Battery drain

[Jorge A. Gonzalez]

I have a 2002 Ford F150, 4.6 engine. If I don’t use the truck for 3 or more days, the battery drains. I had the battery tested at Auto Zone and they said it was good. The alternator is charging 14 1/2 volts. After seeing the video on Parasitic draws, I assumed that I had that problem. I did the test as per Eric’s video. I ensured no key in ignition, no lights on. I removed the negative cable and connected one test cable to the negative cable and the other to the negative battery terminal (multimeter set to 10 amps). The meter displayed 42-43… the video said 50 or under was normal. What could be draining the battery. didn’t get to pull any fuses since the reading was normal…

Topic

[Gumpy Guss]

Then most likely the battery self-discharges. There is no test at a store that can detect this.

Either the battery has an internal discharge path through its chemistry, or there is a small chance if the battery top is very dirty that can conduct a bit. The usual remedy is a tablespoon of baking soda and your old toothbrush and a little water. Clean a one inch circle around each battery terminal.

If that doesn’t help you need a new battery.

[Bill]

Maximum draw should be no more than 50 Milliamps and not 50 amps or even 5 amps.

[Gumpy Guss]

You must mean milliamps, like 50 milliamps, not 50 amps. Most car batteries are good for around 50 amp-hours, so a 50 amp drain would drain the battery in an hour, not 3 days.

If the drain is really 50 milliamps, that’s good for 1,000 hours or about 40 days. If the battery is going dead in 3 days, it must have an internal self-discharge rate of about .75 amps. 72 hours times .75 amps is about 50 amp-hours. Anyway, if you don’t have that much of a parasitic load, either the battery has this kind of internal leakage, or you have that much of external leakage through the battery surface.

[Shaun Flichel]

are you sure the battery is draining? make sure all connections are clean and tight. had a car that would sit for an hr. no start, dim light. and this is a brand new battery. would start with a boost. cleaned terminals, retightened. no more problems

[Hikaru]

Try to remove the battery from your car, or at lease remove all the connector from the positive and the negative.
Mark the voltage with voltmeter, and try mark it again with volt meter in another day, is it drain fast or drain very slow, if in a day you have heavy drain in voltage, it’s sure that you have bad cell on your battery. if it’s a dry cell, you have to replace it, if acid battery you can flush the acid and purr new acid in it, and try to charge it again, and retest, if the problem occur, you can replace the cell at your battery repair, or buy new battery.

if you have good battery, try to series your battery with amp meter
[mass] —- (-) (+)—-(Amp Meter (min 10 Amp setting)—Load(car system), do not put any electrical load, just hook your amp meter as it the car in off position, and mark the amp drain, if you have heave drain, try to do this on suspected load, for example groundings, alarm, central lock, audio hu, power amp, lighting but don’t turn on the device. do that until you have the culprit.

cmiiw

[EricTheCarGuy]

You first need to make sure you’re doing the test correctly. As pointed out you don’t want to see more than 50 milliamps. If you were on the 10 amp scale, if I read you correctly, then you have a significant draw on the system. You might want to re-watch the video to make sure you’re doing the test correctly.

[Jorge A. Gonzalez]

I redid the parasitic draw test again. The multimeter read 0.22-0.24 milliamps. At first it was reading 0.42 milliamps but as I held it a little better, it went between 0.22 to 0.24 milliamps. As I mentioned the battery is good…The terminals are clean and tight. When I installed the battery about a year ago, I installed those fabric looking round things that you put on battery terminals to keep the terminals from corroding. I checked the battery terminals and the terminals are spotless. I used a battery wire brush and cleaned the terminals and the inside of the battery terminal cables and retightened them. After the cleaning and retightening, I didn’t use the truck for 3 days and when I went to start the truck, everything was dead. no lights, no nothing. I put a charger on the battery, selected the 40 amp charge and turned it on. I waited 30 seconds and the truck started right up. If I use it everyday, it starts with no problem. but 3 or more days, dead battery. Any suggestions? Do you still think it’s a bad battery? Auto Zone says it good, so they won’t give me another one, even though I have the 3 year 100% replacement warranty…any help is greatly appreciated. Winter is around the corner her in South Texas, so my battery might be dead after 2 days.

[Its me]

Do you have any aftermarket audio equipment/alarm/anything not stock drawing a load on the battery?

Also, have you taken the battery to another different store for a load test? I might consider that as well…

If all still checked out fine, I would pull the fuses on whatever is drawing a load on the battery (radio/clock, even the ecu)… Pull all relevant fuses until there is no draw and let it sit for three or so days…. Put fuses back in and see if it starts….

I would just wonder if you are around something causing interference… I known the chances are very small, but perhaps a signal from something could be causing issues… Perhaps just disconnect the remote control for the power windows and door locks (if equipped)….. There have been problems with proximity keys (highly doubtful you have one of these on this year/model) but who knows…. grasping at straws here…

-Karl

[Matt]

Bad diode in the alternator….seen it before.

[george gonzalez]

Okay, you must mean 0.25 amps, not milliamps. That is WAAAAY too high a draw. Times 24 hours that’s 6 amp-hours. That will discharge the battery about 25% per day, which exactly matches up with your experience.

Now while keeping that meter hooked up, start pulling fuses, one by one. The one you pull that drops the current down to like 0.05 amps, that’s the circuit with the big drain.

As others have said, the problem could be in the alternator. Most alternators are NOT hooked up through a fuse, so you’ll have to unhook that wire. It’s the thick wire going from the alternator to the battery positive terminal. Sometims, not often, but sometimes a diode in the alternator gets leaky or the voltage regulator keeps the rotor current on all the time, leading to this problem.

[Jorge A. Gonzalez]

Oh, OK, so its AMPS, not milliamps that I am reading on the multimeter?..All I know is that the multimeter was set at 10 AMPS and the reading on the display was 0.22 then it would jump to 0.24, then back and forth. So if the 0.22 reading is in AMPS, then I guess I do have a parasitic draw. OK, now I just have to figure out how to turn the light off when I open the doors to the Ford Truck while I pull the fuses, I can’t see what gets pushed in when I close the door, no door jam/button sticking out that I can see.. any ideas?… thanks for your help..

[Author]

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