SOC and Battery Efficiency Setting

[Matrix]

I had asked before about Syncing SOC when battery SG was reading 100%,

But this morning I did an SG check,  the Classic SOC read 74%.  With The batteries sitting idle for 1 hour (no loads, solar charger off, inverter off),  the Average SG reading for all 12 cells was 1.239, voltage was 25v, and the voltage of each battery was 6.24 / 6.25 / 6.26 / 6.24

According to the Trojan Table,  1.239 and voltage of 25v  Should be about 80% - 81% SOC. At the Classic's reading of 74% my SG should have been more like 1.227

I have the efficiency % in the Classic 150 set to 85%.   Would increasing this number bring my SOC reading from the Classic more in line with my SOC reading as taken from SG? 

Or ... Does adjusting the Classic's battery efficiency change/effect it's SOC reading?   What is the relationship between the efficiency setting and the SOC reading of the Classic?

[ClassicCrazy]

I believe that if you turn the efficiency down it will take more amps to get to 100% .
So if you were down 50 amps it will count up and when it replaces 50 amps then it will take some more amps to get up to 100% since it is less than 100% efficient.

Also depending on how you have some of the other settings once it goes to Float then it goes to 100% even if SOC was lower than that before it went to Float.  You would have to look back on some monitoring software like Mymidnite to see what the SOC was at the point it switched to Float .

Larry

[FNG]

The Classic uses the efficiency to account for the recharge, So if you remove 100AH and have efficiency set at 100% when you put back 100AH it would be at 100% SOC, As you drop the efficiency the classic will need to see more amps go in the battery to hit the same 100%

So if the classic is hitting 100% SOC before the SG shows 100% then drop the efficiency some, Generally speaking a little low is bettter any how as the classic will reset to 100% when it goes to float so it will recalibrate at that point if you will.

[Matrix]

Thanks,   these are what I needed to know.

[boB]

Yes.  Looks like you need to raise your efficiency a bit.

Typically, amp-hour charging efficiency should be somewhere between around 90% to 95% or so...

Unless, maybe the batteries are really old or worn out, then lower capacity rating may be in order.

boB