On Wed, 04 Feb 2009 14:07:23 -0500, E Z Peaces
wrote:

mm wrote:
On Tue, 03 Feb 2009 19:52:20 -0500, E Z Peaces
wrote:

Oren wrote:
On Tue, 03 Feb 2009 16:54:26 -0500, E Z Peaces
wrote:

My regulated charger normally tapers to a fraction of an amp. On this
battery, it will stay at 2 amps indefinitely. Most car batteries will
settle at 12.6V when fully charged. This battery settles at 12.3.

I don't have a hydrometer. Could diluted electrolyte cause this problem?
How old is the battery? Signs of a weakening cell?
The battery looks old. It will hold at 12.3 volts for many days, so it
looks as if all cells hold their charge.

Why do you think there is a problem? Does the battery crank the
engine well? (This test is not as good as it might be since so many
cars start immediately now, less than a second of cranking, but if
yours takes longer, it's a good test.)

The battery behaves pretty well. I haven't bothered to check cranking
voltage because it sounds good. It's in a van belonging to a couple who
are away most of the time. I've been charging it occasionally because
extended sitting without charging harms batteries. A few weeks ago they
were about to replace the battery because the van wouldn't start, but I
found resistance at the positive terminal connection.


If you are looking for the smoking gun, you have found it. The battery
has not been getting a good charge for who knows how long. The
battery, left in a partially discharged state for even a few weeks
would have sulfated. That battery may still take a charge, and appear
okay, but it has lost CAPACITY. The somewhat low voltage measurements
after charging indicate exactly that.

On Feb 5, 2:08*am, wrote:
On Wed, 4 Feb 2009 15:18:43 -0500, (Herb and Eneva)
wrote:

*Some chargers do not drop off completly * *If your charger does not
have the special circut it will just keep on charging and charging and
charging.

What is the CHARGING voltage at 2.5 amps after several hours?

There is so much misinformation in this thread (about lead acid
storage batteries as used in autos) it's hard to know where to start.

A typical auto battery these days has six cells each, nominally, 2
volts.

Hence such systems are called 12 volts systems. Actually 14 to around
11.8 volts!*

Some boats, heavy trucks and some military vehicles and some aircraft
have 24 volt (and occasionally 32 volt) systems. Back in the 1940s six
volt systems were common. Although European vehicles, generally, have
always been 12 volt. But leave that aside.

But the voltage across each cell, also assuming they are all in good
and equal condition and therefore the whole battery, will vary over
fairly narrow limits.

Measuring the voltage of standing battery without load is not
necessarily a good indication of the state of the battery.

You cannot say something such as; 14 volts = 100%y charged, 13 volts =
75% charged, 12 volts = 50% charged ........... etc. And unlike a
propane tank/cylinder you can't weigh the battery to see how much is
in it! :-)

Also one bad cell in the series of six can spoil the battery. The bad
cell (or cells) either can't pass the electric current through, or is
itself sufficiently deteriorated to not output (i.e. turn chemicals
back into electrical current). Low temperatures can aggravate the
ability of the battery to reproduce the electrcity that has been
stored in it.

High temperatures including overcharging** can also cause damage and
cause lead sulphation. That's when the battery cells start losing
their ability to store electrcity chemically and reconvert it back to
electrcity when demanded!

Given that voltage is not an indication of how much capacity the
battery has remaining nor does it indicate the capability of the
battery to do the heaviest job of all 'Cold Cranking' of a cold engine
in winter.

Measuring voltage with of a good or bad battery outside the vehicle is
not a good indicator. .

Any battery will most likely show on a voltmeter alone (Which draws a
few thousandths of an amp) something over 12 volts immediately after
being taken off the charger or immediately after the auto engine
engine stops!

However with a reasonably accurate voltmeter it is is possible to
measure the battery in operation in the vehicle and get some idea of
a) Is it being charged b) Is it capable of providing small amounts of
electrcity and also regulate the output of the engine alternator. c)
Crank the engine to start it.

a) Maximum voltage should be around 2.3 to 2.4 volts per cell. So 6 x
2.35 = 14.1 volts. So charging voltage should be around 14 volts.
b) A reasonably charged battery with engine idling but not actually
charge will probably be around 6 x 2.0 to 2.15 volts per cell. So that
around 12 to 13 volts. urn on a few lights, with engine idling a good
battery should maintain 12 volts.
c) Cranking; this is not so much a matter of voltage. Not only will
the battery voltage drop as the battery puts out, for very short time,
the up to 100 amperes of current needed to operate the starting motor,
there will also be voltage drops in the wiring, the starter switch and
starter solenoid/relay etc. The voltage might drop to say 8* volts and
then recover immediately the internal combustion engine starts and
starter disengages.

Here are some practical voltages for lead acid cells used in large
installations where the cost is many thousands of dollars per battery
string and they must power critical systems, sometimes for 8 up to 24
hours.

A) Recharging: 2.3 to 2.4 volts per cell. (May depend on slight
differences and whether North America or European administration).

B) Floating: In service but neither charging of discharging, just
waiting with a full reserve, 2.15 to 2.17 volts per cell.

C) Discharging: For very long periods while battery supplies 'all it's
got', 2.0 volts per cell.

D) As the last percentage of the battery capacity is used the voltage
will then tail off rapidly; how quickly depending on the load at that
point. Lights will be dimming etc. voltage will drop to 11.0 volts and
below.

The six cell (auto service) equivalents for these are;
A) 13.8 to 14.4 volts.
B) 12.9 to 13.0 volts.
C) 12 volts
D) Voltage tails off .............. nothing left.

If battery is charged normally for a normal time period (not
overcharged) then allowed to stand for say 10 to 24 hours and then
shows around 11.3 volts it is most likely useless!

