hi everyone

[EDDIEVRULZ]

my name is cody and i am a total newbie here, although i have lurked for a while. i own an 82 911 sc and i have a battery drain problem that has plagued me since the day i bought it. (2003) anyway, no one can seem to find the source, but after 2 days, battery is dead. it does have a radar detector mounted under the car that is hardwired in, but i dont know if that is the problem. it was professionally installed, so i would hope that they knew better. anyway, i bought a kill switch/key that i want to install that goes directly to the battery. what gauge wire do i need? (im not a mechanic, but handy enough to install this.... i think) the battery is a interstate megatron plus. any advice/help would be glady appreciated. thanks!

[Rusty Heap]

do you have a good DMM, (digital multimeter) Volts/Amps and so on.

Disconnect your battery and put the amp meter in line with your main battery lead. Measure the amps being drawn out of your battery, then start pulling the fuses one by one to see when the amperage draw takes a major drop. That'll be the circuit you want to troubleshoot and isolate to see what your problem is.

Welcome to the slippery slope, nice car.

[EDDIEVRULZ]

thanks rusty! yep, i have a good meter. never thought of doing that because i assumed all of the mechanics that looked at it, did the same. but, apparently not. either way, if i want to put the switch in for security, what kind of gauge am i looking at getting? thanks for the help!

[M491driver]

My '87 had the same problem and it too had a radar detector hardwired in. Once I removed it my battery drain problem went away. Hopefully yours will be that simple.

[EDDIEVRULZ]

cool, thanks for the reply. ill yank it out and check it.

[JV911SYDNEY]

Welcome cody

battery drain issues here too

was lucky to last a week, then i disconnected the radio and amp. get a few more days now but still not perfect. used to use a trickle charger but my new place doesnt have power in the garage yet

will try as rusty suggested

[EDDIEVRULZ]

ya, it sucks. if i drive it everyday, then its not a problem, but here in IL, we have had some weird weather. im going to try disconnecting the radar detector first. if that doesnt work, ill go for the fuses...

[911pcars]

Sorry if I point you to the archives (search function) for an answer to your battery drain issues, but there's much useful information there.

Most battery cutoff switches mount directly onto the battery (negative post). Remove the ground wire, then install the cutoff switch onto the post. Reinstall the ground cable onto the switch. No additional cables/wires needed for a basic cutoff switch. However, using this switch will lose the radio presets and disconnect source voltage to your alarm system.

The cutoff switch will enable your battery to live while you diagnose the cause of the battery drain. In the meantime, invest in an inexpensive digital multimeter. This will be your main diagnostic tool.

Best wishes,
Sherwood

[EDDIEVRULZ]

thanks sherwood! no offense taken by directing me to the search function. i did try, but probably used the wrong keywords, and im pretty impatient i do appreciate you responding though. i basicallt gave up on the drain and was more looking towards what gauge wire to use. the kill switch i have i want to install in the actual car so i dont have to pop the hood. i will still try to modify my search on the site. thanks again!

[snbush67]

Cody,

Welcome to the board, the battery drainage issue will be in the last wire you check, so start there.

Seriously though, if its not the hard wire radar, then it is probably with an aftermarket alarm or the radio, look to see if you have those and check the areas where they would be spliced in.

Shane

[EDDIEVRULZ]

thanks shane.... no alarm but def an aftermarket radio

[JV911SYDNEY]

Originally Posted by Wickd89

Welcome. Nice car.

After you fix the battery issue, you might consider this:

http://item.express.ebay.com/BATTERY-DISCONNECT-TOP-POST-GREEN-KNOB-CUT-OFF-SWITCH_W0QQitemZ120245501508QQihZ002QQtrZexpQQcmdZ ExpressItem

I use on the Pcar because I drive it on the weekends. But I also use it on the family cars when we go on vacation. Great for the month long vacations or longer.

might get one of those myself

[livi]

Welcome to the forum! Your 911 looks great!

[911pcars]

This type of cutoff switch is also available from Harbor Freight, if one is nearby:

http://item.express.ebay.com/BATTERY...mdZExpressItem

Also available at most auto parts stores.

Sherwood

[Hester]

Here's my $.02: (1) a battery cut-off switch mounted in reach of the driver from behind the wheel is a good safety feature. If its not real obvious, its even better (for security). Unless you use a relay and solenoid actuated switch, mounting a battery cut-off in the passenger compartment will mean running battery cables to and from the switch because the switch will be completing/interrupting the circuit between the positive side of the batteries and the engine compartment. (2) While a battery cut-off switch is a good thing to have, installing one to compensate for a battery drain is overkill. Just find the circuit that is staying hot when the ignition is off. That "professionally installed" radar detector is a good suspect. Ideally, something like that should be wired to a circuit that is hot only when the ignition is on. The method that Rusty recommended is a good one. Another way is to use a 12 volt test light to determine which fuses are "hot" on both sides of the circuit when the ignition is off (make sure the interior lights are off).

[911pcars]

A battery cut off switch to actively disconnect the battery when the vehicle is operating has different requirements. It's not as easy as inserting an inline switch in a battery cable. The alternator must have a load circuit to send output, otherwise it'll burn itself out. The battery connection from the alternator is the normal load circuit. Disconnect either battery cable and there is nada load circuit.

A proper safety cutoff switch includes terminals for the main battery connection as well as a circuit to simultaneously open the alternator circuit and close a "dump" circuit to ground when the cutoff switch swings to OFF.

Sherwood

[EDDIEVRULZ]

thanks for all of the advice guys! im going to tear into it this weekend and i will let you know the outcome. thanks again!

[Paulporsche]

Make sure your trunk light is turning off when the lid is closed.

[EDDIEVRULZ]

yep, we disconnected that. one of the mechanics said that it wasnt turning off, but i still have the drain problem, although not as bad

[FastCarFan]

When I bought my '88 the battery kept going dead after 2-3 days of non-use. Turns out it was the switch in the driver's door jamb that "tells" the car that the door has been opened (& then cuts power to the accessories). The plunger in the switch was sticking, so the accessories stayed "hot", which drained the battery.

A little WD-40 & a new boot over the plunger to replace the rotted-out one & my battery drain problem was fixed.

Good luck.