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
--
| Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |
| Watch out for my e-mail address. Thank UCE. change ^ to @ |
It may be better to live under robber barons than under omnipotent moral
busybodies. The robber baron's cruelty may sometimes sleep, his
cupidity may at some point be satiated; but those who torment us for our
own good will torment us without end, for they do so with the approval
of their consciences. -- C. S. Lewis

mcalhoun wrote:

Harbor Freight $7.99 float chargers:

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

I never had, so I went out (to the garage; brrrr!) and measured one:
13.58 volts. FWIW, the wallwart says "15VAC at 600 ma", but there's a
little plastic box on the wires between the wart and the battery clips.

--Myron.
--
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTX). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

================================================== ========

Now we're getting somewhere. Myron said 15VAC at 600 ma. C/100 is
about 700 mA. Any idea what's inside the little voltage adjustment box?

mcalhoun wrote:

Harbor Freight $7.99 float chargers:

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

I never had, so I went out (to the garage; brrrr!) and measured one:
13.58 volts. FWIW, the wallwart says "15VAC at 600 ma", but there's a
little plastic box on the wires between the wart and the battery clips.

--Myron.
--
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTX). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

================================================== ========

Now we're getting somewhere. Myron said 15VAC at 600 ma. C/100 is
about 700 mA. Any idea what's inside the little voltage adjustment box?

"Bruce W...1" wrote in message ...
This is not ham radio related but I know you guys have the answer.

I need to store a car unattended for a winter in the midwest. And I
want to put a tricke charge on the battery.

I'd rather not buy a fancy trickle charger because it would probably get
stolen. On the other hand I have a vast array of wall wart
transformers.

If I connected one of these transformers how many milliamps should it
put out at 12V? Or rather what's the least current that would do the
job?

It seems that lead acid batteries can dissipate too much current as
heat. In other words I could probably feed it one amp continuously.
But would 100 mA at 12V do the job? I'd hate to lose a 1-Amp wall wart.

Thanks for your help.

Hi Bruce,
you have been given heaps of technical suggestions, heres mine.

1.Pull the battery out of the vehicle and take it back to your place.
2.Every week or so, check specific gravity with a hyrometer (sp) and
if it needs charging, do so.

This solves the problem of someone stealing the car unless they are
really keen, is simple, easy, and lo tech.

73 de VK3BFA Andrew

"Bruce W...1" wrote in message ...
This is not ham radio related but I know you guys have the answer.

I need to store a car unattended for a winter in the midwest. And I
want to put a tricke charge on the battery.

I'd rather not buy a fancy trickle charger because it would probably get
stolen. On the other hand I have a vast array of wall wart
transformers.

If I connected one of these transformers how many milliamps should it
put out at 12V? Or rather what's the least current that would do the
job?

It seems that lead acid batteries can dissipate too much current as
heat. In other words I could probably feed it one amp continuously.
But would 100 mA at 12V do the job? I'd hate to lose a 1-Amp wall wart.

Thanks for your help.

Hi Bruce,
you have been given heaps of technical suggestions, heres mine.

1.Pull the battery out of the vehicle and take it back to your place.
2.Every week or so, check specific gravity with a hyrometer (sp) and
if it needs charging, do so.

This solves the problem of someone stealing the car unless they are
really keen, is simple, easy, and lo tech.

73 de VK3BFA Andrew

According to the manual the Harbor Freight charger is 15.5V. That
seems a little high for a float charge to me. 12-volt LA batteries are
generally float charged at 13.8V. Did you guys measure the voltage
with it connected to the battery or under "no load"?

According to the manual the Harbor Freight charger is 15.5V. That
seems a little high for a float charge to me. 12-volt LA batteries are
generally float charged at 13.8V. Did you guys measure the voltage
with it connected to the battery or under "no load"?

On Thu, 6 Nov 2003 18:37:30 -0500, Bob Lewis (AA4PB) wrote:
According to the manual the Harbor Freight charger is 15.5V. That

I think that's the wallwart, not the voltage applied to the batt.

seems a little high for a float charge to me. 12-volt LA batteries are
generally float charged at 13.8V. Did you guys measure the voltage
with it connected to the battery or under "no load"?

Either way measures the same. The little box is a basic voltage
regulator circuit.

sdb

--
| Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |
| Watch out for my e-mail address. Thank UCE. change ^ to @ |
It may be better to live under robber barons than under omnipotent moral
busybodies. The robber baron's cruelty may sometimes sleep, his
cupidity may at some point be satiated; but those who torment us for our
own good will torment us without end, for they do so with the approval
of their consciences. -- C. S. Lewis

On Thu, 6 Nov 2003 18:37:30 -0500, Bob Lewis (AA4PB) wrote:
According to the manual the Harbor Freight charger is 15.5V. That

I think that's the wallwart, not the voltage applied to the batt.

seems a little high for a float charge to me. 12-volt LA batteries are
generally float charged at 13.8V. Did you guys measure the voltage
with it connected to the battery or under "no load"?

Either way measures the same. The little box is a basic voltage
regulator circuit.

sdb

--
| Sylvan Butler | Not speaking for Hewlett-Packard | sbutler-boi.hp.com |
| Watch out for my e-mail address. Thank UCE. change ^ to @ |
It may be better to live under robber barons than under omnipotent moral
busybodies. The robber baron's cruelty may sometimes sleep, his
cupidity may at some point be satiated; but those who torment us for our
own good will torment us without end, for they do so with the approval
of their consciences. -- C. S. Lewis

The recommended float voltage differs a fair amount with temperature and
with battery type (liquid, starved, or, now very rare, gelled
electrolyte). I'd check the manufacturer's specifications for the
specific cell. Most are on the web these days. If I were floating a
battery outside or in any other environment with substantial temperature
variation, I'd want to use a temperature compensated charger, with the
charger close to the battery.

Roy Lewallen, W7EL

Bob Lewis (AA4PB) wrote:
According to the manual the Harbor Freight charger is 15.5V. That
seems a little high for a float charge to me. 12-volt LA batteries are
generally float charged at 13.8V. Did you guys measure the voltage
with it connected to the battery or under "no load"?