Reverse shunt mod ?

[KirstinS]

Hi

Just replaced a 48v 350w controller with a 500w 48v one

It's pulling too many amps for my battery. 25a vs my battery 20a continuous

I've searched on how to reverse shunt mod but no luck. Plenty on increasing amps by soldering it.

Is is just a case of filing it down by about 25%

Or best to take small notches ?

Any pointers appreciated

 

[Nealh]

Hello Kirstin, put a nick in the shunt to reduce the value you can always resolder later if needed. If you have a KT with Lcd3 you can always decrease amp draw by up to 5a with C10 parameter.

 

[KirstinS]

Hello Kirstin, put a nick in the shunt to reduce the value you can always resolder later if needed. If you have a KT with Lcd3 you can always decrease amp draw by up to 5a with C10 parameter.

Cheers Neal , what I wasn't sure of was wether 25% of thickness of shunt needed removing along whole length.....or wether a single nick cutting in about 25 % would do it

Sadly this is a very basic no hall controller with a basic led panel

 

[Nealh]

A simple nick should do it.

 

[KirstinS]

A simple nick should do it.

Perfect thankyou !

 

[KirstinS]

A simple nick should do it.

Nick made with file on my leatherman, let's see how commute home goes later

 

[Deleted member 4366]

You only need to crimp it. If you're going to file it, be very careful about where the filings go.

Ideally, you need to use a wattmeter to see the results. I use full throttle, then apply the brake (without switch) to slow the wheel right down and draw the maximum current, which you see on the wattmeter. Obviously, if the battery cuts out, you need to crimp a bit more.

Don't forget that anything about power that you see on the LCD afterwards will be wrong. No mater how much you shave from the shunt, it will always show the same maximum power.

 

[KirstinS]

You only need to crimp it. If you're going to file it, be very careful about where the filings go.

Ideally, you need to use a wattmeter to see the results. I use full throttle, then apply the brake (without switch) to slow the wheel right down and draw the maximum current, which you see on the wattmeter. Obviously, if the battery cuts out, you need to crimp a bit more.

Don't forget that anything about power that you see on the LCD afterwards will be wrong. No mater how much you shave from the shunt, it will always show the same maximum power.

Thanks but no LCD and no wattmeter!

So I've filed , very carefully re shavings , not a lot though . I expect more required but I'll test on my 7 miles back

 

[KirstinS]

Didn't work or rather didn't prevent voltage collapsing after a shortish burst of full throttle

But I tested my booster pack and that's the issue, tis buggered. Holds charge but sags under load.

Hobbyking cheapo lipo bought to get me through to end of Jan when my Brighton ebikes BBS preorder comes in