bcurtis

My battery has loss power for the second time and I am not sure what could be draining the power. I had my fuel pumps replaced last month and the guy told me the battery and the alternator tested just fine. The guy at Autozone told me the same thing yesterday. Does anyone know what could be draining the power? When the guy at autozone tested my battery he said it had a 7% charge and 10 minutes later the battery was just fine when I started the motor with my key rather than keyless start (the low battery message on the dashboard went away). A day later the battery died. Before my battery died I also noticed my radio volume would not work. I am not sure what is going on with my car. LOL

green1212

this may sound like a waste of time but try this first before you go spend any money on anything: again, just do it and see, it has solved some of these weird battery problems: unhook your negative terminal on the battery and when you to go replace it back on, make sure you get a good insert of the negative terminal back onto the post with no sparks coming off..... again, i know this sounds "dumb" but it has solved my weird battery drain issues.... i know, wtf right? simple and painless, wont hurt anything but could solve your problem.

bcurtis

I did notice that one of the terminals was not not pushed as far down as the other one. I think its the positive terminal that isn't pushed far down enough. I will give it a try here in a sec. Hopefully this solves the issue. When you say sparks coming off what do you mean? Is this when I jump the battery (with another car)?

green1212

i mean you know sometimes when you go to place the negative terminal back on and if you are "playing" with it, like rubbing the terminal across the battery post, some sparks will come off, very small but you can hear it....
so what i mean is when you go to place the terminal onto the post, do it in a way you do not create any "sparks" or the noise of the spark. also i hope getting that positive termial seated may also do the trick. these cars are very funny man and sensitive too! but if you do hear some "sparks" take the negative off again and try again until you can get it on there "cleanly". best of luck!

marcmaddox

Get a battery terminal cleaning brush and clean the inside of the cable lug and the battery post. Do both the positive and the negative. Also, check the secondary battery, under hood, as well. And remember that every time the battery discharges severely it shortens its life drastically. Typical lead/acid automotive batteries can't survive a low voltage drop to many times. Sulfate builds up and kills them.

Critter

Change the battery, 7% charge is next to dead and to charge it in 10 minutes in ridiculous. If you really want to know if the battery is good, turn on your fan, headlights, high beams also with the key on and wait for 1 minute, now try to start the car. When you do replace your battery clean the posts and the cable end with a battery post wire brush cleaner bought at autozone, or just let the clean them for you prior to the new battery going in. Continue to run with this battery will just fry your alternator as well as cause all kinds of electrical grief. Replace the battery!!!!

moosejaw

why not check the voltage under dyno mode?

Yacht Master

Sparks around a freshly charged battery is asking for a disaster.

Tell us how they tested your battery.

Critter

Does not sound like it was load tested.
Extreme heat and cold are a batteries worst enemy, so they have a tendency to give up on the hottest day or the coldest morning. IMO! and don't forget the least opportune time, lol
Long periods of non use or short sporadic use will diminish a brand new battery in about 3 years.
If you have one 4-5years or older, break down and purchase a new one or two in case of the 55 with the small battery in front.
Unless you like to RTF ( run to failure )

cij911

Just out of curiosity, do you have anything plugged into the OBD2 port (e.g. datalogger) ? If so, that is the problem ....The MB system sees the port as active and draws ~0.4 amps which will kill a battery in just a few days.

The small battery up front is just for the SBC (brakes) and if it has an issue, you will get a very different message.

jonnyc

do you have a habit of opening the driver door before turning the car off?

with the keyless go if you open the door before shutting off the car then the car doesn't go into sleep mode and it will kill the batteries.happened to me about a month after getting the car.drove it Wednesday night all was fine went out Friday afternoon and had nothing.drained the battery so bad i couldn't even open the trunk without using the key.now i make sure the car is off before i open the door and haven't had a problem since.