New batteries when are they at 50 percent?

[SteveJ.]

Originally Posted by Mark_K5LXP

SteveJ's table is a good one to follow for voltage measured under load/in use (not static).

Mark B.
Albuquerque, NM

The chart is for static voltages, not for in use except as a sort of guide.

The key takeaway for me is how temperature affects the voltages at a given state of discharge.

[Mark_K5LXP]

Originally Posted by SteveJ.

The key takeaway for me is how temperature affects the voltages at a given state of discharge.

That condition probably not considered much since most folks operate during warmer months. When I de-winterized this year I did a C/20 capacity test and it came up short. Repeating the test confirmed the result. It's not "cold" here in NM but the batteries were cool, well below 77F. Measured the temperature and checked the data sheet, and there was my discrepancy. The converse is true, when batteries are hot power delivery is more efficient.

Mark B.
Albuquerque, NM

[SteveJ.]

Originally Posted by Mark_K5LXP

That condition probably not considered much since most folks operate during warmer months. When I de-winterized this year I did a C/20 capacity test and it came up short. Repeating the test confirmed the result. It's not "cold" here in NM but the batteries were cool, well below 77F. Measured the temperature and checked the data sheet, and there was my discrepancy. The converse is true, when batteries are hot power delivery is more efficient.

Mark B.
Albuquerque, NM

Agreed on the "most people". I guess I'm odd, but that's OK.

I think the coldest that I've camped at was on BLM land outside of 29palms, CA. We had 22*F, in a the Roadtrek with exposed plumbing.

I started up the engine to get heat from the exhaust to help prevent freezing of the plumbing. It worked.

My normal camping is generally at altitude so it does get cool out.

When I was ignorant of how much the temp changes things I would be thinking that my battery was lower than it actually was from running the furnace. Since that time I've also added a battery monitor that helps immensely.