Checking for Draw?

[04stangman]

Hey guys, one more question? Whats the best way to check for draw on my battery to avoid getting dead batteries when my truck sits? Here is what I have done so far.

With the ignition off I pulled the negative terminal off I put the clamp from my check light on my negative battery cable clamp and the check light point on my negative battery post, no light.

With my ignition off I checked the small wire on the passenger side of my coil with my check light, no light came on....... ignition turned on, light turned on.

I dont know what else to do, and I cant afford another battery if this on goes bad........ Thanks guys~

[fordman]

if you hot now light then your good. if a battery sits too long it will loose power while it sits. you can disconnect the battery to keep it from running down while it sits. i have two trucks like that. i was considering putting a battery cut off under the dash of them to make sure they would be disconnected when i wasnt constantly driving them.

[72stepside]

My father-in-law (NASA Engineer) used the Battery Buddy for years on his motorhome and 65 Vette. The Battery Buddy is no more so I hear.

You might find something here similar to maintain your charge when you aren't using the truck very often.
http://batterytender.com/

[basketcase0302]

stangman,

An easy shade tree trick is to pull the positive clamp off the battery and re-install at night, (in a dark area).
Watch for an arch when you re-install the positive onto the battery post.
Might have to pull the radio fuse for this test though, (as most newer radio's have capacitors that have a draw) and will cause the same spark.
Have spark when you put it back on, you have a draw on the battery.
Old school stuff right there!

Basketcase

[l1k2gadd]

basketcase0302, great advice! This is the way I always test for a draw on a battery that is continually dying on me as it sits in a vehicle over a few days / weeks / or so.

I guess I am too used to the "old" way of doing things (probably because the older generation taught me a lot of the troubleshooting tips I know today).

With the key off you should have no draw on the battery at all unless (as basketcase0302 says) you have newer electronic stereos, amps or electronics in your truck. All of these things should be connected to a circuit that goes off with the ignition key (except for the wires that are needed to be connected to a circuit to keep the memory up on these same electronic devices).

[TheEskimo]

Couldn't one use a test meter. Hold the positive to the battery and the negative side on the positive battery cable? Wouldn't that show how much draw there is, or am I sadly mistaken?

[bluef250]

If you are trying to determine current flow, most VOM's won't work as they are not amp meters. If you use a VOM between negative post and cable end and there is a current, you could burn it up or blow the fuss. If the current is very small, it would register a voltage. A test lamp would tell you if there is a current flow. Light on - current is flowing, no lamp - no current.

If a good battery is being drawn down, then current is flowing. You need to find the source of the power draw. A very dirty battery can cause such a loss, but a short is the most likely problem. As stated, newer electrically equipment will draw down a battery as it has a need for power for clock and internal memory. Also, the equipment can act like a battery with a charged capacitor.

[fordman]

Couldn't one use a test meter. Hold the positive to the battery and the negative side on the positive battery cable? Wouldn't that show how much draw there is, or am I sadly mistaken?

no sir that will just tell you how many volts are in the battery when its shut off.

[TheEskimo]

Ah, I learn something every day.

[fordman]

i mis read that. please disreguard my ealier post. i was falling asleep while reading the forums last night.

[James72]

I had an old caddy with the same problem The easiest way to find a draw is:
1 get yourself a digital multimeter, you can find them cheep and once you know how to use it you'll never use a test light again.
2 disconnect your neg bat terminal and jump it with your MM set on amp scale (when doing this always leave your key off!)
3 check for amp flow, should be 0, if not
4 pull fuses 1 at a time until draw goes away, then you'll know which circuit to pay attention to. Usually it's interior lights, cigar lighter or stereo.
The reason for the digital MM is easy to read and acurate, a test light may not light with a low amp draw. Also if you're looking for voltage with a test light just cause it lights up dose'nt mean you have 12 volts which can be frustrating when installing a stereo.
The problem with my caddy was 1 of the 5 cigar lighters (hidden in the rear seat arm rest) was stuck in.

[James72]

Couldn't one use a test meter. Hold the positive to the battery and the negative side on the positive battery cable? Wouldn't that show how much draw there is, or am I sadly mistaken?

Also, always test from the neg bat terminal and when removing a battery disconect neg first and connect last, a battery makes a scarry welder and painful explosions in a real hurry.

[kentdaryl]

Like James 72 said. There's also an easy way if you don't want to keep checking the meter. Get yourself an old seat belt buzzer and connect a couple of alligator clips to it, disconnect one cable, jumper the buzzer between the cable and the post, let it buzz while you pull fuses to narrow it down to the right circuit. Plus it makes it faster, after hearing the thing going off for a few minutes you want it to stop buzzing!

[James72]

Like James 72 said. There's also an easy way if you don't want to keep checking the meter. Get yourself an old seat belt buzzer and connect a couple of alligator clips to it, disconnect one cable, jumper the buzzer between the cable and the post, let it buzz while you pull fuses to narrow it down to the right circuit. Plus it makes it faster, after hearing the thing going off for a few minutes you want it to stop buzzing!

Very good idea, I love those kind of tricks

[basketcase0302]

kentdaryl,

after hearing the thing going off for a few minutes you want it to stop buzzing!

Neat trick! I gotta think I'd become a pretty fast troubleshooter with that noise in my ears.

Basketcase