Few problems with Electric bike

[RJMcDowell]

Hi there,

I was given an electric bike that needed rebuilding a few weeks ago and thought it would
be a great project for me and my sons but have come accross a few problems.

Im unsure as to what model the bike is (Cant find any stamps/stickers), but it was made by DumarUSA.

Heres a pic of the bike in question (The bikes in several bits though).

Ive knocked up a quick Paint pic of the electrical system.

Both batteries charge up fine and register 12v using a multimeter over the terminals and hold
their charges fine and when Hooked up together they register 24v.

The problem im having is understanding exactly how the electrical bike system is supposed to work.

Im pretty sure that once switched on, the electrical motor should automatically assist as your peddeling?
and the throttle is there if you wish to just use the motor with no peddeling?

The thing is, nothing happens either way.
So out came my trusty multimeter and I tested the feed from controller to motor and it registered 0v with power
switched on, 0v with cycling, 20v with throttle "just on" (and an audible click from controller) 18v with throttle
at Max (I thought it should go higher not less with more throttle?) but nothing span the motor.

Ok I thought, maybe the motor is boorked? so I tested it by bypassing everything and briefly connecting the 24v Battery
setup directly to motor.. It worked really well and powerfully.

The only other idea I came up with is that maybe I needed 3 batterys as theres exactly the right space for a 3rd battery in the housing?
But this would make it 36v and the 24v direct to motor test was fine + the bike has about 4X "24V" stickers on it, that being
said, the LED power indicators on throttle show "low" battery power but multimeter on battery terminals show 12v on each. 24v combined?
I thought it might be the sensors on brakes malfunctioning, but even when disconnected from controller box I had the same.

Ive also stripped the throttle asembly apart and given it a clean = still the same.

Before I go and buy a new controller and/or throttle does anyone have any ideas??

By the way, wheres the best place UK based to get a 24v 500W controller from???

Thanks in Advance

Rich

 

[NRG]

There should be a sensor on the pedal crank if it's supposed to work as a pedelec, look for a plastic disk and some sort of sensor on the bottom crank.

How many wires go to the motor, sound like there's just two meaning it's a brushed motor. Other options would be three or more....

If all connections are good then it's looking like the controller may be defective...

 

[flecc]

Although almost certainly Chinese made, as a USA model it almost certainly won't be pedelec, that only appears there on very few bikes, mainly the couple of Panasonic powered ones they've had there and some Giant models. The fact that you haven't shown a pedelec sensor wired to the controller bears that out.

The most likely causes are usually faulty connections or a failed controller, less likely is a failed Hall sensor in the motor, so start by checking all the connections, paying particular attention to the leads from the motor to the controller. They may be three wires or eight. If it's eight wires, that will be a Hall sensor motor, three thicker leads passing power to the motor and five thinner wires carrying sensor information from the Hall devices.

If its a three wire motor, they usually have to pedalled off the mark to get the motor to run, up to about 3 or 4 mph does the trick. Therefore try this. Either suspend the bike or turn it upside down, then with the throttle held or taped wide open, vigorously spin the wheel in the correct direction by hand and you may find the motror starts running then. Eight wire motors usually run off the mark on throttle alone.
.

 

[Blew it]

Hi Rich

After a little thinking, I believe the batteries are done in!

Fresh off the charger, the batteries should show 25.4 volts or thereabouts ( 2 X 12.7 volts)

You mentioned the voltage read at 20 volts with a whiff of throttle, this is below the low-voltage cut-off of a 24 volt controller, typically 20.5 volts.

When batteries reach the end of life, even though showing 12 volts, it only takes a slight load to cause the voltage to drop dramatically.

The reason the motor ran when connected directly to the batteries is because the controller, and the low voltage protection which is built in to it, was by-passed.

Try powering the system with a couple of car batteries connected in series. If all is well, a couple of new batteries of the correct size should get the bike up and running.

It is possible the machine was originally intended to operate on 36 volts. perhaps this was changed in order to reduce the speed. As the machine is now fitted with a 24 volt controller, then you should not attempt to add a third battery. just run it at 24 volts.

All the best
Bob

 

[RJMcDowell]

I have 2 other mini 12v bikes (purely run on battery) will try taking their batterys out and test using them in tandem.
I did notice that one of ther original batterys did take twice as long to charge than the other so maybe your right.
Will let you know how it goes.