On Thu, 6 Nov 2003 14:15:17 -0700, Sylvan Butler
d wrote:

On Wed, 05 Nov 2003 18:09:46 -0500, Bruce W...1 wrote:
mcalhoun wrote:
Although their normal price is about $15, float battery chargers (wall
wart, coiled cord, little black box with LED, two cords with large
alligator clips on the ends) are often advertised in Harbor Freight
catalogs for $7.99. I must have half a dozen of them now, keeping
batteries here and there up to snuff. I've never measured them, but
they seem to do a real good job, and they're hard to beat at that price!

I have no connection to Harbor Freight except as a satisfied customer,

Ditto to all of the above.

You don't say! Have you ever measured their voltage? Or is it written
on the case?

Mine vary between 13.5v to 13.6v. If you open the little plastic
box between the transformer and the battery terminals you will find
a little adjustment that will let you tweak the voltage.

I have two different styles, one with curly coiled leads and one
with straight leads. I think the straight lead is older and has
been obsoleted. Too bad, because they made a nice low-current
adjustable power supply. The curly lead ones don't. But they
both seem to do a fine job of keeping lead acid batts up to snuff.

I have a couple on my bench. One set to 13.6v and one to 14.1v. I
put a gel cell on the 14.1v to charge after use, then on to the
13.6v to maintain ready for next time.

I have one in the barn. I cut off the clamps and put on a pair of
anderson powerpole connectors. A matching connector on my lawn
tractor allows me to easily attach with no concern for polarity
mismatch whether it is me or anyone else. I got 5 seasons from the
last battery, which is pretty good for a lawn tractor that sits
pretty much unused october thru april.

sdb

I just picked up a couple of the float chargers from Harbor Freight.
They measure 13.55 no load. 13.55 at 130 ma, 13.4 at 175 ma, 12.9 at
230 ma, 12.8 at 250 ma.

Looks like they will only supply about 175 ma max and still be above
13.4 volts. At over 500 ma they will shut down and won't restart until
the load is removed completely.

One problem I see with them is that they draw 36 ma from the battery
if they are hooked up to the battery (at 12.9 battery volts) but not
plugged into the wall. If you loose AC power that will quickly kill
the battery!

They measure 3.6k both ways when you check the resistance but when
hooked to the battery they cause much more draw than 3.6 ma.

These are the ones with the curly cords. Are these internally
adjustable ?

I wonder if there is enough range to add a series diode?

Thanks
Gary K4FMX