GM battery pack & telemetry options

[Kris]

1) Is there any info floating about on exactly what's included in the GM 48v 10Ah pack? I read somewhere that it has a BMS & precharge resistor inside but when I turn the key to on I hear the same loud 'splat' noise I was hearing when I was testing the internal controller smartpie with lead acids on the bench, so I don't t there is a precharge circuit in there at all?

2) We'd also like to look at putting our scooter on the web in real time. Since there is no data stream out of the controller I was wondering if anybody has any experience with serial output smart meters with an ebike?

[Bikemad]

Hi Kris,

I have never seen (or even heard of) a precharge resistor on any of the GM batteries, although some of the heavy duty controllers incorporate something similar, which allows the capacitors in the controller to become fully charged before the main contactor relay is energised.

For the standard GM batteries, it would seem logical to have a two stage key switch that incorporates a pre-charge resistor, but I haven't yet seen one.

Regarding smart meters, I suggest you take a good look at Grin Technologies Ltd (ebikes.ca) with regard to their Cycle Analyst, which "has a serial output stream that can be used for real-time recording the vehicle statistics to a computer or laptop".

Your scooter looks very smart, but you will have to be very careful not to flip it over backwards when you run the Smart Pie on maximum amps, because with that size wheel, I expect it could happen very easily, especially on a steep incline.

Alan
 

[Kris]

Just ordered ourselves an Analyst BikeMad, thanks for the lead. You're not wrong about the torque from the SmartPie, we've learned to have both feet on the foot plate before engaging the throttle else it rears up like a bronco!

[Kris]

We ran our 48v 10Ah lithium pack till the BMS kicked it off line, the red/green/yellow leds on the thumb throttle never changed. Anybody know what battery pack these are optimised for? Are they driven from the internal controller in the smartpie or is it just a stand alone display with it's own voltage thresholds?

[Bikemad]

Hi Kris,

The battery gauge is independent of the controller and is powered from the battery supply feeding the motor harness.

If your throttle does not have a voltage printed on the casing, it will be a 36V throttle, as the other throttles are marked accordingly with either 24V or 48V in white, as you can see on this thumb throttle:


Check out this post for more details on modifying the gauge to suit the battery voltage.
Unfortunately the power lead that supplies the gauge is not easily accessible on the Smart Pies or MPIIIs because the connectors are all pre molded onto the cables, and the same battery supply lead also feeds the LED lighting switch as well.

If you can find enough room inside the throttle, the resistor would need to go between the lighting switch feed and the battery gauge, but I think it may be a little tight for space.

Alan
 

[Kris]

thankyou again squire. Our throttle is stamped 48v as per your photo but all 3 leds remain determinedly. Academic I guess when the CycleAnalyst arrives, still stuff that doesn't work irks me just the same.

[MAGICPIE3FOCUSPOWER]

I have also the 48V throttle, it's not accurate.
The yellow led will lit, while the pack is still at high voltage.