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New Battery Drain - Parasitic Drain
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Rael
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Oct 29, 2022, 7:55 AM
Post #1 of 18
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New Battery Drain - Parasitic Drain
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Good Morning - Hope someone can help me with this issue - Will a brand new - fully charged battery show a noticeable slow discharge when first hooked up? Had an issue with a parasitic drain. Pulled fuses and identified the drain and left the fuse out (rear wiper) - Found and corrected the issue (I think) but prior to finding it, it had totally drained a new battery twice over night down to nothing. Replaced the battery with a brand new one and brought the new one to a full 13.69 charge prior to hooking it up and as soon as I hooked the cables to the new battery it began to discharge 1 number every 5 seconds with out even starting the truck (96 Ford Explorer XLT 4.0). I only let it drop to 13.50 and then disconnected it. Do I still have an issue I haven't found or is this normal at first. If so, at what voltage should this discharge stop. I don't want to ruin this battery like I think I did to the last one.
Side note - the old battery held charge over night after pulling that fuse and the two total discharges. Started right up the following morning - Alternator was showing 13.6 volts at idle. I left to drive to town and within 6 miles the battery was stone dead and I ended up sitting on the side of the road for 5 hours until I could get the truck back home. I assumed that battery was bad so I got this new one. Don't want to go through that again. Thanks in advance for any help here
(This post was edited by Rael on Oct 29, 2022, 8:15 AM)
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Hammer Time
Ultimate Carjunky
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Oct 29, 2022, 8:14 AM
Post #2 of 18
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Re: New Battery Drain - Parasitic Drain
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You have to first understand batteries.
A fully charged battery is 12.6v. Anything over that is a surface charge and will disappear quickly.
You also have to understand that all cars have some degree of parasitic drain and most have modules and things with timers that go to sleep after a period of time.
I would be very surprised if a rear wiper caused a parasitic drain since this is an "ignition on" controlled device.
First you have to make sure you are testing it properly in the first place. Current drain is measured in Ma, not volts.
Here is the proper procedure
You will need a digital ammeter and a jumper wire with clips on the ends to do this.
First rig any door switches so you can have a door open without triggering the interior lights and unplug the hood light. Remove one battery cable and attach the meter in series between the battery cable and battery post. Take the jumper wire and also attach it the same way. Leave the jumper wire on for at least 30 to 40 minutes to expire all the automatic timers. Now remove the jumper wire and read the meter. Anything over 50ma is too much draw. The way you locate this is to start removing fuses one at a time until the meter drops to normal level. This will be the circuit with something staying on. Determine what components are part of that circuit and check them individually until the problem is isolated.
Note that the act of pulling fuses will often restart some timers so you may have to wait for them to expire if that happens
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Oct 29, 2022, 8:16 AM)
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Rael
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Oct 29, 2022, 8:18 AM
Post #3 of 18
(1738 views)
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Re: New Battery Drain - Parasitic Drain
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Thank you - I have a meter so I will start working on this. I will update later
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Rael
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Oct 29, 2022, 9:51 AM
Post #4 of 18
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Re: New Battery Drain - Parasitic Drain
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It would appear the parasitic drain is gone but I believe I have another issue. I believe my alternator may have been stressed to the point where it is no longer good. When the truck died on me the other day it should have remained running even if the battery were disconnected because I never allowed the RPM to go below 1000 but the truck just shut completely down and there was nothing at all. Prior to this happening if I checked voltage while "running" it was 13.6 - today when at an idle it is showing 12.45 steady - when I shut the truck down the battery is showing 12.65 and holding. What should the voltage show on a good alternator when running at idle. Is there another way of testing this. Sorry to be stupid on this but electrical is the one thing in auto mechanics that I hate the most. Always turns out to be much harder than it should be because I do not know the proper way to check a lot of things. Again, thanks for any help - I need this truck back up and running. Live 10 miles from town and is my only transportation.
