My battery seems to be draining every day, and I'm trying to workout where the problem might lie using a Digital multimeter (which I've never used - and will become apparent ). I've done a search, and found a post by Icemark on how to check the current... unfortunately, he completely lost me in the 2nd sentence. Here's the post;

Disconnect the positive battery terminal, close the doors, turn off the dome light.
Insert the meter (set for amperage) between the pos battery post and the pos battery cable. Pos lead of the meter on the Pos battery terminal, neg lead of the meter on the Positive battery cable that was formerly hooked up to the positive battery terminal.

Insert the meter ?!?! I slipped into a coma after reading that.

Also, I have a Mastercraft digi multimeter, and it has 3 holes for the test probes, but they're not marked, and I have no clue which probe (pos & neg), goes into which hole.

Yes, I know I'm pathetic, but that's my cross to bare.
Any help would be appreciated.

 

To check current you wire in the mulitmeter in series with the battery and have your mastercraft digi set on amps... Something high like 100 amps..

To measure current you will also have to move the leads from voltage and common to common and amperage.


for checking voltage you can just put the two leads in parallel with the battery (ie straight across them)

 

BASICALLY THIS IS WHAT WILL LOOK LIKE


- + <--- After disconnecting your cable from here
|------| attach the Multimeter (red) to here.
|------|
|------|
|------|

the black connector of the multimeter for amperage testing would usually go on the left hole of the meter) then you would connect the cable you have removed from the + terminal on the battery to the red cable on attached to the right hole on the meter.

So essentially, you disconnect the cables from the + terminal on the battery and put the red wire from the multimeter in its place. You then attach the black wire from the multimeter to the hefty cable you just disconnected from the battery. This way all electrical flow from the battery must first pass through the multimeter and it can count how many electrons are moving (current) and tell you in amps. Just realize that you shouldn't do it for more than 5 seconds at a time. Most mutimeters are only capable of handling 10amps for 45 seconds.

Hope this helps

 

With all things turned off, and the meter b/t the positive post and the positive cable, the meter should not read more than 20ma (.020a). By golly that's right out of the manual.....somewhere. It's the ECU that is drawing this insignificant amount along with the clock.

 

Thanks for the info people.

With the car off, I'm getting 12.3v from the battery (not fully charged). With the car running, getting 13.3, I think I should be getting about 14.5, so I think it's either the battery losing charge, or the alternator dying.

 

Start the car. Put your neg lead on the neg post. Put your positive lead on the output AT the alternator. If the voltage is in the fourteen volt range, shut down, remove the wire from the alternator and clean it and see if that makes life better.

 

Umm... and the output of the alternator would be where?
Sorry to sound so dumb, but I'm one of those people that need to picture things so I understand exactly.

 

It's IMPOSSIBLE to attach jpgs on this site. Sorry about that. I'm talking about the large black wire on the altermator/ Probably has a small rubber boot over it.