The cells in a lead acid battery hold 2.12v and there are 6 of them in a
12v battery, so a charged battery has 12.7v.
This is true regardless of the size of the cells. Big batteries have the
same voltage as small batteries.
The difference between big and small is the current. Remember that a lead
acid battery needs to supply enough current to spin your engine rapidly on a
cold morning. If it can't your car won't start. These batteries are current
As your battery ages the cell's plates lose functional surface area. That
means that they become smaller and can hold less current. Less current on a
cold morning means it won't start.
Many car shops will test your battery.
A good reply.
(I also assume the OP is referring to his car)
Assuming a cell has not failed outright, it is normal for a battery to
shed "active material" from it's plates during charge.
At one time, it was rare for a car battery to last more than three
years, but now days they can go twice that long.
We do not have the full story from the OP however.
Is the battery getting properly charged in the first place?
With the engine running, the battery voltage should be a bit below 14
volts. If it's under 13 volts, there is a problem with the car's
If the charing system is OK then yes, the battery could be weak...
however there is also a chance something is draining the battery over
night...possibly a light on at all times in the trunk.
A simple test ( if one does not have the ability to test for current
drain) would be to simply disconnect the battery and if it's still dead
the next day, then the battery is indeed bad.
12v wet cell car battery? And how does it
store up electricity? I have one that needs
charging every day. I guess it`s time to
get a new one.
Charging makes a chemical change, some thing
about lead oxide changing to lead sulphate, or
some such thing. You can find this on the web
Car batteries that need a charge every day "might"
be defective, or might be other problems. I had a
Blazer that needed charging every day, even though
the battery was brand new. But, you didn't ask about
that, sorry for rambling on. It was a problem with.....
ah, you didn't ask. Nevermind.
Yeah, replace the battery. It's like heating, it's
always the thermostat. Write back when you get the new
battery in, let us know how it went. It's always the
Maybe, maybe not. It could be dead/dying or there might be a small
electrical short somewhere that is draining it.
The latter happened to a car my wife had. Trouble is, there are so MANY
places where it could occur and could take a long time at expensive hours
to find. Since her car was soon to be replaced anyway, they put a small
trickle on the battery, letting it rest inside the hood; an electrical
wire dangled down and she just plugged in the charger when the car was
garaged for the night.
The easy test, as philo said, is to disconnect the charged battery and see
if it is dead the next morning;if yes, go get a new battery; if no, start
checking for a short. Or get a trickle charger :)
On Thursday, December 11, 2014 9:44:37 AM UTC-5, dadiOH wrote:
Could be, as you say, a parasitic drain. And if it is, if you have to
charge a battery every day, it won't be long before the battery is shot.
Car batteries are designed for starting, not deep discharge. The more
you deeply discharge it, the shorter the life. Letting it sit discharged
is bad too.
This web page explains what happens when a lead acid battery discharges
and what happens when you recharge a lead acid battery:
'How Lead Acid Batteries Work: Battery Basics from Progressive Dynamics'
In a nutshell:
1.) A lead acid battery has positive and negative plates made of lead
immersed in a pool of diluted sulfuric acid.
2.) When you put a load on a lead acid battery, the battery discharges
through that load and lead sulfate forms on the lead plates, thereby
reducing the voltage generated by each of the six cells in the battery.
As the battery discharges, more and more of the lead plate surface area
is coated with lead sulfate. If the battery is left in a discharged
state, the lead sulfate on the plates will harden so that it doesn't
break down on recharging the battery, and the result will be a ruined
3.) When you recharge a lead acid battery, the lead sulfate on the
plates reverts back to lead and sulfur with the lead going back onto the
plates and the sulfur ions going back into solution in the electrolyte,
thereby restoring the battery to it's original condition.
4.) This process of lead sulfate formation on the lead plates happens
over and over again inside the battery every time it is discharged and
'David Martel[_2_ Wrote:
> your engine rapidly on a cold morning. If it can't your car won't
I'm wondering exactly why spinning the engine rapidly is essential for
Is it because rapid spinning ensures good compression of the air/fuel
mixture in the combustion chamber and hence a much more rapid spin once
that cylinder fires and gnerates a power stroke to the crankshaft? It
would seem to me that without sufficient compression, the air/fuel
mixture would still burn, but wouldn't provide a power stroke to the
crankshaft to get the engine running.
