Dead battery over night
#61
a test light in series isn't a very good test as it doesn't say how much current. much better to use a multimeter in its 'DC amps' mode (usually a 10A scale, which requires plugging the red lead into a different socket on the meter)...
yes, the battery has to be charged for the test to be meaningful.
Before even messing with the current test, I'd charge the battery overnight, disconnect the charger and wait a hour or two, and measure the battery voltage, it should be 12.6V or so if the battery is fully charged. Now, start the car, and measure the voltage across the battery terminals, it should be about 1.2-1.5V higher than the at-rest voltage of the battery, like 13.8V or something. if its not, your charging system isn't working, time to look at the alternator, its brushes, and so forth.
yes, the battery has to be charged for the test to be meaningful.
Before even messing with the current test, I'd charge the battery overnight, disconnect the charger and wait a hour or two, and measure the battery voltage, it should be 12.6V or so if the battery is fully charged. Now, start the car, and measure the voltage across the battery terminals, it should be about 1.2-1.5V higher than the at-rest voltage of the battery, like 13.8V or something. if its not, your charging system isn't working, time to look at the alternator, its brushes, and so forth.
#63
a multimeter has 3 basic functions for DC stuff (ignoring AC here).
1) voltage - this is the most commonly used measurement. a charged car battery is about 12.7V, a dead one under 12.0V.
2) current. when in current mode (amps or milliamps, 1000 mA = 1 A), in current mode, the meter is a dead short, so YOU NEVER PUT IT ACROSS A VOLTAGE SOURCE, and take it out of amps mode as soon as you're done testing.
3) ohms, this measures the resistance of a circuit, and should only ever be used on unpowered things. again, take it out of ohms mode as soon as you're done testing.
1) voltage - this is the most commonly used measurement. a charged car battery is about 12.7V, a dead one under 12.0V.
2) current. when in current mode (amps or milliamps, 1000 mA = 1 A), in current mode, the meter is a dead short, so YOU NEVER PUT IT ACROSS A VOLTAGE SOURCE, and take it out of amps mode as soon as you're done testing.
3) ohms, this measures the resistance of a circuit, and should only ever be used on unpowered things. again, take it out of ohms mode as soon as you're done testing.
#65
I'm assuming this is the 1990 240 in your profile.
as others said to the OP, common causes are glove box or trunk light stuck on. power locks with sticking switches. anything electrical added to the car by a hack.
if the charging system is good, then I'd do what the original poster did. make sure everything you know of is turned off, ignition off, and disconnect the battery negative terminal. put the multimeter in its "10 amp" mode (as I said, usually you move the red wire to the other hole on the meter, as well as set the switch for 10A or DC A or whatever), and hook the meter between the battery negative post, and the ground cable. don't freak if you get a little spark when you connect it. you may well see a quarter amp or more of drain, if so then yeah, there's a problem. if its like 0.02 amp (20mA) then that is so small it shouldn't matter. Godfather was seeing 0.8A (800mA), and that was enough to kill his battery in a few days.
if you DO see a load like this, try removing the fuses one at a time, and do the same measurement, and note if it changes. Put each fuse back before removing the next. On a 240, there's a 'blade' fuse in the engine compartment (for the fuel injection system), its somewhere behind the battery or near the left suspension tower, usually 25A or 30A, its on a red wire directly off the battery + terminal... try removing this one too, and see if that changes anything (that was godfather's problem, some hacked wiring in his fuel pump relay circuit, leaving his ECU powered even when the car was switched off)
if one fuse drops the drain from most of an amp to a fraction, then that circuit is probably the problem and we can narrow things down from there.
on the main fuse panel by the drivers door, only fuses 6,7,8,9,10 should be powered when the car is switched off. with all the fuses in place, and the ground cable reconnected, ignition switched off, put your multimeter back in DC VOLTS mode, hold the black lead to a chassis ground, and touch each fuse one at a time, should be no voltage on fuses 1-5 and 11-16, and should be 12V on fuses 6-10. note it doesn't matter which side of the fuses you test, they are the same if the fuse is good.
fuse 6 - in-tank fuel pump (but not the main one under the car)
fuse 7 - brake lights
fuse 8 - courtesy lights, clock, trunk light, engine compartment light, central locks, power antenna, radio
fuse 9 - emergency blinkers
fuse 10 - power windows
as others said to the OP, common causes are glove box or trunk light stuck on. power locks with sticking switches. anything electrical added to the car by a hack.
if the charging system is good, then I'd do what the original poster did. make sure everything you know of is turned off, ignition off, and disconnect the battery negative terminal. put the multimeter in its "10 amp" mode (as I said, usually you move the red wire to the other hole on the meter, as well as set the switch for 10A or DC A or whatever), and hook the meter between the battery negative post, and the ground cable. don't freak if you get a little spark when you connect it. you may well see a quarter amp or more of drain, if so then yeah, there's a problem. if its like 0.02 amp (20mA) then that is so small it shouldn't matter. Godfather was seeing 0.8A (800mA), and that was enough to kill his battery in a few days.