However a friend who is a mechanic took an old uncharged car battery
out of a scapped vehicle to his to his cabin and hooked it up to an
old car radio, probably quarter of an amp? And was surprised that it
had enough chemical action to run the radio for most of the summer!

As Herb says above, some chargers will automatically time or adjust
the charging. Others will just grind away (for a week or more) pushing
current into an already fully charged battery. That merely heats up
the battery and if severe can cause battery to sulphate; which may/
will reduce it's life and usefulness.

One can charge a dead battery for ever and it will not come back to
life. Strengthening the acid, unless some has been spilt is not
advisable, it won't make battery any 'stronger'. Water may/will
evaporate, especially in heat and depending on type of battery may
need to be 'topped up', with chemically pure-clean distilled water.

wrote:
On Tue, 03 Feb 2009 16:54:26 -0500, E Z Peaces
wrote:

My regulated charger normally tapers to a fraction of an amp. On
this battery, it will stay at 2 amps indefinitely. Most car
batteries will settle at 12.6V when fully charged. This battery
settles at 12.3.

I don't have a hydrometer. Could diluted electrolyte cause this
problem?

Most auto parts stores will test a battery for free. Napa, Autozone,
Car Quest, and others. Just take the battery to them and get it
tested.

LM

Yup, and unless they say it's only good to use for table salt, I save
them and use them on the applicances around here that have starters.
Genset, lawn tractor, etc.. They can get quite a bit worse and still
run for years on those! Got 5 more years out of the last one on the
genset before it started to crank slowly.

Cheers,

Twayne

mm wrote:
On Thu, 05 Feb 2009 02:01:50 -0500, E Z Peaces
wrote:

**WE went over the arithmetic on this when I took high school
chemistry, and it's pretty simple and clear once you see it done. It's
not black magic that the voltage continues to a much higher percentage
of normal than the perecentage of charge is.
I'd like to know more about the arithmetic. It seems to me that if the

High school chemistry was 46 years ago. I don't remember the details.

voltage of a certain chemical reaction were 2.1, a 6-cell battery
measured with a 10 megohm meter should read 12.6 whether 1% charged or
100% charged.

For sure not. The amazing thing to me was that the voltage stayed as
high as it does. But given your expectation of 12.6, that shouldn't
amaze you.

Wikipedia says a fully charged cell should be 2.10 to 2.13. It says the
voltage will go down as the charge goes down but doesn't say why.

Alkaline cells are different. A cell that reads 1.45 open may not have
as much life as one that reads 1.35 open. I don't know what causes
differing voltages.

It appears that once a nickel cell has been off the charger awhile, its
no-load voltage won't vary as its charge is used up.


It did happen that everytime I left the lights on for more than an
hour, again the car woudn't start, even with a jump. I used to crawl
under the car, remove the nut, clean the cable end with a knife and
put it back togehter. By the second or third time this was too much
work, too dirty and time consuming, so I just reached down, grabbed
the cablen, and twisted it around the solenoid stud. 10 degrees or
less was enough to make the car start.

I thought about replacing the battery cable--there must have been
something different about it, but I learned not to leave the lights
on.
Neighbors kept calling me when their battery ran down. It seemed to be
the regulator built into their Delco alternator, and I couldn't find the
problem. One day they phoned when their car wouldn't start at the post
office. I happened to touch the positive battery cable and it started.
They'd had somebody replace their starter and the cable wasn't
tightened down at the starter.

They often get dirty in there when they run without being tightened.
Dirt makes resistance, resistance makes heat and a voltage drop. Or
in some other way it doesn't work.

It would work find in the driveway without being touched, so I think at
certain engine speeds the connection was vibrating in a way that
confused the regulator.

Everything had always looked good idling in their driveway, but I guess
sometimes on the road the loose connection would confuse the regulator.
My neighbors called me a fool for not fixing their car sooner. They
considered me their fool because I helped them for free.

These are the same people whose battery you are working on now? They
sound very tactful.

The ones with the battery moved in a couple of years ago and immediately
became best friends with the ones with the starting problem.

On Thu, 05 Feb 2009 02:01:50 -0500, E Z Peaces
wrote:

mm wrote:
On Wed, 4 Feb 2009 04:54:17 -0800 (PST), ransley
wrote:

On Feb 4, 12:43 am, mm wrote:
On Tue, 03 Feb 2009 19:52:20 -0500, E Z Peaces
wrote:

The battery looks old. It will hold at 12.3 volts for many days, so it
looks as if all cells hold their charge.

It depends what you mean by "their charge". 12.3 is too low. When
the connections between the cells were available for voltage
measurement, one could measure the voltage on each cell. Are 5 of
them at 2.1 and the sixth way too low? Maybe. Are all 6 cells at
2.05? Frankly, I doubt it. You probably have a bad cell. A
hydrometer would find it, and I think it is worth the money to have
one and to learn something. When I buy things I keep them forever and
my hydrometer is probably 40 years old now, so the cost of the item
isn't that important. (Unless you are short of storage space.)

A bad cell might have shorted plates. It's more complicated than the
explanatory drawings. There are maybe 6 plus and 6 minus (or more)
plates in each cell and they alternate. This maximizes the power
available for a given size battery. But it also means cells can short,
a plus plate can touch a minus plate, and I don't think there is
anything you can do about it, because the access hole is so small.


If five cells charged normally and one was .3V low, that cell would be
discharged, and I would not expect the charged battery to run the lights
and start the engine normally.


It's not important what you would expect.
An OPEN or high resistance cell will make it so the lights don't light
and the starter doesn't crank properly.

A fully shorted cell is like that cell just isn't there at all - it's
been "jumpered out" - but a fully shorted cell would mean the voltage
(open circuit, no charge being applied) would be 2.1 +/- volts low -
so insted of 12.6 you would have 10.5

10.5 volts from a fully charged 5 cell battery WILL crank and start a
car. When cold, cranking voltage van drop to 9.6 volts and still start
a car.

