 30v and it goes blank.
 
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koco said:
E-HP said:
what voltage is the battery after it shuts down?
Click to expand...

The battery itself is still above 57v when measured with a voltmeter or on the LCD display that is connected directly to the battery. So it doesn't actually drain the entire battery. The LED computer readout drops rapidly down below 30v and it goes blank.
Click to expand...

Might be the display. If it were actually draining the battery through a faulty controller, then the controller would be hot, since the power needs to go somewhere, and if not to the motor, then to heat.
 
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E-HP said:
koco said:
E-HP said:
what voltage is the battery after it shuts down?
Click to expand...

The battery itself is still above 57v when measured with a voltmeter or on the LCD display that is connected directly to the battery. So it doesn't actually drain the entire battery. The LED computer readout drops rapidly down below 30v and it goes blank.
Click to expand...

Might be the display. If it were actually draining the battery through a faulty controller, then the controller would be hot, since the power needs to go somewhere, and if not to the motor, then to heat.
Click to expand...

The controllers still function basically; the scooter moves like 15 feet before it shuts down.
 
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koco said:
The controllers still function basically; the scooter moves like 15 feet before it shuts down.
Click to expand...

Odd.
The things I would try are to check the battery connections to the controllers; then try running one controller/motor at a time; if neither work then I'd unhook both, and use a different load to the battery, like a light bulb, and monitor the voltage to see if it has the same behavior.
 
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E-HP said:
koco said:
The controllers still function basically; the scooter moves like 15 feet before it shuts down.
Click to expand...

Odd.
The things I would try are to check the battery connections to the controllers; then try running one controller/motor at a time; if neither work then I'd unhook both, and use a different load to the battery, like a light bulb, and monitor the voltage to see if it has the same behavior.
Click to expand...

I don't really feel like the battery is falling on its face because the LED voltmeter doesn't drop when it shuts down. Load testing the battery is not a bad idea though. If I can figure out how to isolate controllers I will do that; the front and rear ones are different and have a bridge connection wire, so I don't know if its simple.
 
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Check the wiring and connections from the battery to the controllers. A high resistance connection would limit amps but still show full battery voltage when the load is removed.
 
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Hwy89 said:
Check the wiring and connections from the battery to the controllers. A high resistance connection would limit amps but still show full battery voltage when the load is removed.
Click to expand...

The battery connections to the controllers are the same connections that go to the voltmeter on the key switch and therefore are not at fault. If there was a problem there, you would see the voltage drop at both voltmeters, but that is not the case. I feel as though that point has been eliminated as the problem. Thank you for your input.
 
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