I figure a battery maintainer is a good idea for the winter since I don't drive the 928 in bad weather.... I found the factory porsche battery maintainer that is designed to work through the cigarette lighter...but it said 928's won't work with that charger...your only option is to hook up directly to the battery?

My question is?... will the under hood charging (jump-start) terminal work to charge the battery without harming anything... Using a low current battery maintainer? I've heard good things about a product called "battery buddy" or something like that?

What does everyone else use on their 928's? I'm just looking for something easier to hook up/disconnect that messing with the battery everytime!
Thanks

 

I bought a basis schmaker(sp?) battery maintainer, which is intended to mount inside the car. Instead of mounting it I extended the wires, added a connector & cap. The only thing inside the car is the connector & leads running from the tool kit cover to the battery. As delicate as the electrical system is I would be too scared to use any charger that uses the lighter socket.

 

Before I was aware of any potential problems, I installed a 1.5amp maintainer on the front jump post with a connector attached parallel to the tow eye plug. This makes it easy to plug in and remove and it's virtually invisible.

I haven't experienced any electrical issues "yet", but I'd like the electrical wizard "Alan" to comment on this. I can move it if it may cause problems, but is really is convenient.

Rod

 

I use a product called 'Battery Tender' made by Deltran. Basically connect to the batt terminals, plug it in and leave it 'til spring. Considering the jump post was design to provided 'boost' voltage and current and can't imagine that a trickle charger of 1.25 amps would harm anything but then again I don't have the worry...............I take the batt out and store it in the basement..................-30C kills almost anything!

 

Like Greg, I use a fully automatic Schumaker battery maintainer. Last year, I kept it connected at the jump post without any problems, but this year, because I'm storing it at a warehouse, I connected it directly to the battery.

 

The connections on my car have a wire that starts at the jumpstart post, runs forward theough a fuseholder (5A fuse), the ground side of the pair is connected to the ground point next to the radiator sheet, and the cable has a Molex 2-pole connector at the end, tied to the little cable that connects to the fan controller on the front apron of the car. The whole thing is shrink-wrapped for protection and appearance. You have to look for the connector, and it looks like a factory bit of wiring.

I use the same Schumacher maintainer that others mention. I bought it years ago from Wal-Mart for as little over $20. They were still under $30 last time I looked. The custon connector and interconnecting cable took a few minutes to make using lamp cord. That jump-start connector carries the current that hopefully flows from the alternator to the battery, so the 1.5A max available current from the maintainer shouldn't be an issue.

If I lived in a cold climate, I'd have the battery out, stored in a warm place, with the same maintainer. If the battery had to stay in the car, I'd try to find a way to mount the maintainer to the side of the battery so the heat from the maintainer would keep the battery itself a little warmer. The thing came with some metal strap brackets for that purpose.

When I bought the maintainer, the target was a rack of batteries pulled from the ski boat, the sea-doos, and the race car. Theye were all wired in parallel in the rack with individual fuses, and the one maintainer. Worked great. Now, the thing is never strained compared to the former duty. The 928 got a new battery prophylactically last summer, after it started doing the crank-and-reset routine with the dash computer. 4 Years on the last one, from NAPA. Even with the maointainer on the car whenever it isn't driven for a few days, the battery still only lasted a relioable four years. Hmmm.


Weather today was in the 70's in L.A. I would have driven the car for shopping but the parking lots are just too dangerous. It will be used in the morning Saturday, however.

 

I have a maintainer on my 81' that I bought from Auto Zone. It is wired directly to the battery with a little pig tail that I ran out of the back of the car through the tow hook connection. When I am going to use the car I unplug and stash the pig tail behind the license plate. Has worked great for three winters so far.

 

since you have an 88, check if the lighter socket has 12v when the car is off. some 88's have this and can use the Porsche maintainer there - i do.

 

Here is a link to my battery maintainer install:

Installing a battery maintainer

I have not been able to update my web page for some time now, however I have modified the set-up a bit since then.