Because a cell can be PARTLY shorted, it can reduce voltage by less
than a full cell - it may still crank the engine if it is not too
cold, and lights will still work - but your capacity will be quite
reduced.

Like I said before - the ONLY way to know if today's low maintenance ,
sealed, or semi-sealed batteries are any good is to test them on a
"midtronics" type battery tester.

They can test a battery with less than 30% charge remaining with an
accuracy of somewhere around 95%.
Caveat - the midtronics will NEVER give a false "bad" test - but has
been known to say a battery with an intermittent open intercel
connector was good - ONCE.
Put a good load on it, then test it again, and it fails. I've had that
experience and it is not good when a customer is told the battery is
just fine, and then the car can't start to leave the lot!!!!!

A load test, as recommended by some others, is ONLY accurate if the
battery is fully charged - and there is some question whether this is
the case on this particular battery/vehicle.
If one cell had serious leakage, I would expect the battery voltage to
drop to about 10.5 within a week. It stayed at 12.3.




BTW, same chart points out that even when a car battery is 75 percent
discharged, it will still have have 95 percent of its voltage, 12.05
volts**. Twelve sounds like it's almost 12.6 and people might imagine
that a battery with 12 or 12.3 volts is nearly charged.

**WE went over the arithmetic on this when I took high school
chemistry, and it's pretty simple and clear once you see it done. It's
not black magic that the voltage continues to a much higher percentage
of normal than the perecentage of charge is.

I'd like to know more about the arithmetic. It seems to me that if the
voltage of a certain chemical reaction were 2.1, a 6-cell battery
measured with a 10 megohm meter should read 12.6 whether 1% charged or
100% charged.


So my brother gave me the car when he went to Viet Nam, and I took it
to Chicago, and then to Sears, and said I wanted to buy a battery, and
the service guy said, Do you want our free two thousand point
multi-check, and I said, "Not really. I just need a battery." and he
said "It's free. You ought to take it", so not wanting to argue with
the guy, I let him test the car, and he found a bad connection between
the positive battery cable and the starter motor solenoid stud. He
took off the cable, scraped it with a knife on both sides and put it
back. And the car worked fine thereafter. The dealer, out of
business less than 4 years after I got the car, I think spent too much
time replacing big boxes at the end of the wires and too little time
looking at the wires that connected the boxes. I was very impressed by
Sears.

It did happen that everytime I left the lights on for more than an
hour, again the car woudn't start, even with a jump. I used to crawl
under the car, remove the nut, clean the cable end with a knife and
put it back togehter. By the second or third time this was too much
work, too dirty and time consuming, so I just reached down, grabbed
the cablen, and twisted it around the solenoid stud. 10 degrees or
less was enough to make the car start.

I thought about replacing the battery cable--there must have been
something different about it, but I learned not to leave the lights
on.

Neighbors kept calling me when their battery ran down. It seemed to be
the regulator built into their Delco alternator, and I couldn't find the
problem. One day they phoned when their car wouldn't start at the post
office. I happened to touch the positive battery cable and it started.
They'd had somebody replace their starter and the cable wasn't
tightened down at the starter.

Everything had always looked good idling in their driveway, but I guess
sometimes on the road the loose connection would confuse the regulator.
My neighbors called me a fool for not fixing their car sooner. They
considered me their fool because I helped them for free.

On Wed, 04 Feb 2009 18:22:10 -0500, mm
wrote:

On Wed, 04 Feb 2009 14:07:23 -0500, E Z Peaces
wrote:

mm wrote:
On Tue, 03 Feb 2009 19:52:20 -0500, E Z Peaces
wrote:

Oren wrote:
On Tue, 03 Feb 2009 16:54:26 -0500, E Z Peaces
wrote:

My regulated charger normally tapers to a fraction of an amp. On this
battery, it will stay at 2 amps indefinitely. Most car batteries will
settle at 12.6V when fully charged. This battery settles at 12.3.

I don't have a hydrometer. Could diluted electrolyte cause this problem?
How old is the battery? Signs of a weakening cell?
The battery looks old. It will hold at 12.3 volts for many days, so it
looks as if all cells hold their charge.

Why do you think there is a problem? Does the battery crank the
engine well? (This test is not as good as it might be since so many
cars start immediately now, less than a second of cranking, but if
yours takes longer, it's a good test.)

The battery behaves pretty well. I haven't bothered to check cranking
voltage because it sounds good.

Then I wouldn't worry too much. Especially if they are not there
much, now is no time to buy a new battery. It depends on their
personalities and how much money they have. I at least would rather
have a crummy battery and buy a new one only when i was home, using it
every day or two, and actually having trouble starting.

It's in a van belonging to a couple who
are away most of the time. I've been charging it occasionally because
extended sitting without charging harms batteries. A few weeks ago they
were about to replace the battery because the van wouldn't start, but I
found resistance at the positive terminal connection.

Between the battery cable and the positive post? Certainly possible.
Clean it off with baking soda and water. Once I was in a hurry,
taking a friend to catch his train back to NYC. The car stalled at a
red light something was so bad. I touched the battery posts and one
was burning hot. That's not the powerful post, it's the bad
connection. Put on a glove and I just twisted the cable back and
forth until I got a better connection. After I dropped my friend at
the train station, I took the cable off and cleaned it and the post
with a two-endded battery brush. The connection was so bad, I
couldn't even chargethe battery from the car. (I had been having a bit
of trouble but didn't identify it until on the way to the train
station.)

Normal full charge is 12.6, so 12.3 is low. Of course one of my
meters has a separate scale for checking battery voltage from the one
for measuring other voltages in the 20 volt range. Have you tried
your meter on another battery known to be good and fully charged?
Always worth doing.

