Title: Parasitic Battery Drain
Post by: GigShooTer69 on July 28, 2016, 12:35:04 AM
Post by: GigShooTer69 on July 28, 2016, 12:35:04 AM
Hi Everyone,
88 5.0 V8 Thunderbird
I have a parasitic battery drain that I am having issues with. I tested the battery drain with a Multimeter set to 10A and its drawing a 3.7 from somewhere. I tried unplugging each fuse one by one to try to isolate the issue. No change, so thinking that I possibly missed one, I decided to remove ALL of the fuses and the relays and flasher. Still the same reading I get.
The car was working fine a few days ago, no issues, no changes in parts. It just started draining overnight. I charged the battery to Full several times and leave the neg cable off now when I park. WTF :flip: ? I am asking here before I consider taking it in to a garage.
Any ideas on what to try next? Could it be the Alternator? Ignition Switch? Could it be the battery even if it less than five years old and only summer used?
88 5.0 V8 Thunderbird
I have a parasitic battery drain that I am having issues with. I tested the battery drain with a Multimeter set to 10A and its drawing a 3.7 from somewhere. I tried unplugging each fuse one by one to try to isolate the issue. No change, so thinking that I possibly missed one, I decided to remove ALL of the fuses and the relays and flasher. Still the same reading I get.
The car was working fine a few days ago, no issues, no changes in parts. It just started draining overnight. I charged the battery to Full several times and leave the neg cable off now when I park. WTF :flip: ? I am asking here before I consider taking it in to a garage.
Any ideas on what to try next? Could it be the Alternator? Ignition Switch? Could it be the battery even if it less than five years old and only summer used?
Title: Parasitic Battery Drain
Post by: Haystack on July 28, 2016, 01:18:39 AM
Post by: Haystack on July 28, 2016, 01:18:39 AM
If you can see the voltage drop with the battery Un hooked, it is junk.
There is a fuse able link harness that connects to the starter solinoid. With the battery unhooked, check each fuse able link individually and check resistance to ground. The lower the resistance, the higher the drain and should tell you at least which group of wires to start checking. The fuse able links also power several always hot wires like the brake lights ect.
There is a fuse able link harness that connects to the starter solinoid. With the battery unhooked, check each fuse able link individually and check resistance to ground. The lower the resistance, the higher the drain and should tell you at least which group of wires to start checking. The fuse able links also power several always hot wires like the brake lights ect.
Title: Parasitic Battery Drain
Post by: bodyman on July 28, 2016, 11:57:28 AM
Post by: bodyman on July 28, 2016, 11:57:28 AM
My first check for any parasitic battery drain on an older vehicle is to unhook the wires from the alternator and see if that is it.
A five year old battery is by no means new. The fact that it is summer use only is possibly even harder on it unless you take it out of the car and keep it from the freezing, thawing cycles.
A five year old battery is by no means new. The fact that it is summer use only is possibly even harder on it unless you take it out of the car and keep it from the freezing, thawing cycles.
Title: Parasitic Battery Drain
Post by: CougarGal on July 28, 2016, 12:19:49 PM
Post by: CougarGal on July 28, 2016, 12:19:49 PM
FWIW: I experienced the same thing with my '86 Cougar a few years ago and it turned out to the inertia switch for the fuel pump. Would have NEVER figured it out but parked the car one evening and everything was VERY quite and I heard a slight 'hum' from the rear right quarter panel and was able to figure out what it was from that (thanks to the nice folks on this forum that were able to tell me what it was from my description). Hope you find a solution soon!
Title: Parasitic Battery Drain
Post by: softtouch on July 28, 2016, 03:15:55 PM
Post by: softtouch on July 28, 2016, 03:15:55 PM
I prefer to use a test light between the disconnected negative battery cable and the negative battery post.Then isolate things until the light goes out.
If you accidently ground the positive circuit when disconnecting stuff it may damage or blow a fuse in your meter. With the light, it will just get brighter.
Anyhoo, check simple stuff first. Is there a light on somewhere? Underhood, trunk, glove box. Check the car in the dark.
Then remove the wires from the positive battery cable terminal of the starter relay.
If the light is out, reconnect the positive battery cable. If the light is still out, touch the other wires to the terminal one at a time to see which one has the problem.
Here is a diagram to help get you started. Let us know what you find.
If you accidently ground the positive circuit when disconnecting stuff it may damage or blow a fuse in your meter. With the light, it will just get brighter.
Anyhoo, check simple stuff first. Is there a light on somewhere? Underhood, trunk, glove box. Check the car in the dark.
Then remove the wires from the positive battery cable terminal of the starter relay.
If the light is out, reconnect the positive battery cable. If the light is still out, touch the other wires to the terminal one at a time to see which one has the problem.
Here is a diagram to help get you started. Let us know what you find.
Title: Parasitic Battery Drain
Post by: GigShooTer69 on July 29, 2016, 11:20:48 AM
Post by: GigShooTer69 on July 29, 2016, 11:20:48 AM
Thanks very much for your help, appreciated all around
It was the alternator and I also switched out the battery for good measure. Alternator has never been replaced before
The battery was over 6 years old and was always removed over winter and stored indoors.
The never ending money pit but I love driving this mofookie
It was the alternator and I also switched out the battery for good measure. Alternator has never been replaced before
The battery was over 6 years old and was always removed over winter and stored indoors.
The never ending money pit but I love driving this mofookie