More Electrical Questions....

Jorge022770 · Post by **Jorge022770** » Mon Sep 05, 2005 6:46 am

My friends:

You must think I am the worst electric knowledge-limited guy here, and you are probably right!

But I have little time these days to work on the car, and this weekend I want to finally solve the problem I have shared with you in a couple of postings ("My electric gremlins still laugh @ me", etc.). I got the battery recharged and tested...everything ok. Got a new volt. regulator, and tested the charging with the multimeter, which shows the alternator is also charging fine.

But I want to check to ee if there's a drag (i keep disconnecting the battery every time engine is off just in case) using the multimeter, and don't know how to properly set the wires and dial on the actual multimeter to do the test (also see posting "HOW TO USE A MULTIMETER"). the red wire has 2 choice of where to plug it, and there are numerous settings and values to choose from.

If I leave the settings the way i had them when iI tested the system, and disconnect the -- pole and put one probe on the -- pole and the other on the ground wire, it reads the ame as when i put one on the + battery pole and one on the -- pole! (about 12.3V).

If tht is right, thers a 12V draw! .......any dumb-proof instructions?

Jorge

mikew · Post by **mikew** » Mon Sep 05, 2005 9:48 am

Hmmm...

What you did before when you placed the multimeter across the +ve and -ve battery terminals is a "parallel" connection and is appropriate for measuring the VOLTAGE across a device (the battery in this case!).

You have the right idea trying to take a "series" measurement by placing the probes between a battery terminal and the cable that normally connects to that terminal. However, what you are trying to measure here is the CURRENT through the circuit (not the voltage). To do this you have to set your multimeter to a current setting. It might be marked "I"? A warning here though. A large current flow could damage your multimeter! So....

Not sure?!

If you had a resistor you could place the resistor is series between the battery and cable, and then measure the voltage across the resistor, and use the formula V=IxR to determine the current leak. If you don't have a resistor you could possibly use an old headlamp or similar as a resistor but this is getting messy. (a light filament has resistance - you can measure it with your multimeter in the "R" or "ohm" mode)

Just a thought though... How quickly is your battery going flat? The clock actually draws a fairly large current, and if you have a modern stereo with memory presets that will have a current draw as well. If you are not driving the day at least every 2 or 3 days, you might want to disconnect them.

I'm sure someone else will chime in with an idea.

Mike

Jorge022770 · Post by **Jorge022770** » Mon Sep 05, 2005 2:57 pm

Mike (and JC if you read this too):

I did what you guys told me, and the multimeter reads 9.8-10. The multimeter was set on the 200m which I assume to be correct based on your explanation and on the awful instructions that the meter came with.

So will this mean that I shouldn't have a draw and my battery should be expected to still have charge tomorrow morning?

Jorge

hport · Post by **hport** » Tue Sep 06, 2005 7:57 pm

Jorge,

Yes, 10ma is almost no draw at all. Does you clock work?

I'm not responding to your electrical problems or anyone elses for that matter....... My Alternator died two days ago. It was right after a responded to your alternator questions

Just kidding, just don't let my car find out. I installed a GM one wire. Works like a charm.

Congrads on your electrical 101 graduation.

JC

datsun65 · Post by **datsun65** » Tue Sep 06, 2005 8:10 pm

5 years ago, on my 66 1600 I purchased a brand new Battery because the old one seemed worn out.

A few weeks later, on the drive back from Solvang, the recharging system bit the dust in the middle of nowhere in the total blackness of night. After I had the car dragged home at 2AM, I had a new alternator and voltage regulator installed later that week.

Yet, even after the new alt/reg, the charging system was dead after only a few days. I tried for weeks trying to locate the drain, but couldn't find it. Finally, I checked out the "new" battery again...and guess what...It was fried.

When the Alternator & voltage regulator completely failed, it also ruined the new battery. Once I replaced the battery with another new one, all the issues were resolved.