OT(ish) - car battery / typical ampere-hour rating ?

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "Vim Fuego" saying something like:

Fork trucks and submarines manage it all the time.

According to an IEEE paper I found (by searching google for "lead acid parallel"), there's not much wrong with running a bunch of maintenance-free lead acid batteries in parallel, especially in this application.

There _is_ a reduction in battery life if you use (significantly) dissimilar batteries then perform repeated shallow discharges. They constructed two 24V batteries, one from four 6V/3cell monoblocs (100Ah) and one from twelve 2V cells (550Ah). I _think_ those capacities are per item, so 400Ah v 6600Ah.

Their results were that the battery with a lower capacity would survive 40% less charge-discharge cycles (than on its own) for very shallow discharges, dropping to about a 10% reduction in life for deep discharge cycles. The other battery would last for more cycles than normal.

In short, buying two identical lead acid batteries and putting them in parallel is unlikely to cause either them or you very much harm.