RBP

Anyone know how long the 993 can sit before the battery will drain. I had mine sitting in the garage for about 2 months and the when I went to use the car I was lucky to get it started as the battery had trouble turning the engine over. I know the clock and other small systems stay powered up and will drain the battery. Is about 2 months normal? If not I must have a small short somewhere.

IXLR8

It depends on two things: 1) current drains and 2) battery capacity.

Why not measure your current drain with the doors locked and alarm set.

I've had mine sit well over a month not connected to a maintainer. A quick glance at the on-board digital voltmeter tells me when to connect it.

NC TRACKRAT

+1 to IXLR8. Storage temp in cold weather can also contribute to decline as well as state of charge when initially stored, eg., was it subjected to short stop-&-go before shut down?

pp000830

The only insight I can add is that when you lock the doors with the fob it seems that a few of the powered systems are no longer powered so the battery will probably last longer. I purchased a one amp charger & float charger unit.

http://www.walmart.com/ip/Schumacher...-Each/21642124

If the battery is good it keeps it that way. If the battery is run down to the point where it can't start the car I hook up the charger for four hours or so and it starts right up. I made a cigarette lighter adapter for it so it's a no-brainer to hook it up.
http://www.rightchannelradios.com/cb...lectrical.html

RBP

Thanks for the feedback. Just trying to determine what is "normal" for a parked car after 2 months with a reasonable battery that was fully charged, with doors unlocked. Maybe I will lock the doors if that reduces the draw on the battery with the car parked. I have a battery trickle charger and do use it. I am just wondering if there is something wrong.

92C2Targa#119

Not likely something wrong.
But you can measure the milli amp draw on the battery by putting a meter in series with the battery negative / ground to see what's going on. If the remember correctly my 911 pulled 30-60 milli amps when locked. When I had a problem (after market IPOD adapter) it pulled 600-800 milli amps. Adapter would drain my new battery in 30-60 days were the car would not start.

NC TRACKRAT

As Alex alluded, the only way to find out is to measure current draw when the vehicle is "asleep". This requires a digital ammeter hooked up in series with your battery. Just disconnect the neg. side of the battery, attach one lead of the ammeter to the battery and one to the lead you disconnected. Route the leads outside of the trunk and then close it. Arm the system and give it time to "go to sleep", then note the milliamp draw which should normally be something around 30-35 ma or less.
If you see a larger draw than that, go to your trunk fuse box. Pull one fuse at a time and re-test to isolate the general area of drain.

IainM

50mA for 2 months is 72AHr, not much left in the battery after that.

Matt-atl

This may not be related, but I had a battery draining issue. It turned out that there was a bad batch of batteries from Interstate Batteries. I replaced it and have had no problems since.

Rinty

Alex: have you compared current draw with your car locked, and unlocked?

ToreB

Normal current draw in a 993 with ignition off is 20 to 40 mA. (0.025A) An aftermarket alarm can introduce an additional 5 to 50mA.
Failing door switches are common. They do not only control the interior lights, but also other functions such as keeping the ability to operate the power windows etc.

Connect an amperemeter in series with one of the battery leads to check this.
When measuring, note that open doors will activate the interior lights as well as a relay for enabling the power windows. Also, an open bonnet and/or engine lid will activate the lights there too.
After ignition OFF the CCU with fan will continue to run for 1 to 20 minutes. (about 500mA)
An unlocked car will also have the OBC LCD with light turned on in the tachometer.

Therefore, measure the current with all interior/bonnet/engine lights off, lock the doors, and wait for the CCU to turn off. The light switch in the luggage and engine compartments are placed in the lock mechanism. Depresss the latch to switch off the light.
You might consider opening the windows first to avoid having problems getting in due to a problem with immobilizer or similar.

A value of 100-200mA or so can indicate that some of the above mentioned points are active.

If the CCU does not turn off (0.5A) you may have a problem with an internal transistor. It's an easy fix for an electronic wiz.
Cheers,
Tore