Re: [VAC] Univolt Converter

[Jim Dunmyer <jdunmyer@toltbbs.com>]

Jerry,
 I repaired my ferro-resonant UniVolt once also; mine had a bad solder
joint. It has since failed again, and it appears to be the transformer
this time.

A better replacement for the UniVolt than your power supply is the
StatPower charger. It's designed for battery charging and will be much
kinder to your battery than any simple regulated power supply.

The StatPower has a 3-stage regulator in it: Bulk Charge, where it holds
the voltage at something like 14.6, current at a full 20 amps, until the
battery is mostly charged. It then goes into "Aborption mode", where it
tapers the charge until the battery is full. Lastly, it switches to
"maintenance mode", where it holds the voltage at 13.5 or so. Every 21
days, it goes into Absorption mode for a few hours to keep the battery
topped off and sulphate-free. There's also an equalization mode that can
be switched in manually.

A simple regulated supply like your MFJ, an Astron, or the UniVolt
charges the battery very slowly, at about 3 or 4 amps. Yet, if you leave
it plugged in continously when you're not using the trailer, it will
overcharge the battery, cooking out all the water. They'll work sorta OK
if you're using the trailer steadily and are plugged in while doing so,
but fall short if you expect them to recharge the battery after
boondocking and/or keep it plugged in at home.

                                        Jim