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How old is the battery? Brand of the battery? Are the battery cable terminals clean and tight?
The first thing I would suggest is to have the battery fully charged and then have it load tested. That will determine the overall condition of the battery. It's possible that it could have a dead cell or an internal short.
What is voltage shown on the voltmeter in the car when the engine is running at idle with the battery in a fully charged state? What is the voltage at the large red wire at the alternator?
Assuming you have a good battery, I would check the current through each circuit using a DMM. This way you can narrow down where to start looking within that circuit. Set your DMM on the current setting, pull each fuse (with car & all electronic items off) and probe each side of the fuse slot to see which circuit still has current going through it. Or you can hook your DMM in series with the - terminal and start pulling fuses and watch for the current to drop to narrow down circuit. You could also have a + shorted to ground somewhere.. Check your battery first.
Last edited by SeeFourSix; Aug 31, 2013 at 01:05 PM.
Reason: - terminal is safer to use than + for series current check..
Unplug the alternator and see if the battery still goes dead. Tape up the Batt wire so it doesn't short against any thing. Then wait and see if the bat goes dead as before.
I wouldn't call that a legitimate trouble shooting techique, but it is a common problem, easy to check and conclusive. The alternator will continue to charge and may even pass a FLAPS tester, but will have a shorted diode inside.
I guess you could call that a lazy mans shot in the dark. A guess.
You could use an Ammeter on one of the battery cables as has been suggested. I'd pull the Neg cable off the battery and put the Ammeter there. It's supposed to be safer in case you're a klutz with the wrench, easier to get to and doesn't have any extra wires for aftermarket alarm and stereo amp.
After you connect the Ammeter and see the discharge indicated, I'd go straight to the alternator and pull those wires off.
The battery type is Optima Red, installed about two days before I first posted. Terminals are clean. When engine running and fully charge voltage reading is 15 volts.
Checking the alternator was something I did as a result of recommendations by others.
I purchased the other battery from O Reileys a few months back. But I decided to change it out after reading a number a negative reviews about the quality of their batteries.
This just saved me a bit of digging... I replaced my six month old battery about a month ago when it started dying overnight. The new one, a Duralast Gold, was working fine until two days ago. The car had been sitting for about a week and the battery was dead. I charged it enough to get the car started and drove it for about fifty miles. Yesterday it was dead again so I charged it overnight last night. The car started fine this morning and was running with the system at 14.7 volts. When shut down, I think it was at 13.6, and after sitting for about four hours, it's down to 10 or 11 and too weak to crank the car. There are no interiors lights on, and the lights under the hood are off.
I've heard of issues with Duralast so I'll pull the battery tomorrow or Sunday and get it tested. (It's raining here now.)
If I check for a drain via the fuses, I'm looking for current and not voltage across the fuse terminals, with the meter acting to complete the circuit in place of the fuse, correct?
This just saved me a bit of digging... I replaced my six month old battery about a month ago when it started dying overnight. The new one, a Duralast Gold, was working fine until two days ago. The car had been sitting for about a week and the battery was dead. I charged it enough to get the car started and drove it for about fifty miles. Yesterday it was dead again so I charged it overnight last night. The car started fine this morning and was running with the system at 14.7 volts. When shut down, I think it was at 13.6, and after sitting for about four hours, it's down to 10 or 11 and too weak to crank the car. There are no interiors lights on, and the lights under the hood are off.
I've heard of issues with Duralast so I'll pull the battery tomorrow or Sunday and get it tested. (It's raining here now.)
If I check for a drain via the fuses, I'm looking for current and not voltage across the fuse terminals, with the meter acting to complete the circuit in place of the fuse, correct?
Any additional tips appreciated.
Best
Jerry
Be careful if you do it that way. Your meter is probably fused for 10 amps. So if you have a pull greater than that you blow the fuse in the meter, so make sure you have extra fuses. On the bright side, if you have a drain like that, it easier to find and fix. Textbook total vehicle draw should be no more than 50 milliamps. Based on how fast your battery discharges, it looks like you have a large draw.
Last edited by Mrvettenick; Jul 9, 2021 at 08:14 PM.
Be careful if you do it that way. Your meter is probably fused for 10 amps. So if you have a pull greater than that you blow the fuse in the meter, so make sure you have extra fuses. On the bright side, if you have a drain like that, it easier to find and fix. Textbook total vehicle draw should be no more than 50 milliamps. Based on how fast your battery discharges, it looks like you have a large draw.
The battery was down to nine volts last night after the storm, so yeah, something is pulling significant power. I'll dig into the FSM before I start digging around. I wonder also, if the draw is heavy enough to heat up the circuit. The first thing I"m going to do is put the battery charger back on and then look for warm fuses, I think.
Assuming you have a good battery, I would check the current through each circuit using a DMM. This way you can narrow down where to start looking within that circuit. Set your DMM on the current setting, pull each fuse (with car & all electronic items off) and probe each side of the fuse slot to see which circuit still has current going through it. Or you can hook your DMM in series with the - terminal and start pulling fuses and watch for the current to drop to narrow down circuit. You could also have a + shorted to ground somewhere.. Check your battery first.
A dead short (positive to ground) would pop a fuse, no?
A dead short (positive to ground) would pop a fuse, no?
Jerry
Not really. If it were that simple, you'd blow the fuse, and the battery would stay alive. But, if you have a 10 amp draw on a 15 or 20 amp circuit, that fuse would never blow. Bur if it were a dead short, then yes.
Last edited by Mrvettenick; Jul 10, 2021 at 09:34 AM.
Not really. If it were that simple, you'd blow the fuse, and the battery would stay alive. But, if you have a 10 amp draw on a 15 or 20 amp circuit, that fuse would never blow. Bur if it were a dead short, then yes.
