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 08/18/05 04:47 pm ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

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?

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.

Well, we don't know how much the charger contributed to the problem,
because the electrolyte level wasn't checked for more than a year
because I hadn't realized that it's not a "maintenance-free" battery.

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.

While looking for a hydrometer today, I noticed "Vector" brand "smart"
chargers (10/6/2A and 6/4/2A) that claimed to have 3-stage charging
circuitry and to be suitable for car batteries, deep-cycle batteries,
and gel-cell batteries. Are these likely to be any good?

The battery was still warm, and each cell was still bubbling slightly
after the thing had been disconnected from the charger for about 3
hours. The SG of each cell was pretty much the same at approx. 1.1175,
and the voltage across the whole battery was 12.4. When I put it back on
charge, the voltage rose to 13.3.

What do you think?

Perce

The battery was still warm, and each cell was still bubbling slightly
after the thing had been disconnected from the charger for about 3
hours. The SG of each cell was pretty much the same at approx. 1.1175,
and the voltage across the whole battery was 12.4. When I put it back on
charge, the voltage rose to 13.3.

What do you think?



I think the battery is bad. I may be remembering wrong, but I seem to
recall that SG should be around 1.230 for lead acid cells, I think. Also,
nominal open circuit voltage on a freshly charged battery ought to be at
LEAST 12.8 volts.


Ed K7AAT

Percival P. Cassidy wrote:
On 08/18/05 04:47 pm ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

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?


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.


Well, we don't know how much the charger contributed to the problem,
because the electrolyte level wasn't checked for more than a year
because I hadn't realized that it's not a "maintenance-free" battery.

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.


While looking for a hydrometer today, I noticed "Vector" brand "smart"
chargers (10/6/2A and 6/4/2A) that claimed to have 3-stage charging
circuitry and to be suitable for car batteries, deep-cycle batteries,
and gel-cell batteries. Are these likely to be any good?

The battery was still warm, and each cell was still bubbling slightly
after the thing had been disconnected from the charger for about 3
hours. The SG of each cell was pretty much the same at approx. 1.1175,
and the voltage across the whole battery was 12.4. When I put it back on
charge, the voltage rose to 13.3.

What do you think?

Perce

I can't comment on the chargers you mentioned - I don't know
anything about them. But I wouldn't trust any charger until
I have verified that it 1) does charge the battery, and
2) does not overcharge the battery. And even that has the
possibility of error. A charger that works fine at 50 F ambient
may not work right at 80 F. So my testing, at 50 F, may
not reveal a flaw that occurs at 80 F. (Or vice versa.) The
terminal voltage - the voltage across the battery at which the
charge should terminate - varies with temperature.

Concerning your battery's SG: either your SG tester or the battery
is bad. The SG reading is too low. To verify, check the specs
on your battery with the manufacturer to see what they say the
SG should be. I believe the battery is bad, as there is
corroborating evidence from other facts besides the SG reading

Regarding my comment that there is strong evidence that your
charger is bad: the electrolyte level didn't go down due to
leakage. The alternative is that it went down due to evaporation,
which is a result of heat, which in turn can be caused by
overcharging. As you point out, we don't know how much of the
electrolyte loss was caused by the charger - but the only
possibility that can be linked to what you have posted thus far
is overcharging. Perhaps there are other factors you haven't
mentioned?

Ed

On 08/20/05 01:37 am ehsjr tossed the following ingredients into the
ever-growing pot of cybersoup:

Regarding my comment that there is strong evidence that your
charger is bad: the electrolyte level didn't go down due to
leakage. The alternative is that it went down due to evaporation,
which is a result of heat, which in turn can be caused by
overcharging. As you point out, we don't know how much of the
electrolyte loss was caused by the charger - but the only
possibility that can be linked to what you have posted thus far
is overcharging. Perhaps there are other factors you haven't
mentioned?

But won't an unsealed (i.e., NOT "maintenance-free") battery lose water
by evaporation even if it's not overcharged? Otherwise why the need to
check the electrolyte level regularly?

Perce

"Percival P. Cassidy" wrote in message
...
snip

While looking for a hydrometer today, I noticed "Vector" brand "smart"
chargers (10/6/2A and 6/4/2A) that claimed to have 3-stage charging
circuitry and to be suitable for car batteries, deep-cycle batteries, and
gel-cell batteries. Are these likely to be any good?

The battery was still warm, and each cell was still bubbling slightly
after the thing had been disconnected from the charger for about 3 hours.
The SG of each cell was pretty much the same at approx. 1.1175, and the
voltage across the whole battery was 12.4. When I put it back on charge,
the voltage rose to 13.3.

What do you think?


If the charger was disconnected and the battery open-circuited for 3 hours,
there shouldn't be any *active* bubbling going on. There may be some
bubbles still 'stuck' to the plates, but no new bubbles should be forming.
If there is after 3 hours of open circuit, that would be a sign of internal
current flow (an internal short). And that would be bad.

SG on lead acid batteries have a couple of different ranges depending on the
exact battery details. I've seen 1.250, 1.265 and 1.280 for fully charged.
1.117 seems very low.

The fact that all cells read the same is a good sign. Usually, one cell
will fail before the others and so it's SG will be decidedly lower.

Such a low SG makes me wonder if maybe the electrolyte was lost from
spillage or something and *not* just discharge and electrolysis.
Evaporation and electrolysis just leaves a stronger acid solution chemicals
behind and adding distilled water dilutes it back to the proper
concentration. Actual spilling of acid from a cell needs to be replaced
with new acid of the proper concentration though.

daestrom

But won't an unsealed (i.e., NOT "maintenance-free") battery lose water
by evaporation even if it's not overcharged? Otherwise why the need to
check the electrolyte level regularly?



Not meaning to get this tread off on a tangent, but the above comment
prompts me to point out that even "maintenance free" batteries AREN'T,
necessarily. On many occassions I have found it necessary to peel back the
paper cover on automotive maintenance free batteries, remove the exposed
cell caps, and add water, especially after a year or two operating in a hot
climate. I don't believe marine type batteries would be any different in
this regard.


Ed K7AAT