Drained Battery. WTH?

J

~JM~

Wrinkled Member
Joined
Oct 31, 2007
Car has been sitting in storage. I connect the battery tender about every 30 days. Went to start & it was dead. Recall some discussion about the Fan Relay causing a problem. Is there a tech post on that subject?

What are some other electrical components I should check?

Thank you.
 
The battery tender-maintainer is supposed to be left connected all the time.
The battery could have very well drained itself sitting for a month.
 
Trunk light, underhood light, glove box light, door jamb switch and lights, roof lamp with optional map lamps left on....
 
Found this & unplugged the relay: Fan Trouble Shooting

My +/- 30 day Battery Tender routine has served well for several years.

I've checked the lights listed above. Trunk light turns off with trunk lid about 12" from fully closed. Underhood bulb was removed long ago. Glove box bulb? I can't find that one. Appears to be burnt out. The interior lights are accounted for.
 
The double size delay relay will come on in the middle of the night randomly, I removed mine years ago and never looked back.

And as above, leave the battery tender on 24/7, I do. Or not, it's your car.
 
Make sure that any tender used, has a charge sensing feature that reduces charge rate as batt comes up to full charge. A tender is not the same as a trickle charger.
 
Been using this one & the previous generation.
www.batterytender.com

Battery Tender® 12V, 800mA Lead Acid/Lithium Selectable Battery Charger

INCLUDES - 12V, 800mA selectable lead-acid/lithium (LifePO4) battery charger with LED status light to show battery status- Fused ring terminal accessory cable for hard to reach batteries- Fused alligator clip accessory cable for an alternate connection - 5-year warranty and lifetime customer...
www.batterytender.com www.batterytender.com
 
You should have no more than 50 -75 MA draw on the battery with everything turned off . This can be checked with a DVM in series with the positive battery cable .
 
My old Eldo would drain the battery if not driven every 3 or 4 days. It turned out to be the courtesy lite in the passengers sunvisor mirror! I found it after a late dinner walking up to the car in a dark parking lot.
It used a pair of those long skinny fuse looking bulbs in it.
Try a dark garage.
TIMINATOR
 
The car is located in a garage. It doesn't glow in the dark that I can see.
 
I'd put an ammeter in line with the positive battery cable and measure the draw. 10-20 Amp. Scale to start with.
 
Disconnect the computer wire first. Then go to a lower and lower scale and see what amp draw u have. Check which fuses are powered with the key off. Then pull those fuses one at a time and check to see if any have a draw across them with the amp meter. That will tell you which circuit to look at.
If you have any aftermarket gauges, they may be powered by the battery, not thru the key. I have seen aftermarket gauge lights wired directly to the battery too. Same with an AXIS, MAF translator, Scanmaster, or the like.
The draw may not be large, but it is continous.
Not to state the obvious, but the battery itself could be bad.
TIMINATOR
 
Also, disconnect your underhood light, trunk light and glovebox light. Any of these will kill your battery if they malfunction and stay on.
 
Post #4: "My +/- 30 day battery tender routine has served me well for several years."
So how old is this battery anyway?
Disconnect the battery.
Charge it with a REAL battery charger.
Leave it disconnected.
See if it discharges.
If so, buy a battery.
TIMINATOR
 
TIMINATOR said:
Disconnect the computer wire first. Then go to a lower and lower scale and see what amp draw u have. Check which fuses are powered with the key off. Then pull those fuses one at a time and check to see if any have a draw across them with the amp meter. That will tell you which circuit to look at.
If you have any aftermarket gauges, they may be powered by the battery, not thru the key. I have seen aftermarket gauge lights wired directly to the battery too. Same with an AXIS, MAF translator, Scanmaster, or the like.
The draw may not be large, but it is continous.
Not to state the obvious, but the battery itself could be bad.
TIMINATOR
Click to expand...
I wired a scanmaster and oil pressure gauge to fuse block always on power. Has battery drain. Moved the to switched and problem gone.
 
An alarm will drain the battery too. A stereo that shows clock on screen all the time also.
 
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