1996 850 Wagon Service Light On Topic is solved

[erikv11]

Did you strip down the wire, clean it up well, fresh cut etc? Just dumping in solder may not fix things. Well I suppose the thing to do there is just check if it is still heating up.

[abscate]

It would be interesting to gather a set of reading in Volvo P80 battery cable temps with conditions for diagnosis, my favorite disease.

[PeteB]

I cleaned what I could get at really well, used non-acid flux and our 320W (this is huge wattage)
soldering gun and it worked pretty well. We also did the pos and neg smaller wire bundles that are crimped.

Terminal is cold now.

It would be great to know all of the connections that typically go bad due to oxidation.

Our older version is a bit more powerful than this:
https://www.zoro.com/weller-solder-gun- ... gLa1PD_BwE

Walmart battery is no longer cheap at about $100, anyone know of a decent cheaper battery?

[PeteB]

I'm thinking that when the battery is so dead that it won't open the locks it needs more than
a half our ride to work to charge it.
Problem seems to be intermittent, when I tested it everything seemed fine, other times
there seems to be a drain that kills the battery over night.

Is there anything that's triggered on a light sensor for day vs. night?

[PeteB]

We noticed the red lights built into the doors that go on when they are
opened for oncoming traffic to see, wondering if one is intermittently
stuck on, especially since the doors were hit hard in the accident.
The problem is that then I put an amp meter in there I get nearly zero
drain indicating that whatever the problem is, it is not happening.

Charged it overnight on a 6A old Sears charger and the battery voltage
is now 13.5 no load, no charger, not running. I looked up that 12.7 is
full charge, hmm that's very high! Even with a door open and the light
on it is 13.3.V.

[PeteB]

I found that the big red alternator wire goes to the starter post and back to the
battery through the very large starter wire. This would explain the crimp getting
hot when the battery was completely dead since the charge current would be
very high.
I will get out my bench Fluke meter that will read ohms to two decimal
places and see if soldering the crimp helped to lower the resistance.

[PeteB]

The Fluke meter reads to 3 decimal places on low 2 ohms full scale. It is difficult to
zero but got it within .002 of zero and there was really no difference across the crimp,
or from the terminal to the battery post. Looks good, there could of course be some
non-linear resistance, but who knows.

[PeteB]

OK obviously there has to be some draw for the radio memory etc. and of course the
fuse for amps in the meter was blown. This often happens when you leave the leads
in the amp spot and try to read a voltage. Replaced the fuse and am now getting
500 to 800 mA or over half an amp which is not right.

I removed the nut holding down the smaller wires on the positive terminal and
measured zero to the small wire and the same 500+ on the larger red wire bundle.

The large main wire alone measured some draw but dropped to zero so there is
probably a cap in the voltage regulator.

Have to start pulling fuses in the car to find the draw.

[PeteB]

Next question is which circuits are live when the key is off/out of the ignition?

[PeteB]

Today the leakage is around 250 to 350 mA.

Pulled every fuse in the engine compartment fuse block and none of them fixed it.
Some made it jump up actually!
Putting those back in and giving it time it came back to 250 -350 mA.

Open to suggestions.
Tempted to snip one at a time the bundle at the pos battery terminal to find which one it is.

Found this post with links to wiring diagrams but none for 1996 using 1995 for now:
viewtopic.php?f=1&t=86511