Monday, 17 October 2011

How to check which cell has a problem in a car battery?

I changed my car battery last year. But in this winter, the battery keeps being drained. I had the people from whom I bought the battery from checked it. they said somewhere is draining the battery.

Now I had the battery checked by a service dealer. They said one of the cells in the battery is bad.

How can I tell who is telling the truth? Is there a way I myself can check the battery? How to tell a cell in the battery is good or not?

BTW, I think I am pretty technical oriented and like to buy some small tools to do it.

Your input to the question is highly appreciated.How to check which cell has a problem in a car battery?You can buy a battery tester and check yourself, if the battery is not sealed when it is fully charged remove the covers or screw plugs and tap along side of battery with handle of screw driver not the sharp end, you will notice bubbles rising in the cells if they are ok, if there are no bubbles that cell is dead and you will have to replace battery
How to check which cell has a problem in a car battery?
Really you can't. The battery case is sealed. So just get another battery. You can't revive 1 cell, just replace it
How to check which cell has a problem in a car battery?
Single cells don't usually break down in a car battery; if they do, you can usually tell by the lower level of water in it. Maybe you'd like to check the level(s) first, if necessary, refill with de-ionized water, then check the density of the water/acid mixture with an areometer, these are rather inexpensive. Try to recharge the battery overnight, making sure not to overcharge it, then check again. Next, however, make sure your generator works properly; very often, a faulty generator causes such problems.

A battery usually doesn't go bad in just one year. If it is low repeatedly, it usually means the alternator is failing to keep it charged. But that should be signalled by your %26quot;Battery%26quot; or %26quot;Alternator%26quot; warning light staying on all the time on the dash. Or it's trying to charge but there is corrosion on the battery connections blocking the flow of current. You can disconnect the battery and look at the connections and see if there is clean shiny metal to make contact, or if they are covered with discolored corrosion. There is a special double wire brush ($3.50 at Walmart or the parts store) that does sa good job. The battery installer probably took care of that when they did the battery.

If the dealer said one of the cells is bad, they could have shown you how they arrived at that conclusion, maybe by testing the cells individually with a battery tester (hygrometer-not expensive), which you can do yourself if the cell caps on top of the battery can be removed. Be careful! You're dealing with sulfuric acid! Check the fluids per the directions and rinse the tester off and out, and don't drip it on the carpet or your clothes or hands or shoes! Having a cheap container of water at hand to rinse it in would be a good idea.

You can test the alternator by using a VOM (Radio Shack or Sears or Harbor Freight, under $10) on the battery terminals, set to the smallest Voltage scale. It should read 12.5V, or 13.2V, or something like that. Then start the car (which drains the battery a little) and measure again quickly, while the alternator is pumping current back into the battery using a higher voltage. It should read a volt or two higher than before, for a few minutes, anyway. If it doesn't, the alternator may need changing. A large auto parts store will test it for free, Advance Auto, for one, will test it while it's still on the car. Of course, I had a Toyota Corolla once that wouldn't charge, and it turned out that a lone wire running down beside the engine, with an in-line fuse holder that was completely corroded, was at fault.

Wish you the best!

Assuming your battery isn't sealed, (I know mine aren't) you can check for a dead cell by a specific gravity test. They sell the testers (hydrometer) real cheap. They suck up the fluid from each individual cell so you can compare them. If you have one that's more than .050 lower than the next lowest one, that cell's dead.

Checking for a drain, if you have an ammeter, connect it between the negative battery terminal and post with everything off. It shouldn't read more than about 250 mA. If it doesn't have auto-range, be careful not to open the door, or accidentally honk the horn.

If all you have is a 12 volt test light, you can make sure it goes off after you unplug fuses for everything that should have a drain, like ECM, radio, BCM if equipped, etc.. If it doesn't go off after that, keep unplugging stuff until it does, to isolate which circuit.

P.S. also take out the bulb on the under-hood lamp if you have one.
It won't do any good. If the battery's bad, you need a new one. You can take the battery to a parts store and have it tested for free or put the battery in another car and see if it does the same thing.