voltage low on car battery

Fully charged it has to saturate to 13.3 with 12.8 being full, I have an older charger I opened and found a voltage set screw and adjusted it. What is indefinatly at 2a for a day? 12.6 is to low and will sulfate and ruin a battery.

How old is the battery? Signs of a weakening cell?

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

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

Don't they say to bring it to 14.4-14.7 to be sure of a full charge and remove sulfation?

I was measuring the voltage after stopping the charge and running the lights 15 seconds, which is supposed to be equivalent to letting it sit four hours.

I've left it at 2 amps up to 48 hours at a time.

Was the voltage measuered with the lights still on ?

Without a load on a battery it is difficult to tell anything just by the voltage. They will usually measuer close to the normal voltage unless the battery is very bad and not just weak.

Not normally. Normally the water evaporates, especially if there is over charging, and the remedy is to add distilled water until you see the miniscus, the place where the water level rises above the rectangular area and reaches the 1" round tube that extends down from the battery cap.

"Maintenance Free" batteries are supposed to be even less likely to lose water, but I'm sure they still can.

Do you have reason to think electrolyte has been spilled out, then replaced with only water?

How old is the battery and how long the guarantee (which is their best prediction of product-life.)

"battery looks old" - might be a symptom?

(How old is the battery, asked twice already)

Anti-Freeze, you can test electrolytes with a VOM (meter reading), battery acid is different.... I'm guessing.

Maintenance Free batteries still gas, but at a much lower rate. Most of them will benefit from an electrolyte level check once a year, as most "maintenence free" batteries still have cell covers that you can take off. The manufacturer considers them maintenance free because they usually outlast most of the warranty without needing water added to them. I check mine once a year, and they are usually just a little low and only need a small amount of water.

Might be a temperature thing. I think the fully charged voltage decreases somewhat at low temperature.

Don Young

take it to a car repair newsgroup

Your battery is sulphated and will have a reduced output. Adding acid won't help.

Take it to a good auto parts place that has a battery conductance tester (generically known as a Midtronics tester). If it passes that test it is good. If it fails that test you are running on borrowed time - get rid of it.

Unless it has a "lifetime warranty" in which case it is usually good for about 2 years - - - - - -.

Have it tested but 12.3 is maybe 30-40% charged, id say its junk. 12.6 will ruin a battery from sulfation over just 1 year, 12.6 is not a full charge

s problem?

battery is probably bad.ocally advance auto parts test batteries for free.

charge for a day, let sit and load test.

lead acid batteries last perhaps 4 years. running a bad batter can lead to damaging alternator. after replacing many alternators i now replace my batteries every 3 to 4 years. alternator failures have dropped to near zero, except getting noisey the bearings wear out.

load test battery if it tests ok forget about it some newer no maintence batteries chargew differently. i have a buddy who uses them for wind power, he has noted differences recently

Or you could just buy a new battery. I'm fond of Sears Diehard batteries, even though I don't trust their auto labor department.

That's the lifetime of white spotted moth, isn't it?

I don't know of a good one.

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.)

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.

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.

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?"