Help locating a battery drain

PC PaiN · Mar 17, 2010

Now if someone can help me on my drain. I tested first with the radio fuse pulled because I'm convince it's something in the mach 460 killing my battery. With that fuse pulled I believe I was having about a 8 ma draw if I was reading the meter right. When I put the fuse back in it blows my meter. I'm on my third fuse on my meter before pulling the radio fuse back out and bam my meter doesn't blow this time. Something on that radio fuse circuit is jacked up.

Does anyone know how to track this down exactly? I've been in contact with a guy I found on a forum that had the same problem and come to find out the Mach 460 headunit was the problem. I have also heard the amps can cause a drain, however I hear the amps are on a different fuse which I don't see listed in my owners manual.

BTW this is a 2001 Mustang Bullitt with the Mach 460 system in it.

And to verify that I read the meter right, it was set on 200ma. Before the GEM went to sleep it was reading 150.XX and I believe after it went to sleep it read 8.XX This is 8MA correct? Which is well within spec. I have no idea what it registers with the radio fuse in since it blows my meter everytime.

Dragstr05 · Mar 18, 2010

In theory, the headunit would be the MOST likely cause. The radio will always pull some kind of draw due to the clock anyway. If it were me I'd put a radio in it. I'd like to have an aux/ipod hookup anyway.

PC PaiN · Mar 18, 2010

Dragstr05 said:
In theory, the headunit would be the MOST likely cause. The radio will always pull some kind of draw due to the clock anyway. If it were me I'd put a radio in it. I'd like to have an aux/ipod hookup anyway.

I'm thinking the head unit as well but I don't want to spend the money if I don't have to. If it is the head unit I'm going for an indash nav unit. I also understand the radio will pull a draw but shouldn't be so bad that it blows fuses in a meter.

wmburns · Mar 18, 2010

When you put the radio fuse in, is the rest of the car off? If it is, it does not make sense that it would blow a meter fuse. I suspect that the meter is not hook-up correctly.

How do you have the meter set up? Are you using a shunt? 200ma is very little current. Most meters will do up to 10amp.

How long does it take to discharge the battery? Which fuse are you pulling?

Has any work been done on the radio? Is the top of the battery clean? If not, the acid on top of the battery can drain the battery.

Do you have a speedcal? Any other mods?

trombonedemon · Mar 18, 2010

Are you testing the fuse w/the car running, with the car switch on, or dormant w/the door open. I would start w/testing the alternator first, bad alternator very well could drain a battery. How to Test Your Car Alternator for Power | eHow.com Charging System Checks (Alternator Testing)
Howstuffworks "How Alternators Work"

PC PaiN · Mar 18, 2010

wmburns said:
When you put the radio fuse in, is the rest of the car off? If it is, it does not make sense that it would blow a meter fuse. I suspect that the meter is not hook-up correctly.

How do you have the meter set up? Are you using a shunt? 200ma is very little current. Most meters will do up to 10amp.

How long does it take to discharge the battery? Which fuse are you pulling?

Has any work been done on the radio? Is the top of the battery clean? If not, the acid on top of the battery can drain the battery.

Do you have a speedcal? Any other mods?

The rest of the car is off when I put the radio fuse is in. Meter works fine without the fuse in, so I don't see how it can not be hooked up right. I got one lead on the cable and the other on the battery terminal.

No idea what a shunt is. I have test leads, one clipped to the lead coming off the meter and the other is clipped to the cable/terminal.

I'm running 200ma since I'm trying to see how many ma are being pulled off the battery. Battery is clean. Car is bone ass stock.

Also I'm pulling fuse #27 under dash.

PC PaiN · Mar 18, 2010

trombonedemon said:
Are you testing the fuse w/the car running, with the car switch on, or dormant w/the door open. I would start w/testing the alternator first, bad alternator very well could drain a battery. How to Test Your Car Alternator for Power | eHow.com Charging System Checks (Alternator Testing)
Howstuffworks "How Alternators Work"

Testing with car off, no doors open. Can't get a true sitting draw reading with stuff open/on.

Haven't really thought about testing alternator since as long as shes being driven shes fine.

