Does anyone know or is there a site that will tell me how much draw there is on a bat. with the ing. switch off.I have a new bat. and it goes dead in about a week and I drive about a hundred miles a day.I put a VOM. between the neg.post and the cable and it reads bat.voltage.
Thanks

 

First, welcome to FTE!!!!!!

To measure the current drain on a battery, disconnect the negative battery cable. The connect a current meter between
the negative post on the battery, and the negative battery cable
that you first removed. Connect the current meter negative lead
to the negative battery post, and the positive current meter lead
on the negative battery terminal. This will give you the current
load on the battery.

Before doing that, I would check to see if your charging system is
working properly. With the battery fully charged, run your engine
at about 2000 RPMs, and will all accessories on, measure the
voltage accross the battery terminals. The voltage should be
between 13.5V-14.5V....If the voltage is lower, then you need
to look at the alternator / voltage regulator, and possibly the
wiring between the alternator and the battery....

I hope this helps!!!

 

You can take the battery to an auto zone, pep boys and they will test it for free. Also how is your alternator, I had a similar problem with my truck it turned out my alternator was junk and it was draining my battery making up for the loss juice.

 

Alt voltage is fine tomorrow i am having the Alt. checked for amp output. A VOM connected betwen the neg post and the neg cable shouid show me the bat.drain should'it not .when I did this I grt bat voltage 12.87 volts

 

Everything that Mr. Ayers says is correct. Just keep in mind that an ammeter ACTS LIKE A SHORT. So be careful when your are using it.
I had a vehicle that had a battery drain that would cause an inability to start in three days. First do the Vreg & Alternator checks as Mr. Ayers stated above, If that is good then...
With the car off and the door switch defeated (interior lights off), hook up the ammeter as stated above. I found a battery drain (parasitic load) of 35-ish milliamps (0.035 Amps). I then removed one fuse at a time and re-took the amp reading and the re-inserted the fuse after each check (so you are doing one circuit at a time). I found that my dash clock was drawing most of the current...around 28 mA. Replaced the clock, and parasitic load dropped to 8-ish mA all in. Remember that parasitic will probably never read zero. The lower the better.
Also note that a battery that is going bad, won't hold a charge as a good one will.

p.s. As you take the current readings, you may want to write down the fuse number with the parasitic load next to it...I coulcn't remember the fuse number that gave me the 28mA, so I had to re-do the readings......they say the memory is the first thing to go....don't ask me who said it....I Forgot!

Good Luck
Deano

 

Deano 512 are you saying that I need a amp meter to check bat. drain and not a volt meter

 

Absolutely!!!

If you read my post, I say to use a current meter also, and how
to connect it.

Try doing the voltage measurement I described first...

 

Thanks for the help.The first thing I did was to do a voltage check.Alt output is 14.48 volts.

 

Mkrog,

A little electrial theory.....
The voltage on the battery is always present at 12 volts (unless its dead). When a component is energized (headlights e.g.), it is placed in the circuit (usually via a switch and fuse) in parallel with the + and - terminals of the battery. As you turn on more loads, they are also placed in parallel with any other loads that are "on". The increased loads drive the total circuit resistance down, which causes total current flow to go up (per Ohm's Law). Therefore the only way to read circuit load, is by placing an Ammeter (current measuring device) in SERIES with the battery as Mr. Ayers described above. By removing 1 fuse at a time, you remove 1 parallel load at a time, and any parasitic current draw by that load will stop, and the ammeter will read less.


You'll need to do the current checks next, to check for parasitic load. It'll help to have another person read the meter under the hood, while you are in the cab pulling and re-installing fuses.

What are the ratings of the new battery that you installed??

Let us know how you make out..
Good Luck
Deano

 

Click the link below.

http://www.inliners.org/tech/tech6.html