I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. The original question was about whether it's okay to
leave the battery charger on for a few days to a week. I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.

--
Christopher A. Young
Learn more about Jesus
www.lds.org
..


"BetaB4" wrote in message
...
I posted a question in the newsgroup "rec.boats" about
recharging a
lead-acid battery for an electric boat motor after returning
from a
boating/fishing trip. The original question was about
whether it's okay to
leave the battery charger on for a few days to a week. I
found out that,
unless I have the more modern automatic type of battery
charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger
into a timer and
setting the timer to turn the power off to the battery
charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery
charger will still
be set to "ON", and will still be connected to the battery
after the timer
cuts power to the battery charger, cause the battery to
discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I
could use.

"Stormin Mormon" wrote in news:gukmr0
:

The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.


From what I recall from long ago, all diodes have a leakage current rating.
Whether it's significant in this case I don't know.

FAIK, the old Si/Ge diodes may be obsolete in today's electronics.

On 5/15/2009 3:19 PM Red Green spake thus:

"Stormin Mormon" wrote in news:gukmr0
:

The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.

From what I recall from long ago, all diodes have a leakage current rating.
Whether it's significant in this case I don't know.

They all have a leakage current rating; the leakage is very, very small.

FAIK, the old Si/Ge diodes may be obsolete in today's electronics.

Si/Ge? You mean one or the other; modern diodes are all silicon, except
for a few small-signal ones (1N34, etc.). Not used in battery chargers,
that's for sure.

And of course before that there were selenium and copper-oxide
rectifiers, both long obsolete.


--
Found--the gene that causes belief in genetic determinism

On May 15, 5:36*pm, David Nebenzahl wrote:
On 5/15/2009 3:19 PM Red Green spake thus:

"Stormin Mormon" wrote in news:gukmr0
:

The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.

From what I recall from long ago, all diodes have a leakage current rating. *
Whether it's significant in this case I don't know.

They all have a leakage current rating; the leakage is very, very small.

FAIK, the old Si/Ge diodes may be obsolete in today's electronics.

Si/Ge? You mean one or the other; modern diodes are all silicon, except
for a few small-signal ones (1N34, etc.). Not used in battery chargers,
that's for sure.

And of course before that there were selenium and copper-oxide
rectifiers, both long obsolete.

--
Found--the gene that causes belief in genetic determinism

The reverse leakage should be so small as to be insignificant compared
to the battery self-discharge.

hr(bob) wrote:
On May 15, 5:36 pm, David Nebenzahl wrote:
On 5/15/2009 3:19 PM Red Green spake thus:

"Stormin Mormon" wrote in news:gukmr0
:
The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.
From what I recall from long ago, all diodes have a leakage current rating.
Whether it's significant in this case I don't know.
They all have a leakage current rating; the leakage is very, very small.

FAIK, the old Si/Ge diodes may be obsolete in today's electronics.
Si/Ge? You mean one or the other; modern diodes are all silicon, except
for a few small-signal ones (1N34, etc.). Not used in battery chargers,
that's for sure.

And of course before that there were selenium and copper-oxide
rectifiers, both long obsolete.

--
Found--the gene that causes belief in genetic determinism

The reverse leakage should be so small as to be insignificant compared
to the battery self-discharge.
Hi.
Of course battery internal resistance is a durrent path for discharge.

On Fri, 15 May 2009 15:36:21 -0700, David Nebenzahl
wrote:

On 5/15/2009 3:19 PM Red Green spake thus:

"Stormin Mormon" wrote in news:gukmr0
:

The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.

From what I recall from long ago, all diodes have a leakage current rating.
Whether it's significant in this case I don't know.

They all have a leakage current rating; the leakage is very, very small.

FAIK, the old Si/Ge diodes may be obsolete in today's electronics.

Si/Ge? You mean one or the other; modern diodes are all silicon, except
for a few small-signal ones (1N34, etc.). Not used in battery chargers,
that's for sure.

And of course before that there were selenium and copper-oxide
rectifiers, both long obsolete.


Shottky are becoming more common due to their lower voltage drop
(forward). Half a standard silicon diode drop. (like germanium)

Red Green wrote:
"Stormin Mormon" wrote in news:gukmr0
:

The battery chargers I've used, the DC output goes through
diodes. So, discharge isn't an issue.