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Hammer Time
Ultimate Carjunky
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Oct 29, 2022, 9:59 AM
Post #5 of 18
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Re: New Battery Drain - Parasitic Drain
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That's another important thing you have to learn about electrical systems.
NEVER, EVER disconnect the battery when the engine is running. That will spike the sensitive electronics in the car and can cost you a fortune. That is an old school trick used before computers were put in cars.
The rate of charge will vary with the amount of load on the battery at the time, the condition of the battery and the RPM of the alternator.
A general rule of thumb is 2 volts above sitting battery voltage with no heavy loads being used.
For example, if you turn the AC and headlights on at idle, you will get very little charge at all but will increase substantially if the RPM is raised even slightly.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
(This post was edited by Hammer Time on Oct 29, 2022, 10:00 AM)
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Rael
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Oct 29, 2022, 10:14 AM
Post #6 of 18
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Re: New Battery Drain - Parasitic Drain
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Thank you for the help Sir
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Tom Greenleaf
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Oct 29, 2022, 9:02 PM
Post #7 of 18
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Re: New Battery Drain - Parasitic Drain
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Rael - keep an eye on that battery as going low or fully dead really harms them, new or not.
Also a discharged battery will freeze and can crack case maybe leak + be a royal PITA. It's hard, try not to let that happen,
T
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Rael
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Oct 30, 2022, 7:42 AM
Post #8 of 18
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Re: New Battery Drain - Parasitic Drain
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Thank you - will do - on the alternator, I have been told you can rebuild them. Really stressed for money at the moment. Not sure exactly what to purchase but if possible this would be less expensive (I believe). So far the only thing I have been able to locate are the brushes for the alternator. What is the most likely thing to have gone wrong with the alternator? To replace the alternator I would have to wait at least a week until I get my next check.
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Tom Greenleaf
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Oct 30, 2022, 8:50 AM
Post #9 of 18
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Re: New Battery Drain - Parasitic Drain
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Re: Rebuilding an alternator. I used to all the time hard to find parts now for years.
If you get anything out of it now and minimal tools take that one apart you can see worn/burned brushes or glazed over contacts usually the issue. Super fine wet/dry sandpaper see if it will clean up contacts if brushes have life left are still OK clean those too same sandpaper.
I can't find "diodes" for sale anywhere if one goes bad it's over.
Only thing tricky is hold brushes back withe wire or a paper clip to put back together indexed to same "clock position" it was in - mark it first if you go there.
Search away it's a "diode trio" and brushes is all rebuilts get as new is so cheap if you hunt it's not worth it. Bearing on pulley end YOU need to know by sound or feel if it's good new is like $10-15 bucks will fail faster than a good original.
One smear of grease (high temp electrical grease a fav to rear bushing NOT TOO MUCH.
Doubt you'll find parts if so let me know where privately if yours was worked too hard it can't be redone,
Tom
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Rael
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Oct 30, 2022, 9:35 AM
Post #10 of 18
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Re: New Battery Drain - Parasitic Drain
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Thank you - will do - haven't decided if I am going to rebuild or just replace - with possibly an alternator from a salvage yard. Money is that tight right now and I really didn't need these issue right now
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Hammer Time
Ultimate Carjunky
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Oct 30, 2022, 11:48 AM
Post #11 of 18
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Re: New Battery Drain - Parasitic Drain
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You can't find parts for these things and even if you could it would likely be cheaper to buy a reman.
Nobody tries to rebuild these things any more. It's not worth it. You don't have any of the required equipment to do this.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Rael
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Oct 30, 2022, 11:51 AM
Post #12 of 18
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Re: New Battery Drain - Parasitic Drain
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Thank you - kind of what I was seeing when looking for the parts.
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Rael
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Oct 31, 2022, 5:14 AM
Post #13 of 18
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Re: New Battery Drain - Parasitic Drain
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Last question, I promise - ready to bite the bullet and purchase the reman alternator but confused. My neighbor came over yesterday - retired electrical engineer (NOT automotive). He said my alternator is good but I question that because of the past things. Will explain below.