I really like the batt charger/maintainer plug-in, but I found that the loose cord was not ideal in a working area. So with this inexpensive recoil light, I made a retractable battery cord.


















*** I have also put a fuse in the wiring between the battery and the charger/maintainer plug to guard against shorting. Sorry no pic yet. ***

Words cannot describe the convenience!

Cheers,
Mike

 

I could write a book on the ways to prematurely kill a battery during winter storage: the way to do the least harm is to connect a fused lead to the +ve, a second lead to the -ve, and disconnect the ground strap to chassis wingnut.
Periodically during hibernation, I take a voltage reading on these two leads as they peek out under the hatch seal - and fire up a 1-2amp charger if required. With the ground strap off, surprisingly infrequent recharging is required - and batteries tend to last longer .....

 

Hey Garth, how's it goin?

 

I tried a similar setup with my GT as well as my motorcycle with immediate bad results. I'm not sure what the problem was, but I believe that some chargers with maintainer features are designed to be attached directly to the battery....or at least via very low resistance, heavy gauge connections/plugs....unlike the 16 or 18 gauge pigtails that I was using. My thought was if the charger was only trickle charging at a rate of 1.5 or 2 amps, the pigtail could be light gauge.
My charger/maintainer has circuitry that monitors the battery and detects a shutoff point when the battery has reached a full charge. When I set up a solidly connected pigtail on both my GT and motorcycle and connected the the charger/maintainer to it, it failed to shut off @ full charge, and began to boil the battery after a day or so (both cases). Probably a more basic maintainer, such as Gman's would work fine, however.
Somebody tell me if I'm wrong (dr bob?), but I believe that some chargers (the ones that desulfate, for instance) require a direct connection to the battery in order to properly monitor the status of the battery (impedence readings?). A high resistance connection to the battery (such as a light gauge pigtail) gives it false readings, and it continues to charge when it should be shutting off.
BTW, I'm using a plug-in-the-lighter-socket solar maintainer to counteract the drain that comes from infrequent use. It's not intended to help an undercharged battery however, just maintain a healthy, charged one. I'll know how it works w/in a month or so...but here's another question, along the lines of Dave's post:
A through-the-socket maintainer is not going to work if the lighter socket is hot in ignition on/accessory position, and not hot in key off position, right? Wouldn't the circuit to/from the battery be broken in that instance?

 

The weather in stockton, especially in my garage never really gets that cold, maybe 50....but there will be times when I don't drive the car for a week or two in the winter & since the battery is going on its third year...I know its not 100% anymore...just looking for an easy way to keep it 100% charged...I will look for a Schumacher battery maintainer at Walmart and find a way to make it quick release!

 

Brian,
If the unit you're looking at is a maintainer and a charger, I'd double check to see if you can use a pigtail with a charger/maintainer (a non-direct connect to the battery) before you pick a specific model. It's probably okay with a unit that's solely a maintainer, or a basic charger/maintainer, but some models might give you trouble (like mine).
Mike,
It looks like you're using a charger/maintainer in your setup. What was the lightest gauge that you used? Maybe there's a minimum gauge that will work without giving you trouble.....

 

I have two Battery tenders (I think they are The Battery Minder and The Battery Minder II - one from Car Care Specialists and one from Griots).

Each came with a set of alligator clip cables and a set of ring-terminaled cables. The BM's have a modular plug that works with either type of cable. The ring-terminal type has a plastic cap to prevent the contacts from corroding when not in use. I ordered an extra set of ring terminal connectors so I had three sets. For each 928 I connected the ring terminal cable to the battery post bolts, ran the cable out the bottom of the battery box through one of the vent holes, and secured the cable with a couple of tie-wraps to the bottom of the battery box. Now to hook-up or disconnect the BM I just reach under the car, pull the cap from the end of the cable and plug in the cable for the BM - OK, so I use a creaper; it's still easier than any other method. I don't have to open the hatch and I don't have anything hanging around.

I swap the two BMs between the three sharks on a week-or-two basis all winter (and summer too) and have never had a problem. The factory original battery in the GTS is stil going strong.