classic_cars

Went to take the shark out for a ride last night and she wouldn't start. She's been sittin for about 2 weeks and never really gets a good run so the battery was low.

I'm gonna pick up a battery maintainer. Is a connection to the cigarette lighter ok? (hate to keep the battery compartment opened up all the time ...)

Here is a link to the one I'm considering:

http://www.sears.com/sr/javasr/produ...26+Boosters&BV

Thanks!

Jim R.

I have one very similar, but a few years old now. I ran a set of wires with an inline fuse through a factory grommet in the battery box, used black plastic split wire loom and ran it to under the rear bumper. Easy job, just reach under the bumper for the connector and plug it in. I like this better than running a power cord into the car and using the cig lighter. So far 3 years with a fully charged battery on a weekend toy.

Jim

Mike Frye

How are you with a multi-meter?

I think there's something in the Newbie FAQ about troubleshooting voltage drains. Not to knock the 'battery tender' idea, but a voltage drain could be caused by a short, and if it gets worse it could leave you stranded somewhere.

You should be able to isolate a drain on the battery in a long, patient, methodical afternoon. It could be as simple as a corroded or loose connection somewhere.

Alan

No it won't work - the lighter socket is not switched on except when the key is in... It will likely appear to be working - because other things are also powered from the supply that feeds the lighter socket - but it will not be connected to the battery. Several people have bought these (some by recommendation of the Porsche dealer - go figure!) and they are convinced they are working because the charging light goes on... In fact all they are doing is powering all their accessory connections.

Instead wire direct to the battery and hide the connections behind the tool tray. Put an inline fuse at the battery on the + connection. You can add a push fit connection your maintainer & on the wire ends to make this easy - since the wire only need to be ~16-18 AWG you can easily snake these through the hatch & close it OR route under the car with a grommet. you can also connect to the battery post and the ground point just in front of it if you'd prefer a front mount (snake it out of the grill area?).

Another alternative is to permanently mount the maintainer in the car and have a 110V connection to plug in somewhere.

Your battery should remain in good condition for at least 2-3 weeks of not driving the car - if not you probably do have a excess parasitic current drain...

Alan

F4GIB

Easier fix is to connect the supplied short cord with the ring connectors to the jump start terminal at the front passenger side of the engine compartment. Positive goes to the jump start terminal (inside the black plastic box), negative goes to the cross-brace bolt. You may have to clip on a larger diameter ring connector for the bolt. Lay the cord along the side, over the radiator, etc to the front as far as it will go.

Then you stick the quick-disconnect cord from the maintainer through one of the bumper openings and connect it up. Then you can lock the hood closed if you want.

I left my 928 on this all winter in a public garage. Started up on first turn of the key.

classic_cars

Thanks for the info! I'll get her wired up tomorrow.

How much current does that pesky clock draw? What should I read with everyting off? (but the clock)

F4GIB

My battery tender plus puts out 1.25 amps. That appears to do the job with everything off except the computer. It will gradually top off the charge (light changes from red to green) and turn itself off (green light stays on).

Alan

You can't really turn everything off - the ECU has memory - so do many head units and the alarm is always at least partially alive.. (add whatever extra goodies the PO left for you) but with all this on you should ideally be at about 15-20mA. A little higher is not catastrophic - but more than 50mA and you are going to see some discharge issues unless you drive it very regularly.

BTW rather than connect to the strut brace mount for ground - you will see there is a ground point just in front of the radiator under the fender lip on the passenger side - quite neat and tidy.

My maintainer connects that way too - do put an in line fuse (5A-10A) under the cover next to the jump post in case the line ever gets pinched. My maintainer is actually permanantly installed in the front passeger fender (~under the headlight) so I just have a 110V IEC socket in the front grille. Not sure your proposed unit is ideal for this (you need water tight encapsulation) - but I like it since its convenient for use anywhere.

Alan

dr bob

Mine is "permananently" wired from the jump-start terminal with a fuse as Alan recommends, to a 2-pin molex-type plug that sits just in the front apron next to the fan controller. I'f I'm away for more than a week, I put the maintainer on teh front apron and leave the hood open a bit, sitting on the maintainer. The hood propped up an inch or two is a reminder to disconnect before flight, but it all sits low enough for the cover to fit over it all.

I picked up the ground at MP-II, the point on the fender panel under and forward of the jump-start terminal. All the wiring and the connectors are soldered and heat-shrinked, and are routed with the factory harness up under the fender lip so it's all completely invisible except for teh tip of the little plug peeking out right at the front where the corner of the fender laps the front apron.

I had a similar plug in the rear, but was concerned about having the accordian tube squeezed in the rubber seal at the rear hatch; The hatch has to be closed and latched to get the interior lights to go out. The idea of running the cable out of the battery box forward grommet is a good one, but then there's a wire that needs to be armored and fastened up safely out of the way. Pop rivets through the plastic gas tank will not seal even with a generous dab of silicone, plus the exhaust routes across the front of the battery box too. The front mount was fairly easy to build and install. Biggest pain was removing the AT cooler to gain good access to the ground point bolt. I will have to go fishing for the fuse if it is accidentally blown, thoughh; It's way hidden up there!

F4GIB

That's why I went to the cross-brace bolt. It's a good ground and right out in the open. My way is a true "3 minute" job.

Alan

Actually I didn't find any clearance issues with this GP at all - my GTS is a manual though - not sure that the (unused) AT cooler is different though...?
I think its the engine oil cooler anyway on mine...

It is a little fiddly under the fender lip for sure but not really hard to access at all. It becomes a trade off between ease of implementation and hiding it all away. Just depends what your priorities are I guess.

On much earlier cars this ground point is even further forward (more or less where the fan controller is on the later cars) and much easier to access.

Dr Bob - I put my inline ATC fuse/holder right next to the jump post under the plastic cover - well hidden but very easy access.

Alan

Pfunde

Yep, easy to use and you can charge your car everywhere . But also do a battery check up. Just had mine changed, and after sitting 4 weeks it just turned right away and fired up. On the old battery maximum was 3-4 days.

dr bob

Mine is forward and to the right of ('right' in the car is under the fender lip, tied to the existing harness/bundle there. I can get to it, but it is not something that needs regular or critical attention so no worries.


On using the crossbar bolt for ground because it's easy access and out in the open-- These are reasons not to use that bolt IMO. A wire attached there has a greater risk of being damaged, and frankly I feel that wires just strung around and tied down will-nilly look less tidy and professional. Again, my opinion only. I'd liek the car to look like everything was designed in from the start, all looking like the original wiring. On some things I take the liberty of adding a little solder and heat shrink for water-resistant security, and I sometimes add some accordian loom, plastic sleeve, or shrink sleeve to bundles for physical protection. But in the end it really needs to look like it belongs. For this install, I could easily sell a concours judge on the idea that this is a factory feature, except that the connector is non-standard.

If I was the **** perfectionist, I'd add a connector to the fan controller, and backfeed the battery from that through 28/29 and the feeders that go directly to the battery. Put the fuse inside the fan controller, a waterproof cap over the connector, and all would be fine in the world.

Randy V

Well, just the fact that you considered this sorta qualifies you, Boberino!

dr bob

The thought process started out with a DUFO controller donated by a lister. I have the FET's for the fix on it, then started down that dangerous path that includes diagnostic LEDs, a test socket and such so one could swap it into the car and see what signals it's getting, push either fan individually for test purposes, stuff like that. The primary-power LED's attach to the incoming power feeds from battery via the fuse panel, so you can see how easily I added the "charge" function to the test connector list of things it can do.