XJ current draw

Carl McFly · Unread post by **Carl McFly** » Sun Mar 20, 2011 6:46 pm

Anyone know the typical current draw for an XJ, when it's parked and turned off? I have a brand new battery that goes dead after 3 - 5 days. I found a wire going through the dash (no grommet!) that had worn insulation. This was from the PO, it was to power an add-on switch for after market lights. Not convinced that's the cause, because it was fused and the fuse is intact. But I still removed it, for troubleshooting

I noticed my voltage drops when it's parked. I can literally watch it drop, about .01 V every 10 - 20 seconds at first, then the rate slows after a few minutes. I pulled the positive cable and checked the current draw, and have about 16 mA. Sounds reasonable to power the clock and whatever else it needs. Anyone know if that's typical?

Also saw the battery still lose voltage, without the positive cable connected. Not a lot, .02 - .03 V after a few minutes, but that doesn't seem right. I'm thinking defective AZ battery. Thoughts?

johnsxj · Unread post by **johnsxj** » Sun Mar 20, 2011 8:42 pm

If you've charged the battery, you'll see a steady drop for a short time as it stabilizes to 12.6v +/- a couple points.

Charge it, leave it disconnected for a couple days, and see what the voltage is. Or you can start pulling fuses to see which circuit is causing the draw and go from there.

nostaw · Unread post by **nostaw** » Sun Mar 20, 2011 9:32 pm

That is odd... I'd say to swap the battery with another "normal" vehicle in your fleet and see how it behaves.

JW

Kurt · Unread post by **Kurt** » Mon Mar 21, 2011 11:14 am

Stick an DC ampmeter in series with one of the battery cables and then start yanking fuzes.
When the current drops dramatically you've found the culprit.

nostaw · Unread post by **nostaw** » Mon Mar 21, 2011 3:07 pm

Kurt wrote:Stick an DC ampmeter in series with one of the battery cables and then start yanking fuzes.
When the current drops dramatically you've found the culprit.

Note - Don't try to start the engine with the ammeter in place... You'll fry it when the starter engages...

Also, if the problem is the battery has a bad cell, this approach probably won't help find the issue.

JW

Carl McFly · Unread post by **Carl McFly** » Mon Mar 21, 2011 7:28 pm

Kurt wrote:Stick an DC ampmeter in series with one of the battery cables and then start yanking fuzes.
When the current drops dramatically you've found the culprit.

I'm not sure that 16 mA is excessive, seems reasonable to power the clock/radio and whatever else the on board 'puter may need. Prolly has capacitors for short term data retention but after they drain..... it's going to need something to keep the volatile memory from going "huhhhh?????"

Pretty sure it's a bad battery, I'll see when I get home in a few days. I just want to be prepared if/when I talk to the AZ "experts"

Kurt · Unread post by **Kurt** » Mon Mar 21, 2011 9:11 pm

16 mA is nothing. About as much as a single LED.
Prolly a bad battery...

zenophryk · Unread post by **zenophryk** » Wed Mar 23, 2011 9:30 am

yea, 16 mA isn't enough to kill a battery. It sounds like a bad battery.
I put a new battery in my pickup about a year ago, and 3 months later it was dead. no physical damage. so they just replaced it under warrany.

ZAEDOCK · Unread post by **ZAEDOCK** » Wed Mar 23, 2011 3:11 pm

Put a wrench across the battery. If there is a big spark, it's good.

Frank · Unread post by **Frank** » Wed Mar 23, 2011 6:38 pm

If the spark is weak its not ! FjR68

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