I checked the meter on a battery that I'd charged two days before. 12.6.

OK. Well 12.3 is's low.

In that connection, I had switched to 10A to check the charging current.
Then I checked voltage across the terminals. Zero... uh-oh, the plugs
were in the 10A jacks. I've damaged meters that way before, and I never
learn. This time there was no arc.

That's strange. You probably blew a fuse. Even some cheap ones have a
fuse.


Poly-fuses are getting pretty cheap these days and are used for a lot
of those applications. It's like a conductive wax thet melts when it
gets hot - and doesn't conduct when melted, but when it cools it
reforms and conducts again.

That is NOT the exact explanation of how it works. Note I said it is
LIKE - so don't bother flamong me if you happen to be an electronics
wizzard.
You can also replace the resistor if you burned out one of those. If
you can't determine what the resistance shoucl be, often there is
apattern, 2 ohms 20, 200, 2k, 20K, 200k, 2Meg. Or maybe 5.1 etc.
Plus maybe you can find the schematic.

At home, I checked it on a 5A
source and got a good reading. Could my cheap DMM have circuit
protection on the 10A inputs? I need to take it apart and see!

Maybe. It might even have what's it called, that lets the current go
ahrough when the voltage is high enough.

More below

Get someone to measure the voltage why you are cranking the engine.
Take off the coil wire to the distributor if you have to. If the
voltage doesn't fall much, the battery's good, but I forget how much
is not much. I think if it stays above 9 or 10 volts, you're in good
shape. Less in cold weather.

Siphon some water out of each cell (turkey boaster) and add battery
acid, then try another charge.

I'm just curious about the symptoms.

It would be easier to buy a hydrometer. If they're all a little dilute,
I think I'd leave them alone.

They certainly won't all be dilute, unless somehow electrolyte was
spilled out of all of them.

Have you even checked the water level yet? As my brother puts it,
"Check your erl and your bachery?"

The water level is good. As I don't know where the battery came from, I
don't know what it was filled with.

Decades ago, I got a manual a major manufacturer had published for
dealers. It said that a battery sold in Toronto may have a stronger
electrolyte than one sold in Miami. Higher acid concentrations help in
cold weather but shorten battery life in hot weather.

I think some batteries are shipped dry, and the dealer adds a mixture of
distilled water and acid drawn from a bulk container.

Absolutely Delco advertised for decades that its batteries were
dry-charged, shipped without acid. I think that means they don't
discharge or age in any way when they sit on the shelf in the
warehouse or the store. Maybe they don't do that anymore, but the
motorcycle I bought 2 years ago was like that. It came with a plastic
bag/box of acid for me to add.


Suppose the
dealer used a mixture 30% too weak, perhaps for longer hot-weather life
or because he didn't have enough acid or because he wasn't good at
measuring. I wonder if that could cause the effect I see.

Could that actually happen? I always thought the acid was pre-mixed.
It certainly was with the motorcycle battery I bought. I am opposed
to shipping water around (like the pre-mixed windshield washer fluid)
but no6 in this case.

If the battery has sulfation too hard for the charger to break down, I
guess that, too, could keep the battery from charging fully.

Slow charging, with a 1-amp charger, works best, but takes over 24
hours to charge a fully discharged battery. Now that I have a job,
I'm happy to use my 10 amp max charger, which puts enough in to start
the car after 10 minutes. After the car started, I used to then keep
the heater fan on high (which uses a lot more current than headlights
do, and is actually sufficient to lower the charging rate) while I
drove, so that the battery would charge more slowly. Now that the
stupid new cars don't even have ammeters, and the thrill of installing
one only lasted me through one car, I don't even bother. It doesn't
really seem to have shortened my battery life. I still get 5 years,
and I had never been able to get more than that anyhow.

On Thu, 05 Feb 2009 01:25:11 -0500, E Z Peaces
wrote:

mm wrote:
On Wed, 04 Feb 2009 14:07:23 -0500, E Z Peaces
wrote:



In that connection, I had switched to 10A to check the charging current.
Then I checked voltage across the terminals. Zero... uh-oh, the plugs
were in the 10A jacks. I've damaged meters that way before, and I never
learn. This time there was no arc.

That's strange. You probably blew a fuse. Even some cheap ones have a
fuse.

You can also replace the resistor if you burned out one of those. If
you can't determine what the resistance shoucl be, often there is
apattern, 2 ohms 20, 200, 2k, 20K, 200k, 2Meg. Or maybe 5.1 etc.
Plus maybe you can find the schematic.

I opened the meter. It's about 40mm of wire, about 12 gage, between the
10A and Common terminals. No sign that it has been hot. On meters I've
damaged, the only visible sign was discoloration of the wire, but they
would no longer give consistent amp readings.


At home, I checked it on a 5A
source and got a good reading. Could my cheap DMM have circuit
protection on the 10A inputs? I need to take it apart and see!

Maybe. It might even have what's it called, that lets the current go
ahrough when the voltage is high enough.

It's a cheap meter. I've often had to use contact cleaner to get
continuity at the input jacks. My theory is that due to invisible
corrosion, the contact patch between the test-lead plug and the jack was
so small that when the battery surge hit, it immediately overheated,
breaking contact and protecting the meter. What luck! Cheap stuff
works best!


Suppose the
dealer used a mixture 30% too weak, perhaps for longer hot-weather life
or because he didn't have enough acid or because he wasn't good at
measuring. I wonder if that could cause the effect I see.

Could that actually happen? I always thought the acid was pre-mixed.
It certainly was with the motorcycle battery I bought. I am opposed
to shipping water around (like the pre-mixed windshield washer fluid)
but no6 in this case.

If the battery has sulfation too hard for the charger to break down, I
guess that, too, could keep the battery from charging fully.

