Car Battery Troubleshooting Help Needed

MoonRiver · #1 11/21/12, 11:34 AM

My battery keeps going dead. Charge it and in a couple of days, either the Blazer won't start or is difficult to start.

This is where I need help. I must be doing something wrong, but have no idea what.

I disconnected the battery ground cable and hooked my voltmeter between the ground cable and the battery. My com is plugged into 10A and switch is set to A DC. I read 20.xxxx.

I unplugged the under hood light and still read 20.xxx. I used a block of wood to depress the door switch and pulled all the fuses. Still read 20.xxx.

Any ideas on what I am doing wrong?

agmantoo · #2 11/21/12, 11:50 AM

On your volt ohm meter set the black lead to COM and then put the red lead to 10A. Put the battery cable back to ground where you got it. Disconnect the Positive battery lead. Put the VOM red lead to the battery post and the black lead to the positive battery cable and see what you read. The reading should be a small amp draw. If the reading on the VOM shows reverse polarity reverse the connection of the red and black VOM leads at the battery cable and the battery post.

How old is the battery? Report what the amp reading is with all the doors closed and switch and all lights off.

Barn Yarns · #3 11/21/12, 12:23 PM

Can you take it in to where you purchased it and have it tested? I had a brand new on in my car a few years back and if I didnt turn off the headlights before I shut it off, Id have to pop the clutch to get it going again. turned out it was a bad cell. got a new on for free! You shouldnt be charged to have it tested.

MoonRiver · #4 11/21/12, 12:48 PM

Thanks. That got me a little farther.

It looks like the under dash light doesn't go out like it should. When I use the remote unlock or open the door, the under dash light comes on, but doesn't turn back off. If I turn the headlights on, the under dash light goes off, and when I turn the headlights off, the under dash light stays off. I haven't figured out a way to turn off the light and then open/close the door to get out without the light coming back on. So I disconnected the battery again.

What causes the light to turn off normally?

ETA: Opened and closed the tailgate door. Now the light goes off like it's supposed to. I see being stranded in my future.

MoonRiver · #5 11/21/12, 01:30 PM

Quote:

Originally Posted by Barn Yarns

Can you take it in to where you purchased it and have it tested? I had a brand new on in my car a few years back and if I didnt turn off the headlights before I shut it off, Id have to pop the clutch to get it going again. turned out it was a bad cell. got a new on for free! You shouldnt be charged to have it tested.

Sorry I wasn't clear. It's not the battery, but a parasitic drain that I am having trouble finding.

agmantoo · #6 11/21/12, 03:18 PM

Take the bulb out of the light that is remaining on. Do another amp drain test. You will always have a small drain and I am unsure of what that drain amperage will be. However I would appreciate your sharing the reading you get.

MoonRiver · #7 11/21/12, 04:17 PM

Quote:

Originally Posted by agmantoo

Take the bulb out of the light that is remaining on. Do another amp drain test. You will always have a small drain and I am unsure of what that drain amperage will be. However I would appreciate your sharing the reading you get.

It works fine since I opened and closed the back door, so I don't know if that was the problem or not. I just recharged the battery and will check tomorrow to see if I am still losing the charge. Thanks for the help.

MoonRiver · #8 11/22/12, 05:14 PM

Battery was weak but started the car.

I checked amps and there was still a draw. Unplugged the under hood light, and amps dropped to 0.

I still don't think I found the problem, but will recheck tomorrow.

agmantoo · #9 11/22/12, 08:55 PM

Does the battery rating match or exceed the requirement for the vehicle. I do believe that the batteries from discount stores overstate the cold cranking amps. I always attempt to buy the largest battery with the highest cranking amps available that will fit in the battery box of the vehicle. Undersize amp batteries are rough on the starting system. Remember as the voltage drops, the amps will rise. As the amps rise so does the heat in the circuitry. Heat damages starter brushes, solenoids and starter wiring.

MoonRiver · #10 11/23/12, 07:13 AM

Quote:

Originally Posted by agmantoo

Does the battery rating match or exceed the requirement for the vehicle. I do believe that the batteries from discount stores overstate the cold cranking amps. I always attempt to buy the largest battery with the highest cranking amps available that will fit in the battery box of the vehicle. Undersize amp batteries are rough on the starting system. Remember as the voltage drops, the amps will rise. As the amps rise so does the heat in the circuitry. Heat damages starter brushes, solenoids and starter wiring.

