On Oct 12, 11:04*pm, "RogerN" wrote:

Some of the chargers description described as charging and then monitoring
the voltage, when it falls below a certain point it charges again. *This had
me thinking that it monitors voltage with almost no current flow. *I'd guess
it also monitors voltage during charge with current flow. *I thought if I
were brewing my own, I would use shielded 4 conductor, 2 wires for charge
and 2 others for measuring voltage.

Kelvin connections won't help you with lead-acids. They charge to an
artificially high voltage due to "surface charge", which takes time to
dissipate. This article says 4 - 8 hours:
http://www.batteryuniversity.com/partone-13.htm

/I have found that I need a "dumb" charger to start batteries who have
/been seriously discharged and then allowing the smart charger to
/finish...again that little chip in the smart charger being a bit too
/"smart".

Agreed. I need the homebrew lab-supply chargers for older batteries
whose cells have become unequal or sulphated.

I would think that would be the best way to get the ultimate charge without
overcharging.

I've played with an adjustable regulator circuit in Electronics Workbench
simulator. *I used the typical voltage divider circuit to set the open
circuit voltage and used an inline resistor so that the voltage goes down as
the current goes up. *I got an open circuit voltage of 14.201V, .19A at 14V,
2A at 13V.

RogerN

You don't need the series resistor, the exact shape of the knee
(constant-current to voltage transition) doesn't matter.
http://www.national.com/mpf/LM/LM317.html

jsw