Slow charging, with a 1-amp charger, works best, but takes over 24
hours to charge a fully discharged battery. Now that I have a job,
I'm happy to use my 10 amp max charger, which puts enough in to start
the car after 10 minutes. After the car started, I used to then keep
the heater fan on high (which uses a lot more current than headlights
do, and is actually sufficient to lower the charging rate) while I
drove, so that the battery would charge more slowly. Now that the
stupid new cars don't even have ammeters, and the thrill of installing
one only lasted me through one car, I don't even bother. It doesn't
really seem to have shortened my battery life. I still get 5 years,
and I had never been able to get more than that anyhow.

I have another theory now. Whenever you start an engine with a battery
that's not fully charged, you may pop sulfate off the plates. Batteries
have room at the bottom where it can settle without causing electrical
leakage between plates. The sulfate that pops off is lead and acid that
can't be recovered by charging.

I'll bet that battery has been used countless times to start when not
well charged. I'll bet sulfate at the bottom of the battery accounts
for my inability to charge it above 12.3V. (About 60%?)

That is what is known as a "shorted" cell. And it is not sulphate,
necessarily. It is "active material" which is spongy lead and lead
oxide.. When a battery is dead, both plates are basically lead
sulphate (pbS04) and the electrolyte is basically water. Fully charged
the electrolyte absorbs the sulphate, becoming H2S04 leaving one plate
pb and the other pb02.

terry wrote:
On Feb 5, 2:08 am, wrote:
On Wed, 4 Feb 2009 15:18:43 -0500, (Herb and Eneva)
wrote:

Some chargers do not drop off completly If your charger does not
have the special circut it will just keep on charging and charging and
charging.
What is the CHARGING voltage at 2.5 amps after several hours?

There is so much misinformation in this thread (about lead acid
storage batteries as used in autos) it's hard to know where to start.

A typical auto battery these days has six cells each, nominally, 2
volts.

Hence such systems are called 12 volts systems. Actually 14 to around
11.8 volts!*

Maintenance-free batteries resist high charging voltages better than
conventional ones, and 15V can be appropriate. (I think the appropriate
voltage can be higher in cold weather. Modern regulators figure that
stuff out.)

In my car, I made a panel meter using a cheap movement, diodes, and
resistors. The needle swings 90 degrees between 11.8 and 15 volts. It
may serve better than an ammeter. Before I start, when I turn the key I
expect about 12.6V. After I start, it shows what the alternator is
doing. If it's not over 14 by the time I get home, I know I haven't
been driving enough to keep the battery charged and I'd better use a
charger. In winter it's often at 15.



But the voltage across each cell, also assuming they are all in good
and equal condition and therefore the whole battery, will vary over
fairly narrow limits.

Measuring the voltage of standing battery without load is not
necessarily a good indication of the state of the battery.

I don't understand the chemistry, but it shows me if a battery is
charged. Different authorities may give slightly different figures.

On Thu, 5 Feb 2009 05:00:50 -0800 (PST), terry
wrote:

On Feb 5, 2:08Â*am, wrote:
On Wed, 4 Feb 2009 15:18:43 -0500, (Herb and Eneva)
wrote:

Â*Some chargers do not drop off completly Â* Â*If your charger does not
have the special circut it will just keep on charging and charging and
charging.

What is the CHARGING voltage at 2.5 amps after several hours?

There is so much misinformation in this thread (about lead acid
storage batteries as used in autos) it's hard to know where to start.

A typical auto battery these days has six cells each, nominally, 2
volts.

Hence such systems are called 12 volts systems. Actually 14 to around
11.8 volts!*

Some boats, heavy trucks and some military vehicles and some aircraft
have 24 volt (and occasionally 32 volt) systems. Back in the 1940s six
volt systems were common. Although European vehicles, generally, have
always been 12 volt. But leave that aside.

But the voltage across each cell, also assuming they are all in good
and equal condition and therefore the whole battery, will vary over
fairly narrow limits.

Measuring the voltage of standing battery without load is not
necessarily a good indication of the state of the battery.

You cannot say something such as; 14 volts = 100%y charged, 13 volts =
75% charged, 12 volts = 50% charged ........... etc. And unlike a
propane tank/cylinder you can't weigh the battery to see how much is
in it! :-)

Also one bad cell in the series of six can spoil the battery. The bad
cell (or cells) either can't pass the electric current through, or is
itself sufficiently deteriorated to not output (i.e. turn chemicals
back into electrical current). Low temperatures can aggravate the
ability of the battery to reproduce the electrcity that has been
stored in it.

High temperatures including overcharging** can also cause damage and
cause lead sulphation. That's when the battery cells start losing
their ability to store electrcity chemically and reconvert it back to
electrcity when demanded!

Given that voltage is not an indication of how much capacity the
battery has remaining nor does it indicate the capability of the
battery to do the heaviest job of all 'Cold Cranking' of a cold engine
in winter.

Measuring voltage with of a good or bad battery outside the vehicle is
not a good indicator. .

Any battery will most likely show on a voltmeter alone (Which draws a
few thousandths of an amp) something over 12 volts immediately after
being taken off the charger or immediately after the auto engine
engine stops!

However with a reasonably accurate voltmeter it is is possible to
measure the battery in operation in the vehicle and get some idea of
a) Is it being charged b) Is it capable of providing small amounts of
electrcity and also regulate the output of the engine alternator. c)
Crank the engine to start it.

a) Maximum voltage should be around 2.3 to 2.4 volts per cell. So 6 x
2.35 = 14.1 volts. So charging voltage should be around 14 volts.
b) A reasonably charged battery with engine idling but not actually
charge will probably be around 6 x 2.0 to 2.15 volts per cell. So that
around 12 to 13 volts. urn on a few lights, with engine idling a good
battery should maintain 12 volts.
c) Cranking; this is not so much a matter of voltage. Not only will
the battery voltage drop as the battery puts out, for very short time,
the up to 100 amperes of current needed to operate the starting motor,
there will also be voltage drops in the wiring, the starter switch and
starter solenoid/relay etc. The voltage might drop to say 8* volts and
then recover immediately the internal combustion engine starts and
starter disengages.

