question

kevin-reilly avatar image
kevin-reilly asked

Smart Shunt behavior when changing modes

I am using a Smart Shunt on the input side of another brand PWM solar charge controller for an experiment. Originally, I had the Smart Shunt incorrectly set to "battery monitor", but it was consistently reading ~115-130A in full sun.

Then I changed the "Mode" to "solar charger" on the Smart Shunt, so that its data would be used properly by the the VRM. After that, the highest current reading I see is 80A, even in perfect sun. I did make the mode change in daylight, while drawing about 100A.

Is it possible the device resets its calibration when changing modes? Is there anything else that might cause a change in how the current is counted or calibrated when doing that?

SmartShunt
1 comment
2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.

Alexandra avatar image Alexandra ♦ commented ·

@Kevin Reilly

Get a clamp meter and verify. Or use the mppts data if it has that option.

The fact that it is pwm though means that it will vary alot in production what may have changed is likely is the sample rate the shunt uses.

1 Like 1 ·
1 Answer
kevin-reilly avatar image
kevin-reilly answered ·

Just for posterity, I tracked this down to bad blocking diodes. Power was dropping in stages as the individual diodes were burning up, cutting out one additional panel every few days.

2 |3000
Toggle Comment visibility. Current Visibility: Viewable by all users

Up to 8 attachments (including images) can be used with a maximum of 190.8 MiB each and 286.6 MiB total.