I get that a draw of less than the fuse amperage wouldn't usually blow the fuse. And clearly that's a likely scenario here. But a circuit is either shorted or not, and the situation you describe, positive to ground, is a dead short.
I don't mean to quibble over a definition. I genuinely don't understand. What am I missing?
I get that a draw of less than the fuse amperage wouldn't usually blow the fuse. And clearly that's a likely scenario here. But a circuit is either shorted or not, and the situation you describe, positive to ground, is a dead short.
I don't mean to quibble over a definition. I genuinely don't understand. What am I missing?
Jerry
I don't think you're missing anything, If there are no blow fuses, then something is staying active, Is there an alarm system in the car? A relay, or something that's solid state could stay active or no disarm causing a high draw without being shorted. It could even be your instrument cluster, a courtesy light timer, or anything that's solid state or electronic.
Last edited by Mrvettenick; Jul 10, 2021 at 05:07 PM.
I don't think you're missing anything, If there are no blow fuses, then something is staying active, Is there an alarm system in the car? A relay, or something that's solid state could stay active or no disarm causing a high draw without being shorted. It could even be your instrument cluster, a courtesy light timer, or anything that's solid state or electronic.
Thanks. Understood and that's what I thought I was looking for. Got focused on a definition, I guess...
Well that was a wasted hour or two. I pulled out the FSM and checked the troubleshooting procedure. It's pretty much the same as you've all talked about. There's a neat looking tool that makes pulling the current more elegant but I think I'll pass. After that, more time digging for tools that actually working on the car. My digital multimeter is shot and I completely forgot until I tried to use it. The other multimeter doesn't do current. And my MT-2100 looks like it only does voltage, not current. But I won't be sure until I dig out the manuals tonight or tomorrow. (Why they're not in the case, I don't remember...)
On the other hand, the battery has not drained significantly since last night. This leads me to think that I'm going to pull it and take it back as there may be a cell going or gone.
I went out this morning and the battery was still sitting a 9.x volts. No further drain overnight. This leads me to believe that the battery has a bad cell. The math works out pretty close. 12v less 1 cell (2.3ish volts) is nine and a fraction, which is where the car had been sitting for the last two days. So I went and swapped the battery. It was covered by warranty but I feel like this is the last time I'm buying Duralast.
So, I swapped out the battery and drove over the the Horrible Fright in the next town over. While driving, I kept a pretty close eye on the voltage as reported by the car and a source plugged into the cigar lighting. It fluctuated from 12.6ish to 14.3. I'm wondering about the alternator and, specifically the voltage regulator. I remember when GM moved the regulator into the alternator. It was a ceramic piece and you could replace it pretty simply. But with the voltage dropping so low, I think I need to test the alternator. What's my best bet here?
A cheap quick way is to turn on all of your electric accessories a/c. blower high headlights on high beam, radio, etc. If the voltage across the battery is over 13volts, then the alternator is OK. If the voltage falls below that, then it's not putting out as it should. Usually, if the alternator has a problem. you'll see it under load.
A cheap quick way is to turn on all of your electric accessories a/c. blower high headlights on high beam, radio, etc. If the voltage across the battery is over 13volts, then the alternator is OK. If the voltage falls below that, then it's not putting out as it should. Usually, if the alternator has a problem. you'll see it under load.
Thanks for this. It's what I remembered. I drove the car, turned everything on, and it dropped to 12.7 for a moment as I pulled up to a stoplight, then went back above 13. I did the same in the driveway at idle, and it didn't drop below 13.5. So I'll keep an eye on it.
I wanted to take a moment and wrap this up. The issue cleared up as soon as I replaced the battery, so I think I got a bad one in in May. I went ahead and replaced my multimeter. The new one will handle 20A on the unfused side. I also bought a Parasitic Drian tester on Amazon. (
). It looks like the difference between this one and the Kent Moore unit is wire gauge. I wouldn't try and start the car with this one hooked up. It's nice though, as it plugs directly in to the multimeter and is fused on both leads. I played around a bit today and it looks like, with everything off, the draw is around 240 milliamps. This is about right with the CCM awake. I need to try this again though, with the battery fully charged and with the under-hood lights disconnected. (the were off for that reading, but I want to put a switch on them anyway.
Cheers,
Jerry
Last edited by gdgeorge; Jul 14, 2021 at 02:31 PM.
I wanted to take a moment and wrap this up. The issue cleared up as soon as I replaced the battery, so I think I got a bad one in in May. I went ahead and replaced my multimeter. The new one will handle 20A on the unfused side. I also bought a Parasitic Drian tester on Amazon. (https://www.amazon.com/dp/B00RGN5UAY...roduct_details). It looks like the difference between this one and the Kent Moore unit is wire gauge. I wouldn't try and start the car with this one hooked up. It's nice though, as it plugs directly in to the multimeter and is fused on both leads. I played around a bit today and it looks like, with everything off, the draw is around 240 milliamps. This is about right with the CCM awake. I need to try this again though, with the battery fully charged and with the under-hood lights disconnected. (the were off for that reading, but I want to put a switch on them anyway.
Cheers,
Jerry
ive been driving a jeep with one dead cell for over a year, as long as it gets started and driven daily its fine. so dont be so quick to blame a battery if it passes a load test you probably have not isolated or corrected your issue and you have something draining a substantial amount of current.
by the way its a duralast platinum i bought in late 2015. agm batteries are hotter than a normal lead acid battery and the surface charge they can hold will allow the thing to have a ton of amps, even when its down to 10-11 volts. the bargain duralast batteries are junk. pay the extra for the duralast platinum agm battery its well worth the upcharge. but seriously it sounds like you have an obscure interior light or switch draining the system.
