Troubleshooting: 2016 ZEV S-8500 cuts out

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Buffalo Chip
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Transferring this discussion from "Test Ride of the ZEV Scooters," which became a mash-up of various ZEV topics. (I think ZEV deserves a folder here, like other brands.)

The problem: I'll be riding my ZEV S-8500 in any throttle position, then there's a complete loss of power (motor cuts out) until I zero the throttle for a second and twist again. Since this sometimes coincides with riding over a bump, I searched repeatedly for loose/faulty connections. But it doesn't seem to be a simple power interruption. When the bike is apt to do this, it starts rougher (hesitates a bit) from a stop, and there's a quiet growling or groaning sound, from the hub I think, especially when first accelerating. Other times when it accelerates smoothly and quietly, the cutting-out is rare or absent. I used to think a fresh charge made it run better, but that is no longer true. The scooter comes right off the (new) charger now, rides normally for a block or two, then starts cutting out like crazy, multiple times each block.

I bought the scooter from a guy who had it a year and put 600 miles on it. He reported no such problem, but I can't vouch for his honesty. It has a Cycle Analyst (not with throttle control) and an upgraded ZEV 180 amp controller, the former installed by ZEV and the latter by the owner. The included charger went dead in mid-August and I bought a new one, the latest model, from ZEV. Interesting factoid: The cutting out disappeared completely for over 2 weeks when I started using the new charger — I thought the problem was solved. Then for no apparent reason it returned. The new charger seems to work as designed, with an (initial) 12 amp bulk charge, then eventually top-balances with a fraction of an amp. The bike's resting voltage after this is about 101.5, but it immediately drops to about 96 as soon as I start to ride, and stays there. The Cycle Analyst shows no sudden voltage drop when it cuts out, and Vmin is in the mid-80s.

Here's what I tried so far without effect:

- Both brake micro-switches and the side-stand switch are disconnected.

- I repeatedly inspected, and shot with aerosol contact cleaner, all cable connections and small wire connectors behind the dashboard and under the seat, plus the 24-pin connector on the controller. All battery and circuit breaker connections are tight.

- I confirmed constant voltage from the key switch to the controller, including when I jiggle wires and bounce the bike up and down.

- With the bike running on the center stand, I was unable to make it cut out by handling/jiggling wires behind the dash or under the seat. Or the key in the key switch.

- On two separate occasions I measured all cell voltages when fully charged, and again after running the batteries down to where the controller stops the motor. Both times the fully charged cells were all close to 3.34. The first time I found two discharged cells with voltages around 2.8 as compared to about 3.1 for the rest. I charged them individually, bottom-balanced the pack, then fully charged as usual. The cutting out still happened. The 2nd time, all discharged cells were between 3.04 and 3.13. I didn't bother to bottom-balance, and just charged as usual. The cutting out was bad as ever.

Darus Zehrbach at ZEV walked me through most of this, and I sincerely thank him for trying to help. However, his simple/brief suggestions often result in hours of frustration for me. For example, it sounds easy to remove the plastic covering from the handlebars to trace the wires from the throttle, kill switch, etc. I twisted and squeezed and pried and swore until I finally started breaking off the plastic tabs on the covers, so I gave up. I also spent many hours several weeks ago removing the top row of batteries, unnecessarily it seems. There's apparently no wiring diagram or service manual, and I'm still fairly new to EVs, so nearly every step means either guessing or emailing Darus, or both. I'm hoping others here recognize these symptoms and can point me in the right direction. In particular, I think the only possible culprits I haven't checked/tested yet are the BMS and controller themselves. (And maybe the Hall sensor?) Are there any tests I can perform with a multimeter on these components? I assume swapping out controllers is expensive, I haven't really checked. Is there a bad ground wire I may have overlooked?

This has been incredibly frustrating, and I don't mind saying I very much regret the purchase. On the other hand, if I ever get it working reliably, this scooter would be just about perfect for my intended use. Thanks for your suggestions and insights.

