How do I figure out shunt value for my CA?

[Synon]

I recently got a CA v3 for my bike (DP type even though the controller doesn't have a plug, not a big deal, just made the connections myself). I need to input the controller shunt value so I can get an accurate amp draw reading, but I don't know what that value is and my googling on figuring that out has been fruitless. I got the motor/controller from a friend years ago, I know it's a Yescomusa 1kw/48v kit. I believe the controller is between 26a and 35a. No stickers or markings on the outside of the controller, I also don't see much on the board itself either. The shunt has 3 wires, I've included some pictures of the board below, the shunt is just behind the black wires.

http://i.imgur.com/PDpoZPg.jpg
http://i.imgur.com/80emNzx.jpg
http://i.imgur.com/ft9Gstm.jpg

If anyone has a trick to find out the value, please let me know!

 

[Jon NCal]

Search on youtube:
https://www.youtube.com/watch?v=okpFsoHNE7I

 

[Synon]

I have a Thunder 1220 charger and it does not have a "foam cut" feature that the iCharger does. Is there some other way to do this?

 

[Jon NCal]

Download the guide and go to section on Rshunt value:
https://endless-sphere.com/forums/viewtopic.php?p=571345#p571345

 

[teklektik]

As mentioned above, there are several means to calibrate your shunt called out in the Guide.

You can also try #2 below - that post is in a discussion about the Satiator, but it should work fine for any charger - just hook a DMM in series with either of the charger leads.

From this post: https://endless-sphere.com/forums/viewtopic.php?f=2&t=88138#p1286217

There is no particular reason to use a constant current source to calibrate the CA - the Guide calls this out simply because the charger mentioned there is very common. The only important point is to have some sort of current limiting in play so the shunt or power source don't vaporize.

If you have an accurate DMM you can simply calibrate the CA using your regular battery charger. Here are two strategies - in either case just hook up the DMM in line with the charger to monitor the charge current and use the same calibration correction calculation from the Guide using the CA and DMM current measurements.

1. Use the approach in the Guide section "6.10 Monitoring Charge Current". This requires adding a wire to your charger but allows the CA to update the 'Ah consumed' as the battery is charged so you can ride with only a partial top-up. This incidentally gives you the opportunity to use a DMM to externally monitor charge current - which is what is needed for shunt calibration.
   
   
2. If you don't want to modify the controller, use the hookup outlined in <<this post>> which works the same as (1) but is a one-time hack hookup just for the purpose of calibration. Although the diagrams in that post are drawn slightly differently, you can see that they differ only in the negative charger connection - this second approach just uses the internal FET flyback diode in place of the controller mod.