Battery keeps draining...
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TECH Senior Member
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Joined: Jun 2004
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From: Jacksonville, FL
Battery keeps draining... Ok the battery keeps draining. It's a brand new battery and alternator. If I drive the whole week and then don't drive it saturday it won't crank on sunday. Basically if I leave it sitting for a day without driving it, it won't start. It won't even open when I use the keyless remote. So now I have a "pocket electrical tester." Question is exactly how do I go about testing for the draw. It has a lot of different settings. It has DC_V 2.5, 50, 250, 1000. AC_V 10, 50, 250, 1000. DCmA 10, 250. BAT 1.5v, 9v. OHM x10, x1K. What setting do I need it on, and do I just hook the cables in and attach it to the batter terminals on the car? I'm dumb when it comes to electronics.
I would reccomend checking it with a test light or a light bulb.
Disconnect the negative battery cable, and connect the test light to the battery, and the pointed end to the negative battery cable, or connect one wire from a light bulb to the battery and the other end to the neg. cable. If you have a key off current draw the light will light up. Make sure you have the doors closed, and all accesories turned off. Anything pulling power from the battery will cause the light to light up. Dome lights, radio, etc, etc. When you first connect the test light it is normal for the light to come on for a few seconds while capacitors in the pcm and elseware are charging, but it should go off in a few seconds. If it doesn't, you have a key off battery drain. Now you can start pulling fuses one at a time and then replacing until the light goes out. When you pull a fuse and the light goes out, you have found the circuit that is draining the battery. I would try the radio and accessory fuses first. Once you figure out what circuit it is, replace the fuse, and disconnect things in the circuit one at a time until the light goes out. It would be very helpful to have a wiring diagram, at least for the problem circuit. Pretty common for a radio or amplifier to go bad and cause this type of battery drain.
I hope this will help you. If you need any help, let me know.
Disconnect the negative battery cable, and connect the test light to the battery, and the pointed end to the negative battery cable, or connect one wire from a light bulb to the battery and the other end to the neg. cable. If you have a key off current draw the light will light up. Make sure you have the doors closed, and all accesories turned off. Anything pulling power from the battery will cause the light to light up. Dome lights, radio, etc, etc. When you first connect the test light it is normal for the light to come on for a few seconds while capacitors in the pcm and elseware are charging, but it should go off in a few seconds. If it doesn't, you have a key off battery drain. Now you can start pulling fuses one at a time and then replacing until the light goes out. When you pull a fuse and the light goes out, you have found the circuit that is draining the battery. I would try the radio and accessory fuses first. Once you figure out what circuit it is, replace the fuse, and disconnect things in the circuit one at a time until the light goes out. It would be very helpful to have a wiring diagram, at least for the problem circuit. Pretty common for a radio or amplifier to go bad and cause this type of battery drain.
I hope this will help you. If you need any help, let me know.
Staging Lane
Joined: Apr 2004
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xtremespeed is right, but i disagree with using a test light.
Any OBDII vehicle will have an off-key draw, and may light your tester. I highly recommend you use a test meter instead, set to the DC milliamps range, and follow xtremespeed's instructions. You should be able to find it.
Remember, a 30mA off-key draw is probably the normal limit for most late model computer controlled vehicles, and some will draw very near the limit under normal operation, depending on equipment. Any more than that, is a problem. Also remember, some modules will not go into 'sleep' mode right away, and will show up on your draw test, so leave your test meter connected in series for at least 30 minutes.
I suspect average should be 15mA or less, but refer to the appropriate service manual for specifications.
Any OBDII vehicle will have an off-key draw, and may light your tester. I highly recommend you use a test meter instead, set to the DC milliamps range, and follow xtremespeed's instructions. You should be able to find it.
Remember, a 30mA off-key draw is probably the normal limit for most late model computer controlled vehicles, and some will draw very near the limit under normal operation, depending on equipment. Any more than that, is a problem. Also remember, some modules will not go into 'sleep' mode right away, and will show up on your draw test, so leave your test meter connected in series for at least 30 minutes.
I suspect average should be 15mA or less, but refer to the appropriate service manual for specifications.
You could do it either way.
If you don't have someone to help you, it is easier to use a light as opposed to trying to read a meter Imo. I usually use a headlight bulb with two wires attached.
PrototypE is right, if your tester light is too small, it could light, even with the acceptable current draw. As long as you don't use a really small bulb there isn't enough current to keep the bulb lit. Even my cheap autozone test light has a large enough bulb to work. It will light for a few seconds to charge the capacitors, and then it will go out, unless you have a big drain. I have done this on my 00 with a headlight bulb and it works fine.
If you don't have someone to help you, it is easier to use a light as opposed to trying to read a meter Imo. I usually use a headlight bulb with two wires attached.
PrototypE is right, if your tester light is too small, it could light, even with the acceptable current draw. As long as you don't use a really small bulb there isn't enough current to keep the bulb lit. Even my cheap autozone test light has a large enough bulb to work. It will light for a few seconds to charge the capacitors, and then it will go out, unless you have a big drain. I have done this on my 00 with a headlight bulb and it works fine.
Thread Starter
TECH Senior Member
iTrader: (21)
Joined: Jun 2004
Posts: 6,697
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From: Jacksonville, FL
So should I set my DCmA to 10 or 250? I set it to 10 connected the positive side to the battery and then put the negative on the negative side of the battery and it blew the fuse in the tester. Was it because I hit the battery dead on? Do I need to use the 250 setting. I'm still somewhat confused, mainly on how to connect it. I understand the general consensus of how to go about finding the draw.
Launching!
Joined: Mar 2005
Posts: 297
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From: Chicago
The idea is to measure current, not voltage.
You want the meter inserted INLINE, not across.
Disconnect 1 battery terminal, place meter leads inbetween (1 lead goes to battery, other goes to disconnected cable).
I would start on the 10A range just to be sure you dont have a large draw (otherwise you'll blow the fuse again). OTOH, most meter's 10A ranges are not fused. If the concensus here is that the draw with the car off does no exceed 30 mA, then go ahead and use the mA range.
You want the meter inserted INLINE, not across.
Disconnect 1 battery terminal, place meter leads inbetween (1 lead goes to battery, other goes to disconnected cable).
I would start on the 10A range just to be sure you dont have a large draw (otherwise you'll blow the fuse again). OTOH, most meter's 10A ranges are not fused. If the concensus here is that the draw with the car off does no exceed 30 mA, then go ahead and use the mA range.