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MEroller
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

When growling out of the hub motor is heard you must have a faulty contact in the 5- or 6-Pole connector coming from the hub motor. It should dependalbly power the three Hall Effect switches in the stator that tells the controller when to fire up which of the three phases and in which order. If either the Plus 5V or Ground connection is periodically lost you will have a complete motor cutout, and if just one of the three hall switch outputs gets interrupted you get power loss and growling/stuttering in the motor. So either the connector is at fault, or one or some of the wires have had their insulation rubbed through and there may be occasional shorts, or a cable is even broken inside the insulation. The cable comes out the motor axle, together with the three thicker phase cables. Follow that 5 or 6-lead wire until to you find the connector I am talkig about, and take a VERY close look at all that. Maybe you will find your gremlin there...

__________________

My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

LeftieBiker
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

My ZEV turned out to be this kind of nightmare as well, but not with these particular symptoms. Chinese scooter parts are Chinese parts no matter who assembles them. Given the facts above, my thought is that you have a bad controller, because I don't think a bad connector would give those little warning clues in advance of cutting out as yours seems to do. Controllers don't usually do that either, of course, so your best (not easiest, though) option at this point would be to see if you can swap in another controller - after first checking that hall wire connector. Does your bike have the spare set of hall sensor leads?

Buffalo Chip
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

MEroller, I like your idea about the Hall switches, as it explains all the symptoms. The ZEV hub motor has two sets, one is a spare. The leads/connector from the active one look fine, although I still need to inspect the wires more carefully for breaks or shorts, especially as they run under the batteries to the controller.

Soon after buying the scooter, I noticed the spare sensor wires were damaged. The insulation was worn away and several of the wires were broken. I didn't try to repair them, instead I isolated the cut ends with electrical tape so they wouldn't touch each other. I removed the tape for this pic:

IMG_0250.JPG

Tonight I also discovered that this spare is already butt-spliced where it exits the wiring conduit from the motor. It looks neat enough to be from ZEV, not the prior owner:

IMG_0249.JPG

I don't see how the unused/unpowered set of Hall switches could cause any problems, but I thought I'd mention it, just in case. Strange that one connector is spliced like this, though, isn't it? Maybe I'll repair those wires and try running with the spare. I also learned that I can test the Hall switches with a voltmeter, so I'll try that too.

LeftieBiker, thanks for your thoughts. Reading the long threads about your ZEV (and Zero) woes led me to post on this forum in the first place. Obviously, I hope my problem is the Hall sensor signal, not the controller. But I seem to be narrowing down to the few remaining components I've been unable to check/test yet. The controller and BMS are still "black boxes" as far as I'm concerned... I don't really know how they work or how to test them. Blindly swapping out parts isn't my style, but I may be stuck doing that... I'll keep you posted.

Buffalo Chip
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Points: 29
Re: Troubleshooting: 2016 ZEV S-8500 cuts out

Here's a little follow-up. I was suspicious that the wires from the Hall sensor connector to the controller may be pinched under the upper battery box and the frame tube it rests on. This would explain why a bump in the road sometimes makes it cut out. So I re-routed those wires so nothing can pinch or stress them. I also continuity-tested them, but found no breaks... which doesn't mean there aren't any. I then repaired the wires for the spare Hall sensor (see the 1st pic above), and tested that sensor using my multimeter to read dc volts. Checked out ok: the sensor receives constant power via the red and black leads, and each of the 3 outputs (blue, green, yellow) switched on and off as I turned the rear wheel. I took a short test ride, maybe a mile, over bumps and hills that normally make it cut out quickly. While the motor didn't sound perfectly smooth, it was "almost" perfect, and it cut out only once, over a big bump (San Francisco streets are in surprisingly poor shape, with lots of rails and similar).

I consider this a big improvement. It makes me think the Hall sensor or its connection to the controller has been the problem. Maybe it helped to free the wires from under the batteries, or maybe it was my switching to the "spare" sensor. Of course, I've been wrong before: the new charger "fixed" the problem for 2 weeks, then it didn't. My 15 miles or so on Mondays is a much better test, so I'll let you know.

