I have a 115AH deep-cycle battery that I bought as a stand-by battery
for my amateur radio station. It has been in a "battery box" on
trickle-charge (using a charger with a "deep-cycle" setting) for most of
the time since I bought it over a year ago, and it has been called on to
supply power only a few times.

Recently I noticed that the "fully charged" LED on the charger was not
on and started investigating further.

Having not encountered any batteries in the last few decades that have
not been sealed and "maintenance free," I was surprised to find tiny
print about checking the electrolyte level every 30 days -- but even
then it took me a few minutes to figure out how to get access to the
cells to check this.

Anyway, when I removed the cunningly disguised covers, I found that the
cells looked totally dry, and each took close to a pint of distilled
water to bring the electrolyte level above the plates.

The battery has now been on charge for about 20 hours at the charger's
12A setting, but most of the time the ammeter on the charger has shown
only about 5A. The cells are all still gassing.

Is this battery likely to come back to life again, or is it toast? Any
remedial actions to take?

Perce
(This is my usenet alias. I *am* an FCC-licensed "ham," but my real name
and callsign have no relevance to this question.)

My sense is that the battery's capacity will be severely impaired. You may
have the voltage, but the ampere hours won't be the same. A pint per cell
.... the poor thing was dry!

Trickle Chargers do just that ... constant low rate. But doing that to a
fully charged battery warms the cells and evaporates electrolyte. Monthly
service is probably about right.

A better solution is a battery 'tender' or 'maintainer' that totally cuts
off the charge current based on battery voltage. Kits for these are
advertised in QST.


"Percival P. Cassidy" wrote in message
...
I have a 115AH deep-cycle battery that I bought as a stand-by battery for
my amateur radio station. It has been in a "battery box" on trickle-charge
(using a charger with a "deep-cycle" setting) for most of the time since I
bought it over a year ago, and it has been called on to supply power only a
few times.

Recently I noticed that the "fully charged" LED on the charger was not on
and started investigating further.

Having not encountered any batteries in the last few decades that have not
been sealed and "maintenance free," I was surprised to find tiny print
about checking the electrolyte level every 30 days -- but even then it
took me a few minutes to figure out how to get access to the cells to
check this.

Anyway, when I removed the cunningly disguised covers, I found that the
cells looked totally dry, and each took close to a pint of distilled water
to bring the electrolyte level above the plates.

The battery has now been on charge for about 20 hours at the charger's 12A
setting, but most of the time the ammeter on the charger has shown only
about 5A. The cells are all still gassing.

Is this battery likely to come back to life again, or is it toast? Any
remedial actions to take?

Perce
(This is my usenet alias. I *am* an FCC-licensed "ham," but my real name
and callsign have no relevance to this question.)

I have a 115AH deep-cycle battery that I bought as a stand-by battery for
my amateur radio station. It has been in a "battery box" on trickle-charge
(using a charger with a "deep-cycle" setting) for most of the time since I
bought it over a year ago, and it has been called on to supply power only a
few times.

Recently I noticed that the "fully charged" LED on the charger was not on
and started investigating further.

Having not encountered any batteries in the last few decades that have not
been sealed and "maintenance free," I was surprised to find tiny print
about checking the electrolyte level every 30 days -- but even then it
took me a few minutes to figure out how to get access to the cells to
check this.

Anyway, when I removed the cunningly disguised covers, I found that the
cells looked totally dry, and each took close to a pint of distilled water
to bring the electrolyte level above the plates.

The battery has now been on charge for about 20 hours at the charger's 12A
setting, but most of the time the ammeter on the charger has shown only
about 5A. The cells are all still gassing.

Is this battery likely to come back to life again, or is it toast? Any
remedial actions to take?

The battery may be recoverable, but I suspect it's going to take some
effort, and it may well have passed the point of no return.

The fact that the cells are drawing low current, but are
electrolyzing, suggests to me that you've got a combination of a high
charge voltage (above 14.4) and some pretty badly sulphated plates.
The bottom parts of the plates (where there was still some
electrolyte) may be OK, while the upper portions may be sulphated
and/or the separators may be clogged with solids.

First thing I'd do, is just give it some time on the current setting,
checking the electrolyte level periodically and refilling as
necessary. Given some time, the relatively high voltage may clear out
some of the sulphation and residue.

If not, then it might be worth trying to recondition the battery.
There are electrical desulphators available, which hit the battery
with a high-voltage high-frequency pulse in order to break up and
redissolve the sulphate crystals - some people say these work very
well, others are less impressed. I've also seen chemical desulphation
suggested, via the addition of some sort of chelation chemical (I
*think* EDTA is used but don't trust that possibility without
confirming it!).

If some of the plate material has disintegrated and fallen to the
bottom of the cell, then the battery is probably a goner. The residue
can end up shorting the cell.

--
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!

Dave Platt wrote:

snip


If not, then it might be worth trying to recondition the battery.
There are electrical desulphators available, which hit the battery
with a high-voltage high-frequency pulse in order to break up and
redissolve the sulphate crystals - some people say these work very
well, others are less impressed.

http://www.homepower.com/files/desulfator.pdf

It works, but much depends on the condition of the battery.
According to the author, it eliminates the need for periodic
equalization, too. But it won't rescue batteries with
warped plates or shorted cells or those with too much of
the plate material gone, or polluted electrolyte.

Aside from attempting to rescue his battery, the OP has got
to fix or replace that charger, and adopt a maintenance
schedule that includes electrolyte level monitoring.

Ed

On 08/17/05 10:50 pm ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

Aside from attempting to rescue his battery, the OP has got
to fix or replace that charger, and adopt a maintenance
schedule that includes electrolyte level monitoring.

