Just a few more comments to add to what has been posted about batteries
and grease. Yes, I am an electrical engineer and have been working with
lead-acid batteries, mostly in telecom systems, for more than 30 years.
There are three practical versions of lead-acid batteries on the market
today, flooded, gel and absorbed glass mat (AGM). If you really want to
get the most life out of your battery you need to learn a little about
them. The chemistry is basically the same; charging produces hydrogen
and oxygen gas (not hydrogen sulfide!) in the process of making the
electrolyte heavier (higher specific gravity). These gases are not
corrosive, but they usually leave the battery with quite a bit of
sulfuric acid vapor, which is, hence the rusty looking vent above my
(and everyone else's AS battery door. The hydrogen and oxygen come from
the water that dilutes the acid in the battery. If the gases are allowed
to escape, you need to replace the water. There is an option, it's a
special battery cap called a Hydrocap which has a small piece of
platinum catalyst in it. Hydrocaps are about $10 each and last about two
battery lifetimes, typically. They work really well.
Sealed, so-called valve regulated lead acid (VRLA) batteries (either gel
or AGM), almost all have recombining catalysts equivalent to Hydrocaps
in them. For a given size, though, a flooded battery will usually be
cheaper and will usually last longer than a gel or AGM battery, and
while adding Hydrocaps won't make it spillproof, it will reduce the need
for watering tenfold or better. It's also much easier to make a flooded
battery that will supply several hundred amps for a few seconds (motor
starting). The key for both of these technologies is that the water in
the electrolyte is immobilized -- either with silica gel, or with
fiberglass mats. There have also been significant advances in the
chemistry so that gel and AGM batteries are no longer certain to fail
sooner than flooded ones are. But they will be more expensive, and they
are very intolerant to overcharging.
Can't agree more with the comments on grease to keep electrical things
happy. But it is not dielectric grease! You use that when you want to
insulate things. The best for this application is plain yellow bearing
grease, with a little more oleic acid added to make it bond with the
metal better, aka cosmoline. This is still available from San-Chem as
No-Ox-Id, we use No-Ox-Id Special A which has a little solvent in it,
the regular stuff is so stiff that you need to heat it. Dielectric
grease, typically based on silicone oil, tries to form an insulator if
it can, and this is not a good idea.
While I would probably choose AGM batteries if money were no object just
to make things simpler, and avoid needing to keep the wasps out of the
vent I built to discharge the gases from my battery box, for economy you
still can't beat (and I still stick with) flooded golf cart batteries. I
pay about $75 each for Trojan T105's that I can pick up at a battery
jobber here in town, 2 in series in a marine battery box under the
gaucho have worked for me. There is a big solar panel on the roof and a
simple controller to keep it from overcharging.
--
David Josephson