need advice - two motors, single battery

[fiddyschmitt]

hi,

great forum! this is my first post.

Can i damage a 36v lifep04 battery if I hook a second motor to it? At the moment I only use 30% of the battery for my commute. I would like a second motor for hill climbing ability and I don't mind if I use closer to 80% of the battery.

Is it possible the battery can get damaged by having two motors drawing current? The original motor is 250W and I would like to put a 500W in the front. The bike is an a2b hybrid 26. The rear wheel is controlled by pedelec but the new motor I intend to control with a hand throttle.

Thoughts would be muched appreciated!

thank you

 

[GrayKard]

hi,

great forum! this is my first post.

Can i damage a 36v lifep04 battery if I hook a second motor to it? At the moment I only use 30% of the battery for my commute. I would like a second motor for hill climbing ability and I don't mind if I use closer to 80% of the battery.

Is it possible the battery can get damaged by having two motors drawing current? The original motor is 250W and I would like to put a 500W in the front. The bike is an a2b hybrid 26. The rear wheel is controlled by pedelec but the new motor I intend to control with a hand throttle.

Thoughts would be muched appreciated!

thank you

What you need to know is the "C rating" of your battery. This combined with the amp hours will tell you how many continuous amps you can draw from the pack. If this is less than what the two motors will draw under a continuous load then you are going to stress the pack.

If I was to take a guess I would say that the pack will not have any headroom and will be quite stressed running a second motor. Basing that on the fact that the makers aren't going to supply a pack with a lot higher C rate then the bike needs as built.

Gary

 

[fiddyschmitt]

thanks Gary

 

[dogman dan]

There should be some headroom, but not much. Another 250 w motor might be ok. That's not a large battery, so the best approach would be another battery to power the front motor. Or replace the old battery with one able to pull big amps, like perhaps an A123 pack.

 

[fiddyschmitt]

thanks dogman

 

[GrayKard]

There should be some headroom, but not much. Another 250 w motor might be ok. That's not a large battery, so the best approach would be another battery to power the front motor. Or replace the old battery with one able to pull big amps, like perhaps an A123 pack.

Yeah, a second pack might be the answer. Does that bike have a way to add a second pack? Maybe by stacking them?

Gary

 

[fiddyschmitt]

Yes I think I have two options - the first being to put a similar shaped battery on top of the other. The other is to use a drink bottle shaped battery that fits in the drink bottle attachment.
10ah and 9ah respectively...