IDK how 'common' this is, but my factory radio developed an excessive draw problem that would drain the battery in 3-4 days. Took quite a bit of time to isolate the exact problem. Check the FSM for power-off draw procedures.
One common problem that I've read about is that an interior light fails to turn off.
J

 

I'd first be confirming a power vampire with an ammeter at the battery with the key off. That will rule out battery failure or charging system. If you confirm a draw of more than a few mA, the fun then begins with hunting the vampire. If you're lucky, as stated above, it is just an interior light. My Jeep now sits in storage, and has sat in several -0f overnight temps. I stopped by storage last night and she fired right up on a 5yr old battery....

 

Another factor may be installation of aftermarket remote start. Draws current continuously.

Sent from my SM-G998U using Tapatalk

 

You asked what devices and siphon off abnormal amounts of power from the battery. I assume you know how to use an ammeter to look at the current flow on the battery as a whole, and how to isolate all the circuits and then check each circuit one at a time for current draw, noting what circuit seems to have an excessive amount. There is a section inf the FSM that describes the power off draw test procedure, approximate wait times for devices such as the SKIM and alarm systems to reduce their power draw once the key is turned off and all doors closed, and what the power off quiescent normal current draw should be. If memory serves, I believe it is 50ma-75 ma. Would have to double check that. Anything above say 90ma is too much. (The current range depends on model config and any aftermarket stuff you may have added, such as remote start, alarm bypass module etc.

Just remembered, the under hood light in some models was also a common issue - hard to see since it is under the hood.
J

 

You asked what devices and siphon off abnormal amounts of power from the battery. I assume you know how to use an ammeter to look at the current flow on the battery as a whole, and how to isolate all the circuits and then check each circuit one at a time for current draw, noting what circuit seems to have an excessive amount. There is a section inf the FSM that describes the power off draw test procedure, approximate wait times for devices such as the SKIM and alarm systems to reduce their power draw once the key is turned off and all doors closed, and what the power off quiescent normal current draw should be. If memory serves, Ibelieve it is 50ma-75 ma. Would have to double check that. Anything above say 90ma is too much. (The current range depends on model config and any aftermarket stuff you may have added, such as remote start, alarm bypass module etc.

Just remembered, the under hood light in some models was also a common issue - hard to see since it is under the hood.
J

im thinking 14 ma. very little

 

What voltage have you got across the battery posts at tickover measured with a multimeter please Will?

 

Please will you proof-read this for me and point out my errors, my brain has run out of ram.

You should have an Ignition Off Draw fuse in box next to your battery Will.
I you take you IOD fuse out, you should stop ignition off draw from your battery.
If you pull the IOD fuse when you park up you should get respite from flat batteries.

Chasing the draw.
Before I start, I check that the fuses in my multi-meter are good, if not I fit good fuses.
I have some extra long leads for my multimeter.
Long enough to reach from the battery to the floor under the fuse box (Junction Box) in the car.
The long lead have ring connectors at the battery end.
My negative battery post has a small hole drilled in in which sits a small screw.
The negative battery clamp is also drilled and has a small screw in it.

I also have a 2" square piece of thin board with a 3/16th slot half way across it.

And so to business.
I make no apologies for crossing all the is and dotting all the ts
If you want to catch Mr B's elusive Vampire then you have to work very methodically.

That said, simply switching the interior lights off may save all these shenanigans.
As may checking IOD through aftermarket stuff

1. I disconnect the limit switch on the bonnet to fool security.
2. I open the driver's door, and trip the latch on it to fool security.
   1. Security now thinks the hood, and the driver's door are closed
3. I connect the long meter leads to the meter, and hook the ring connectors on the meter leads to the screws on the battery post and the battery clamp.
4. I set the meter on 10 amps.
5. I now spend 20 mins or more drinking a cuppa which gives security time to settle down after I've opened the doors etc,
6. I measure the IOD through the negative battery leads with a clamp meter to check the current / draw is less than 10 amps.
   1. that check lasts until I get bored.
      1. A lot of us get a mysterious "Botty Cough" noise several minutes after switching off.
         1. That botty couch takes current out the battery.
      2. Which goes to show IOD may vary as different black boxes switch on and off as and when they please.
7. If I get bursts of current over 10 amps, I have to get a helper to read the clamp meter while I disconnect various circuits.
   1. I had a SAAB in once that occasionally ran it's battery flat in an hour or so.
8. If the current stays below 10 amps,
   1. I check the multi-meter is set on 10 amps
   2. I lift the battery negative clamp, and slide the cut out in the board past the ring connector so that the board stops the clamp touching the post.
   3. Now, all IO draw goes through the meter in the cab.
9. I go to the cab and watch the meter for several minutes.
   1. the 10 amp multi-meter reading helps me decide what I need to set the meter on.
10. Before I set the meter, I reconnect the negative battery post.
    1. Now the multi-meter is out the circuit so I can set it to read say 200m (200 milliamps).
11. Once the multi-meter is set to 200m, I disconnect the negative battery post, which means the multi-meter is live.
12. I start pulling fuses in order to find the circuit, or circuits using current.
13. Reconnect & replace hood security switch.

