[VAC] Re: Batteries

["Dr. Gerald N. Johnson, electrical engineer" <geraldj@xxxxxxxx>]

Many Univolts tend to be harsh on all batteries. Deep cycle marine would
probably fare worse.

"Best" is hard to define. One can emphasize capacity at the cost of
price, and needed care, or emphasize freedom from care at the cost of
price and capacity, or emphasize cost expecting some care needed and
expecting a shorter life. It depends a lot on the needs. One who is
living way from power lines for long periods depending on solar panels
needs greater capacity and longevity that those of us who make a few
trips a year and might need battery power for a couple weeks. The
longest lived batteries and the lowest care batteries don't live better
from not being used. The lowest cost batteries may serve the week or two
or month trip quite well and then if they don't last to the next year,
there's little lost. The lowest cost (car starting batteries) won't take
kindly to many deep cycles, nor over charging. But when the lowest cost
allows installing a greater capacity than needed, deep discharge cycles
need not happen often.

As for care, that involves keeping terminals clean, battery top clean,
and except for gel cells and starting batteries, keeping the electrolyte
level up by filling with distilled water regularly. Allowing
overcharging to lower the water level below the tops of the plates cost
battery capacity that often does not return when the battery is
refilled.

A battery being ignored or stored will self discharge and not survive
well. It needs some activity to last. Shallow discharges by loads that
followed soon by charging is better than slow discharges.

The Univolt will generally tend to overcharge the battery and produce
lots of hydrogen and oxygen bubbling up out of the electrolyte that can
carry some sulfuric acid out the vents to corrode the battery's
terminals and surroundings. And that mix of hydrogen and oxygen as it
leaves the battery has the optimum ratio of hydrogen and oxygen for the
loudest bang that might be triggered by static electricity or a light
switch. Overcharging is not a healthy thing to do for occupants or
battery. There are more modern chargers that will treat a battery
better.