Here are some practical voltages for lead acid cells used in large
installations where the cost is many thousands of dollars per battery
string and they must power critical systems, sometimes for 8 up to 24
hours.

A) Recharging: 2.3 to 2.4 volts per cell. (May depend on slight
differences and whether North America or European administration).

B) Floating: In service but neither charging of discharging, just
waiting with a full reserve, 2.15 to 2.17 volts per cell.

C) Discharging: For very long periods while battery supplies 'all it's
got', 2.0 volts per cell.

D) As the last percentage of the battery capacity is used the voltage
will then tail off rapidly; how quickly depending on the load at that
point. Lights will be dimming etc. voltage will drop to 11.0 volts and
below.

The six cell (auto service) equivalents for these are;
A) 13.8 to 14.4 volts.
B) 12.9 to 13.0 volts.
C) 12 volts
D) Voltage tails off .............. nothing left.

If battery is charged normally for a normal time period (not
overcharged) then allowed to stand for say 10 to 24 hours and then
shows around 11.3 volts it is most likely useless!

However a friend who is a mechanic took an old uncharged car battery
out of a scapped vehicle to his to his cabin and hooked it up to an
old car radio, probably quarter of an amp? And was surprised that it
had enough chemical action to run the radio for most of the summer!

As Herb says above, some chargers will automatically time or adjust
the charging. Others will just grind away (for a week or more) pushing
current into an already fully charged battery. That merely heats up
the battery and if severe can cause battery to sulphate; which may/
will reduce it's life and usefulness.


You've been pretty well on the mark so far - but you missed it here. A
fully charged battery will NEVER sulphate as all the "sulphate" is in
the acid. Discharged batteries sulphate.

One can charge a dead battery for ever and it will not come back to
life.

This is the classic result of "sulphation" All the "sulphate" is in
the lead and can't be driven back into the electrolyte. (to turn the
water back into acid)

Strengthening the acid, unless some has been spilt is not
advisable, it won't make battery any 'stronger'. Water may/will
evaporate, especially in heat and depending on type of battery may
need to be 'topped up', with chemically pure-clean distilled water.

You are right.

Strengthening the acid will make the battery put out more voltage -
for a very short time - but will certainly not fix it. It WILL make
the Hydrometer read closer to what you want it to read - but that's
about all. The plates are still very close to uniform in composition -
PbS04
A total waste.

On Thu, 05 Feb 2009 04:04:59 -0600, wrote:

On Tue, 03 Feb 2009 16:54:26 -0500, E Z Peaces
wrote:

My regulated charger normally tapers to a fraction of an amp. On this
battery, it will stay at 2 amps indefinitely. Most car batteries will
settle at 12.6V when fully charged. This battery settles at 12.3.

I don't have a hydrometer. Could diluted electrolyte cause this problem?

Most auto parts stores will test a battery for free. Napa, Autozone,
Car Quest, and others. Just take the battery to them and get it
tested.

LM
MOST of them even have a MidTronics tester!!

wrote:
On Thu, 05 Feb 2009 02:01:50 -0500, E Z Peaces
wrote:


If five cells charged normally and one was .3V low, that cell would be
discharged, and I would not expect the charged battery to run the lights
and start the engine normally.


It's not important what you would expect.
An OPEN or high resistance cell will make it so the lights don't light
and the starter doesn't crank properly.

If a cell drained through leakage between plates of a couple of amps or
so, I would expect fairly high resistance from watery electrolyte. I
say that because if a battery goes flat (leaving lights on, for example)
it won't accept much charging current at first.

If a cell were nearly drained, I might see more than 12V with no load,
but I would expect less than 10.5 with the lights on.

A fully shorted cell is like that cell just isn't there at all - it's
been "jumpered out" - but a fully shorted cell would mean the voltage
(open circuit, no charge being applied) would be 2.1 +/- volts low -
so insted of 12.6 you would have 10.5

When the battery kept drawing 2 amps from the charger, the first thing I
did was check for a shorted cell with a voltmeter.


10.5 volts from a fully charged 5 cell battery WILL crank and start a
car. When cold, cranking voltage van drop to 9.6 volts and still start
a car.

If 6 cells will feed a starter 10 volts, 5 cells would feed it only about 8.


Because a cell can be PARTLY shorted, it can reduce voltage by less
than a full cell - it may still crank the engine if it is not too
cold, and lights will still work - but your capacity will be quite
reduced.

I think a battery with partial shorting could work fine shortly after
charging. I disconnected the battery to get rid of the 30ma drain from
the van's equipment, then checked the battery a few days later. The
voltage was the same.


Like I said before - the ONLY way to know if today's low maintenance ,
sealed, or semi-sealed batteries are any good is to test them on a
"midtronics" type battery tester.

They can test a battery with less than 30% charge remaining with an
accuracy of somewhere around 95%.
Caveat - the midtronics will NEVER give a false "bad" test - but has
been known to say a battery with an intermittent open intercel
connector was good - ONCE.

I once had a battery like that.

Put a good load on it, then test it again, and it fails. I've had that
experience and it is not good when a customer is told the battery is
just fine, and then the car can't start to leave the lot!!!!!

A load test, as recommended by some others, is ONLY accurate if the
battery is fully charged - and there is some question whether this is
the case on this particular battery/vehicle.

This battery holds its charge and handles the starter load very well, so
I wouldn't tell the owner to buy a new one yet.