The battery was fine until I replaced the driver side rear view mirror. The 1st thing I did was unplug the electrical connection to the mirror, but the battery still went dead.

joejeep92 · #11 11/23/12, 07:40 AM

Acceptable draw on a newer vehicle is .05 Amps. This is allowing for time after you shut down the car for all modules to go asleep so for the first little while it will be more. Meter goes in series with the circuit so that you can accurately measure flow. Best place is between positive lead and battery. Then unplug fuses and shake wires until your number drops. Some guys will use a test light across the two posts of the battery and watch for when the light changes for a good simple visual indicator.

agmantoo · #12 11/23/12, 09:11 AM

If you disconnect the battery the evening before will the vehicle start as per normal? I think I asked how old the battery was but I do not recall seeing an answer. Since you did not have an amp drop after disconnecting/correcting the lamp issues lets try another test. Charge the battery. With the battery charged and the battery charger disconnected turn on the head lights. Using a watch leave the headlights on for a full five minutes. At the end of the clocked 5 minutes attempt to start the vehicle. Acknowledge the results here.

catahoula · #13 11/23/12, 09:17 AM

It's always the battery, well, except for when its not.
You might have more than one thing going on. If it were me the first thing I would do is have the battery load tested. It's free, and it will eliminate it as a suspect.

MoonRiver · #14 11/23/12, 09:29 AM

I tested amps again, and am getting only about .01 amp. (corrected. I originally typed this as .1)

Tested battery and get about 12.3 volts and it drops to between 5 and 6 volts when I crank it. Does this mean the battery is bad? Battery is less than 2 years old. Problem started almost a year ago and I have recharged the battery probably at least 10 times.

The last time I had it in the shop, they told me the battery tested good and tried to tell me I had left the light on. This didn't make sense because the light they said I left on, only comes on when the ignition is on. I think what was happening is that they had the same problem I did, that the under dash lights weren't turning off automatically. That problem seems to have gone away.

agmantoo · #15 11/23/12, 10:12 AM

MoonRiver.

My thoughts are that the battery is history. Rather that state that outright is why I asked you to do the 5 minute test above. Either the battery is taking what I call a surface charge or the battery is defective or way undercharged. If the 5 minute test fails go get a new battery and buy a quality battery.

MoonRiver · #16 11/23/12, 12:58 PM

Battery is not defective, but guy (me) hooking up the battery charger is. Somehow it was set on deep cycle. I have it set correctly now and am recharging battery.

agmantoo · #17 11/24/12, 06:35 PM

MoonRiver

What was the outcome after charging?

MoonRiver · #18 11/25/12, 08:21 AM

Quote:

Originally Posted by agmantoo

MoonRiver

What was the outcome after charging?

Yesterday I charged the battery and it measured 12.8 v after being charged. I disconnected the battery from the car and retested and it was still 12.8 v. Tested this morning and it was only 10.6 v.

So does that tell me the battery is bad even though the test machine at Advanced Auto parts said it was good? If the battery wasn't fully charged, would this happen?

The charger is doing something I don't understand and can't find in the manual. After an hour or 2 of charging, the needle drops to 0 and then jumps up to about 4-5 amps and then repeats. Over time, it stays longer and longer on 0 before jumping up.

agmantoo · #19 11/25/12, 09:54 AM

The 12.8 VOLT reading is great. You have not done a load test from what I can decipher from here. A load test will verify that your battery is capable or not of delivering AMPERAGE while maintaining the VOLTAGE. Both are a must.

Truthfully I did not feel comfortable that you had solved your battery issue and that is why I posted post #17. I did not see where you ever did my crude 5 minute headlight test either so I have no idea of those results. That said I am going to tell you how to fix the problem. Go buy a battery and buy it based on CCA @ 0 degree F and get the highest amp battery that will fit in you battery box. Deka brand batteries are my choice. Do not buy a brand that you never heard of from a big box store or discount auto place!

MoonRiver · #20 11/25/12, 10:02 AM

Quote:

Originally Posted by agmantoo

The 12.8 VOLT reading is great. You have not done a load test from what I can decipher from here. A load test will verify that your battery is capable or not of delivering AMPERAGE while maintaining the VOLTAGE.

Truthfully I did not feel comfortable that you had solved your battery issue and that is why I posted post #17. I did not see where you ever did my crude % minute headlight test either so I have no idea of those results. That said I am going to tell you how to fix the problem. Go buy a battery and buy it based on CCA @ 0 degree F and get the highest amp battery that will fit in you battery box. Deka brand batteries are my choice. Do not buy a brand that you never heard of from a big box store!

I did your test Friday. Left the lights on for about 7 minutes (I got distracted), and was able to start the car, but it was slow cranking. That's about how it is if I charge the battery and then try to start the car the next day. Some days it will start and some days it won't.