Starting college again after 31 years has been ... taxing; not so much free time on my hands. I'll be back on form soon enough!
If Victron would only add a Peukert compensation for "low current" (slower discharge than the 20 hour rate) to their BMV battery monitors, not just high current Peukert compensation, we'd be getting better accuracy for SoC..
I am well versed in what Peukert is. It is a "thing" in many Ah counters, including Victron, that take Peukert into consideration to aid in determining the SoC of the battery. Sadly, the algorithms in most of them, only account for high rate discharge Peukert effect, not for low current discharges.We're close to the same age, and I can't imagine something that would compel me to go back to school...
Good on you.
This isn't a Victron thing. Peukert doesn't work that way. It's an exponent. It's only designed to find reduced capacity due to higher current.
You could enter your own by using a longer C period.
use https://planetcalc.com/2268/ to calculate the exponent for your situation between C?? and C20.
Enter the C?? capacity instead of C20 and the calculated exponent.
Or you can just accept the more conservative SoC based on C20 and be content in the knowledge that you have more than it says.
Responding to all Peukert's law relating postings & comments on this website and not necessarily to this post.I thought this video explains the Puekert Effect very well, including the significant differences between lead-acid and lithium-ion.
Yes, the SoC would increase over time, as would the battery's voltage. And the (resting) voltage is a good indicator of SoC when temperature corrections are applied.@fat_old_sun, nice write up.
I do wonder, though, if I discharge the hell out of my battery but then stopped at say 10% SoC (peukert corrected coulomb count), would my battery's SoC then increase over time? I guess the answer is yes, though this doesn't seem intuitive.
Yes, the SoC would increase over time, as would the battery's voltage. And the (resting) voltage is a good indicator of SoC when temperature corrections are applied.
It appears that you overlooked the word resting in my response. Temperature corrected resting voltage is a good indicator of a battery's SoC. However, it not a practical method for determining the SoC of a battery in use.Why would the SoC raise? If the SoC is based on voltage, it's not accurate, and you're the only one on hear that thinks voltage alone is a good indicator of SoC. The only way I'll agree with you is if it has been at rest for several hours.
if the voltage is still changing, it simply means that the battery has not fully rested. go for a long walk & re-measure. it's not hard!Not overlooked at all. I even quoted it. "Resting" simply means no current is flowing. The "resting" voltage of a 12V can change substantially over time, and that change is NOT dependent on temperature. "Resting" voltage is only meaningful after several HOURS of rest.