Newbie with a broken bike

[pmb6552]

Hi all,

My name is Phil. I'm retired now but I have an electrical work background. I live in Swansea UK and have ridden my home-built e bike around the area for nearly two years.

I built the bike using a neighbours unwanted wreck, three motorbike batteries, a used brushed 180w hub motor bought on ebay and a controller and twist-grip type throttle, again off ebay via Hong Kong. The bike has been great and taken me on all my errands, back and fore to the local yacht club and a 6 mile commute to the place where I worked part time. (also to the pub to avoid the drink/drive laws).

I now have a problem. With the battery fully charged I left home to cycle to the pub. Within 50 yards the motor began to judder and eventually stopped working. The following day I checked the batteries and they were ok. I checked all my connections - ok. I wired the battery directly to the motor - off load - the motor was ok (Isuspected a brush problem).

I emailed the supplier of the controller and throttle for advice and he told me to place a multimeter on the red and black throttle connector wires of the controller. I got 5.7v. Also I am getting 37v on the indicator connector of the controller. I mailed him my results but he has failed to reply.

Can anyone tell me:
1. Are the readings I'm getting correct
2. If not what reading should I be getting on the various controller/throttle wires
3. With limited test equipment how can I test the throttle

Any advice would be gratefully accepted.

Thanks

Phil (pmb6552)

 

[dogman dan]

It could be the brushes, but if it's the controller at least brushed ones are quite low priced. Put the multimeter on the power wires to the motor, and see what you get there. To test the motor, just take one battery, and hook the wires up to the motor, if it's good it will spin, if it doesn't, then most likely you need new brushes.

You might want to check your drunk driving laws, here in the US you can get a dui on a horse, bike, skateboard, etc. Of course cases like that are usually tipped off to cops when the guy starts puking. :lol:

 

[pmb6552]

Hi Dogman, nice pic!

Thanks for the reply. I tried the motor with one 12v battery and it purrs around quite nicely so it's not the motor.

I set everything up again with the motor disconnected and checked my readings on the controller connectors.

37v from the battery. 37v on the indicator connector. 5.7v on the throttle connector. Nothing on the motor connector at any level of throttle. So, operating the throttle does not make the controller send out a voltage to the motor. What sort of signal does the throttle send to the controller? Can it be duplicated, or do I need to use another, reliable throttle?

As you say the items are cheap and a new set would cost around 60 bucks, but I don't want to throw away a perfectly good controller if I don't need to. I just need to know how to test it.

 

[spinningmagnets]

As a motor warms up, some parts expand slightly. Perhaps your motor is telling you the brushes are quite worn and will soon retire from working. If shipping and the Value Added Tax (VAT) wasn't such a big pill to swallow, I'd suggest buying a new motor from TNC (Most parts from China, TNC is in Tennessee).

If you have grown to depend on your bike, keep an eye out for your second bike, and your next battery pack, and your next motor. Peltzers one-horsepower Scott motor was cheaply sourced from an Ebay auction, and the motor came from a retired floor-scrubber. Good to have two of the things you depend on...

Start looking around to see whats available in the UK. Oh, and perhaps pull out the brushes to inspect them, and compare them to pics on the web. Typically, brush replacement kits are quite cheap (roughly the cost of a pint down at the pub)

edit: We were typing at the same time, Phil, glad its not the motor! best of luck...

 

[deardancer3]

Hi all, My name is Phil. I live in Swansea UK and have ridden my home-built e bike around the area for nearly two years.

I built the bike using a neighbours unwanted wreck, three motorbike batteries, a used brushed 180w hub motor bought on ebay and a controller and twist-grip type throttle, again off ebay via Hong Kong. The bike has been great and taken me on all my errands, back and fore to the local yacht club and a 6 mile commute to the place where I worked part time. (also to the pub to avoid the drink/drive laws).

The following day I checked the batteries and they were ok. Any advice would be gratefully accepted.

Thanks Phil (pmb6552)

my thoughts:

Welcome Phil. Actually you have been a member for some time, you just did not know it. Three motorcycle Lead batteries giving two years of serevice will be suspect. How did you test you batteries? these batteries, when going weak, are infamous for looking good under no/light loads., when their internal resistance is causing lower voltage and lower current.
Put some 12v headlights across each one and see if one is going weak. And that charger, what is it?

Most of us would be lucky to get that kind of service from batteries. what size in AH were they? Were these standard batteries to start motorcycles, or were they deep cycles? It might be time to replace them anyway.

d

 

[dogman dan]

I'm just a replace it when broken kinda guy, but others here might know how to repair a controller. And if not now, then I'd think soon, the batteries will be going dead. But at 37v, I doubt it's the controllers low voltage cutoff. But if when tested under load, 24v might be low enough to cause the controller cut off. But hot off the charger you should have more like 40v, so they are not fresh batteries at all.

 

[torker]

Yea check those batts before you worry about the motor. My little sla setup shows 40 v hot off the charger and over 38 volts even after setting awhile. Has the temperature dropped there lately. sla really don't like cold.

 

[Drunkskunk]

37v from the battery. 37v on the indicator connector. 5.7v on the throttle connector.

2 things strike me here about this. 3 lead acid batteries should have a recharged voltage of 40 to 42 volts. 37 volts isn't flat but isn't charged either. it may indicate a bad battery.

Lead Acid Batteries, even when bad, may show normal, or near normal voltage, but then the voltage drops low when under load. The best way to test them is while riding the bike, and measuring the voltage as you go down the road. If the voltage drops low enough, the LVC on the controller might be cutting the power out.

2 Years on Lead Acid batteries is a long life for this sort of thing.

The other thing is the throttle voltage. The output is generaly 5 volts, and since it's the output from a chip, the high voltage can mean a blown chip.

Some controllers are smart enough not to put out voltage to the motor unless the motor is hooked up and functional. a fault with the brushes may mean the controller sees it open and doesn't send power.

 

[torker]

FYI I charged my pack after my last ride a week ago and I just checked voltage before I rode just now and they were still at 39.2 v and only 2 of my batteries are actually fairly new and match. One battery is older and a different brand. So if yours show 37 after a charge that is pretty low.