On Mon, 31 Jan 2011 19:00:05 -0500, "Percival P. Cassidy"
wrote:

On 01/31/11 03:26 pm, Robert Green wrote:

A "marine" bettery may or may not have a carrying strap, is designed
to take more vibration than an automotive battery, and is generally
somewhere between a common SLA (starting, lighting, and Accessory)
battery and a deep charge battery in construction and capability.

FWIW, I've always known SLA to stand for "Sealed Lead Acid" battery.

I think what you mean is usually called a Starting-Ignition-Lighting (SIL),
aka the typical car battery. They should not be used where they will be
discharged to lower than 50% of the amp-hour rating because the plates will
become damaged.

SLA's are the deep DIScharge batteries found in UPS's, golf carts and wheel
chairs and usually have no caps or covers for the individual cells as car
batteries do. They are often called "gel cells." They can tolerate much
greater discharges than car batteries without damage, although it's
recommended that they not be deeply discharged too often because they too
can suffer damage when completely discharged. They need to be sized
correctly for the application.

The only Golf Cart batteries (GC2, 6-volt 220Ah) I have found recently
are *not* sealed, unfortunately, which makes me hesitate to use a pair
of them as an *indoor* emergency power supply for my amateur radio
station: (a) they will need to be topped up regularly; (b) they will
emit hydrogen under charge, with its explosive propensity.

BTW, SLAs can be gel cells, AGM (absorbed glass mat) or be -- as I
understand Optima batteries to be -- liquid-electrolyte batteries with
catalytic recombinant components.

Further, I have seen "Marine Starting," "Marine Deep Cycle" and "Marine
Dual Purpose" batteries.

Perce
Catalitic caps can be had for GC2H batteries - they reduce the water
loss by better than 90%. I had 8 GC2H batteries in the old Fiat
ElectraMobile