On Fri, 06 Feb 2009 15:14:17 -0500, E Z Peaces
wrote:

wrote:
On Thu, 05 Feb 2009 02:01:50 -0500, E Z Peaces
wrote:


If five cells charged normally and one was .3V low, that cell would be
discharged, and I would not expect the charged battery to run the lights
and start the engine normally.


It's not important what you would expect.
An OPEN or high resistance cell will make it so the lights don't light
and the starter doesn't crank properly.

If a cell drained through leakage between plates of a couple of amps or
so, I would expect fairly high resistance from watery electrolyte. I
say that because if a battery goes flat (leaving lights on, for example)
it won't accept much charging current at first.

You don't get it. The cell is SHORTED. By definition, a short is a
VERY LOW resistance. The watery electrolyte has absolutely nothing to
do with it.

If a cell were nearly drained, I might see more than 12V with no load,
but I would expect less than 10.5 with the lights on.

A fully shorted cell is like that cell just isn't there at all - it's
been "jumpered out" - but a fully shorted cell would mean the voltage
(open circuit, no charge being applied) would be 2.1 +/- volts low -
so insted of 12.6 you would have 10.5

When the battery kept drawing 2 amps from the charger, the first thing I
did was check for a shorted cell with a voltmeter.

And how did you do that? On TarTops you COULD check cell to cell with
a voltmeter with high accuracy. On monoltyhic hard tops that is pretty
difficult.

Have you taken the battery in to have it tested on a Midtronics
tester?

If not, you know NOTHING.

10.5 volts from a fully charged 5 cell battery WILL crank and start a
car. When cold, cranking voltage van drop to 9.6 volts and still start
a car.

If 6 cells will feed a starter 10 volts, 5 cells would feed it only about 8.
Not necessarily - depends on the resistance of the "shorted" cell.


Because a cell can be PARTLY shorted, it can reduce voltage by less
than a full cell - it may still crank the engine if it is not too
cold, and lights will still work - but your capacity will be quite
reduced.

I think a battery with partial shorting could work fine shortly after
charging. I disconnected the battery to get rid of the 30ma drain from
the van's equipment, then checked the battery a few days later. The
voltage was the same.

You think wrong my friend. A battery with a shorted cell, or a partly
shorted cell will NEVER work FINE. It MIGHT kinda sneak by, but that
is all.


Like I said before - the ONLY way to know if today's low maintenance ,
sealed, or semi-sealed batteries are any good is to test them on a
"midtronics" type battery tester.

They can test a battery with less than 30% charge remaining with an
accuracy of somewhere around 95%.
Caveat - the midtronics will NEVER give a false "bad" test - but has
been known to say a battery with an intermittent open intercel
connector was good - ONCE.

I once had a battery like that.

Put a good load on it, then test it again, and it fails. I've had that
experience and it is not good when a customer is told the battery is
just fine, and then the car can't start to leave the lot!!!!!

A load test, as recommended by some others, is ONLY accurate if the
battery is fully charged - and there is some question whether this is
the case on this particular battery/vehicle.

This battery holds its charge and handles the starter load very well, so
I wouldn't tell the owner to buy a new one yet.

That's up to you - but if the battery voltage is consistently low
SOMETHING is wrong. It COULD be your voltmeter, you know.
Not likely, but possible.

For more than you probably want to know about batteries:

http://www.batteryfaq.org

wrote:
On Fri, 06 Feb 2009 15:14:17 -0500, E Z Peaces
wrote:

wrote:

An OPEN or high resistance cell will make it so the lights don't light
and the starter doesn't crank properly.
If a cell drained through leakage between plates of a couple of amps or
so, I would expect fairly high resistance from watery electrolyte. I
say that because if a battery goes flat (leaving lights on, for example)
it won't accept much charging current at first.

You don't get it. The cell is SHORTED. By definition, a short is a
VERY LOW resistance. The watery electrolyte has absolutely nothing to
do with it.

You just said it was "an open or high resistance cell." I thought by
"high resistance" you meant a slow internal drain.


When the battery kept drawing 2 amps from the charger, the first thing I
did was check for a shorted cell with a voltmeter.

And how did you do that? On TarTops you COULD check cell to cell with
a voltmeter with high accuracy. On monoltyhic hard tops that is pretty
difficult.

It's easy if you read the numbers on the meter. If you have one shorted
cell, you'll see about 10.5V.


If 6 cells will feed a starter 10 volts, 5 cells would feed it only about 8.
Not necessarily - depends on the resistance of the "shorted" cell.
Because a cell can be PARTLY shorted, it can reduce voltage by less
than a full cell - it may still crank the engine if it is not too
cold, and lights will still work - but your capacity will be quite
reduced.
I think a battery with partial shorting could work fine shortly after
charging. I disconnected the battery to get rid of the 30ma drain from
the van's equipment, then checked the battery a few days later. The
voltage was the same.

You think wrong my friend. A battery with a shorted cell, or a partly
shorted cell will NEVER work FINE. It MIGHT kinda sneak by, but that
is all.

You've introduced the concept of partial shorting. They're all like
that. I believe a new conventional lead-acid battery on the shelf will
drain in a month or so at room temperature. (Maintenance-free batteries
drain more slowly.) New batteries have "partial shorts" and most work fine.

Rich256 wrote:
For more than you probably want to know about batteries:

http://www.batteryfaq.org

Thanks, it looks like a gold mine.

I see you can expect 1000 starts if your battery is typically at 60%
charge and 13,000 starts if it stays at 100%. That's why I made a panel
meter to alert me when my battery needs topping off.

I'll see if the site leads me to a chemical explanation of why voltage
works as an indicator of the state of charge.

On Sat, 07 Feb 2009 12:27:32 -0500, E Z Peaces
wrote:

wrote:
On Fri, 06 Feb 2009 15:14:17 -0500, E Z Peaces
wrote:

wrote:

An OPEN or high resistance cell will make it so the lights don't light
and the starter doesn't crank properly.
If a cell drained through leakage between plates of a couple of amps or
so, I would expect fairly high resistance from watery electrolyte. I
say that because if a battery goes flat (leaving lights on, for example)
it won't accept much charging current at first.

