Problem with 36v13ah ebike

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Ian
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Problem with 36v13ah ebike

I'm wondering if anyone with more technical know-how than me can tell from the following info, whether my problem is with battery pack or with controller?

I am Running 36v 13ah nimh pack with new crystalyte 36-48v brush controller 25 amp rated, with watts up meter.
Pack was just returned from batteryspace with an a-ok after I asked them to check it out after a minor fall and one of the cells looked slightly dented.

First 2 miles everything is fine under 1c load, then I hit the first incline and throttled to a sudden load of 18amp - and right after that suffered at least 50% power drop and I had to head back with watts up showing voltage ok but no more than 5 to 7 amps even on full throttle.

I figure the pack did get some damage before and I need to have it checked out again, but wondered if problem might be controller as it was the first time I used it? Or is it not possible for a controller to have these kind of symptom so problem must be batteries? I checked the wiring and controller, all looks fine on the outside.

Thanks
Ian

reikiman
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Re: Problem with 36v13ah ebike

Is this their pack which is based on D cells or F cells? I ask because their D cells are rated at 10A max draw. IIRC their F cells have a higher rating. If you draw current out at a higher rate than their rating you risk damaging the cells.

You can test while in the shop by holding the bike up in the air, operating the throttle, and using the brakes to simulate going uphill or other loads.

Generally controllers either work or they don't work. For example if the components inside get fried they usually let out the magic smoke and no longer do anything. But motors can have stuff inside go wrong that might have this behavior.. do you see a way to open the controller? I recall the crystalyte website had a tutorial on opening the motor.

Ian
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Re: Problem with 36v13ah ebike

thanks reikiman for the comments.

It is the f cell pack with 13ah cells, and I have run it a few months going to 2c with no problem, it is advertised up to 3c or 40amp continuous so 18amp is well within specs.

that does answer my question about the controller, as I wanted to know if it would be a work or don't work deal, so from what you are saying either they work fine or it is fried, which does not tie in with my " semi-working" scenario as is happening here.

I reason from my non-technical point of view that it can't be the motor as the watts up meter is reading what is going on before any power goes to the motor, the motor is indeed performing according to the watts up reading, rather than performing 50% less than what it should be according to the watts up reading, if that makes sense?

unless anyone sees it differently, it seems like it must be a battery problem and possible damage to a cell maybe 2? the pack has 30 of the cells at 1.2v, and the minor accident I had with it previously, seemed to dent at least one. so I am guessing that damage to a cell or two could explain the sudden drop in output. This is what I'm trying to get some clarity on, before going through the process of sending the pack back etc

NickF23
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Re: Problem with 36v13ah ebike

if the voltage is ok and the current is very low at full throttle, then likely either have something wrong with the controller or more likely you have a bad connection somewhere. It could be in one of the cells itself but probably just a connector or bad soldering somewhere. I think batteryspace are famous for there badly connnected packs, though some people have had good results with homemade packs using their cells.

Other than a visual inspection one way to find a bad connection is to run at full throttle for a couple of minutes and search for any hotspots.

Ian
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Re: Problem with 36v13ah ebike

Many thanks for your help Nick- I followed your advice this evening and think I found a faulty connection between throttle and controller, and now it seems to be back to normal after testing in the garage, zipped right up to 20 amps no prob when I applied some resistance to rear wheel and went full throttle! So I will take bike out tomorrow weather permitting to make sure.
got another 9.4v nimh arriving this week so majorly glad to have this sorted!

cerewa
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Re: Problem with 36v13ah ebike

I don't think this sounds like a battery problem.

The only time your battery pack will give reduced amperage output (if everything else works right) is if it also drops in voltage. the only way to get high volts and low amps is for resistance to be high (amps are always equal to volts divided by resistance) meaning your controller or your motor is having a problem.

I think it's possible that something went wrong in your controller so that it is behaving as though the throttle is lower than it really is. Could be its over-aperage protection circuit or something else.

If it's the motor, perhaps one or 2 of the motor phases (brushless system) or brushes (brushed system) is cutting out under high power. This could easily show on the watts up meter as high voltage/ low amperage.

What brand/type of motor and controller do you have?

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