When the old battery had been ran totally dead twice and it was in the truck after a charge, I checked the battery voltage "while running" and it was 13.6 - when I shut it off the bat was at like 12.? - NOW with a brand new battery the voltage is showing 12.48 both running and off. As I turn things on in the truck the voltage begins to drop. It never goes back up to the 13.6 it was at the other day?? He said that is because the voltage regulator is maintaining it there. He said he is not sure why it was 13.6 the other day but said maybe because that battery was bad. I would almost believe him if not for the fact that now as I turn more and more things on in the truck while running the voltage shows a steady decrease for each thing added. Plus when the truck died on me the other day at over 1000 RPM, I would have thought it would have remained running just from the power coming from the alternator. I wonder if the bad battery and the truck running was just to much for the old alternator? I really can't afford to waste money right now, my son and I are hurting and this is kicking my butt. Sorry for so many questions but just want to make sure I go the right way.
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Hammer Time
Ultimate Carjunky
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Oct 31, 2022, 5:27 AM
Post #14 of 18
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Re: New Battery Drain - Parasitic Drain
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You need to slow your roil here.
I think you are jumping to conclusions about the alternator.
First, the symptoms are very different between a bad charging system and a parasitic draw.
The draw kills the battery after sitting overnight.
A charging system problem kills the battery while the car is being used.
Even if a charging system problem is confirmed, that doesn't automatically take you to a bad alternator.
There are fuses that operate the alternator. There is also a fusible link between the alternator and the battery along with related connections. A loose belt will also lead to insufficient charging. So will a bad battery.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Rael
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Oct 31, 2022, 7:45 AM
Post #15 of 18
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Re: New Battery Drain - Parasitic Drain
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Wow things were so much easier back in the 60's and 70's - I was unaware of the fuses for the alternator system. The parasitic drain was corrected by removing the 15 amp fuse for the rear wiper system - but looking at the diagram of the under hood fuse box the alternator system fuse is a 15 amp also and it shows lines running between those two fuses? I am not sure if disconnecting one would effect the other. Glad I haven't purchased an alternator yet but still without transportation and that is what is driving me up a wall. I have a handicapped child here and if needed I can't go anywhere. Arrggghhhh Why wasn't I born rich instead of beautiful LOL Thanks 
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Rael
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Oct 31, 2022, 10:13 AM
Post #16 of 18
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Re: New Battery Drain - Parasitic Drain
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Alright everyone jump onboard and tell me what a idiot I am. NEW INFO first off when I eliminated the parasitic drain it was NOT the rear wiper fuse it was the alternator fuse that I pulled "that eliminated the drain". Just to test it I just reinstalled the fuse and started the truck - alternator was putting out 14.65 as it should be - I shut it off and checked for the drain and sure enough it is back. I have pulled the fuse for the moment. How do I identify what is causing it in the alternator system? The alternator appears to be working just fine when running - I just can't ever shut it off. With gas prices that is going to become costly LOL
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Hammer Time
Ultimate Carjunky
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Oct 31, 2022, 10:17 AM
Post #17 of 18
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Re: New Battery Drain - Parasitic Drain
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The alternator can cause the draw. The best way to find out is to just disconnect the alternator wiring and see if the draw is still there.
As I told you earlier the wipers are powered by the key so they cannot be your draw with the key off.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Rael
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Oct 31, 2022, 10:30 AM
Post #18 of 18
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Re: New Battery Drain - Parasitic Drain
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Ok - Yeah I was looking at the drawing upside down and thought that was the one I had pulled and it kind of made sense because the night before this all started it rained like hell and I noticed the the rear wiper rubber plug was out of place which would have allow water in there. I jump to a conclusion that I shouldn't have. Thank you for all the help with this - I now know where it is coming from and I will do as you said and figure this out
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