The reason the old Univolts are less than great (by today's standards) is
that they are a single voltage level charger.
Thus they are slow at recharging a battery with a low charge, AND have too
high a voltage to maintain a fully charged battery (which causes them to
"Cook" or boil off the electrolyte in a fully charged battery). This latter
characteristic is a serious shortcoming with the now common "maintenance
free" batteries which typically are difficult or impossible for one to add
electrolyte to replace the boiled off water.
The Intellipower/Charge Wizard, on the other hand, will put out more current
(and a higher voltage) to recharge a dead or low charge battery, and then
reduce the charge rate as the battery reaches a full charge. It also can
tell if the battery is overheating and reduces its charge rate. When the
battery is fully charged, the converter backs off to a lower voltage to
prevent overcharging and boiling off electrolyte.
However, a fully charged battery on a light "trickle" charge can actually
lose some of its capacity (and charge)due to electrolyte stratification
(where the electrolyte separates into different concentrations of acidity at
different levels within the battery. To prevent this, the Charge Wizard
causes the converter to up the voltage "and stir up the electrolyte" by
executing a 15 minute or so higher voltage charge every day or two.
The old Univolts were built like tanks, and weighed almost as much. The
Intellisync/Charge Wizard, on the other hand is quite light and typically a
more potent charger.
Oliver Filippi