Hey OM:

All well and good but taking the battery up to 15.5volts is ok as long
as you keep adding water and have a well vented area to charge them
in. I tried a tested and true way of not going over 14.2 volts took to
long to get the full charge you can check it with a hydrometer and see
that best you can get is 80% of full charge going with 14.2 volts.

With a 18volt unregulated supply and the VSAT of 4 volts the max
charge current voltage can only be 14.00 volts period
you have to take it up to 15.5 volts to get the full charge period.
been there done that.

73 OM
de n8zu



On Feb 13, 3:36*pm, philo wrote:
On 02/13/2011 08:17 AM, Percival P. Cassidy wrote:



On 02/13/11 03:14 am, No Spam wrote:

I'm looking for charger/maintainer -- either an off-the-shelf unit or a
schematic so I can build my own -- suitable for a flooded deep-cycle
battery, either a pair of 6V "golf cart" batteries in series or a Group
31.

I don't want an RFI generator: I already have one.

I already have a few 13.8V 25A power supplies, one of which I would be
quite willing to "crank up" to a higher voltage to compensate for the
voltage drop in the control circuitry.

Something like the West Mountain Radio "Super PwrGate" (PG40S) would
work, although the automatic switch-over feature is not essential. That
device is intended for Gel-Cell and AGM batteries and not recommended
for flooded batteries -- absorption-charge voltage too low and
float-charge voltage too high, their tech support people tell me.

I am quite happy with my IOTA DLS-45 with the IQ Smart Controller

http://www.iotaengineering.com/iq.htm

Once a week it equalizes my batteries using 14v pulses. The batteries are
on their 14th year and can still run my shack for 5 days. (down from a
week when I initially purchased the batteries and charger)

I wish I'd known about that IQ unit before I bought an Astron RS-35A
just a month or two back.

I was hoping I could find something not too expensive to take power from
that P/S or from one of my RF-quiet "switchers" to look after the
batteries. Texas Instruments has battery-charging ICs, but I haven't
seen a practical circuit that uses one.

"Perce"

You do not need anything too fancy...
to "float" the batteries all you need to do is keep them at approx *2.25
volts / cell...so it's possible that your 13.8 v charger will do the job....

You can test it by checking the total voltage after a 24 hour period...

ideally, a 12v battery should float at about 13.5 volts.

If the float voltage is a little higher or lower it won't be too
critical...but make sure it's well below the 14.2 v gassing point.

I've been in the lead-acid battery business for 36 years...
so have quite a bit of long term empirical data