You don't get it. The cell is SHORTED. By definition, a short is a
VERY LOW resistance. The watery electrolyte has absolutely nothing to
do with it.

You just said it was "an open or high resistance cell." I thought by
"high resistance" you meant a slow internal drain.


When the battery kept drawing 2 amps from the charger, the first thing I
did was check for a shorted cell with a voltmeter.

And how did you do that? On TarTops you COULD check cell to cell with
a voltmeter with high accuracy. On monoltyhic hard tops that is pretty
difficult.

It's easy if you read the numbers on the meter. If you have one shorted
cell, you'll see about 10.5V.

If you nhave a totally dead battery you will too, or if you have
several partly shorted cells. But you are right, GENERALLY a battery
that is down roughly 2 volts AND STILL CRANKS AN ENGINE has a shorted
cell.

If 6 cells will feed a starter 10 volts, 5 cells would feed it only about 8.
Not necessarily - depends on the resistance of the "shorted" cell.
Because a cell can be PARTLY shorted, it can reduce voltage by less
than a full cell - it may still crank the engine if it is not too
cold, and lights will still work - but your capacity will be quite
reduced.
I think a battery with partial shorting could work fine shortly after
charging. I disconnected the battery to get rid of the 30ma drain from
the van's equipment, then checked the battery a few days later. The
voltage was the same.

You think wrong my friend. A battery with a shorted cell, or a partly
shorted cell will NEVER work FINE. It MIGHT kinda sneak by, but that
is all.

You've introduced the concept of partial shorting. They're all like
that. I believe a new conventional lead-acid battery on the shelf will
drain in a month or so at room temperature. (Maintenance-free batteries
drain more slowly.) New batteries have "partial shorts" and most work fine.

No, new batteries do not have "partial shorts" they have self
discharge, which is "normal" but it won't drain in a month. A GOOD
lead acid battery will hold about 80% charge for 6 months.
A "pure lead" battery = no calcium or antimony, will hold a LOT longer
than that. A Hawker Genesis EP has a "shelf life" of almost 3 years.

On Sat, 07 Feb 2009 12:49:18 -0500, E Z Peaces
wrote:

Rich256 wrote:
For more than you probably want to know about batteries:

http://www.batteryfaq.org

Thanks, it looks like a gold mine.

I see you can expect 1000 starts if your battery is typically at 60%
charge and 13,000 starts if it stays at 100%. That's why I made a panel
meter to alert me when my battery needs topping off.

I'll see if the site leads me to a chemical explanation of why voltage
works as an indicator of the state of charge.
That's simple - the electrical potential difference between dislike
materials. Lead to lead oxide is 2.15 volts, more or less. Between
lead sulphate and lead sulphate is 0 volts. The percentage
concentration of lead sulphate difference between the plates indicates
the level of charge and the potential difference between the plates.

wrote:
On Sat, 07 Feb 2009 12:27:32 -0500, E Z Peaces
wrote:



When the battery kept drawing 2 amps from the charger, the first thing I
did was check for a shorted cell with a voltmeter.

And how did you do that? On TarTops you COULD check cell to cell with
a voltmeter with high accuracy. On monoltyhic hard tops that is pretty
difficult.
It's easy if you read the numbers on the meter. If you have one shorted
cell, you'll see about 10.5V.

If you nhave a totally dead battery you will too, or if you have
several partly shorted cells. But you are right, GENERALLY a battery
that is down roughly 2 volts AND STILL CRANKS AN ENGINE has a shorted
cell.

A totally dead battery won't show 10.5V with the lights on.

What would be the point of trying to crank the engine? If five good
cells cranked it one day, they might not do it the next. Under a big
load, they could produce less than 8V.


You've introduced the concept of partial shorting. They're all like
that. I believe a new conventional lead-acid battery on the shelf will
drain in a month or so at room temperature. (Maintenance-free batteries
drain more slowly.) New batteries have "partial shorts" and most work fine.

No, new batteries do not have "partial shorts" they have self
discharge,

All batteries have electrical leakage within the cells.


which is "normal" but it won't drain in a month. A GOOD
lead acid battery will hold about 80% charge for 6 months.

On the shelf, a typical car battery will be down to 80% in 12 days at
100F, 30 days at 80F, and 100 days at 50F. A particular model may
discharge faster or slower.

A "pure lead" battery = no calcium or antimony, will hold a LOT longer
than that. A Hawker Genesis EP has a "shelf life" of almost 3 years.

That's lead-tin stored at a cool temperature. Are they practical?

Car manufacturers use batteries intended to start the vehicle after two
weeks parked. If you disconnect the battery, the time you can park and
still get started varies from 1 to 6 months, depending on the
temperature and the model of battery.

wrote:
On Sat, 07 Feb 2009 12:49:18 -0500, E Z Peaces
wrote:

Rich256 wrote:
For more than you probably want to know about batteries:

http://www.batteryfaq.org

Thanks, it looks like a gold mine.

I see you can expect 1000 starts if your battery is typically at 60%
charge and 13,000 starts if it stays at 100%. That's why I made a panel
meter to alert me when my battery needs topping off.

I'll see if the site leads me to a chemical explanation of why voltage
works as an indicator of the state of charge.
That's simple - the electrical potential difference between dislike
materials. Lead to lead oxide is 2.15 volts, more or less. Between
lead sulphate and lead sulphate is 0 volts. The percentage
concentration of lead sulphate difference between the plates indicates
the level of charge and the potential difference between the plates.


Why does the acid concentration change the 2.15V between lead and lead
oxide? Is there a table somewhere? Does temperature affect it?