Battery/Electrical Question- Losing charge

[mlazinski]

I always had a small current draw in the car when off, but about a month ago it became larger, where I couldn't start the car if it sat over 3-4 days. I put a kill switch on the battery, but now it seems to still lose voltage (12.1 to 11.7 in two days) charge even with the switch pulled (I put it on the negative). Is this normal? Is there something I can do differently? Thanks for any advice. PS. The battery is less than 1 year old, and the alternator is new- pulls 14.1 when car is on.

 

[idvette]

Your battery should be able to start your car after sitting 4 days with no problems, assuming it's in good shape. You can find the source of your draw by performing a parasitic load test to see what's draining it. You can remove the negative terminal from the battery, set a volt meter to read milliamps, and connect it between the battery lead and battery terminal. Some tool manufacturers actually build a tester specifically for the purpose, but probably not nessecary considering the age of the car and simplicity of it's wiring. With all circuits off, keep an eye on the voltmeter as you pull fuses one by one. If you're maintaing an amperage, and it drops when you pull a fuse, you know the problem is in that circuit. Keep in mind the clock will use some power, you want to see less than 50 milliamps. (50 is what I've gone by, there must be specs somewhere for your car somewhere)

Hope you find your problem!

EDIT... I had used improper wording, confusing millivolts with milliamps, sorry!

 

[6880 Mike]

Do you have a sealed battery? If not, check the water levels.

 

[bb2kksy]

Dead battery

I have a 79 and if the battery remains connected it will be flat in 4 days. With a disconnect on the positive side my battey was good after sitting for four months. Maybe the disconnect is not working. Open the switch and try the horn, If the horn sounds the disconnect is not working.

 

[LLC5]

I always had a small current draw in the car when off, but about a month ago it became larger, where I couldn't start the car if it sat over 3-4 days. I put a kill switch on the battery, but now it seems to still lose voltage (12.1 to 11.7 in two days) charge even with the switch pulled (I put it on the negative). Is this normal? Is there something I can do differently? Thanks for any advice. PS. The battery is less than 1 year old, and the alternator is new- pulls 14.1 when car is on.

Start with the basics first. You need to be absolutely certain that the battery is good, have it properly load tested as it could be bad even though the battery is less than a year old. Good luck with it.

 

[mlazinski]

Thanks for the suggestions. I tried performing the amp reading using both sides of the disconnect and had nothing (.07A) but might disconnect and try again, and move the disconnect to the positive side (should this have any bearing on it?) I will also get the battery checked. As for finding my main problem I will do the fuse trick- sounds like a great way to localize the problem.

 

[LLC5]

Thanks for the suggestions. I tried performing the amp reading using both sides of the disconnect and had nothing (.07A) but might disconnect and try again, and move the disconnect to the positive side (should this have any bearing on it?) I will also get the battery checked. As for finding my main problem I will do the fuse trick- sounds like a great way to localize the problem.

The amperage reading will be the same using either the positive or negative cables. For safety it is always recommended to disconnect the negative cable for parasitic drains.

 

[mlazinski]

battery ended up being 2 years old, and cranking 370 amps ad. New one was free due to warranty, but I upgraded to a deep cycle battery? They said it had more CCA and could deal with getting charged/discharged better. Now onto finding the reason for my current draw. Anyone have any suggestions of a top five places to look? Thanks again guys.

 

[LLC5]

battery ended up being 2 years old, and cranking 370 amps ad. New one was free due to warranty, but I upgraded to a deep cycle battery? They said it had more CCA and could deal with getting charged/discharged better. Now onto finding the reason for my current draw. Anyone have any suggestions of a top five places to look? Thanks again guys.

First make sure that there is a big enough parasitic draw to chase down, with an ammeter in series with the negative cable and battery terminal and the key off and all doors completely shut. Anything aftermarket, dome lights and trunk light if applicable, clock, horn relay stuck with bad horns, cigarette lighter if applicable. Start by pulling the battery sourced fuses one at a time and see if the parasitic drain goes away. Good luck with it.

 

[idvette]

X2, Something killed that battery, it could lead to problems with your new one as well! On another note, don't assume higher cca means a better battery. What ther do to get more amps out of a battery is stuff more plates in a cell, therefore they're closer together, and usually thinner. Under high amp loads (big stereo system, high compression engine/high torque starter, etc) the plates can physically warp and over time touch each other, causing a dead cell. I look for the largest battery that will fit my application with a reasonable cca and high rc.

 

[mlazinski]

Thanks for the advice on chasing down the draw. The horn doesn't work, so it might be broken and stuck open? I will try to chase down next weekend. All I know is that with this new battery it starts stronger than it ever did, so that is nice.

 

[LLC5]

Thanks for the advice on chasing down the draw. The horn doesn't work, so it might be broken and stuck open? I will try to chase down next weekend. All I know is that with this new battery it starts stronger than it ever did, so that is nice.

The horn button grounds the horn relay, and the horn relay sends power to the horn, so actually the relay would be stuck closed. If the parasitic drain is in the horn circuit, then it is most likey a stuck horn relay or the horn button is bad and grounding the relay at all times. Of course the horns would either have to be bad, unplugged, or missing for this to occur as they would be on all the time. Good luck with it.

 

[joe paco]

battery ended up being 2 years old, and cranking 370 amps ad. New one was free due to warranty, but I upgraded to a deep cycle battery? They said it had more CCA and could deal with getting charged/discharged better. Now onto finding the reason for my current draw. Anyone have any suggestions of a top five places to look? Thanks again guys.

had a similar prob when I bought my used 91. previous owner replaced battery (THANKS) AND NEW ALERNATOR (GREAT.) Still, after a few days idle it lost the battery, enough. Tried the parasite voltage/amperage trick, but didn't locate the solution. Finally -one day got into the glove box for something and the light was so hot it burned my hand. Been on all the time! The switch was defective. Had looked after dark for lights, but the lid is so tight, no light was escaping. Your prob is different, since other components are failing, but...it seems that all things are possible with electronics.