 

Please will you proof-read this for me and point out my errors, my brain has run out of ram.

You should have an Ignition Off Draw fuse in box next to your battery Will.
I you take you IOD fuse out, you should stop ignition off draw from your battery.
If you pull the IOD fuse when you park up you should get respite from flat batteries.

Chasing the draw.
Before I start, I check that the fuses in my multi-meter are good, if not I fit good fuses.
I have some extra long leads for my multimeter.
Long enough to reach from the battery to the floor under the fuse box (Junction Box) in the car.
The long lead have ring connectors at the battery end.
My negative battery post has a small hole drilled in in which sits a small screw.
The negative battery clamp is also drilled and has a small screw in it.

I also have a 2" square piece of thin board with a 3/16th slot half way across it.

And so to business.
I make no apologies for crossing all the is and dotting all the ts
If you want to catch Mr B's elusive Vampire then you have to work very methodically.

That said, simply switching the interior lights off may save all these shenanigans.
As may checking IOD through aftermarket stuff

1. I disconnect the limit switch on the bonnet to fool security.
2. I open the driver's door, and trip the latch on it to fool security.
   1. Security now thinks the hood, and the driver's door are closed
3. I connect the long meter leads to the meter, and hook the ring connectors on the meter leads to the screws on the battery post and the battery clamp.
4. I set the meter on 10 amps.
5. I now spend 20 mins or more drinking a cuppa which gives security time to settle down after I've opened the doors etc,
6. I measure the IOD through the negative battery leads with a clamp meter to check the current / draw is less than 10 amps.
   1. that check lasts until I get bored.
      1. A lot of us get a mysterious "Botty Cough" noise several minutes after switching off.
         1. That botty couch takes current out the battery.
      2. Which goes to show IOD may vary as different black boxes switch on and off as and when they please.
7. If I get bursts of current over 10 amps, I have to get a helper to read the clamp meter while I disconnect various circuits.
   1. I had a SAAB in once that occasionally ran it's battery flat in an hour or so.
8. If the current stays below 10 amps,
   1. I check the multi-meter is set on 10 amps
   2. I lift the battery negative clamp, and slide the cut out in the board past the ring connector so that the board stops the clamp touching the post.
   3. Now, all IO draw goes through the meter in the cab.
9. I go to the cab and watch the meter for several minutes.
   1. the 10 amp multi-meter reading helps me decide what I need to set the meter on.
10. Before I set the meter, I reconnect the negative battery post.
    1. Now the multi-meter is out the circuit so I can set it to read say 200m (200 milliamps).
11. Once the multi-meter is set to 200m, I disconnect the negative battery post, which means the multi-meter is live.
12. I start pulling fuses in order to find the circuit, or circuits using current.

A couple of observations:
1) clamp on ammeters are handy but the user should check the DC specs of their meter. I've seen DC clamp on current meters that specify a rang from 400ma to 400A, which for checking current draw below 400 ma would be useless.
One can use an inline ammeter on the 10A range with no problem, unless you have it in line with the battery and do something to significantly increase the current, like start the vehicle. In doing the power off draw test, there is no need to start the vehicle, or put it in a state of large current draw.
My preferred way is to use an inline ammeter with a shunt. Open the shunt when you want to read the current, then close it when finished with the reading.
2) Most newer (in the last 15+ years) meters are auto ranging. An exception to this are low price budget meters. An auto ranging meter eliminates all the scale changing.
3) Having extra long leads for the ammeter is usually necessary - good point. Standard lead lengths are 24"-30" I have 4' leads that were very handy for this kind of work.
4) IDK why you wait 20 mins for anything. In particular, the the Jeep WJ, the current draw reaches steady state within 3 minutes (or what ever the FSM states, definately less than 5 mins). There was one case that I ran into that it took 4 mins but this vehicle had an after market remote start. IIRC, there are two, perhaps three current plateaus when doing a test. For example, 0-30 seconds ~ 3 amps (until interior lamps turn off,etc.), 30 sec to 1 min, somewhere around 1 amp, 1 min - 2.5 mins ~ 400ma, then aftr 2.5 min the current drops to ~ 60 ma. The numbers in this example are not specific to the jeep, they are meant to show the progression of how the current steps down.

J

 

13) Reconnect & replace hood security switch.

 

If you have a multimeter, it's an easy diagnostic to find the draw.

 

not a bad video but.... he says, 'looking for broken wires' is not correct statement. If a wire is broken, by definition, no current is going to flow through it. now if that wire is shorted to ground, then it will draw current but the odds are that an inline fuse will blow.

Also, probes supplied with good DMMs can handle 10A DC with no problem. The wires are not going to melt. If the circuit does see a current spike, the 10A fuse inside the DMM will blow, and the probe wires will not melt. Good idea to a spare fuse on hand. They are usually the cartridge type. Get the exact replacement because it has the correct time-current response.

If following his narrative, pay attention to how he has the test leads inserted into the meter. In one segment he talks about the lead configuration for measuring current and the next segment he is talking about checking for continuity and doesn't mention that he moved the test lead from the 10A contact to the Volt-Ohm contact. Ppl unfamilar with DMMs will definitely trip over this..