On Nov 17, 7:41*pm, Grumpy The Mule wrote:
Agreed! *I designed a DC UPS power supply for Harris using the
UC3906 to charge a 4Ahr gell cell for wireless pbx. *The only
down side is it requires some head voltage for the regulator,
so it won't work well off a 12V vehicle system unless the engine
is running and then not so great.

I still have two of those Harris power supplies one runs an HT
monitoring a repeater and the other runs a scanner and a small
transmitter. *The batteries are ten years old and show little
loss of capacity.

raypsi wrote in news:355e6bae-ab52-4d0e-8fde-
:



TI makes a really sweet ic for charging batteries the UC3906. Is the
greatest IC since sliced bread for charging batteries. It took forever
to charge my deep cycle marine battery like a110AHr. A straight
charger it would take a week to charge 100% it's that last 15% that's
the toughest. The UC3906 charged my deep cycle marine battery to full
charge from dead in 10 hours. It's one of the greatest homebrew jobs
I've done. I used it to charge a 110AHr deep cycle marine battery for
my electric bike. I could ride 2 days on a single charge like $0.25
worth of electricty back and forth to work. 45 miles on a single
charge.

73 OM
n8zu- Hide quoted text -

- Show quoted text -

I think I am going to try charging it through a 10 amp constant
current source. If it works the way I am thinking as the battery nears
full charge the pass transistor should saturate applying nearly full
generator voltage across the battery topping off the battery. Im
thinking(hoping) that when this occours the voltage drop across the
transistor may be just enough to yield nearly the ideal float voltage
for the batteries.
The batteries normally power my heater and lights for my popup camper
and a couple of radios that are mostly used for rx. With only an
initial charge from the battey charger before leaving home I can camp
about 4 days. With some additioal charging I am hoping to extend it
another 2 oor 3 days. Since our trips usually include a few hours a
day of driving I thought I would use this oppurtunity to top off the
batteries. I have leaned against the idea of just running the engine
for that purpose. The incandescent bulbs I am using in the camper are
the main draw on the batteries perhaps going to LEDs would help.