# recharging 12 v battery

What exactly happens when you charge a 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.
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herb white wrote:

What changes is the composition of the lead on the plates and the strength of the acid electrolyte . If it won't hold a charge you need to replace it .
--
Snag

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Herb,
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 sources. 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.
Dave M.
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On 12/11/2014 07:18 AM, David Martel wrote:

(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 charging system.
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.
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On 12/11/2014 8:36 AM, philo wrote:

The OP only suggested replace. Didn't ask any questions.
. Christopher A. Young Learn about Jesus www.lds.org .
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On 12/11/2014 6:26 AM, herb white wrote:

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 some where.
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 battery.
--
.
Christopher A. Young
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On Thursday, December 11, 2014 8:22:49 AM UTC-5, Stormin Mormon wrote:
It's too hard to type "How does a lead acid battery work?" into Google? Maybe he doesn't know how Google works either.
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On 12/11/2014 8:39 AM, trader_4 wrote:

Actually, no, I didn't write that.
- . Christopher A. Young Learn about Jesus www.lds.org .
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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 :)
--

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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.
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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' (http://www.progressivedyn.com/battery_basics.html )
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 battery.
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 recharged.
'David Martel[_2_ Wrote: > ;3319952']

> current.

> your engine rapidly on a cold morning. If it can't your car won't > start.

I'm wondering exactly why spinning the engine rapidly is essential for starting.
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.
--
nestork

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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 connection.
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.
Priority Start.
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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.
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On 12/12/2014 06:50 AM, trader_4 wrote: '
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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 them anymore.)
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 winter.)
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.
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On 12/11/2014 11:37 PM, micky wrote:

It's not likely that you "ruined" a new battery, even if you over-discharged it.
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 too long.
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.
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On Friday, December 12, 2014 4:20:19 AM UTC-5, philo  wrote:

e
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 new battery.
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Two old codgers sitting in the living room, Everyone else somewhere else. One codger tells the other, We went to a great restaurant last night.
What was it called?
Uh..., uh..., what's the name of the flower that's red and has thorns...?
Do you mean a rose?
That's it! ROSE, what was the name of the restaurant we went to?

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On Thu, 11 Dec 2014 08:23:11 -0500, Stormin Mormon

It's like television. When there was no picture, every customer thought it was the picture tube.

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On 12/12/2014 12:43 AM, micky wrote:

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 for refund.
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 Learn about Jesus www.lds.org .
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