if you DO see a load like this, try removing the fuses one at a time, and do the same measurement, and note if it changes. Put each fuse back before removing the next. On a 240, there's a 'blade' fuse in the engine compartment (for the fuel injection system), its somewhere behind the battery or near the left suspension tower, usually 25A or 30A, its on a red wire directly off the battery + terminal... try removing this one too, and see if that changes anything (that was godfather's problem, some hacked wiring in his fuel pump relay circuit, leaving his ECU powered even when the car was switched off)
if one fuse drops the drain from most of an amp to a fraction, then that circuit is probably the problem and we can narrow things down from there.
on the main fuse panel by the drivers door, only fuses 6,7,8,9,10 should be powered when the car is switched off. with all the fuses in place, and the ground cable reconnected, ignition switched off, put your multimeter back in DC VOLTS mode, hold the black lead to a chassis ground, and touch each fuse one at a time, should be no voltage on fuses 1-5 and 11-16, and should be 12V on fuses 6-10. note it doesn't matter which side of the fuses you test, they are the same if the fuse is good.
fuse 6 - in-tank fuel pump (but not the main one under the car)
fuse 7 - brake lights
fuse 8 - courtesy lights, clock, trunk light, engine compartment light, central locks, power antenna, radio
fuse 9 - emergency blinkers
fuse 10 - power windows
Last edited by pierce; 04-16-2013 at 08:34 PM.
#66
Yes charge it up.. and follow what pierce told me to do .. it would be better to start your own thread as well being this one has been read to death lol..good luck
#68
#69
alright got my battery charged, but I think my multimeter doesnt work, I couldnt get a voltage reading from it. but I took the battery to autozone and they put their tester on it and that said it was 100% charged at 12.7 volts. I hooked up the positive cable and test light between negative post and battery and the light didnt come on, so its not a draw. gonna have my alternator tested. If I need a new one are there more powerful ones available? I have a sub in my car and Im assuming thats what killed the alt as its only 80 amps.
#70
any larger alternator would probably require you to fabricate a custom mounting bracket/tensioner.
80 amps at 14V is 1100 watts. even if you have a '1000w' subwoofer amp, odds are really good the sustained average draw is less than 100 watts (8 amps)
first, I'd verify your alternator is working properly. if your multimeter doesn't work, a perfectly good multimeter is like $20 or $30 now, well worth the investment. but, first, check its battery and most have a fuse or two inside to prevent against shorts.
80 amps at 14V is 1100 watts. even if you have a '1000w' subwoofer amp, odds are really good the sustained average draw is less than 100 watts (8 amps)
first, I'd verify your alternator is working properly. if your multimeter doesn't work, a perfectly good multimeter is like $20 or $30 now, well worth the investment. but, first, check its battery and most have a fuse or two inside to prevent against shorts.
#71
I have 500w RMS amp, Im wondering because about 3 months after I got my sub, my alternator died completely, so I got a brand new one, and its been just about 4 months since then. Also when I turn my stereo past 30 (mine goes up to 50) the whole system turns off then back on and I have to turn it down.
Does wiring a second battery in just put more wear on an alternator?
Does wiring a second battery in just put more wear on an alternator?
#72
the car stereo folks have these things called 'electronic capacitors, about the size of a small fire extinguisher that you hook up between your amp and power supply. these store power and deliver it when the amp needs momentary spikes above the system capability.
however, if your system is shutting down its quite possible the power wire or ground to the amp is inadequate, so when the amp needs a lot of current, the wires can't deliver it, so the voltage the amp sees is too low and powering down to protect itself. high power amps need mondo big wire run directly from the battery, and equally big ground cables. with the volume cranked way up, measure the battery voltage, then measure the voltage at the power terminals to the amplifier. if the amplifier voltage is bouncing with the bass, you need better wiring.
Does the AMP shut down, or does the head unit shut down? I've got 50Wx4 head units in most of my cars, and never had a problem with the head unit shutting down at volumes sufficient to rattle the interior of my car (and I went to great lengths to dampen that rattling), this is up there in ear ringing volumes (I don't have any subwoofers, but I do have 6.5" component mains).
many times, when a Bosch alternator 'wears out' or is measured as failing, it just needs new brushes. this is a $40 fix, they just screw on to the back of the alternator, don't even have to disconnect anything. the sorts of rebuilt alternators they sell at the big box stores like Autozone are just old ones that have been cleaned up, and had new brushes put on them and undergone minimal testing.
however, if your system is shutting down its quite possible the power wire or ground to the amp is inadequate, so when the amp needs a lot of current, the wires can't deliver it, so the voltage the amp sees is too low and powering down to protect itself. high power amps need mondo big wire run directly from the battery, and equally big ground cables. with the volume cranked way up, measure the battery voltage, then measure the voltage at the power terminals to the amplifier. if the amplifier voltage is bouncing with the bass, you need better wiring.
