Parasitic Draw

[PrchJrkr]

So, I jumped the battery in the 2005 Wrangler today after it sat in the yard covered in snow/ice since our snowstorm.

After getting it running, cleaned off, and gassed up, I let it sit for several hours. I tried to start it again, but the battery was too low. I had driven it several miles and let it run for probably an hour while I cleaned it off and piddled around with it. The voltage meter on the dash was hovering right below 14V running. I had shut it off and restarted several times.

I replaced the battery and connected my multimeter between the negative terminal and cable and got a reading of 7.62A or something like that with everything turned off. I removed the alternator positve lead, tested again and got a reading of several milliamps and then it went to zero. I reconnected the positive lead and it again showed several milliamps and went back to zero. My question is, if a diode is bad and de-energized, can it "reset" or something when the power to it is shut off to it? A voltage test between the post and cable shows 11.47V or something very close to that, but no amps. I figured I'd ask here, since a search hasn't given me anything to go on.

 

[Sneakers]

I removed the alternator positve lead, tested again and got a reading of several milliamps and then it went to zero. I reconnected the positive lead and it again showed several milliamps and went back to zero.

This is 'normal'. When you hook up the battery, there are electronics that wake up, do what they have to and fall asleep again.

If you disconnect the battery for a while (10 min or so, up to 45-1 hour), the electronics can reset themselves. Not always the case. The battery should read around 12.5-13.0 v with the charger not running.

The dash gauge may be off. Use your multimeter to see what it thinks the charger is putting out.

 

[Clem72]

This is 'normal'. When you hook up the battery, there are electronics that wake up, do what they have to and fall asleep again.

If you disconnect the battery for a while (10 min or so, up to 45-1 hour), the electronics can reset themselves. Not always the case. The battery should read around 12.5-13.0 v with the charger not running.

The dash gauge may be off. Use your multimeter to see what it thinks the charger is putting out.

7.62A seems a bit high for electronic housekeeping don't it?

 

[Ken King]

Doesn't the Jeep's PCM control the alternator?

 

[Grumpy]

So, I jumped the battery in the 2005 Wrangler today after it sat in the yard covered in snow/ice since our snowstorm.

After getting it running, cleaned off, and gassed up, I let it sit for several hours. I tried to start it again, but the battery was too low. I had driven it several miles and let it run for probably an hour while I cleaned it off and piddled around with it. The voltage meter on the dash was hovering right below 14V running. I had shut it off and restarted several times.

I replaced the battery and connected my multimeter between the negative terminal and cable and got a reading of 7.62A or something like that with everything turned off. I removed the alternator positve lead, tested again and got a reading of several milliamps and then it went to zero. I reconnected the positive lead and it again showed several milliamps and went back to zero. My question is, if a diode is bad and de-energized, can it "reset" or something when the power to it is shut off to it? A voltage test between the post and cable shows 11.47V or something very close to that, but no amps. I figured I'd ask here, since a search hasn't given me anything to go on.

South Main Auto on youtube has dozens of vids on diagnosing parasitic draws, might be worth a look. Lot of other vids on other car things but he is a wiz on the electronics.

 

[Sneakers]

7.62A seems a bit high for electronic housekeeping don't it?

Yes, but he said it went away after disconnecting.

 

[PrchJrkr]

Doesn't the Jeep's PCM control the alternator?

That, I do not know. I specifically bought this year/model because I wanted a straight 6 4.0 and she wanted more room and an automatic trans. Thank God the one we found was a soft top, otherwise, what's the point?

 

[PrchJrkr]

7.62A seems a bit high for electronic housekeeping don't it?

Yes, but he said it went away after disconnecting.

This is what puzzled me the most. I figured there was a bad diode in the alternator pack, but after disconnecting and reconnecting it drew no amps, but still 11.62V between the post and cable.

Normally, I would just go ahead and replace the alternator and test again, but because I don't understand diodes, I thought maybe when power went away, they may "unshort" or something. The only added accessories, which are lights, were left disconnected during testing.

Thanks to everyone who offered input. I at least I have something to search now. I just couldn't, for the life of me, figure out how to word my search. This is beyond my mechanical ability. It's her beach buggy, so I want it to be as dependable as a 20 year old Jeep can be.

 

[Sneakers]

This is what puzzled me the most. I figured there was a bad diode in the alternator pack, but after disconnecting and reconnecting it drew no amps, but still 11.62V between the post and cable.

Almost sounds like a relay was stuck. Not uncommon.

 

[PrchJrkr]

Almost sounds like a relay was stuck. Not uncommon.

It could very well have been. The more I look at this Jeep, the less I like them.

The frame rails are pristine though. I thought if they weren't rusted and/or patched up, surely the rest of the vehicle was in decent shape.

I'll dig deeper tomorrow when it's light out and warmer (hopefully).

 

[Kinnakeet]

Between the positive and negitive terminal 11-12 volts if less battery is bad or going bad
When motor is running and alt.is working 13 or more volts less then alt is going or is bad
Your radio is always drawing voltage to save your stations and keep the time correct and IM sure there are other things that draw power when the motor is shut off.

 

[Kinnakeet]

That, I do not know. I specifically bought this year/model because I wanted a straight 6 4.0 and she wanted more room and an automatic trans. Thank God the one we found was a soft top, otherwise, what's the point?

You cant take off the hard top?
And those soft tops are noisy atleast on the jeep I had.

 

[PrchJrkr]

You cant take off the hard top?
And those soft tops are noisy atleast on the jeep I had.

You sure can, if you have the rig to lift it off and the space to store it. The Jeep is her toy. It's modified for driving on beaches. My vision was an open air vehicle which is more easily achieved by unzipping a few panels. If she wants quiet and comfort, she can drive her fully loaded Honda Pilot.

 

[Kinnakeet]

You sure can, if you have the rig to lift it off and the space to store it. The Jeep is her toy. It's modified for driving on beaches. My vision was an open air vehicle which is more easily achieved by unzipping a few panels. If she wants quiet and comfort, she can drive her fully loaded Honda Pilot.

15 psi and go on the sand