mena661 wrote:
pnichols wrote:
I guess I need to attend a schooling session - how can an amp hour meter know the aging curve of a particular brand of battery or tougher yet, a particular battery's aging curve that occurs during real use - so as to automatically recalibrate itself?
I'm obviously missing some subtly here or confusing the words "reset" and "recalibrate".
It can't know which is why I don't recommend one unless you understand their limitations. In the case of my meter, the amp-hours removed and SOC gets auto-reset to zero once amps into battery bank goes below 1 amp (and I can modify that setting).
The Trimetric has a similar auto-reset but you can turn that off. You will want to do that if you have solar. You want the AH counter to stay running but with the auto on, it will reset as soon as the amps go negative when the sun goes down so you "lose count"
The Trimetric instructions explain all that. Does the Victron?
Phil, the way they work is you must enter a capacity figure to be the baseline for "full" plus enter your definition of "full" using both when a certain high voltage is reached together with the amps having dropped to a certain amount.
This to me is entirely bogus and I don't set those things. I have my own idea of "full" for capacity at any ambient temperature and use the AH counter as verified by the "morning voltage" to keep track of SOC.
So you can enter a new figure for capacity (recalibrate) and you can reset your AH counter which are two separate things.
Eg these days when the batts get near full by lunchtime on solar, the controller will have dropped to Float voltage but the batts are still accepting some amps and the AH counter might be say, minus 12.5AH. Then later, you might see the AH counter has gone past zero and is now positive 8.5AH and climbing since the amps readout is still showing amps going in. (positive amps)
If you have previously reset when not full, all this means is you are getting up to where full really is. You can check the SG and see you are not up to baseline yet and the batts are not full. That evening, when amps go negative, showing draws instead of solar charging, you reset the AH counter and now your new zero is closer to real zero than it was.
Or, you find you are at baseline so the batts are full. But you still see positive amps and the AH counter is still positive and climbing till dark. That means your solar is doing an overcharge and it is going off as heat. You can reset the AH counter to zero as soon as amps go negative, and now your AH counter is bang on, showing zero at "full" and you are on track for a while.
The Trimetric allows 4% for heat at all ranges of SOC, so it can lose track of AH when there is more or less gassing than that. If you do shallow cycles at higher voltages most days, on solar you will need to reset that AH counter to zero at observed baseline SG more often.