On Thu, 11 Dec 2014 03:26:50 -0800 (PST), herb white
It doesn't store electricity. For one thing, electricity is the flow
of electrons and when something is stored it woudl be a waste of energy
to keep it flowing.
It stores substances which have the power to generate electricity.
It won't start the car in the morning? Even if you drove yesterday?
It might be the alternator and not the battery. It might be a bad
My brother once bought a brand new car and the dealer replaced the
alternator, the battery, and the starter, all twice, and still didn't
fix it. After my brother went to Viet Nam, I took the car to Sears for
a new battery (which it did need) and they did their free 23,246 point
multi-check and found the problem in less than 5 minutes. It was a
dirty connection where the battery cable was bolted on to the starter.
But an alternator can do that too. When the car is running, the voltage
across the battery posts shold be over 13 volts. I think the proper
value is 13.4 or 13.6, but I forget. But it must be several points
higher than the voltage of a moderately charged battery itself, which is
12. 6. If it's not higher it won't be able to force current into the
battery in the opposite direction from the one the battery wants to use
to force current out.
On Friday, December 12, 2014 12:22:05 AM UTC-5, micky wrote:
You should tell that to the idiots or liars
at one of the Advanced Auto Parts stores here. I took a two year old
alternator in that was under warranty, that wouldn't keep the new
car battery charged. They hooked it up to their tester and proclaimed
that it passed, it was OK. I asked what voltage they were seeing,
because, like you say, I was not seeing much above 12V. They said
12.3V. I'm telling them that a fully charged battery is 12.6V, and
you need higher than that, ie the 13V+ that you're talking about.
They assured me that it was perfectly fine and that I should put it
back in the car, bring the whole car to them, so that they could do
further testing, because their alternator tester doesn't put as large
a load on the alternator as the actual car. Makes sense, right? The
alternator can only put out 12.3V with their smaller load, so it's
going to work better with a larger load? And the freaking alternator
is rated at 120A. You would think a decent tester would load it to
that. And this tester was the size of a small refrigerator, not a
handheld unit. A mechanic happened to be in the store, overheard what
was going on and he told them 12.3V is a bad alternator, but they
wouldn't budge. Like I'm going to put a bad alternator back in the car?
So, I learned from that. I went to another Advanced Auto Parts and
this time, instead of telling them I had an alternator that was under
warranty, I just said "Can you test this alternator please?" Within
5 mins they declared it toast. At which point I said, "well, the bad
news for you is that it's under warranty....."
And then the story gets even better.
This was a 2 year old Beck/Arnley rebuilt alternator with a 3 year warranty.
They no longer carry B/A. So, you would think they would give me
whatever they do carry that is roughly the same, which of course they
had. But they had their own unique approach. They credited me back
for the full price of the B/A alternator, which was $250. Then they
sold me another rebuilt one, that one only cost $190. So, I got a
replacement rebuilt alternator and $60 back.
The story continues though. That alternator wouldn't fit, because
while the car will take either a Bosch frame or Valeo frame alternator,
the pulley is 1/2" different between them and you need the right
pulley. That lead to the next fiasco, many trips to the auto parts
stores, because while the part number indicates it's Valeo, what's
actually in the box is Bosch. Then some of them come with a pulley,
most don't. If it came with the pulley, then there would be no problem.
But I had a Valeo pulley and can't use it with the more common Bosch
frame ones. Ultimately I got one at PEP Boys. It took tracking down
which stores showed it in stock, then having them pull several boxes
to see what was actually in them. Finally one turned out to be the
Valeo, which would work. But the best part is that alternator cost
$150 and has a lifetime warranty. Not bad, $100 back and upgrade to lifetime warranty. But it sure wasn't worth all the trips and screwing around.
