Controller Problem I think?

[whytey33]

Hi all. I am a complete noob 2 electric bikes but I decided 2 get 1 to get me out and about a bit more healthily!! I bought a unworking bike of ebay thinking even with limited electrical knowledge and my love for tinkering I could get it 2 work! I have succeeded by cutting the wires and rerouting them through a controller purchased off ebay. The problem I have is it severely loses power after about a mile. The battery display still says full. I am thinking it may be the wrong controller. It is 24v 350w. The trouble is I have no idea what the battery output voltage or the motor wattage is. Would a 24v controller work on 36v battery? and would a 350w controller work with a 250w motor? I have emailed electricbikes.co.uk for assistance as I believe the bike came from there originally but they were unable to help. It has cambridge electo-motion stickered on it as well as hybrid. That is all the identifying marks as far as I can tell. And advice would be greatly appreciated.

Dave

 

[Blew it]

If we start with the motor. Most 24 volt motors will run at 36 volts. As for the rest of the system, it is essential that you first find out the battery voltage. You will need a multi-meter to do this. These can be purchased reasonably cheaply. Once you have established the battery voltage, it may then be possible to offer further advice and hopefully get the machine up and running.

All the best
Bob

 

[whytey33]

Thanks for the quick reply. Just looked at charger and battery is 24v, I cant believe I never looked there before!! So could the problem be the controller outputting 350w to the motor? which I assume is 250w. Thanx

Dave

 

[Blew it]

Yes, I think that may be case, especially if the battery is on it's way out. Unfortunately, we come back to the need for a multi-meter. The battery when fully charged should show around 27 volts. It sounds as though after one mile the voltage is sagging below the low-voltage protection circuit in the controller, LVC usually occurs at 20.5 volts. If the battery is unable to hold up under load due to it approaching the end of its life, the voltage will sag below the 20.5 volts cut-off.

How to check this: Start your run with a fully charged battery, when the power starts to drop, immediately check the voltage of the battery with your nice new multi-meter. If the voltage has fallen to around 20.5 volts, then it would be safe to assume the battery is failing and needs replacing.

That'll keep you busy for a while.
Have fun
Bob

 

[whytey33]

Excellent thanks for that Bob. Ebay multimeter it is!!

Dave

 

[Jimod]

Excellent thanks for that Bob. Ebay multimeter it is!!

Dave

Why waste time with Ebay. You'll get a multimeter from Screwfix a lot quicker and it will only cost you £10

 

[andrewgardner]

[ Screwfix ]

I thought that was a dating agency.

 

[Blew it]

Excellent thanks for that Bob. Ebay multimeter it is!!

Dave

Dave,

I'm trying to figure out what your machine looks like. Could you post the Ebay auction number as I think it will still show the item even though the auction has ended.

Likewise, could you post the auction number for the replacement controller. This will enable me to post pics and links which may be of use to other members in helping to resolving your problems.

Regards
Bob