dead battery... antenna/alarm culprit?

david.avery · david.avery's Garage

Hey all

My 911 has a dead battery, second time in a week after two days of sitting.

I have two suspicions: one, the ungo box alarm, which is currently off, which had a malfunction a month ago when some water leaked in the car and wet the brain.

The other, I suspect may be the antenna: See this post:
Battery keeps dying!!!

I noticed that sometimes, the antenna does not fully collapse - it makes a "skip skip skip" noise, then sits about a foot extended. I lubed it once with a film of wd40, and it behaved, but heck, it's 20 years old, it happens.

What I am wondering, is whether the motor is constantly energized and trying to collapse the antenna when this happens, even with key off? It seems to stop making the clunking sound after it gets so far. I know this circuit is live with no ignition, as the antenna collapses as I walk away key in hand. Is this a known problem with these antennas?

Thanks!

-DMA

david914 · 08-26-2004, 08:28 AM

Two things. Have you removed the Ungo Box Fuse? If not, do so. Second, if your antenna is the kind that uses limit switches as opposed to current sensing to cease motor movement, then that could be your problem. The motor may be stopping due to a thermal overload breaker, but once it cools back down, it will try to retract again, starting the whole cycle over.

Wil Ferch · 08-26-2004, 10:40 AM

Similarly....pull the fuse that affects either ( or both) the antennae or alarm. Or do a stand-by current draw check on these two ( if separate) circuits...and find out which one has a high ( > 16-50 mA) stand-by current draw. That should narrow it down.
--Wil

911pcars · 08-26-2004, 01:00 PM

If your suspicions are correct, disconnecting one or both fuses should do it (insofar as preventing a battery drain). Fixing the malfunction is something else, but first things first.

If those circuits are okay, insert an ammeter in series between the ground cable and battery post, then yank fuses one at a time until you pinpoint the circuit causing the excessive current draw (Parasitic current draw).

Sherwood

david.avery · david.avery's Garage

Thanks guys

I cut the lead to the power antenna (there was already a frankensplice there) and put on some nice ancor insulated spades, and left it not-connected. I also spent some time finding out about the alarm.

You won't believe this... there was a fuse holder visible in the bundle wrapped in tape (loads of it) right under the ignition switch. Twist and "pop" fuse comes out, alarm is disabled. I can't believe it was that easy, any thief could just pull a couple of fuses sticking out under the dash, then drive away.

Oh well, battery recharging, will see what tomorrow brings. Thanks for all your replies.

-DMA

Lukesportsman · 08-26-2004, 06:57 PM

Have you pulled the ground cable with everything turned off and check for power flow here? If you have power flowing at something more than a few mAmps then you still have a problem.

david.avery · david.avery's Garage

Hi Luke

That's the next step, just got the dvm/ammeter back from it's seemingly semi-permanent loan to a neighbor

I really suspect the ungo, because the night of the big rain, the alarm went off (brain got wet) at 3:00am and would not shut off.

Thanks,

DMA

david.avery · david.avery's Garage

Well, did some more checking, turns out my ol' interstate battery was probably part of the culprit. Wired in the optima from the spyder, and it seems happier.

I did do a multimeter test, testing amperage draw, and I sit at .05a, which I think is a bit high. This is with the hood lamp, power antenna and alarm disconnected.

Does this seem too high? My next suspicion is the stero, which looks like Dr. Frankenstein himself wired up. I have a nice nakamichi 450Z to put in, so if you'all say this is too much static draw, I'll dig out the stereo fusing and measure without that as well.

Thanks

DMA

Wil Ferch · 08-30-2004, 08:46 AM

like I said.....Stock for 84 is 16 mA.....

Stock for the later 964'a is about 50-64 mA...and become candidates for a battery tender...

At 0.05A....that's 50 mA.....

Wil

david.avery · david.avery's Garage

Thanks for the reply will. I wasn't aware stock was 16ma... time to start pulling some fuses!

-DMA

Wil Ferch · 08-31-2004, 04:36 AM

Let us know how it goes !!
--Wil

david.avery · david.avery's Garage

Thanks again Will. I had measured current draw with the light in the boot unplugged, but there is a current draw even with the light unplugged, if the switch is open. Once I pushed the switch in, current draw went to 6ma, which is probably just the memory for the stereo... nice! I wonder if this is some type of loop with my now deactivated alarm?

My problem was twofold... one, the excessive draw of the alarm, and the second, the interstate battery was about 4 years old and was unhappy with cycling I think. The Optima I borrowed from the 550 spyder has held up well, I just ordered an optima red top with a bracket to replace the ailing and incredibly heavy/large interstate. Thanks again for your help!