controler drawing too much current

[greenleaf]

Our newly acquired hub motor works perfect with a SLA battery pack, but when we hooked it up to a lithium battery pack the controller draws too much current. this blew the factory supplied fuse and every subsequent fuse. Here is a link to the battery specs that we're testing

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=3140
 
As far as we can tell the fuse was never intended to handle this much current and we aren't sure how to make this beast of a battery (40A) play nice and pretend to be a SLA while still getting the most out of this mother of a pack.

[myelectricbike]

Have you tried using a progressively larger fuse or placing a power resistor between the battery and the controller?

[OneEye]

Is it really blowing 40A fuses 

Highest draw reported to date was 30A, with a delivered power to motor of 20A as limited by the controller.

Is it blowing the fuse on hookup, at max speed, full throttle, or as you start to turn the throttle on?  Some other combination of grade/accelleration/speed/throttle position?

The motor should not be drawing 40A over any real period of time.  If it is a fast blow fuse it might be seeing an instant spike, which could be moderated with an in-line inductor and a capacitor.  They can be set up to work together and spread out instantaneous current spikes.  An in-line resistor (as suggested by myelectricbike) can also help limit inrush currents if it is blowing at hookup.

[mustangman]

 What was the amp rating of the factory fuse??

[erdurbin]

I think he is talking about the 15 amp fuse that comes with the kit. I blew this the first time I turned the throttle. I replaced with a 30 amp inline and have not blown one since.

[OneEye]

Hey, if that's the case, throw in a 40A fuse and see what happens.  The point of the fuse is to protect the batteries, not to protect the controller.  The controller has its own protection measures and is supposed to limit current anyway.  If the pack is rated for 40A of current, the fuse should match that rating.

If it's still blowing a 40A fuse, then it's time to investigate further.

[myelectricbike]

Actually the fuse between the battery pack and the controller is intended to protect the conductors both inside and outside of the contoller and battery pack so you want to use a fuse size that will accomodate the longest length/smallest diameter conductors.

[johnbear]

Maybe file a bit off the shunt to decrease the current drawn by the controller. Do you have a watt's up or cycle analyist?

[greenleaf]

thanks Erdurbin and OneEye, you were right , we thought the fuse that came with the kit was a 30a fuse. No wonder it blew a hole right through. ebikes are the sh it.

[Dalecv]

Put at least a 50 amp fuse in, this fuse is primarily to prevent the batteries from damage due to a short circuit. Controllers have internal fuse/thermal protection.

[myelectricbike]

At the factory it seems that you have some people wanting to add things to the kit like both male and female pigtail connector sets, some that come with fuses, who may not be knowledgeable of the electrical requirements and go for the lowest price. If you check the AWG of the wiring you may find that a 15 amp fuse is correct for protecting the particular wiring its comes with and that it is in fact the wiring AWG that is too large.    Its the old saying about good intentions paving the road to Hades, right before our eyes.  You might want to look into replacing the connector set as well. While appropriate for a charging circuit it may not be appropriate for the power circuit.

[mustangman]

On my kit, I kept the end with the fuse just for charging the batteries, then installed a separate one with a large higher amp rated blade type inline fuse with 8 guage wire to the controller with Grote #84-9626 crimp style connectors. These connectors are rated for 50 amps continuious use and can be found at most heavy truck parts dealers. Like Anderson Power Pole connectors, they can only be connected one way and have the + - markings cast in the plastic.

[myelectricbike]

That sounds like a very good replacement setup. Since I'm using 18Ah batteries with screw terminals I've been able to use 8AWG stranded with very think rubber insulated jumper cables and the large European style screw type terminals from Radio Shack. I think I'll give the Grote's a try on the more portable 12 Ah battery powered bike.

[mustangman]

 When I said "large" blade type fuse, I mean really large like an 1-1/2" long! These fuses start at 30 amps and go all the way to 100 amps. In automotive use you would find them right next to the battery under to hood. Their primary duty is to save the wiring harness from fire if a direct short develops and also prevent battery explosion. The inline fuse holder I picked up at the local heavy duty truck (Big Rig, 18 wheeler) supply dealer had 8 gauge wire in which on one side I put a crimp eye connector and on the other end the Grote connector . Also, I might mention that jumpers from battery to battery are 6 guage wire as the ground wire to the grote connector.       ( I had the 6 gauge wire leftover from a high power automotive stereo installation job. (500 watt amp))
    The whole point is that this hub motor draws about 10-20 amps going down the road and can spike up to 40 amps on hills and grades. Replacing that funky electronics power cable with undersized wire with one that can easily handle up to 40 amps will help the performance of the system. To keep the installation looking neat and add an extra layer of protection, I use the split pvc corregated wire wrap to cover all wires. This helps prevent abrasions on the insulation(like when the bike falls over or crashes), therefore reducing the chances of a short and other gremilins.