To solder, or Not to solder (my shunt) Are my battery & controller up to it?

[jackhandy]

If possible, I'd appreciate advice on whether or not I would gain an advantage by soldering the shunt on my controller: I'll try to provide as much relevant information as possible:-

I fitted an 8fun kit, front motor, to my Carrera Kraken mtb about 6 weeks ago:
I use the motor in low assist when on trails with the family, as speeds are low, medium assist when I'm on the road, particularly when trying to keep up a bit & keep high assist for b@ll-breaking hills

I don't need more speed - If I'm doing 15 mph I don't need assistance; my legs'll cope, but I could do with a bit more grunt on those hills, to ensure road speed stays above 8mph as I understand that, below this, I'll waste power as heat.

With the front wheel off the ground:
low = 12mph : med = 15mph : hi = 18mph

When riding, I get useful assistance to:
low = 10mph : med = 12mph : hi = 15 mph

If I solder the shunt, will I get more grunt At these Speeds, or will the speeds increase along with the grunt? (which I don't really need).

Now for the 64,000 dollar question....

Are my battery & controller up to the job?

Controller:
Rated current 7amps
Max. current 14amps

Battery, with panasonic cells:
Continuous current 15amps
Pulse current (10 minutes) 18amps.

I've recently bought a 2nd hand 2009 Powabyke X6 LS (Brushed motor)for my wife, but the battery only has a range of 8-10 miles, so I'm thinking to get another of the bottle batteries, from 8fun, to put on her bike: flecc warned that the brushed motor on her bike would be more demanding on a battery than my brushless one.

Does anyone know if the battery as specified above should be OK?

8fun controller:

Powabyke controller:

 

[Deleted member 4366]

The only way to know for sure is to open up the battery and read the designation on the cells. Then you can look up the data sheet. If you believe the 15 amp rating on the battery (which is probably true), it should be OK for both, but wouldn't it be better to get a battery rated at 18 amps or more for the Powabyke, and mount it on the rack?

Soldering the shunt is best done with a watt-meter or ammeter so that you can set it accurately. 18 amps is a reasonably safe max for your motor and battery provided that you don't use full power for prolonged periods, which is hardly likely as it only happens during hill-climbing. 10 mins at 8mph would be 1.3 miles of steep hill.

 

[NRG]

+1 to what Dave said, fit the watt meter, you may find the controller is already peaking some 3 amps over its max setting already...control is very imprecise. Then understand what battery you have and take it from there...

 

[jackhandy]

Thanks to you both.

I'll get an ebay watt meter before doing any mods. & do a bit more research into a suitable 2nd battery that'll be good for both bikes.