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"?

Alright, so I built a voltage regulator with parts that I have around,
an LM7812 with a few diodes connected to a 500 mA 12VDC wall wart. I
hope you guys are happy now.

However I still maintain that a properly sized wall wart could do the
job with no voltage regulation.

Alright, so I built a voltage regulator with parts that I have around,
an LM7812 with a few diodes connected to a 500 mA 12VDC wall wart. I
hope you guys are happy now.

However I still maintain that a properly sized wall wart could do the
job with no voltage regulation.

Alright, so I built a voltage regulator with parts that I have around,
an LM7812 with a few diodes connected to a 500 mA 12VDC wall wart. I
hope you guys are happy now.

What sort of open-circuit voltage are you getting out of it?

However I still maintain that a properly sized wall wart could do the
job with no voltage regulation.

Hey, it's your battery (or your neighbor's) - if you want to
experiement and see if you can figure out whether that sort of
charging regime will appreciably shorten the life of the battery, go
for it!

I just figure that doing the job right isn't really very much harder
than doing it "maybe right, or maybe we shorten the battery's life by
a year?".

[and I really do like the idea of those Harbor Freight float chargers...
$7.95 for a tweakable-voltage half-amp charger is so low I don't
see much sense in homebrewing my own any more! I'll have to pick up
a couple.]

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Alright, so I built a voltage regulator with parts that I have around,
an LM7812 with a few diodes connected to a 500 mA 12VDC wall wart. I
hope you guys are happy now.

What sort of open-circuit voltage are you getting out of it?

However I still maintain that a properly sized wall wart could do the
job with no voltage regulation.

Hey, it's your battery (or your neighbor's) - if you want to
experiement and see if you can figure out whether that sort of
charging regime will appreciably shorten the life of the battery, go
for it!

I just figure that doing the job right isn't really very much harder
than doing it "maybe right, or maybe we shorten the battery's life by
a year?".

[and I really do like the idea of those Harbor Freight float chargers...
$7.95 for a tweakable-voltage half-amp charger is so low I don't
see much sense in homebrewing my own any more! I'll have to pick up
a couple.]

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

Andrew VK3BFA wrote:

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

Screw that. This is a charity case to begin with. There's no way on
God's green earth that I'd haul the battery back to my place.

Andrew VK3BFA wrote:

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

Screw that. This is a charity case to begin with. There's no way on
God's green earth that I'd haul the battery back to my place.

Roy Lewallen wrote:

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

Hmmm, temperature compensate at a certain distance from the battery.
Can you model this Roy?

Roy Lewallen wrote:

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

Hmmm, temperature compensate at a certain distance from the battery.
Can you model this Roy?

LMAO! How many people does it take to screw in a lightbulb, or in this
case to charge a battery?


Sylvan Butler d wrote in message boi.hpZ.com.invalid...
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