Peukert's law - Wikipedia, the free encyclopedia
under "external links" there is a calculator showing that a battery that gives 100ah at 1 amp gives only a tiny fraction at a higher load of 20 or so amp draw.
according to the chart a battery that is 125ah at 1 amp is absolute total dirt at 23amps, due to the peukert effect allowing for a battery to last an incredible amount of time when discharged so slowly. have a look at the calculator.
it's hard to believe the wal mart battery is so bad, I'd love to try a $60 battery from wal mart and a $60 battery from batteries plus and see how it goes...