Help finding the fault, old e-trike

[Gully.Moy]

Hi guys. I just bought an electric tricycle on eBay that has "been sat outside for a while". It was dirt cheap and sold as untested so I wasn't expecting it to go first time. Hoping for some help to get it going
http://i.ebayimg.com/images/g/6~0AAOSwYlRZMC9r/s-l1600.jpg
Charger works and lead acid battery read 37V, so happy with that.
It didn't come with keys (I'm not worried about it having been stolen because the sellers were really genuine, it was purchased for an elderly father two years ago and never used + keys lost), so I shorted out the key switch. Charge indicator lit up so I'm guessing that worked. Key ignition throttle is "Wuxing" brand and identical to this, https://ae01.alicdn.com/kf/HTB1qwQrKpXXXXb2XpXXq6xXFXXXW/Wuxing-Brand-Ignition-Key-Model-48V-36V-24V-Electric-Bicycle-Twist-Throttle-Speed-Handle-Gas-Accelerator.jpg_640x640.jpg
But no wheel movement when throttle is twisted. So I've back probed the three big wires going from the control box to the hub motor. With idle throttle I get ~14 mV on each to battery's negative, then when I turn it it spikes up to something in the V range momentarily then drops straight back to ~20mV and slowly back to ~14mV regardless of whether I keep the throttle on. So for some reason it's not maintaining power.

I thought this could be:
1). Controller fault - inside the controller box looks to have kept dry with no signs of corrosion to metal contacts etc. Model is a YinYun e0207 36V350 although it also says 250/350W. I think my motor is 250W.
2). Motor fault - I've read these brushless DC motors have sensors inside to monitor what's going on. So I guess if something's wrong it's cutting the voltage. This seems most likely and most expensive too replace. Do I have much chance of fixing if I open it?
3). Wiring fault - The three big wires going to the motor travel along the bike frame separately to 5 smaller wire (which I guess are for sensors?). Then at the top of the fork, before entering the hub they're all consolidated into one wire and sealed with heat shrink which is a little loose. Perhaps moisture has ingressed and corroded terminals. Worth cutting it open? Slightly reluctant because I don't know how to reseal it waterproof.
4). Throttle fault. Seems unlikely but could be that the throttle is not maintaining the "Go" signal. Are they just simple potentiometers? It's got three wires coming out. Guess I could test V or R across it whilst on and off. =

So not sure really how to proceed with testing. Does anyone have any suggestions as to how to isolate the problem?

Many thanks

 

[LewTwo]

You are going to need to study how an ebike actual works but I will try to give you the short version. First of al note that there are three large wires going into the motor. There are also probably 5 smaller wires there as well but maybe not. The three wires are "pulsed" to generate a magnetic field that oppose the magnetic field of permanent magnets in Hub shell. There two variations: 1) without sensors and one with hall sensors. If you motor has Hall sensors theh it will have those five smaller wires. These tell the controller when to pulse current to which field in the motor and at what polarity. Without the sensors startup can be tricky as the only thing the motor can do is send out a pulse and hope it is right. Many times these motor are used in bike that require the rider to be moving before the motor kicks in. The throttle outputs a control signal to the controller between 0 and 5 volts (well really more like 4.5).

You might want go back to EBAY and acquire one of these ...

http://www.ebay.com/itm/182361382618

Manual attached: View attachment Ebike Tester Manual.pdf

By the way: That is a geared front hub motor

 

[999zip999]

So you have three 12v batteries all charged to 13.6volts each ?

 

[d8veh]

So you have three 12v batteries all charged to 13.6volts each ?

It's a brushless motor, so you can't test the phase wires like you did and get meaningful results. The first thing to check with everything switched on is that you have 5v between the red and black throttle wires. That shows that the controller is actually working.

 

[Gully.Moy]

Thanks everyone. The tester is £22 unless I wait for it to arrive from China. Not really worth it seeing as controller aren't much and I'm only going to use it once.

Each lead acid battery charged to about 12.5V. I know it's low after charging, but should be enough to power the bike for testing. I don't mind buying new ones once I know the rest is working.

Will try testing the Voltage across the throttle tomorrow, cheers. But it has three wires if I recall. Don't know what that means

 

[Gully.Moy]

Ok so across throttle's red and black wires measures 4.4V so I take it that the controller is functioning on some level, which would be consistent with the voltage spike to the motor when the throttle is twisted.

Across throttle's black and white wire measures ~ 0.8V when throttle is idle, rising to ~3.8 when the throttle is twisted. So I'm taking it that the white wire is the wire the throttle uses to send a Go signal to the controller. The voltage remains ~3.8V for as long as the throttle remains twisted so I'm ruling out throttle from the problem.

Spinning the wheel and trying the throttle didn't work.

I'm thinking it's probably a problem with the motor or its hall sensors. Yes it does have the 5 small wires as well as the 3 big ones. As previously said their conduit joins that of the three big wires just before entering the hub and is sealed with heat shrink. Time to open the hub? Or should I look inside that heat shrink first?

Cheers

 

[LewTwo]

Of the five small wires to the motor you should have two that are power (+5 volts) and ground. The other three are signal wires. Put the VOM meter between a signal wire and ground and spin the wheel. You should get a spike. Do the same for the other two.
Unless something is 'burned up' in the motor I would lay odds on the controller (or a bad connection).

 

[d8veh]

Just to clarify that. Turn the wheel slowly backwards and you should see each of the three hall signal wires switching on and off with 5v (approx).

 

[Gully.Moy]

Hi. Thanks for that. Reading about testing hall sensors last night I came across this test. Thing is my wheel won't turn backwards! I had assumed that the design of the motor wouldn't allow it to turn backwards. But reading about this I now realise that this is a problem. So I'm now thinking that the motor is jammed up in side and only turns forward on the freewheel.

I found this thread https://endless-sphere.com/forums/viewtopic.php?f=2&t=81069&start=0 so thought I'd go through the tests you recommended there. Will post back when I know more.

 

[Gully.Moy]

Front wheel wont turn backwards including when entirely disconnected from controller. So I'm thinking I've got seized internal gears or clutch. Does that sound like a fair assumption?

Now I'm trying to open the hub. It had 4 small bolts around the edge which came out fairly easily, but I don't know what's next. I've seen some videos where you have to unscrew the hub, and some where you have to hit the axle from the other side. Here's what mine looks like:

http://i.imgur.com/jIM3avW.jpg
http://i.imgur.com/d8HNCwH.jpg
http://i.imgur.com/0okH0Uu.jpg

I've given the whole area a decent spray with WD40, then tried giving the axle a bash but not too hard yet. Ten I tried getting a screwdriver wedged in one of the small grooves close to the centre and hitting it with a hammer anticlockwise, but again only cautiously so far. It looks like someone has already been bashing those groves before me, but clockwise interestingly... just trying to get it really tight for me!?

 

[Gully.Moy]

As an update to this, I've concluded that because mine is most likely a geared brushless motor and has those groves, the cover needs to be unscrewed (not axel bashed). I know how aluminium likes to fuse together after time and weather exposure. I have given it some pretty hard whacks with the screwdriver + lump hammer but I'm just messing up the grooves. Guess what I want is a tool like this:
http://www.greenbikekit.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/b/a/bafang-8fun-bldc-hub-motor-openning-wrench.jpg.
But don't know if that one will fit my motor or if anywhere will sell one for mine. This diameter on the inside of the grooves is 40mm, does anyone know what the Bafang one measures?

I'm thinking about just hack sawing it open and then Epoxying it closed after. What do you think? Cheers