How to measure controller's shunt to increase amps accuratly

[rg12]

Hey Guys,

I have done some shunt soldering on controllers before but never knew what I was doing in terms of how much solder to add in order to increase exactly the amount of amps that I want.

So...how do I measure the shunt's resistance and calculate the added amps BEFORE closing the controller's case?
I know that there is a right way to do it so I would love to hear it in case you guys have any experience with that.


Roy

 

[wesnewell]

I doubt you can accurately measure the shunt resistance, Still, it's easy to calculate how many amps you want to get assuming you know the starting controller amperage. Answer is here.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=31643

 

[999zip999]

That's a trick with two C.A. Im not smart enough. Ilia walk my thru it 7yrs ago.

 

[motomech]

I wire-in a temp. mini Amp meter;
http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR0.TRC0.H0.TRS2&_nkw=+DC+Digital+Voltmeter+Ammeter+LED+Amp+Volt+Meter+%2B&_sacat=0
I have shunt-modded several controllers in the 12 A to 20 Amp range and the results were fairly consistent.
Coating 1/3 to 1/2 of a single wire shunt increased Current by 2 to 3 Amps.
Squeezing the two wires of a 2-wire shunt together and filling in the gap and coating 1/2 to 2/3 increased the Current 5A to 6 Amp.s.

 

[rg12]

I usually deal with 45A controllers as a minimum...
I checked the links provided above and still haven't found a way to calculate resistance somehow in order to know how many amps I'm adding before testing the controller all connected through an amp meter.

 

[motomech]

But you don't need to calculate resistance as the whole mod is quick and dirty.
On most controllers I have looked at, the shunt is accessible thru the end plate. I leave the controller connected to the harness, apply the solder, rev the motor while applying the brake and get the reading in Amps. Solder is easily added or removed, although,my experience is, after a lite coating, added more does not result in more Current.