PC PaiN · Mar 18, 2010

Also the radio when it's off should not pull so much juice that 200ma is too little IMHO. If it's pulling even 1 amp when off it's jacked up

wmburns · Mar 19, 2010

PC PaiN said:
The rest of the car is off when I put the radio fuse is in. Meter works fine without the fuse in, so I don't see how it can not be hooked up right. I got one lead on the cable and the other on the battery terminal.

No idea what a shunt is. I have test leads, one clipped to the lead coming off the meter and the other is clipped to the cable/terminal.

I'm running 200ma since I'm trying to see how many ma are being pulled off the battery. Battery is clean. Car is bone ass stock.

Also I'm pulling fuse #27 under dash.

An amp meter has to be installed "in series" with the load. Disconnect the battery negative. The amp meter is used to "bridge" the open gap. One meter lead goes on the battery and the other goes to the unconnected battery cable.

An amp meter full scale 200ma is not enough to work with. This is going to require enough amp scale so that loads can be brought on/off without blowing fuses.

A shunt is a device used to extend the range of an amp meter. Think of it as a high power resistor of a known value. The shunt can multiply the range x10 or x100.

You did not answer the questions about how long it takes to discharge the battery. Assuming no Speedcal or any modifications to the sound system.

Fuse F2.27 is for the sub amps and the radio. These are on a "hot at all times" circuit. Normally, the sub amps take a power on/off signal from the head unit so that they only turn on when the head unit is on.

We need to narrow down if it is the head unit or the sub amps drawing the current. This is why you need an amp meter with more range. Once you have an amp meter with enough range, disconnect the amps and radio one at a time and record the power draw. Post the results.

PC PaiN · Mar 19, 2010

wmburns said:
An amp meter has to be installed "in series" with the load. Disconnect the battery negative. The amp meter is used to "bridge" the open gap. One meter lead goes on the battery and the other goes to the unconnected battery cable.

An amp meter full scale 200ma is not enough to work with. This is going to require enough amp scale so that loads can be brought on/off without blowing fuses.

A shunt is a device used to extend the range of an amp meter. Think of it as a high power resistor of a known value. The shunt can multiply the range x10 or x100.

You did not answer the questions about how long it takes to discharge the battery. Assuming no Speedcal or any modifications to the sound system.

Fuse F2.27 is for the sub amps and the radio. These are on a "hot at all times" circuit. Normally, the sub amps take a power on/off signal from the head unit so that they only turn on when the head unit is on.

We need to narrow down if it is the head unit or the sub amps drawing the current. This is why you need an amp meter with more range. Once you have an amp meter with enough range, disconnect the amps and radio one at a time and record the power draw. Post the results.

My meter does 10 amps, I'm just using 200ma setting. If the setting I'm using on the meter is causing my fuse problem then let me know, I don't use the thing often.

How you describe hooking up the meter is how it's hooked up as I posted.

Battery drain occurs in less than two days. Car will not start.

wmburns · Mar 19, 2010

So why not repeat the test on the 10 amp scale rather than keep blowing fuses? Once we know the size of the draw, we can pick the best scale to give us an useful answer.

Can you re-run the test with the meter set on the 10 amp scale and post the results? Next, disconnect the sub amps and post the results. Follow this by doing the head unit.

FWIIW; on the 10 amp scale the meter most likely uses an internal shunt to multiply the range of the amp meter.

PC PaiN · Mar 19, 2010

wmburns said:
So why not repeat the test on the 10 amp scale rather than keep blowing fuses? Once we know the size of the draw, we can pick the best scale to give us an useful answer.

Can you re-run the test with the meter set on the 10 amp scale and post the results? Next, disconnect the sub amps and post the results. Follow this by doing the head unit.

FWIIW; on the 10 amp scale the meter most likely uses an internal shunt to multiply the range of the amp meter.