Does the AMP shut down, or does the head unit shut down? I've got 50Wx4 head units in most of my cars, and never had a problem with the head unit shutting down at volumes sufficient to rattle the interior of my car (and I went to great lengths to dampen that rattling), this is up there in ear ringing volumes (I don't have any subwoofers, but I do have 6.5" component mains).
many times, when a Bosch alternator 'wears out' or is measured as failing, it just needs new brushes. this is a $40 fix, they just screw on to the back of the alternator, don't even have to disconnect anything. the sorts of rebuilt alternators they sell at the big box stores like Autozone are just old ones that have been cleaned up, and had new brushes put on them and undergone minimal testing.
#73
the car stereo folks have these things called 'electronic capacitors, about the size of a small fire extinguisher that you hook up between your amp and power supply. these store power and deliver it when the amp needs momentary spikes above the system capability.
however, if your system is shutting down its quite possible the power wire or ground to the amp is inadequate, so when the amp needs a lot of current, the wires can't deliver it, so the voltage the amp sees is too low and powering down to protect itself. high power amps need mondo big wire run directly from the battery, and equally big ground cables. with the volume cranked way up, measure the battery voltage, then measure the voltage at the power terminals to the amplifier. if the amplifier voltage is bouncing with the bass, you need better wiring.
Does the AMP shut down, or does the head unit shut down? I've got 50Wx4 head units in most of my cars, and never had a problem with the head unit shutting down at volumes sufficient to rattle the interior of my car (and I went to great lengths to dampen that rattling), this is up there in ear ringing volumes (I don't have any subwoofers, but I do have 6.5" component mains).
many times, when a Bosch alternator 'wears out' or is measured as failing, it just needs new brushes. this is a $40 fix, they just screw on to the back of the alternator, don't even have to disconnect anything. the sorts of rebuilt alternators they sell at the big box stores like Autozone are just old ones that have been cleaned up, and had new brushes put on them and undergone minimal testing.
however, if your system is shutting down its quite possible the power wire or ground to the amp is inadequate, so when the amp needs a lot of current, the wires can't deliver it, so the voltage the amp sees is too low and powering down to protect itself. high power amps need mondo big wire run directly from the battery, and equally big ground cables. with the volume cranked way up, measure the battery voltage, then measure the voltage at the power terminals to the amplifier. if the amplifier voltage is bouncing with the bass, you need better wiring.
Does the AMP shut down, or does the head unit shut down? I've got 50Wx4 head units in most of my cars, and never had a problem with the head unit shutting down at volumes sufficient to rattle the interior of my car (and I went to great lengths to dampen that rattling), this is up there in ear ringing volumes (I don't have any subwoofers, but I do have 6.5" component mains).
many times, when a Bosch alternator 'wears out' or is measured as failing, it just needs new brushes. this is a $40 fix, they just screw on to the back of the alternator, don't even have to disconnect anything. the sorts of rebuilt alternators they sell at the big box stores like Autozone are just old ones that have been cleaned up, and had new brushes put on them and undergone minimal testing.
#74
I have 4 gauge wiring, which is supposed to be good for up to 1000w RMS, but Ive been curious about my ground location. its a bolt holding in the seatbelt for the 3rd row seats. anyone know a better ground location in the trunk of a wagon? and yeah my alt is from autozone...where can I get a better one? Im also going to get new battery power/ground cables.
#75
I get most of my aftermarket parts from Volvo Parts, Accessories and Performance Specialist Since 1963 and Car Parts - OEM & Genuine European Replacement Parts Catalog | FCP Euro, and genuine Volvo stuff from TascaParts.com or Volvo Parts - Authentic OEM Volvo Parts direct from Volvo Parts Webstore | VolvoPartsWebstore.com ...
re: the ground. there's a ground screw over on the left side under the carpet and floor panels for the in-tank fuel pump and power antenna, I think. take a digital multimeter meter, in DC volts mode, and put one probe on your amplifier ground terminal, and the other probe on that antenna motor ground screw, when your amp is cranked up loud. see any volts? if its pretty close to 0.0, then your ground is good. you might try AC Volts too, this will read audio 'noise' in the ground.
re: the ground. there's a ground screw over on the left side under the carpet and floor panels for the in-tank fuel pump and power antenna, I think. take a digital multimeter meter, in DC volts mode, and put one probe on your amplifier ground terminal, and the other probe on that antenna motor ground screw, when your amp is cranked up loud. see any volts? if its pretty close to 0.0, then your ground is good. you might try AC Volts too, this will read audio 'noise' in the ground.
Last edited by pierce; 04-17-2013 at 11:41 PM.
#76
#77
Did you get your problem solved? I had a car that drained the battery; I found the problem when I leaned against the alternator when the engine was cold: the alternator was warm. Hummm.... turned out the voltage regulator in the alternator was not disconnecting the field when the car was shut down, and it drained the battery. new alternator fixed 'er right up.
Recap: unexplained battery drain: check if alternator is warm with engine cold and a charged battery. It should not be warm If the engine is cold.
Recap: unexplained battery drain: check if alternator is warm with engine cold and a charged battery. It should not be warm If the engine is cold.
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