On Mon, 06 Nov 2006 10:00:40 -0500, mm
wrote:
In terms of not damaging my motorcycle battery, which must remain
outside but unused this winter, is there a real difference between my
1 amp battery charger that I got used from my 80-year old cousin in
1967 versus the new ones they sell now that say they regulate the
voltage as the battery reaches full charge?
Is there a benefit to me to buy one of the new ones, when the old one
still works fine.
Mine has a a circuit breaker (a little glass thing that looks
something like a small Christmas tree light) that trips when it goes
over 1 amp. It trips every 5 seconds and resets automatically in 2
seconds. But below one amp, it charges at the full rate that can be
squeezed into the battery, declining as the battery becomes fully
charge, but never reaching zero, I think. I have always wondered what
is going on when the battery is fully charged but I'm still charging
it, and that includes a car battery. When cars still had ammeters,
even maybe when the car was idling, but certainly at higher speeds,
there were always 5 amps entering the battery. How come that doesn't
hurt it?
The motorcycle battery is 12 ampere-hours, and since I haven't been
able to get the cycle runnning yet, it will have to be charged maybe
once a month during the winter.
Remove NOPSAM to email me..
I wouldn't be surprised if this unit from the 60's didn't use a
selenium rectifier...
These operated on the bulk charging principle and relied on the
voltage difference between the rectifier output and the battery
voltage to determine the current drawn. When the battery is flat the
output voltage from the rectifier is high relative to the battery
voltage. In this case the maximum current available from the rectifier
passes through the battery and the current operated thermal switch
then operates to prevent the transformer from burning out. Ideally, As
the battery voltage rises with each successive charging burst the
difference between the rectifier output voltage and the battery
voltage diminishes to the point where they are hopefully nearly equal
at around 14V or thereabouts. The thermal switch now remains closed
even though some current is being pushed through the battery.
Unfortunately, it is never possible for the transformer to regulate at
around 14V when the battery is fully charged since because the
charging current diminishes the rectifier output voltage tends to
increase slightly thus resulting in a voltage differential which
produces a fairly high trickle charge. Prolonged trickle operation
will damage the battery.
If you want to retain this relic for sentimental reasons you may be
able to fit it with an add-on charge regulator kit like this one which
was specifically designed for simple low cost units like yours.
http://www.jaycar.com.au/productView.asp?ID=KA1795