Now that I know that this is not a "maintenance-free" battery, I'll get
into the habit of checking the electrolyte level.

But are you saying that the "Automatic - Deep Cycle" setting on an
"ordinary" battery charger (it's one I bought originally for the car
batteries, but the "Deep Cycle" setting seemed like a bonus) is not a
reliable way of keeping the batery in good shape?

Perce

On Thu, 18 Aug 2005 13:33:15 -0400, "Percival P. Cassidy"
wrote:

On 08/17/05 10:50 pm ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

Aside from attempting to rescue his battery, the OP has got
to fix or replace that charger, and adopt a maintenance
schedule that includes electrolyte level monitoring.

Now that I know that this is not a "maintenance-free" battery, I'll get
into the habit of checking the electrolyte level.

But are you saying that the "Automatic - Deep Cycle" setting on an
"ordinary" battery charger (it's one I bought originally for the car
batteries, but the "Deep Cycle" setting seemed like a bonus) is not a
reliable way of keeping the batery in good shape?

I don't know what he's saying, but I'll say No, it isn't if it's a
run-of-the-mill cheapie.

Suggest you look at:

www.amplepower.com

and check out their primer. Some of this is self-serving but on
balance is good stuff.

In article ,
Percival P. Cassidy wrote:

But are you saying that the "Automatic - Deep Cycle" setting on an
"ordinary" battery charger (it's one I bought originally for the car
batteries, but the "Deep Cycle" setting seemed like a bonus) is not a
reliable way of keeping the batery in good shape?

It's quite possible that this charger is not well suited for long-term
float charging of a battery, "automatic" or not.

Many standard chargers are designed mostly for "refueling" a depleted
battery. They often use a two-step charging algorithm, to perform the
"bulk" charge (high initial current level which brings the battery up
to about 80% of full capacity), and then a "topping" charge (lower
terminal voltage, resulting in a lower current) to bring them the rest
of the way up to full capacity. The switchover between bulk and
topping charge happens automatically based on the battery's terminal
voltage and/or the current level... it's done at a point which trades
off the speed of recharge, and the possible loss of electrolyte.

The terminal voltage during bulk and topping charge can often exceed
14.5 volts, and might be over 15 volts depending on the charger design,
battery type, and temperature. It's high enough to result in some
loss of electrolyte, if the battery gasses rapidly enough that its
recombination catalyst can't turn the gasses back into water.

Many of these chargers do *not* incorporate circuitry which will
detect the "full charge" state, and switch over to a proper
float-charging regime. Proper floating voltage is a good deal lower
than recharging voltage, and depends on the temperature... I've seen
figures ranging from 14.1 volts (freezing) down to as low as 13.4
volts (40 degrees C). It also depends to some extent on the specific
battery type and chemistry.

A two-phase bulk/topping charger is likely to keep the voltage on the
battery rather too high for proper floating. Gassing and loss of
electrolyte can occur as a result.

For best charging performance, you really want to have a sophisticated
three-phase charger, with temperature compensation for all phases of
the charging cycle.

As an alternative (possibly cheaper), use your car-battery charger to
recharge the battery after use, and buy/build a well-regulated
low-current voltage supply to use as a float charger. If your battery
will be stored in a location which has a relatively constant
near-room temperature, you could build a simple LM317-based voltage
regulator, trim its output for 13.6 volts, and be pretty confident
that you could float your battery on this without risking excessive
outgassing.

--
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!

Percival P. Cassidy wrote:

But are you saying that the "Automatic - Deep Cycle" setting on an
"ordinary" battery charger (it's one I bought originally for the car
batteries, but the "Deep Cycle" setting seemed like a bonus) is not a
reliable way of keeping the batery in good shape?

Perce

Aside from attempting to rescue his battery, the OP has got
to fix or replace that charger
^^^^

We already have strong evidence that the charger you used
cooked the electrolyte. I made no reference to the "universe"
of ordinary chargers - I was thinking specifically of yours.
But you raise a good point, expanding the question - and others
have answered.

Whatever charger you use, you need to verify that it is
doing the job properly. Consider building an add-on
monitoring/control circuit. Perhaps a comparator with
a sonalert to notify you that something is wrong with
automatic charger shut-off when the voltage exceeds
some level. I built a comparator into an ordinary
10 amp charger to turn it on and off automatically.
A 339 works fine - 4 comparators in one chip, so you
can have a voltage too low output turn the thing on,
and a voltage too high turn it off. Still have two
comparators left over to use as you like. Add a couple
more 339 chips and you could add a 10 step led
voltage monitor, for example.

Ed

On Tue, 16 Aug 2005 09:37:16 -0700, "Fred Leif"
wrote:

My sense is that the battery's capacity will be severely impaired. You may
have the voltage, but the ampere hours won't be the same. A pint per cell
... the poor thing was dry!

Trickle Chargers do just that ... constant low rate. But doing that to a
fully charged battery warms the cells and evaporates electrolyte. Monthly
service is probably about right.

A better solution is a battery 'tender' or 'maintainer' that totally cuts
off the charge current based on battery voltage. Kits for these are
advertised in QST.


A good place to buy a Battery Tender Plus is here
http://www.motorcyclebatteriesusa.com/

Dick

The battery has now been on charge for about 20 hours at the charger's
12A setting, but most of the time the ammeter on the charger has shown
only about 5A. The cells are all still gassing.

Is this battery likely to come back to life again, or is it toast? Any
remedial actions to take?


It sounds to me that it is likely to survive, but I hope you
are not over charging?! I assume you are also monitoring the voltage? To
be sure how it turns out, you really ought to get a guage to measure the
specific gravity of the electrolyte in each cell and check. Should be
available cheap at auto supply stores.


Ed K7AAT