[Edit: 10 hours later] Yep, too optimistic as usual. It cut out 5 or 6 times on my 4 mile ride to work. This is less bad than it's been lately, but still not good. Seemed less related this morning to going over bumps in the road, more when taking off from a stop. Much less likely at constant speed. Anyway, my gut tells me I'm on the right track; I'll dig back into the inputs to the controller when I have a spare hour or two.

LeftieBiker
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

This bike was acquired used, right? I suspect the first owner had similar issues, and tried to repair wires in the same manner you did, eventually switching hall sensor wire sets. If so, that suggests something worse than one bad wire.

Buffalo Chip
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Points: 29
Re: Troubleshooting: 2016 ZEV S-8500 cuts out

Well, Leftie, you may be right.

As I was saying, it cut out 5 or 6 times on the way to work yesterday. Then only once on my afternoon ride of about 4 miles. As usual, I can't explain why it cut out in the morning, but (almost) didn't on a very similar ride only a few hours later. Finally, my 5 mile ride back home in the evening was "the best of times and the worst of times." No cutting out at all for several miles — I was actually enjoying silently zipping along a major city street at 40+ mph, thinking my scooter problems weren't so bad. Then suddenly it started cutting out like crazy, maybe the worst ever. I could hardly go 10 feet before the motor died again. This had nothing to do with bumps in the road, and it seems to me that an open wire would make the bike not function at all, not this "power-up-and-die" thing over and over. I had to use the emergency flashers (handy accessory for this scooter...) and inch home the last couple miles in the bicycle lane.

Once I got it in my garage last night, I put it on the charger. Didn't touch any wiring or even look under the seat. Tonight after work I unplugged it and took a mile ride. It worked without any cutting out. I can't explain how simply charging a bike would remedy a wiring (or Hall sensor) issue. Given that I twice tested the batteries, maybe the problem is the controller after all. I'm running out of alternatives. Should I get online and shop for e-scooter controllers, something I know nothing about? Or buy (another) one from ZEV? The phrase "good money after bad" is ringing in my ears...

LeftieBiker
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

I agree that the behavior isn't that suggestive of a bad wire. The problem is that we still haven't narrowed it down to one component. It could be a bad pack, or a bad controller, or maybe even still bad hall sensors that behave better at the bike's highest voltage than at lower voltages, although I don't see how that would work...

This vaguely reminds me of a seemingly unrelated anecdote: I was about half as old as I am now, and my father had bought a running but rusty Volvo P1800E, just for the good nose on it, which he planned to transplant into his 1800E. I convinced him to instead sell me the car for what he had paid for it, and it was a great running car - until I washed the engine compartment. I knew how to do it safely, but the car just wouldn't restart, and had to be towed from the car wash to the shop of an older, experienced mechanic. Against all odds he found the problem: the ignition primary wire had broken inside the insulation, with no external sign of failure. Talk about a needle in a haystack...

Buffalo Chip
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Points: 29
Re: Troubleshooting: 2016 ZEV S-8500 cuts out

I believe I isolated the problem... to the controller unfortunately. I took it out for about 5 miles today, and as usual it started cutting out during the 2nd half of the trip. When I got home, I put it on the center stand, clamped pliers on the throttle to keep it running (slowly), then wiggled wires and connectors trying to make it cut out.

Wiggling stuff didn't do it, but knocking on the side of the controller did. Pretty reliably, in fact. I was also getting the initial hesitation, like the motor doesn't know whether to go forward or backward.

Here's a video, about a minute and a half, of the rear wheel of my scoot as I slowly twist the throttle. On the 1st attempt, it runs backwards, without my touching the forward/reverse switch, and I cut the throttle. On all other attempts, the motor dies either quickly by itself, or after it spins up and I gently bump the side of the controller with my knee while holding the throttle constant.

