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Testing with car battery

Posted: Tue Jan 06, 2015 12:09 pm
by Rodders
Hi, I have acquired a mobility scooter which uses 2 x 12v 34AH batteries, scooter has been standing unused for 4+ years in a shed and the batteries are shot.

I have 2 x 12v 55ah batteries from a car which are fully charged and was wondering if I could test the drive motor of the scooter with these just to see if everything works, this will not be a permanent fix as I intend to buy the proper batteries if the drive motor kicks in to life.

I just don't want to be spending big money on new batteries if the drive motor is also shot.

Re: Testing with car battery

Posted: Tue Jan 06, 2015 4:19 pm
by Grumpy-b
For testing the ah isnt important, just the voltage, and some way of mounting them.


Re: Testing with car battery

Posted: Tue Jan 06, 2015 7:11 pm
by Rodders
Mounting them isn't a problem, they'll just sit on the foot platform with some longer cable to reach the connections, scooter will not be ridden on during the test which should take about 30 sec's max.
The two 12v scooter batteries are connected in series to give 24v at the motor.
The two 12v car batteries will be connected the same way.

I am just concerned that testing with an higher AH would damage the motor.

Edited to say the car batteries are 45ah and not 55ah as stated in my first post.

Re: Testing with car battery

Posted: Tue Jan 06, 2015 7:30 pm
by glyndwr1998
Not sure but I think that it's the motor that defines how much power comes from the battery,
Ie, the motor needs 30 amps to pull the scooter up a hill, it will pull 30 amps, if the battery is too small the battery will overheat and get damaged as its being loaded too much,
Or if the battery is too big ie 55ah the motor still gets its 30 Amps but the battery is now cruising as its not being loaded to much, just over half its capacity......
If that makes any sense.
Use them pal, better than buying new if you already have them to hand.

Re: Testing with car battery

Posted: Wed Jan 07, 2015 4:15 pm
by Rodders
Sorted, connected the two car batteries this morning and the motor ran as it should.

Sourced two used 12v 33ah scooter batteries this afternoon for free, put the meter on them and they both read 11.8v each, connected them to the scooter and whizzed off down to the shops and back for a test run.
Now on charge ready for a 10mile test run tomorrow.
Whoohooo. :D

Re: Testing with car battery

Posted: Mon Oct 19, 2015 8:54 am
by dirk
Using the car batteries to test that the motor works will be ok if you are only using it for a 30 sec test and not riding it.

4 1/2 years for a deep cycled battery or for that matter any battery sitting there without a charge will be shot