T i m wrote:
Hi all and knowing there are some scientists / mathematicians walking
amongst us ... ;-)

I'm trying to see if there is a (rough even) way of measuring the
Depth Of Discharge voltage / cutoff point versus current load value
for a specific lead acid battery.

The manufacturers have provided me the following values (@ 50% DOD).

11.75V @ 93A (12.4V initial)
12.05V @ 18.2A (12.7V initial)
12.10V @ 4.65A (12.75V initial)

(The general chart starts at the values marked 'initial' so that would
be for those currents but at 0% DOD but I'm not sure if that is
relevant).

Now, it's obviously not a straight line (Peukert's law), but can you
extrapolate a graph (or create a formula that would be more useful for
my project) from just 3 points please?

Maybe Peukert's law itself would give those with a brain wired
differently than mine the answer? ;-)

https://en.wikipedia.org/wiki/Peukert%27s_law#Formula

Cheers, T i m

p.s. The nearest *I* could get to an answer would be some graph paper
and a Flexicurve. ;-)



Three points is a bit tough, 6 points fine.
Plot using excel. then use ADD Trendline to try different type fits
then on the options tab, you can get it to display the equation of the
trend line.