For anyone who has that problem, and that might well be the OP, I r
recommend Priority Start.
It's a box that connects between the postive terminal of the battery and
the positive battery cable. It's about 3x5x1 inch thick. Maybe a
little more. It also has one wire that must be grounded, possibly to
the negative battery terminal.
It monitors the voltage and disconnects the battery when the volage gets
too low. To reconnect, turn on something that uses more than a tiny bit
of electricity. For example, put your foot on the brakes. Actually I
think it's worked for me when I've only opened the door and turned on
one light bulb next to the rear seat, but I'm not sure.
I needed new battery soon after I got my last car, and I forget how,
but I ran the battery down several times and somehow that pretty much
ruined it. At the time I was using a Battery Buddy, which is similar
to , but has a better name than, Priority Start. (MY first Battery
Buddy lasted over 20 years, but the second one only 3. They don't sell
Priority Start seems to have been designed for fleet trucks, it even has
a 24 volt version, but it works in cars fine.
My battery is so bad, I can only listen to the radio with the engine off
for less than a minute. But when I put my food on the brake, 5 seconds
later, the car starts easily. Then I can turn the radio back on.
I felt guilty about ruining a new battery. I could return it and pay
little for a replacement, but with Priority Start, I've gone almost 2
years, never wasting more than 10 seconds in the morning. (Once the
car starts in the morning, I have no more problems that day, even in the
Unlike the Battery Buddy, Priority Start uses a motor, that pulls one
large contact away from the other to disconnect, and then pushes the
contacts back together to reconnect. The motor is geared up 600 to 1
iirc, and it presses the contacts togetheer with hundreds of pound of
force. When the motor stops, it doesn't back off.
I carry jumper cables and it's not very hard to get a jump. I got one
from a pretty young girl once. Even though most of tthem are scared,
even outside in broad daylight, she showed none of that. Just the kind
of girl I'd like if she hadn't been to young for me.
But since the Buddy and Priority Start, I've only used the cables about
twice in the last 24 years.
It's not likely that you "ruined" a new battery, even if you
When a battery is discharged so completely that it will not recover to a
point anywhere near 12 volts...it /can/ be recovered.
One problem often seen is that automatic battery chargers need to see at
least 10 volts or so in order for them to start.
What needs to be done with an over-discharged battery is to place in on
a manual charger or a variable voltage charger.
With a manual charger, some current will flow and though the ammeter may
initially show almost no current, eventually the battery will /usually/
recover. In some cases I've seen batteries run so low that it was
required for me to crank the voltage up rather high in order to get the
current to start flowing.
If using a variable voltage charger, it's important that the current be
closely monitored because as the battery begins to recover, the current
will initially rise.
In all the years I was in the battery industry, I was able to recover
all over-discharged batteries if they had not been sitting in that state
Should a battery sit over-discharged too long ( 3 -6 months) stage
three sulfation will inevitably have set in and any such battery would
only be partially recoverable at best.
On Friday, December 12, 2014 4:20:19 AM UTC-5, philo wrote:
Agree. It's more likely the battery was defective to begin with.
Running a car battery down a few times isn't a good thing and it
will shorten the life, but it shouldn't go from brand new to shot
with 3 discharges.
You also have to wonder about the wisdom of using a BatteryBuddy
with a bad battery to try to keep using it instead of just getting a
Two old codgers sitting in the living room, Everyone else somewhere
else. One codger tells the other, We went to a great restaurant last
What was it called?
Uh..., uh..., what's the name of the flower that's red and has
Do you mean a rose?
That's it! ROSE, what was the name of the restaurant we went to?
I went to do some lock work for a friend. It was
winter, and hot in the house. I asked why he had
the heat up so high. Well, he'd noticed the same,
and had replaced the thermostat. Four times. And
kept getting defective stats. I had a look, and
found a bad relay on the furnace circuit board.
By that time, he'd had another thermostat or two
he'd purchased, and had to go back to the store
No kidding. Real story.
BTW, when an air conditioner or central AC doesn't
blow cold, it's ALWAYS low on freon.
Christopher A. Young
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