Cytronex kit works for 2 revs, then cuts out for 10 secs. Pt.2

[Alan Quay]

Finally got a chance to carry out some more tests today, apologies for hanging onto your loan kit Mike for longer than expected.

Dave, with battery at about 36v, I've got 4.3v as the throttle. Throttle signal measures 3.5v when throttle is fully off, dropping to 0.7v at full throttle.

At a signal level below about 3v (approx 1/3 twist) the motor kicks smoothly in either low, medium or high power setting. As before the motor spins for about 1/3 rev before cutting out.
If i keep the throttle more then 1/3 open, the motor kicks repeatedly for 1/3 rev, then cuts out, then cuts in after 1-2secs for another 1/3 rev etc etc.

Battery voltage (measured with a cheap DVM that is showing average voltage and I don't know what the refresh rate is), shows that voltage generally stays above 32v, but occasionally drops below 30v. However DVM reports voltage as being above 32v for most of the time, during which the motor is kicking on/off.

I'm starting to suspect that the battery is weak, and the refresh rate on my DVM is to slow to show this.
Does the SKU65 drop out immediately when voltage hits 30v, or does it have a soft ramp down from say 32v?

I'm going to try to get to kit set up on a test bench at work and either use a scope to measure battery voltage with a suitable high frequency, or try pressing the kit from a bench top power supply.

In the meantime I'll leave the battery on an overnight charge and try again tomorrow.

Does that sound sensible?

Cheers, Adam

This does sound like a battery problem. Why is it only 36v? It should be closer to 42v when fully charged.





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[Slimjim]

When I first picked up the system and charged the ni-mh battery until reported as full, I measured 46v open circuit on the battery, and 50v on the charger.

To say that the motor has only run for the equivalent of one minute since then, it does seem to have plumneted...

I've cracked the battery bottle halves open to have a look if I can measure cell or string voltage, but I'd probably have to do some surgery to get to any cell measurement points.

However, the connector OK there bottle has something like twelve pins, which get commoned in the harness, When I measured all pins back to the 0v pin they were all at same voltage, but then I guess they're probably also all commoned to the same output voltage rail/wiring inside the battery?

 

[Slimjim]

 

[Slimjim]

The locking nut has been glued on the outside, so I'll need to crack that off before I pull the guts out of the top half, intact.

 

[Deleted member 4366]

Dave, with battery at about 36v, I've got 4.3v as the throttle. Throttle signal measures 3.5v when throttle is fully off, dropping to 0.7v at full throttle.

That's working in reverse compared with a normal ebike throttle. Supply should be about 4.5v. Zero thrrottle should be about 1v and full throttle about 4v. IIRC the Powabyke had a reverse throttle.

 

[Slimjim]

That's working in reverse compared with a normal ebike throttle. Supply should be about 4.5v. Zero thrrottle should be about 1v and full throttle about 4v. IIRC the Powabyke had a reverse throttle.

Hmm I'll double check tomorrow night in case i was being dumb and measuring between positive and signal

 

[Alan Quay]

Hmm I'll double check tomorrow night in case i was being dumb and measuring between positive and signal

How far have you got with this?

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[Slimjim]

How far have you got with this?

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Hi Mike, unfortunately not very far since last update - despite having fully charged battery and checking all the wiring, I'm getting no response from the motor at all now. The controller is getting slightly warm so is receiving power, and throttle voltage range is normal.

We're in the middle of packing up the house to move, and work has been too busy to borrow power supplies or test equipment, so I've boxed your kit back up the other day and will post it back this week rather than risk losing anything in the house move later this month.

Apologies for hanging on to the kit for longer than expected, but thanks again for the loan.

I'll find some time to investigate my kit further in a few weeks after we've moved, and let you know what I find.

Cheers, Adam