EZee Torq Cut Out

[Tiberius]

Given the interesting comment, much discussed around here, that the eZee manufacturer cannot understand why any of us should be experiencing cut outs, I decided to investigate. What I was really doing was just to measure what voltages the LEDs indicate but I discovered something about the cut out in the process. It is widely reported on this forum that the Li Ion battery suffers more from cut outs than the NiMH.

I've seen two types of cut outs with mine, with Li Ion battery, one where it self recovers and one where I had to recycle the on off key.

I set the bike up in a lab, running off a variable power supply instead of the Li Ion battery. BTW, the battery was showing orange under heavy load and measured 40.0 V off load.

On the bike, the indicator LEDs change:

(on the way up)​

(on the way down)

Orange to Green at 36.1 V​

Green to Orange at 35.4 V

Red to Orange at 34.0 V​

Orange to Red at 33.1 V

Stops blinking at 34.0 V​

Controller starts blinking at 30.9 V


I could not get a total shut down. What I could get was that if the voltage dropped below Vmin then the motor stops and will not start again until the voltage rises to 34.0 V the point at which the Orange LED comes on.

Vmin is tricky to measure; I would need 3 hands to adjust everything simultaneously but its between 33 and 30 V. Further research is needed with a better test set up.

I suspect what we have been reporting as a cut out is the voltage dropping below Vmin and then not rising to 34.0, so it requires cycling the key to get it going again.

My guess is the manufacturer intended a first level of cut out, that is not particularly troublesome, and only requires recycling the throttle. It may be that in some modes of operation the rider would not even register it as a cut out. The second level is a natural, but not necessarily designed in effect of the controller. So he is quite right in saying that what we're reporting is outside what he expects. But we are quite right in saying that it does happen.

Now, it may also be that the NiMH batteries recover to 34.0 V better than the Li Ion, which could be a reason for the thinking that Li Ion cut out more than NiMH. Although officially, cut outs do not occur with either, what we may be experiencing is that the first level of cut out is successful with the NiMH in stopping the progression to full cut out, but not with Li Ion.

I am assuming that the controller, etc,on the bike is the same whichever battery is used. Ie, only the battery and charge differ.

Nick

 

[flecc]

Thanks for the tests Nick. In fact previous tests have shown that Vmin is almost exactly 32 volts. The controllers do vary, and I've recorded a bit higher than you for the minimum to blink. Equally I've found the upper voltage supply cutoff varies from about 43.3 to 44.7 volts depending on the controller. They are the same for both NiMh and Li-ion, all eZee bikes except the F series being originally designed with NiMh, the Li-ion being an aftermarket item at first.

I've tended to refer to it as cut out since that is what is abruptly experienced and not just the motor stopping though low voltage. While bench tests do have some value usually, on these batteries they are always misleading, hence the dispute between the manufacturer and customers. The test that does always count is the on road experience when the Li-ion cuts out under high load or continuous load.

Did you just test by raising the loading, or did you also test over time with a more moderate loading? In fact the latter is the most common type of cut-off, occurring as the battery chemistry tires, the cathode increasingly fails to deliver, and the voltage drops in consequence. It's here that the battery manufacturer's tests always fail to show the problem most commonly experienced.

However, as I've said before, neither ever occurs with NiMh, nor does the voltage ever get so low that the motor stops running. On Torq or Quando with NiMh, I can drive them heavily loaded up a steep hill until the bike comes to a halt and the motor stalls while humming, without any cut out, first or second. Therefore it's a good enough battery for the job, and any theoretical disadvantages of NiMh are just academic.

In the course of my 18 months in an extremely hilly area with the Torq/T bike, and 16 months with the Quando/Q bike, I've used three Li-ions, all now failed, two at six months, one at ten months, and three NiMh, all still working perfectly in every respect.

I'm sure you'll agree that ultimately that's all that really matters.
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[Ian]

The specifications on the Ezee site state that the low voltage protection operates at 31.5V, more or less in line with that determined experimentally by Flecc. subject of course to tolerances.

 

[Tiberius]

flecc,

Thanks for confirming the controllers are the same. I was testing without the battery. I wanted to see what the LEDs and the controller were doing, so I connected a variable voltage supply in place of the battery. It wouldn't be too difficult to test the batteries but a) I don't have suitable gear to hand and b) it would be better if I had both types available.

3 Li Ion doing the same and 3 NiMH doing the same is a reasonably convincing result. From that one would conclude that either the Li Ion batteries don't perform well or that the controller is not suitable for them.

Nick

 

[flecc]

The controller seems ok Nick, but the battery chemistry just isn't up to continuously supplying current at the rate these powerful eZee motors need. Of course it could be governed down to prevent such high power, but I think the real answer lies in the battery.

I see two possible solutions. One within the present case size by using a hybrid cobalt manganese battery which could deliver at a higher rate while retaining the manganese safety benefits.

The other by using 1" taller non standard cells to increase the cathode size, increasing the battery height by about 2", this being possible within the current eZee bikes.

The problem in both cases is in eZee trying to get that done by a manufacturer for such a comparatively small production requirement, while keeping the cost within bounds. That's a tall order.
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