Hi I have acquired an older e bike , pedal assist only no throttle, 36v it has brand new lead acid cells a couple of weeks ago. Switch it on, light appears, motor runs, off we go but after a few minutes the light goes out . Turn key off and on again and off we go again ad infinitum . If I turn ignition on and leave it, don't move the bike it still turns off after about 5 minutes. Can anyone advise the way to repair this, is it the controller breaking down in a transistor somewhere? Or something else causing voltage drop.? Can Brushed Motor Controller with pedal and wheel sensors still be bought ? Dont know which way to go so help would be appreciated. Maybe tear it off, add new standard front wheel and use as a standard bike is the best bet. I am not well clued up electrically so words of one syllable would help too. !!
Newbie needs some electrical Tech advice if poss
- Thread starter mikegraham26
- Start date
Hi, Welcome to the Forum, It would be helpful if you could state the make, and model of bike. Did you replace the battery yourself, or were you told that it was new on purchase? The problems you state seem to lead towards a duff battery(s), but could be also other problems but I think the battery would be the first thing to look at.
Its a Classic, no model lisetd on it anywhere. The batteries were purchased new a couple of weeks ago from the local Battery Supplier. HE did run a test on them when he fitted them in the battery holder.
Maybe a picture posted could be helpful. I assume there are three 12v batteries run in series which should give a voltage of around 40v+ if you have can test the voltage output or test the output of the individual batteries which should show over 13v. do you have a electric test meter to test the voltage
D
Deleted member 4366
Guest
The things that normally make a controller shut down are over temperature and under voltage. You should be able to feel the controller getting hot if it's over temperature, and a voltmeter will sort out whether or not you've got a voltage problem.
A short-circuit somewhere could cause both problems, but.if the bike's working for a few minutes. I can't think of a place where it could be. One other possibility is that you have a 48v controller and a 36v battery.
Assuming a 36v controller, you need to measure the voltage of the battery before you start, and then again immediately after the controller switches off. Ideally you want to see it in real-time so that you can see how it changes. This measurement will helpa lot in diagnosing the cause of your problem.
A short-circuit somewhere could cause both problems, but.if the bike's working for a few minutes. I can't think of a place where it could be. One other possibility is that you have a 48v controller and a 36v battery.
Assuming a 36v controller, you need to measure the voltage of the battery before you start, and then again immediately after the controller switches off. Ideally you want to see it in real-time so that you can see how it changes. This measurement will helpa lot in diagnosing the cause of your problem.
Hi thanks for taking the time to try and help. I have checked the battery box with my meter, All three batteries are linked in series and each one is giving out over 12 volts (around 13/14). Cant check the total output as it only goes up to 18 volts , dont want to blow meter up.
Thanks. In reply to d8veh. I have switched it on with my meter checking the output of the batteries. I can only check each one individually, dont have a meter equipped to measure above 20 volts. They all read 13 or 14 volts with ignition light on. When light went off the output from all three was unaltered. The controller did not feel hot although it is still assembled and I haven't taken it to bits to feel the board inside.
D
Deleted member 4366
Guest
You need to borrow a voltmeter or multimeter from somewhere. You need to measure exact voltage of the pack.
Digital LCD Multimeter Voltmeter Ammeter OHM AC DC Circuit Checker Tester Buzzer | eBay
Digital LCD Multimeter Voltmeter Ammeter OHM AC DC Circuit Checker Tester Buzzer | eBay
I got the meter. When connected to the fully charged battery box voltage reads 40v. Switch on ignition current drops gradually over a few mins to 39.6v then remains constant. Ignition light goes off motor switches off. Voltage still shows 39.6v. Switch ignition bakc on voltage still 36v and motor works again and the cycle continues, 6 mins switches off, turn key off and on again and motor works again.
On my bike, if I leave it without moving, it switches off after a few minutes, likewise, if the magnet for the speedo isn't set right so doesn't read, the bike switches off. The bike is designed to do this. Make sure the speedo gets a signal when moving. It might just be something simple like that.
D
Deleted member 4366
Guest
I'm not familiar with your particular bike. The meter shows that the battery is OK, so something must be telling the controller to shut down. I think Jimod's suggestion is good. Is there a speed sensor on the fork/frame and a magnet on one of the wheels?
Yes there is a sensor on teh front fork and a magnet on the front wheel, here is also a sensor on the frame by the pedals and 4 magnets on the inside of the pedal sprocket that holds the chain. Should I test these in some way?
D
Deleted member 4366
Guest
You could try testing them, but check them visually first. The magnet on the wheel needs to pass the sensor towards the bottom and fairly close. Check that it hasn't twisted round sideways on or facing the wrong way. The one on the crank should also be close to the sensor - about 1mm gap is ideal.
The sensor on the forks is a switch. It should have two wires, but could have three. Unplug it from wherever it goes. Use the "beep" on your meter. It should beep when the magnet is right next to the sensor.
The sensor on the crank pulses. you need to test it at its connector while connected and the bike switched on. With your meter on 20v DC, stick your probes up the back of the connector in the black and non-red (probably green) wires . It should step on and off 5v each time a magnet passes the sensor.
Some bikes require that you pedal while using the throttle. Did you try that, or just use throttle only?
The sensor on the forks is a switch. It should have two wires, but could have three. Unplug it from wherever it goes. Use the "beep" on your meter. It should beep when the magnet is right next to the sensor.
The sensor on the crank pulses. you need to test it at its connector while connected and the bike switched on. With your meter on 20v DC, stick your probes up the back of the connector in the black and non-red (probably green) wires . It should step on and off 5v each time a magnet passes the sensor.
Some bikes require that you pedal while using the throttle. Did you try that, or just use throttle only?
He has no throttle so I guess the crank sensor is working as the bike does work temporarily.
Pickup at the forks sounds like a good option. I'm not sure it's a reed switch though so a beep tester might not be much use.
I think I would time this operational period exactly. Then we can rule out intermittent faults. Then just before it's going to turn off you can offer up a large magnet for a moment, which should reset the cut off timer, if one is present.
I don't know much about bikes. D8veh helped me a lot with my parts list. I do know about testing though
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