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I have an 08 300, small V6. Replaced the alternator and battery, thought I had it figured out, but I'm having the same issue. No mods, car is stock. No lights left on in trunk or glove compartment, phone charger disconnected and lighter USB disconnected, and stereo powered OFF when I leave the car. Car isn't throwing any codes. Car was fine before engine work was done on it, since then, having this issue. Please help!
 

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I have an 08 300, small V6. Replaced the alternator and battery, thought I had it figured out, but I'm having the same issue. No mods, car is stock. No lights left on in trunk or glove compartment, phone charger disconnected and lighter USB disconnected, and stereo powered OFF when I leave the car. Car isn't throwing any codes. Car was fine before engine work was done on it, since then, having this issue. Please help!
Check your engine and cars grounds to be sure they are solid, also check any recent wiring, you may be shorting out somewhere that will not throw a code.
 

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I have an 08 300, small V6. Replaced the alternator and battery, thought I had it figured out, but I'm having the same issue. No mods, car is stock. No lights left on in trunk or glove compartment, phone charger disconnected and lighter USB disconnected, and stereo powered OFF when I leave the car. Car isn't throwing any codes. Car was fine before engine work was done on it, since then, having this issue. Please help!
First of all, STOP firing the 'Parts Cannon'!

Start from scratch. Fully charge the battery then 'load test' the battery with a load tester of the proper rating as the battery class.

If the battery checks out, then reinstall the clean battery with secure connections. Next, you will need a multi meter that reads mA. Find out what the acceptable 'parasitic draw' is for your car, probably not more than 50mA.

Disconnect the negative cable from the battery and connect the meter between the negative battery post and the clamp. Make sure all doors are closed and everything is turned off for at least 2 minutes.

If you find that you have excessive parasitic draw, you will have to play Sherlock Holmes and track each circuit by pulling fuses/circuit breakers to find the malcontent. Leave meter hooked up to the battery as stated previously.

Good luck.
Tire Wheel Cannon Plant Tree
 

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I have an 08 300, small V6. Replaced the alternator and battery, thought I had it figured out, but I'm having the same issue. No mods, car is stock. No lights left on in trunk or glove compartment, phone charger disconnected and lighter USB disconnected, and stereo powered OFF when I leave the car. Car isn't throwing any codes. Car was fine before engine work was done on it, since then, having this issue. Please help!
One more 'heads up' - incredibly simple. Affects some cars but not all. Should be standard practice anyway.

Whenever you connect-disconnect a motor vehicle battery:

1. ALWAYS disconnect the negative cable first.

2. ALWAYS reconnect the the negative cable last.

3. Same procedure with jumper cables - booster box, etc.


Most modern cars/trucks will keep the power on for up to a minute after turning the key off, to briefly operate the windows, lights, radio, etc. Sometimes this function gets out of whack and the very first thing many techs will do (after checking the battery) is to disconnect-reconnect the battery in the manner described, as it may help a stubborn electrical system reorient itself.

Worked for me on a 2005 Mustang GT - FoMoCo even had a service bulletin about it that dealers apparently didn't read.... :(

Worth a try. :)
 

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First of all, STOP firing the 'Parts Cannon'!

Start from scratch. Fully charge the battery then 'load test' the battery with a load tester of the proper rating as the battery class.

If the battery checks out, then reinstall the clean battery with secure connections. Next, you will need a multi meter that reads mA. Find out what the acceptable 'parasitic draw' is for your car, probably not more than 50mA.

Disconnect the negative cable from the battery and connect the meter between the negative battery post and the clamp. Make sure all doors are closed and everything is turned off for at least 2 minutes.

If you find that you have excessive parasitic draw, you will have to play Sherlock Holmes and track each circuit by pulling fuses/circuit breakers to find the malcontent. Leave meter hooked up to the battery as stated previously.

Good luck. View attachment 177370
Parts Cannon............ I like it. Is that what most dealers do?????
 

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Concur with the fact that you obviously have a leak somewhere to earth/something running, what Joe says is exactly right. Fully charge battery, then load test to eliminate that, THEN go looking for the drain.

Just to add to what Joe said above............... measuring current can blow up a meter in seconds if people don't understand "measuring current." It is ENTIRELY DIFFERENT to measuring voltage. He has rightly told you to measure it "in the line" between battery and battery lead (that is "in series" ie no other path) - BUT..........................

(Sorry for the suck eggs, if you already know this, then is basic. If not, may save a blown up meter).

Voltage is measured in parallel, (one of multiple paths) because voltage along a line is like pressure in hyd - equal and throughout - that is like when a mech oil gauge measures pressure. A very small part is bled off and fed to the gauge. The gauge can handle the full pressure, it isn't "open ended", that is the bit bled off goes into the gauge and nowhere else = shows pressure. A voltmeter can handle the voltage - it's own internal resistance stops the meter drawing excessive current; same as an oil gauges sealed end stops "oil going everywhere"

Current is measured in series, ie in line with the cct. Start on the highest setting on the meter, and work down. Current measurement is like putting a flow meter in line with a water line. You don't want any restriction, because you want to change the flow. Therefore a flow meter has NO RESTRICTION. Same as a meter on current. So, while measuring current in line, it will show what is flowing in that line. But if any ccts running (and some run residual for a short time, as Joe rightly says above) if you have the meter on low mA setting, it will try and put a few amps through a cct designed to measure a fraction of that = fry the meter. While most meters have trips/fuses, extreme current will damage before they trip.

The BIG deal is NEVER EVER use the current setting across polarities. That is obviously REALLY obvious to anyone who understands electrics. And while may sound silly, so many assume that "I measure voltage all the time, will try to measure current".............. hook it up the same way.

Measuring current is harder (in a car easy, as remove battery lead) as in most ccts have to cut/break a line; so is often a last resort in more complex ccts.

It is hard to blow up a meter on a car with voltage. But if set to current and put across pos and neg, that is a short, as meter has NO internal resistance. It can damage the cct, or if battery, the meter will attempt to conduct a thousand amps before it explodes. So only EVER use it in line, never across voltage.

Be careful.

Again, sorry to the people who understand current measurement and for who the above is "Duhhh." :)
 
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