From what I recall from long ago, all diodes have a leakage current rating.
Whether it's significant in this case I don't know.

FAIK, the old Si/Ge diodes may be obsolete in today's electronics.

Here's the rectifiers I like:

"http://www.kpsurplus.com/products/view/16558"

BetaB4 wrote:
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. The original question was about whether it's okay to
leave the battery charger on for a few days to a week. I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.


I checked two chargers. The manual charger had no drain at all. The
automatic drained 7ma. It would take a week to draw off 1 amp-hour.

On May 15, 4:01*pm, "BetaB4" wrote:
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. *The original question was about whether it's okay to
leave the battery charger on for a few days to a week. *I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

Batteries need to be monitored by voltage, not guessing. Your battery
charger may or may not work or even charge properly to 100%.
www.batteryuniversity.com has all the info you will ever need to
maintain them properly, but basicly keep the voltage to low and its
ruined by sulfation, keep it to high and the plates deteriorate.
Battery maintainers take care of these issues and they are cheap.
Knowing proper voltage is something you will always need to know and
check to be sure your chargers actualy are working as intended.

On Fri, 15 May 2009 17:47:00 -0700 (PDT), ransley
wrote:

On May 15, 4:01Â*pm, "BetaB4" wrote:
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. Â*The original question was about whether it's okay to
leave the battery charger on for a few days to a week. Â*I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

Batteries need to be monitored by voltage, not guessing. Your battery
charger may or may not work or even charge properly to 100%.
www.batteryuniversity.com has all the info you will ever need to
maintain them properly, but basicly keep the voltage to low and its
ruined by sulfation, keep it to high and the plates deteriorate.
Battery maintainers take care of these issues and they are cheap.
Knowing proper voltage is something you will always need to know and
check to be sure your chargers actualy are working as intended.

A good 3 stage marine charger (particularly the "mountable" type)
should be safe to leave connected, either plugged in or not.
Some (mainly older units) have "relay" isolation - physically
disconnected when not charging. (or not powered on)

"BetaB4" wrote in message
...
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. The original question was about whether it's okay
to
leave the battery charger on for a few days to a week. I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say
12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will
still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and
drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.




I'm sure (well, pretty sure), as others have pointed out, that any draw from
leaving it connected to your battery would be insignificant. But since I'm
too lazy to actually check it I disconnect the charger from the battery when
done. Hell, I might foget about it for weeks or more.

As ransley stated you really need to know your charge voltage and charge
rate and duration to properly care for your batteries. This info is usually
available from the manufacturer. Some "Smart Chargers" are probably pretty
safe to use in general but some other "Automatic" chargers may ruin your
batteries in a fairly short time.

On May 15, 8:19*pm, "Ulysses" wrote:
"BetaB4" wrote in message

...





I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. *The original question was about whether it's okay
to
leave the battery charger on for a few days to a week. *I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say
12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will
still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and
drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

I'm sure (well, pretty sure), as others have pointed out, that any draw from
leaving it connected to your battery would be insignificant. *But since I'm
too lazy to actually check it I disconnect the charger from the battery when
done. *Hell, I might foget about it for weeks or more.

As ransley stated you really need to know your charge voltage and charge
rate and duration to properly care for your batteries. *This info is usually
available from the manufacturer. *Some "Smart Chargers" are probably pretty
safe to use in general but some other "Automatic" chargers may ruin your
batteries in a fairly short time.- Hide quoted text -

- Show quoted text -

Years ago I got a "great" charger, only to find out many years later
it was never calibrated to charge 100% or went out of calibration, My
batteries never lasted or turned over the car when -20f. One day after
learning about what 100% charge is I luckily inside found a screw that
adjusted the voltage up. I think most new units are computer chip and
probably unadjustable. Not having a battery maintainer has ruined many
batteries for me.

ransley wrote:

Years ago I got a "great" charger, only to find out many years later
it was never calibrated to charge 100% or went out of calibration, My
batteries never lasted or turned over the car when -20f. One day after
learning about what 100% charge is I luckily inside found a screw that
adjusted the voltage up. I think most new units are computer chip and
probably unadjustable. Not having a battery maintainer has ruined many
batteries for me.

I think the screw was for temperature compensation. At -20F, a typical
battery may require 16V. At 30F it may require 15V and at 110F, 13V.
Chargers and regulators used to be set manually, taking the estimated
temperature into account.

