Surface charge effect battery test

[Donald]

If you pull off the battery charger and used a conductance battery charger will the reading be effected by a surface charge on the battery?

 

[Chris142]

Yes

 

[Rand]

I have no technical basis for my answer but yes.

Noticed a difference if freshly tested vs after 1-2min with headlights on.(testing with lights off..)

 

[Donald]

I mean the voltage is effected by a surface charge but I thought the conductance test being more sophisticated would not be effected.

 

[zrxkawboy]

Based on my experience, yes.

 

[Donald]

My conductive test today before is 790 CCA. 13.32V.

Load test passed at 10.3 V at 50% CCA for 15 seconds

After conductive test 780 CCA 12.53V

Battery is 800CCA marine starting group 27

 

[The_Jeff]

If it's fully charged the charger will warm the battery up, which lowers its internal resistance, so, yeah.

 

[Donald]

Now the interesting thing is the battery is from a boat I bought and probably was not treated all that well. It was on the boat all last winter without being charged.

For a several year old 800 CCA battery to read 780 seems pretty good.