Smart Shunt Reading Incorrectly

[AdrianChen]

That's about right, 80A is about 0.2C rate for a 400AH battery and if current falls below 20A (0.05C), on that rate you are full if you hit 14.4v. If you terminate at 14.2v, then a little absorb is needed, even at low amps. The reason is: the higher the rate, the higher inflated charge voltage. Try hit it with a smaller rate and you will observe less inflated charging voltage. The cell at 3.45v is about 95% full. Then, as it reaches 3.5v it starts to climb fast and current tappers off quickly. With solar it is even more problematic as the rate can vary, hence a absorb time and tail current is needed to compensate for a variable rate. And this is where we try to match our bmv settings with the charger.
On a bench is very easy, as you have a constant and fix supply.

We have 45mins absorption on all the chargers, tail is set at 2% but because one day can be sunny and the next cloudy I've given up trying to dial it in any closer! Thankfully we don't have a bluetooth app on the battery to compare against the shunt, or I would have a nervous breakdown!

 

[Raul]

We have 45mins absorption on all the chargers, tail is set at 2% but because one day can be sunny and the next cloudy I've given up trying to dial it in any closer! Thankfully we don't have a bluetooth app on the battery to compare against the shunt, or I would have a nervous breakdown!

I wouldn't worry about it. the fact that amps tappers quick atfer 13.8v, tells you got some very healthy cells.

 

[barsteward]

Sorry can you elaborate what I need. I've got 400w solar with victron 50a controller, no mains charger.

This may help as a complete novice I found it very helpful.