E Z Peaces wrote:
ransley wrote:

Years ago I got a "great" charger, only to find out many years later
it was never calibrated to charge 100% or went out of calibration, My
batteries never lasted or turned over the car when -20f. One day after
learning about what 100% charge is I luckily inside found a screw that
adjusted the voltage up. I think most new units are computer chip and
probably unadjustable. Not having a battery maintainer has ruined many
batteries for me.

I think the screw was for temperature compensation. At -20F, a typical
battery may require 16V. At 30F it may require 15V and at 110F, 13V.
Chargers and regulators used to be set manually, taking the estimated
temperature into account.

Use a hydrometer to check the specific gravity
of the electrolyte in a lead acid battery if
it's one that you can open. Some batteries
actually have a little indicator that turns green
when the specific gravity is within the proper range.

TDD

BetaB4 wrote:
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. The original question was about whether it's okay to
leave the battery charger on for a few days to a week. I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.



Hi,
If you have a smart charger with electronic brain, it is OK to leave it
on all the time.

On May 15, 10:16*pm, Tony Hwang wrote:
BetaB4 wrote:
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. *The original question was about whether it's okay to
leave the battery charger on for a few days to a week. *I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

Hi,
If you have a smart charger with electronic brain, it is OK to leave it
on all the time.

That would be my suggestion too. Just buy a new smart charger. In
the grand scheme of things, especially when you're talking about
boats, they don't cost that much. Also, if proper charging gets you
some extra battery life, it could pay for itself,

NO

EJ in NJ

BetaB4 wrote:
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. The original question was about whether it's okay to
leave the battery charger on for a few days to a week. I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say 12
hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

BetaB4 wrote:

"If I do the timer idea, could the fact that the battery charger will still
be set to "ON", and will still be connected to the battery after the timer
cuts power to the battery charger, cause the battery to discharge and drain
back through the battery charger?"

The self-discharge rate of the battery will be magnitudes greater than
any discharge back through the rectifiers of the charger.

Very surprising that your charger doesn't switch to trickle charge mode
once the battery is charged. Even the cheapest chargers nowadays do
that, i.e.
"http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=45005"
"http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=66783"

SMS wrote:
BetaB4 wrote:

"If I do the timer idea, could the fact that the battery charger will
still be set to "ON", and will still be connected to the battery after
the timer cuts power to the battery charger, cause the battery to
discharge and drain back through the battery charger?"

The self-discharge rate of the battery will be magnitudes greater than
any discharge back through the rectifiers of the charger.

Very surprising that your charger doesn't switch to trickle charge mode
once the battery is charged. Even the cheapest chargers nowadays do
that, i.e.
"http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=45005"
"http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=66783"

A trickle charge is supposed to compensate for self-discharge. The
2-amp trickle of those chargers will be magnitudes greater than
self-discharge.

Thanks all.

Based on what everyone wrote, I've been looking for an "automatic" battery
charger. I checked Harbor Freight and one person suggested.

Here's the instruction manual for one Harbor Freight battery charger:

http://www.harborfreight.com/manuals...6999/66783.pdf

On Pages 8 and 9 of the manual, it talks about not leaving the charger on
and the possibility of the battery overheating with the charger on. So, I'm
a little confused. Does the automatic shutoff actually work or not?


"BetaB4" wrote in message
...
I posted a question in the newsgroup "rec.boats" about recharging a
lead-acid battery for an electric boat motor after returning from a
boating/fishing trip. The original question was about whether it's okay to
leave the battery charger on for a few days to a week. I found out that,
unless I have the more modern automatic type of battery charger, that is a
bad idea -- due to overcharging the battery.

Then someone suggested just plugging the battery charger into a timer and
setting the timer to turn the power off to the battery charger after say
12 hours.

My question now is,

"If I do the timer idea, could the fact that the battery charger will
still be set to "ON", and will still be connected to the battery after the
timer cuts power to the battery charger, cause the battery to discharge
and drain back through the battery charger?"

I tried a Google search but didn't find too much info that I could use.

On Fri, 22 May 2009 21:02:40 -0400, "BetaB4"
wrote:

Thanks all.

Based on what everyone wrote, I've been looking for an "automatic" battery
charger. I checked Harbor Freight and one person suggested.

