Dead Battery current leak

So I had this electrical problem. Last May at 52,000 miles. The battery
spontaneously died while at a baseball game. My wife insisted she hadn't
left any lights on. We had the car towed home. The alternator tested good.
We replaced the battery and did not have a problem for another year.

Last week at 60,000 miles, I drove the car home from a restaurant, stopped
at the store for ten minutes, and when I came out the battery was super
dead. Usually if the battery is dead, it clicks when you try to start it. It
was so dead, it clicked when I turned it to 'on'. When I turned it to start,
it went all black, no dash lights, no radio, nothing. I was able to drive it
home after I got a jump.

I tried to have the alternator tested, but the tool was broken at the shop,
and my good multimeter was loaned out. So, I decided (against better
judgement) to replace the alternator, even though I hadn't proved it was
bad. After about two hours of replacing the alternator (first time, $120, 2
hours labor) and the battery (second time, 30$.5 hour labor), and it was
still draining the battery according to a volt meter.

So I finally broke out the meter and tested the battery for current with the
key off, and Voilla!! there was current, so I pulled the fuses starting with
the 30's until I got to the cooling fan fuse. It turns out there was a .1
amp short from the coolant fan fuse to chassis ground in the main fuse block
in the engine compartment that was sucking down the juice. I pulled the
fan relay, which disconnects all wiring outside the block and the ground was
still there. Which meant that the short was inside the block.

I disconnected the battery and sprayed the block with electrical cleaner and
it appears to be working normally now.

There is still a ground but it's only 5 milliamps. so using the battery
mumbo jumbo calc of drain times time =amphours. It should take the battery
about 100,000 hours to discharge. Well, it should be fine for up to a week
at least.

I was wondering if anyone else has seen problems with wierd shorts in the
main fuse box.

 

One possible problem might be from road salt that found its way onto the
power connections. Dry salt is not a problem but when it gets damp or even
in high humidity, it can let currents flow. This also causes corrosion which
is the best indicator of where the problem is.

If this is the case, clean off with a brush as much as you can and flush
with copious ammounts of clean (preferably de-ionized) water. Let it dry and
spray with a waterproofing silicone after verifying that the leakage current
is no longer flowing.

ps - what you describe is a leakage current, not a short.

Hope this helps
Oppie

 

If this is the case, clean off with a brush as much as you can and flush

Sorry if this is a dumb question, but what (if any) is the difference
between distilled water and de-ionized water? Where do you get
de-ionized water?

I understand the purpose - it is the ions in the water (ie, NaCl), not
the water alone, that allows current to flow.

-rj
98SL2

 

Actually distilled and deionized are the same for this purpose.

Distilled is boiled off and condensed leaving any ionic contamination
behind. (for biological applications, distilled is also preferable as it is
sterile).

Deionized is usually made by a reverse osmosis (RO) process. We had such a
system in our lab. With new columns we got 20 meg ohms per centimeter (a
measure of conductivity. The higher the number, the less ionic content). We
replaced the columns when the conductivity dropped to 10 meg ohms/ cm.

Where do you get it is another matter. If you have an up-scale home with a
RO filtration system, you are all set. A 'water softener' is not the same
thing. These actually wind up adding some salt to the water (as I recall).
Otherwise you can usually buy distilled or deionized water at the
supermarket.

Oppie