Can someone suggest how I can get more torque

[wesnewell]

Actually the battery I got replies rated for 25A continuous, 50A peak which seems to be a perfect match for the controller I have which is supposedly 13A/26 max but I'm pretty sure is actually rated for 25A/50 max (1200W and 2400W peak).

If the above is true I'm thinking I'll keep this bike as is and build a better one next time around with higher rated components and a lighter frame.

Any ideas how I can check the true input potential of the controller with a multimeter? I've posted a high res picture of the controller a few replies up.

If your battery is rated for 50A peak, then do a 50% shunt mod to boost max amps to ~40A on the controller. Shouldn't be a problem for the controller. Most controllers never draw max amps. they may get close to it for a few seconds, but will then ramp down quite a bit when speed increases. That will give you a noticeable increase in acceleration.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=31643
As for controller potential, there's no certain way. Each controller is built to certain wattage specs. To understand those, see this.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=74403

 

[Bogus]

Actually the battery I got replies rated for 25A continuous, 50A peak which seems to be a perfect match for the controller I have which is supposedly 13A/26 max but I'm pretty sure is actually rated for 25A/50 max (1200W and 2400W peak).

If the above is true I'm thinking I'll keep this bike as is and build a better one next time around with higher rated components and a lighter frame.

Any ideas how I can check the true input potential of the controller with a multimeter? I've posted a high res picture of the controller a few replies up.

If your battery is rated for 50A peak, then do a 50% shunt mod to boost max amps to ~40A on the controller. Shouldn't be a problem for the controller. Most controllers never draw max amps. they may get close to it for a few seconds, but will then ramp down quite a bit when speed increases. That will give you a noticeable increase in acceleration.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=31643
As for controller potential, there's no certain way. Each controller is built to certain wattage specs. To understand those, see this.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=74403

Thanks Wes, could you give my controller a look and tell me where the shunts are?

http://i.imgur.com/r340t5J/

 

[wesnewell]

I think I see one at the very end of the board hidden by the big caps. There's usually 2 or 3 on a 12 fet controller, but there might only be one. Can't tell from that photo.

 

[d8veh]

Just in case you didn't get it, your battery is probably already a bit marginal regarding power. If you're going to add some solder to the shunt, don't go past 25% of its length starting from one end.

 

[fechter]

I think I see one at the very end of the board hidden by the big caps. There's usually 2 or 3 on a 12 fet controller, but there might only be one. Can't tell from that photo.

+1
It looks like it might be on the end by the caps. It will be connected to the battery negative on one side and the FET rail on the other side.

 

[Bogus]

Just in case you didn't get it, your battery is probably already a bit marginal regarding power. If you're going to add some solder to the shunt, don't go past 25% of its length starting from one end.

So you're saying it's about the distance or does the amount of solder matter more? Can I just wrap copper wire around for a more accurate modification?

 

[fechter]

So you're saying it's about the distance or does the amount of solder matter more? Can I just wrap copper wire around for a more accurate modification?

If the shunt is a single wire, that should work fine, but you still need to solder the copper.
Similarly, you could use a piece of straight copper soldered to the side of the shunt. This would be easier to remove if needed.

 

[Bogus]

OK so I did a 25% shunt mod and definitely felt a kick on my ride today but I think I'd like another

Since the controller is rated at 13A/27A and my battery is rated at 25A/50A it would be safe to go a little closer to a 50% shunt mod right?

 

[fechter]

Yes, but at some point you will let the smoke escape from the FETs.

What is the part number on the FETs?

 

[Bogus]

80NF 70

Also, can I test the current from my battery with this?
http://m.harborfreight.com/5-in-1-digital-multimeter-98674.html?utm_referrer=direct%2Fnot%20provided

 

[fechter]

Those FETs are rated 68 V, 0.0082 Ω, 98 A.
50A might make them get pretty warm. Watch the controller temp.

No, that meter won't be able to measure that much current. It could work in conjunction with a shunt resistor designed for current measurement.

 

[docw009]

I've owned an Extest clamp-on meter for almost 18 years. No need to break the circuit. They clamp on over a wire and measure the current by sensing the magnetic field it produces. Very handy for checking charging systems in my cars, and now I use it on my ebikes.

This is not the same model, as mine could measure down to 100 ma range, but ought to be good for bikes.
http://www.amazon.com/Extech-MA120-Ampere-Current-Detector/dp/B000BEZV5O/ref=sr_1_33?s=industrial&ie=UTF8&qid=1463943573&sr=1-33

And Sears also has one. Claims 3% accuracy. I've seen something like it at the Sears stores for under $40.
http://www.sears.com/craftsman-digital-clamp-on-ammeter/p-03482369000P?prdNo=2&blockNo=2&blockType=G2

When looking for clamp-on ammeters, make sure it can measure DC amps. There are a lot of inexpensive ones good only for AC. Even some of the ads will claim DC current, and you look at the picture and the meter says AC only.