Gotcha now, I'll test tonight when I get off work. Hopefully on the 10 amp she doesn't blow another meter fuse. I'll stop by radioshack again first to get another pack of fuses

ejbrandt · Mar 20, 2010

Guys, I am having a similar problem but I do not get a amp drop when I pull fuses from the fuse box in the car. I get the drop when I pull the 40 amp fuse from the box under the hood, the marked I/P. My question is does the amp reading on the meter drop right off when you pull the fuse? The amp readings drop off when I pull the I/P fuse but when I pull fuses from the box in the car nothing happens to the readings?

wmburns · Mar 20, 2010

ejbrandt said:
Guys, I am having a similar problem but I do not get a amp drop when I pull fuses from the fuse box in the car. I get the drop when I pull the 40 amp fuse from the box under the hood, the marked I/P. My question is does the amp reading on the meter drop right off when you pull the fuse? The amp readings drop off when I pull the I/P fuse but when I pull fuses from the box in the car nothing happens to the readings?

The car's model year is important. The 1996-1998 is a different car than the 1999-2004 electrically.

The post states the fuse panel is labeled I/P. This means your car is a 1996-1998. Because of the differences, you should open your own thread. The reduced number of circuits is going to change the procedure to narrow down the problem.

Note, your post doesn't mention WHICH 40amp fuse is pulled. There is more than one.

It would also help to post the amp reading before and after the fuses are pulled.

Note, if the top of the battery is not clean, this can created a small draw. Clean the battery and terminals.

Be sure to mention all of the mods. You would be suprised the number of ppl that fail to mention a navigation system or speedcal wired into an "always on" circuit.

ejbrandt · Mar 21, 2010

WM,

My car is a 2001 GT Conv. Looking at the battery junction box (fuse box under the hood) it is the 40 amp fuse marked I/P. It is next to the fuse marked IGN SW. What I have done so far.
-Put a new battery and fully charged that
- Hooked an amp meter in series and it reads 3.05. When I pull the I/P it goes to less than .5
- Put the I/P fuse in and pulled all fuses one at a time from under the dash
- unplugged the rear window defrost, the amps in the trunk and the alternator
- I plan to unplug the radio

So I am not sure if I am doing something wrong or it takes a while for the readings to register?
The car has no mods
I see in the wiring manual that the I/P is listed as instrument cluster and PCM

PC PaiN · Mar 21, 2010

ejbrandt said:
WM,

My car is a 2001 GT Conv. Looking at the battery junction box (fuse box under the hood) it is the 40 amp fuse marked I/P. It is next to the fuse marked IGN SW. What I have done so far.
-Put a new battery and fully charged that
- Hooked an amp meter in series and it reads 3.05. When I pull the I/P it goes to less than .5
- Put the I/P fuse in and pulled all fuses one at a time from under the dash
- unplugged the rear window defrost, the amps in the trunk and the alternator
- I plan to unplug the radio

So I am not sure if I am doing something wrong or it takes a while for the readings to register?
The car has no mods
I see in the wiring manual that the I/P is listed as instrument cluster and PCM

Just to verify you are waiting for the GEM to shut back down after hooking up the meter? Takes about 45 minutes give or take.

PC PaiN · Mar 21, 2010

Also guys I still haven't done any more testing on mine yet. I'll post back up tomorrow afternoon when I get it narrowed down to radio or amps

PC PaiN · Mar 22, 2010

Update on my findings

With the radio fuse in the car and everything connected I have a .13 - .14 A draw. With out the fuse in the car I have a .008 A draw. I have the radio fuse in right now and both rear amps unplugged and I still have a .14 A draw. I'm going to wait alittle bit just because I don't know if opening the truck wakes anything back up. I'm going to assume that with both amps unplugged and if it's still showing a .14 A draw that my issue is the radio itself.

Also something kind of weird, when I unhooked just one amp I was showing a .27 A draw when it was .14 before I unplugged it.

PC PaiN · Mar 22, 2010

Alright after checking again with the amps unplugged, truck closed, and waiting another 35 minutes I'm showing .00 on the meter. So I'm thinking it's safe to say its the amps causing my problem.

PC PaiN · Mar 22, 2010

Driver side amp is my draw. Does anyone know for sure if it's the amp or can the radio be faulty and sending a signal to this amp to stay on?

Help locating a battery drain

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