On Oct 12, 8:35*pm, "RogerN" wrote:
"James Waldby" wrote in message

. ..




Smart chargers are based on a chip that have the lead acid charge/
decay curves telling it how to act. I suspect it monitors the voltage
of the battery and if that info is faulty then the charger works
erractically.
jiw

The 2A rating on a lead acid battery charger is more like 2A for a
discharged battery and lower current depending on the state of charge, quite
different than a 2A constant current charger. *

RogerN

The "2A" range on my 2/10/50A Schumacher starts at 4 - 5A and
decreases as the battery comes up; it passed smoothly through 2A but
didn't stay there, IIRC at cutoff the current was less than 1A.

An LM317 adjustable regulator IC is enough to make a decent trickle
charger. Adjust the pot that sets it to the end voltage, the device
limits the current to 1.25A max, then it falls off as the battery
nears the set point. You could print the temperature compensation
chart and tape it to the box.

This is a commercial version with voltage and current meters:
http://www.testequipmentdepot.com/la...4606?ref=gbase
The one-turn voltage adjustment is tricky but good enough for lead-
acids, though you'll need a separate voltmeter with more resolution

jsw