Hey guys, I don’t normally hang out here in this forum but I think this would be where I might get some help. I am not very smart when it comes to power and stereo stuff so please bare with me.
I have killed 3 main batteries in the last 3 months all while the car sits still. I replaced my std (dead) battery with an Optima red top that only lasted about 1 month. The next one was the same story. Now the 3rd one is dead under the hood. :mad:
To give a little bit of info, the car was decked out in some serious sound gear. A year or so ago I somehow fried my ignition switch and overloaded something. After that the stereo would come on, but no sound from the speakers. I am still not sure why I had no sound, but I decided to remove the head unit and amps to do some other work and I found the 2nd gel-cell battery that I had forgot was back there. There is also (2) 1-ferad (sp?) caps next to it. I now realize that the gel-cell is dead and probably has been since the switch problem. I do remember being able to run the whole car off the battery in the trunk with out one under the hood. That no longer is the case.
So my questions are:
Is the 2nd battery responsible for killing my main battery? (I am sure the 2nd one is dead and I will have it tested this weekend)
Could something like the caps be the cause?
2b) If yes, can a cap be tested?
I doubt that the 2nd battery killed your primary but it may be possible if it’s wired improperly. You really should use an isolator for your batteries if you are running one for the audio system. Now… a second battery is only going to help you if you like bumping around in parking lots with the car off or if you compete. It will not help you make more power… period. That being said, I highly doubt that your caps are to blame either and yes… you can test them but I would advise against it with traditional test equipment because of the high voltages.
My suggestion (if you still have the amp connected) would be to see perhaps if you have the amp’s remote turn-on wire connected to a constant 12V source. This would keep your amp powered all the time and would kill your batteries one after the next till the cows come home. If you don’t have your amp connected, you may have your head unit getting power from a constant source and perhaps you might be leaving it on? Failing those ideas, you likely have a circuit going to ground after the car has been powered down. The first step is to measure the amount of parasitic drain you have from your battery. Take a meter and set it so DC AMPS (mA if available - DO NOT START CAR WITH THIS SETTING) at a fairly high resolution. Then on the negative terminal of your battery, put one probe right on the terminal and the other at the end of the first connection past that (you’ll have maybe a foot or so between the two probes). What kind of reading are you getting? You shouldn’t get much at all except a small amount for LEDs from alarms and the backup from clocks, etc. You should be well below 20mA and likely even under 10mA. Anyway, if you are going through batteries as fast as you say you are, my guess is that your drain voltage will be much higher than 500mA. This is no good (as you probably figured out).
The next thing to do is to start to try to troubleshoot your problem. Start from the amplifier/s, processors, and work your way back to the head unit. With the amp/s disconnected, to you still get the same amount of drain when measuring the battery with the key off? If you do, try disconnecting the headunit (pulling the fuse may be good enough but I suggest disconnecting power from that circuit entirely). If you need more help, feel free to email me. This should be easy to fix. If you have a suspect circuit that you think may be shorting out to ground, probe the fuse panel with a test light. You should notice one particular circuit drawing much more voltage than another (i.e. the light will be brighter - you can use an automotive light for this as well if you have no test light). Anyway, when you find the ‘brightest’ circuit, connect the test light with some aligator clips or monkey the wires in there somehow if you don’t have the right gear… now… go over all your possible suspect circuits one by one (each time looking at that bright test light). When you finally fix the problem… the light will go out. When the light goes out… that Optima should take you through the next 10 years.
if you do have a digital meter a reading of about 410 mA current draw would kill any battery within 2-4 days (give or take).
I may be dumb when it comes to electrical, but I am pretty sure the alt can’t do anything just sitting still.
neex - Thanks for the suggestions. I don’t have ANY test equipment (meters, lights, etc…). Kind of lame I know. Let me just fill in a few other blanks of info…
Yes there is an alarm that works fine when the battery is charged. No recent changes to the alarm either. The head unit has not been in the car for almost 1 year, the engine and road have been my music. :burnout: The amps did power on and off with the car if I trust the LED on the top. Now, with the last dead battery I have removed them too. I also removed the gel-cell, and bolted the connectors together that used to be on the terminals. I believe this effectively bypasses the 2nd battery. So all this was removed over the weekend after the last battery died. I just wanted to eliminate as much as posible. The 2 caps are still in there. I think I know what you mean about the caps. I do remember the tech guys saying to me “DON’T EVER TOUCH THESE, THEY DISCHARGE VERY HIGH VOLTAGE”. As you can guess, I have no intention of touching them.
