> Once again, most battery chargers are NOT voltage regulated.
It occurs to me that this may be a bit obscure to some. Simple battery
chargers (like most inexpensive units) are nothing more than a transformer
to convert AC line voltage to a suitable value, and a full wave rectifier to
convert it to DC. Among other things, this means that their output voltage
depends on their input voltage, which can vary substantially, as much as 30%
or more. (Yeah, I know, the specifications are tighter than that, but
consumer appliances have to deal with reality, not specifications.)
To deal with the varying input, inexpensive chargers typically have a
relatively high open-circuit voltage and then limit current output by having
a relatively high internal resistance.
The other way of solving the problem is to have some sort of electronic
circuit that senses the input (or output) voltage and makes appropriate
adjustments ... this is known as voltage regulation. Since it adds
significant cost to the unit, voltage regulation is not found in most
inexpensive battery chargers. A fully regulated 10 amp 12v power supply may
cost several hundred dollars, while I recently saw a 10 amp 12v battery
charger on sale for $30.
Randall
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