Re: Battery capacity -- Next Day

the connectors... I really like the connectors you mention. I printed
out the picture from the link you gave me and when around to all the
automotive parts stores, hardware stores, etc., and could not find
them. I am in a town of 40,000 in rural north western ND so I am not
surprise. I'll be traveling soon and will be looking for them while
on the road.

The table I have does not go below 12.25 and that's at 40%.
Interstate said the lowest point of discharge is 10.5 volts. Below is
a paragraph about how they define the AH.

"The Ampere-Hour rating measures the current-delivering capability of a
battery in amps, at 80 degrees F, for a period of hours until the
battery's terminal post voltage drops below 10.50 volts (1.75 volts
per cell). 5 amps for 10 hours = 50 ampere hours. 30 amps for 3 hours =
90 ampere hours."

My inverter cuts off at 11 amps.

thanks.

Larry

William P.N. Smith wrote:
"larry.greenwood@xxxxxxxxxxxxxxx" <lgreenwood@xxxxxxx> wrote:
I have been using battery voltage under load to determine the
remaining capacity of the battery, ie., 12.25 volts = 50% capacity.

Well, we already know that's wrong, it's open circuit voltage with no
load, and it's accuracy increases with time after the load (or charge)
has been removed, up to about 24 hours.

The table that I have reference illustrates that relationship this way:
12.75 100%
etc

So it's 11.7V at zero percent? If so, it matches the rule of thumb
I'm familiar with.

My question is, are these figures (guidelines or estimates) or are they
precise?

It's probably a good rule of thumb, but will vary depending on battery
construction, temperature, specific gravity, and phase of the moon.

Either way, would I use the load voltage or the voltage not under a
load for determining remaining battery capacity?

I've always seen these numbers used as no-load after 24 hours.

Did you fix your connectors yet?

.

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