The original setup had been professionally installed and running for a few years and I didn’t “rewire” anything so I doubt it was that. As I said, it all seemed to go south after my ignition switch blew. At that point the power with the key on seemed to flash like a turn signal flasher. IE - on, off, on, off, on, off. Needless to say that was a fun experience. :bang:
At this point, I am only concerned with getting the car to stop discharging the battery so I can drive it. I will worry about the stereo after.
Well sure enough, both batteries were DOA. I had Advance auto check/charge both today, and the Optima was near 0. The guy said it is fully charged now, but we will see how long that lasts. The gel-cell (2nd battery) would not even register on the machine. It would not take a charge at all. I asked the guy if this could be my problem, but he was clueless.
neex - I was going to borrow a multimeter from work to take a reading, but I am still kind of at a loss. I know what the neg term is but I am not sure about that other connector you mentioned. I look at the wire, and it goes somewhere down under the front of the battery. Oh yea, and I don’t have the OEM cables under the hood. Most were replaced with 0/2 gauge wire for the stereo.
Here is a simple test just to elimenate the stereo as the problem, disconnect it, all of it, pull the plug on the HU, and diconnect the power, [at the batt.] for the amps, if problem is still there you will know its not the system, and you can stop wasting time looking there.
To check draw with a multimeter, set meter to DC amps, plug probe, [to start] into 10amp input, turn everything in car off, [don’t forget domelight] disconnect pos. (+) batt. term. place one of the probes of the MM on the batt. post, and the other to the term., if no reading move probe input on MM from 10amp input to mA input , [ don,t forget that the caps have to be charged] and BTW did you charge the caps before you hooked up the the charged/new batt.? also there is a simple test for the caps, onced charged, and batt. hooked up, open door so domelight is on, [ign. off] disconnect batt. pos. and see how long it takes for the domelight to go out, if it slowly gos out the cap is good if it gos out as soon as you disconnect the batt. it is N/G, this is not an accuret test of the cap/caps, but it can tell you if the cap will hold a charge or not, and yes a bad cap can kill a batt. :hmm: 94
Ok, hows this for testing… After Advance Auto parts charged the battery I took it home where it sat for 3 days in my garage supposedly with a full charge. I put it in the car a couple days ago aaaannnnnnnndddd… nothing! There is power to most of the car, but not enough to turn the starter over. I turn the key and the battery goes dead.
Now being the idiot I am when it comes to power, I know those batteries sit on the store shelf for weeks so a few days in the garage shouldn’t mean squat. Anyway, I am still thinking that what ever happened to this battery before I removed the 2nd battery (in the trunk) killed it but good. I plan on taking it back to get a new one (AGAIN) and see if the gel-cell was the problem all along. It didn’t sound good when the guy said he couldn’t even get a reading off the gel-cell.
Have you had somebody test the current draw from battery when the ignition is off and no accessories are running? This is the key to see what kind of appreciable loss you might have. It would appear that the parts shop would have load tested your baterry and found it to be good. They have pretty decent equipment and would have likely found that it didn’t go lower than 9-10V while loaded with the full current of the starter, no lower than 12V at rest, and about 14-14.6V while charging from the alt. If that’s the case, you have a problem that points to either your grounding system/shorts, or a poorly functioning charging system. Can you confirm that you read 14-14.6V while metering the barttery with the car running? If not, suspect wither corroded connections on the charging system or a worn/failing alternator. You might try the simple stuff first in hopes to keep the costs down. Clean all the connections from the battery to the alternator and the fuse block/ground. Check the wiring and replace anything that looks really corroded or torn.
You will need to do some basic testing with a meter before you can tell the story of what’s causing your problem. Thowing solutions at the problem without full understanding of your charging system’s behaviour will only aggravate you into 2005.
.and on that note… Happy Holidays and all the best for '05.
Maybe a G2IC member near you can help?? It’s amazing what beer and pizza can do for you…
Thanks.
Andrew.
aka neex.