Here's the instruction manual for one Harbor Freight battery charger:

http://www.harborfreight.com/manuals...6999/66783.pdf

On Pages 8 and 9 of the manual, it talks about not leaving the charger on
and the possibility of the battery overheating with the charger on. So, I'm
a little confused. Does the automatic shutoff actually work or not?

Check out any of the Sure Charge family as sold by Northern Tool.
I keep my generator plugged into one, 24/7. It starts when I need it
and has for the past 9 years [Same battery].
http://www.northerntool.com/webapp/w...2128&R=1212 8

Thanks, but that wouldn't work for me. I need a battery charger for
recharging a boat battery (that operates the electric motor) after running
the battery down during a fishing trip. And, I sometimes need to be able to
leave the charger on for a week or more without it overcharging the battery.
So, I need a battery charger that will recharge fairly quickly but can be
left on the battery.

starrin wrote:
On Fri, 22 May 2009 21:02:40 -0400, "BetaB4"
wrote:

Thanks all.

Based on what everyone wrote, I've been looking for an "automatic"
battery charger. I checked Harbor Freight and one person suggested.

Here's the instruction manual for one Harbor Freight battery charger:

http://www.harborfreight.com/manuals...6999/66783.pdf

On Pages 8 and 9 of the manual, it talks about not leaving the
charger on and the possibility of the battery overheating with the
charger on. So, I'm a little confused. Does the automatic shutoff
actually work or not?

Check out any of the Sure Charge family as sold by Northern Tool.
I keep my generator plugged into one, 24/7. It starts when I need it
and has for the past 9 years [Same battery].
http://www.northerntool.com/webapp/w...2128&R=1212 8

BetaB4 wrote:
Thanks all.

Based on what everyone wrote, I've been looking for an "automatic"
battery charger. I checked Harbor Freight and one person suggested.

Here's the instruction manual for one Harbor Freight battery charger:

http://www.harborfreight.com/manuals...6999/66783.pdf

On Pages 8 and 9 of the manual, it talks about not leaving the charger
on and the possibility of the battery overheating with the charger on.
So, I'm a little confused. Does the automatic shutoff actually work or
not?


I think the problem is that the Chinese engineers hired an English major
to write the manual, and the author tried to make sense of it in a hurry.

Page 9 makes it sound as if the 10A mode is not regulated. That's the
one where you have to keep an eye on it.

It says in the auto mode (apparently 2A), you can go away, and it will
turn on only as needed.

I'm curious about the note of Page 8: "This charger is not recommended
for batteries with a built in Hydrometer eye. The reading of the
built-in eye will conflict with ammeter readings."

I imagine what it means is that you should ignore the eye while charging
because tiny gas bubbles from charging could make the eye read falsely.

On Sat, 23 May 2009 12:54:48 -0400, E Z Peaces wrote:
BetaB4 wrote:
Thanks all.

Based on what everyone wrote, I've been looking for an "automatic"
battery charger. I checked Harbor Freight and one person suggested.

Here's the instruction manual for one Harbor Freight battery charger:

http://www.harborfreight.com/manuals...6999/66783.pdf

On Pages 8 and 9 of the manual, it talks about not leaving the charger
on and the possibility of the battery overheating with the charger on.
So, I'm a little confused. Does the automatic shutoff actually work or
not?


I think the problem is that the Chinese engineers hired an English major
to write the manual, and the author tried to make sense of it in a hurry.

that'l be a first.

On Sat, 23 May 2009 13:50:31 -0500, AZ Nomad
wrote:

On Sat, 23 May 2009 12:54:48 -0400, E Z Peaces wrote:
BetaB4 wrote:
Thanks all.

Based on what everyone wrote, I've been looking for an "automatic"
battery charger. I checked Harbor Freight and one person suggested.

Here's the instruction manual for one Harbor Freight battery charger:

http://www.harborfreight.com/manuals...6999/66783.pdf

On Pages 8 and 9 of the manual, it talks about not leaving the charger
on and the possibility of the battery overheating with the charger on.
So, I'm a little confused. Does the automatic shutoff actually work or
not?


I think the problem is that the Chinese engineers hired an English major
to write the manual, and the author tried to make sense of it in a hurry.

that'l be a first.

Chinese English Major - not an engineer or scientist or anyone with
knowledge of both the product and English - so you get Chinglish.