Forum Discussion
BFL13
Sep 14, 2019Explorer II
I have the manual adjustable PowerMax converter, so I do it for ambient.
Here is an old thread on all this which has the temp comp table I use (I printed it) thanks to Mark there.
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26669731/srt/pa/pging/1/page/2.cfm
I don't take battery temp which will be higher than ambient once charging gets going. I suppose that battery temp being higher will somewhat compensate for the battery voltage being less than the charger's set voltage. IMO it doesn't matter to such accuracy in real life, and while camping you can't create lab conditions.
I just set the charger voltage at the specified Vabs (adjusted for temp) and that's that. Can't do anything about the battery voltage. It rises all the way through till full. It does not get to the charger setting until the end. Doing a 50-90 it is not there at 90, but is still a bit lower than charger voltage.
EDIT--BTW, with an adjustable voltage charger, you have to set the voltage before connecting to the battery. Once connected, the voltage seen at the charger terminals is lower, due to "middling" with the battery voltage.
With a charger that has an external pot knob, you can set a few common voltages and mark the casing around the knob. Now you can leave the charger connected to the battery and use your marks for setting the voltage.

Here is an old thread on all this which has the temp comp table I use (I printed it) thanks to Mark there.
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/26669731/srt/pa/pging/1/page/2.cfm
I don't take battery temp which will be higher than ambient once charging gets going. I suppose that battery temp being higher will somewhat compensate for the battery voltage being less than the charger's set voltage. IMO it doesn't matter to such accuracy in real life, and while camping you can't create lab conditions.
I just set the charger voltage at the specified Vabs (adjusted for temp) and that's that. Can't do anything about the battery voltage. It rises all the way through till full. It does not get to the charger setting until the end. Doing a 50-90 it is not there at 90, but is still a bit lower than charger voltage.
EDIT--BTW, with an adjustable voltage charger, you have to set the voltage before connecting to the battery. Once connected, the voltage seen at the charger terminals is lower, due to "middling" with the battery voltage.
With a charger that has an external pot knob, you can set a few common voltages and mark the casing around the knob. Now you can leave the charger connected to the battery and use your marks for setting the voltage.

About Technical Issues
Having RV issues? Connect with others who have been in your shoes.24,210 PostsLatest Activity: Mar 04, 2025