ZEV S-8500 motor cutting out

Although Darus advised me not to disassemble the controller, I think my next step is to unscrew the end plate in hope of finding a loose connection inside. However... (1) It's still remotely possible that knocking on the side of the controller is vibrating a wire attached to it, and not the controller itself, and (2) I still don't see how charging the batteries — or letting the bike rest a while, which may be the real issue — can affect this. But it seems to.

[edited to add video]

MEroller
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

Yes, the controller seems to be guessing at every start in which direction to turn the motor, there is too much hesitation and growling - EVERY time! It still could be one of the hall inputs to the controller that is acting up, either at the connector or inside the controller.

__________________

My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

Buffalo Chip
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Points: 29
Re: Troubleshooting: 2016 ZEV S-8500 cuts out

It's not so easy to get into the guts of the controller. Unlike the smaller controllers for e-bicycles shown on YouTube, this one is filled with a hardened glue or resin, to fight vibration I assume. Unscrewing the end caps had no effect. To gain access, I removed the controller from the bike, then removed the 8 small screws on the backplate. Then you see this:

IMG_0253.JPG

There are no visible broken wires, worn insulation, or burned/melted components. If anything's broken it's where I can't see or reach it.

The 3 intact metal sides of the controller are heatsinks and don't seem to come apart. The ends stay stuck even without their 4 screws each, and there are cables or wires running through them. I might be able to pull off the end with the big cables without destroying anything, but I still won't be able to see anything with the glue/resin in there. And if I dig out the resin I'm likely to break something. Unless anyone here has another suggestion, I'll contact ZEV about repairing/replacing the controller.

By the way, I discovered "brushless motor controller testers" for sale on Ebay for about $15, from China. Although they're made for lower voltage controllers, I imagine one could be useful for troubleshooting a problem like this. I might order one myself, just for kicks.

LeftieBiker
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Re: Troubleshooting: 2016 ZEV S-8500 cuts out

Look closely at those capacitors, to check for signs of bulging and/or discoloration. The photo isn't high enough resolution to see from that. Check EVERYTHING you can see for subtle things like browning...

Buffalo Chip
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Points: 29
Re: Troubleshooting: 2016 ZEV S-8500 cuts out

I'm almost afraid to say it, but I may have fixed the problem. In the photo of the controller above, in the middle of the pic there is a small bundle of multicolor wires that terminate in a white connector. Here is an enlargement:

Attachment-1-3.jpeg

You can see that the black (ground?) wire on the left has an exposed solder joint, and the end of the wire sticks into the insulation of the capacitor. I thought (1) it could be a bad solder connection, and (2) the wire could be shorting against the outside of the capacitor. (#2 shouldn't be a problem if the outside of the cap is the ground, but I don't know enough electronics to say.) So yesterday I bent the end of the wire down, away from the capacitor, and re-soldered it. I then took the scooter on a 7 mile ride, and it didn't cut out even once. And today I rode it to work, about 10 miles round-trip. Again not one cut-out. :-)

If this indeed fixed the problem, it explains why it was so hard to diagnose. The cutting out acted like a loose connection, which it was, but it could not be found in the exposed wiring. It's also apparently part of the Hall sensor circuitry, accounting for the motor grinding and hesitating.

If the cutting out is gone, my only remaining complaint with this ZEV S-8500 is the suspension: it's an awfully rough ride over the potholes, transit rails, and asphalt patches here in the city. No wonder things shake loose. And aside from the suspension, that's gotta be rough on a hub motor. But on smooth pavement it's a magic carpet ride...

MEroller
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Points: 842
Re: Troubleshooting: 2016 ZEV S-8500 cuts out

Yes, that could indeed have been your problem's root cause. The magic of Chinese soldering quality...

__________________

My rides:
QvR vR one: a Swiss package of pure understatement - innocent and to some eyes (from some angles) exceedingly ugly looks, but with raw and hardly containable electron power up to real 95 to 100km/h! And a literally rock-hard suspension due to a carrying capacity of twice it's unladen weight... Now converted to more controllable and efficient brushless motor and vector-contoller.

E-Sprit Fury (basis is the Erider Thunder 5000) since May 03, 2011. Highly moded - but now in active retirement

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