The Charge Efficiency Factor compensates for the Ah losses during charging.
In the BMV history the Discharged and Charged energy is measured.
So is the Charge Efficiency Factor equal to the ratio of these two figures?
Or does the Factor count the "losses" during charging and then we have to also take in consideration the "losses" of disharging?
So for this example is the Factor equal to 84% or is it equal to 92% (8%lost in charging and 8%lost in discharging)?
Hi @vbelijohn
You're close, but it's not an arbitrary split. The Peukert Exponent attempts to estimate the losses during discharge, and is largely a 'rate of discharge' thing. Ie, the faster the discharge, the more the losses.
Victron don't really recommend changing the default from 1.25 (pb's), but their website has a Peukert calculator you can use if you have your battery Ah ratings at two C levels, eg C20 and C5. It's always higher than unity, so not expressed the same as the Charge factor.
So your "84%" might mean ~10% higher in the charge setting. And also change between summer and winter (temps and length of days), and with load patterns.
All you can do is try. I reckon I can get my system down close to 0.1% SOC, but also know I'll need to change as the seasons do.
Have fun.. :)
Ok. I understand what you describe about the peukert value. But my question is about the Charge efficiency factor. If I use 100 Ah to charge a battery and then receive 84 Ah when I discharge it, does this mean the factor is 84%?
Sorry to bother but please clarify if my calculation is correct
Well sort of yes, but it's irrelevant to any settings used in the BMV.
But 'sort of', because Ah isn't technically correct as it needs the same V to compare. Wh is correct, and that's what your pic shows.
Ah is perhaps another of the USA's contributions to global metrication. I'm glad Victron don't use it very often..
