Hi all,
I do have a 330Ah setup. The shunt is showing SOC 40% but 230ah consumed.
330Ah*60%=198Ah and not 230ah
Maybe I did something wrong.
Can someone help to find the issue?
Thanks
Sascha
You need to read up on the Peukert effect. A simple overview is a 100Ah battery is specified to deliver 100Ah with a 5A load over 20 hours. With a 20A load it will deliver less than 100Ah and SOC will fall faster than Ah drawn. When drawn down slowly, say at 1A you will get more than 100Ah so SOC falls more slowly than Ah drawn.
The battery monitor allows for this so the SOC and Ah drawn may not necessarily be the same. This is set by the Peukert exponent setting and the effect is small for lithium and the Peukert should be set to around 1.05. The default for lead acid is 1.25.
in your case, if a lot of the discharge has been at less than 16.5A then the SOC will be higher than the figure calculated from the Ah drawn. I see this effect on my boat where most of the discharge is lower than the C20 rate.