danglerb

I have a few of the $5 HF and two real chargers (old and seriously ancient). The HF is very tempting as a small project redoing the box with the LED so it does something useful, but so far they have worked OK at least 50% of the time. The red LED lights up as long as the battery has voltage, ie even if the wall wart portion isn't connected to AC. The other failure mode is if the battery is low enough to exceed the 1/2 amp or so the HF wart can supply, the wart may overheat and/or shut off.

My alarm is too twitchy to leave the battery connected, so I've gotten in the habit of either putting it on a charger of some type or disconnecting the ground to battery strap.

dr bob

I still have a couple of those "old and seriously ancient" chargers in a box too. Transformer, rectifier bridge, thermal circuit breaker, and an Ammeter. They still work fine, but they do require regular attention in use. The larger one, at 6-amps max, will go as high as 16 volts if left to its own way for too long, so it will boil a battery and fry delicate electronics if not used carefully. The new "smart" chargers are much better for the battery, but you should still isolate the battery from the car when charging beyond maintaining.

Plus, if you haven't plumbed the vapor hose out of the battery well, you need to pull the battery out for any serious charging. Otherwise you'll end up with a rather high concentration of explosive (and corrosive) fumes in the well, with potentially catastrophic results easily possible. Moving the connection point from the charger out of the well helps a lot, but is still not a total safe solution. A couple feet of plastic tubing is all it takes to vent the battery outside the well.

chasles22

Thanks M928!! i think that will work perfectly with the one i've bought. I was looking at more complex installs or under the hood, but ya, behind the tool kit is ideal, and makes the install clean. plus it nullifies my original concern of running the charger through the entire electrical system and wiring....

R.Pires

Hi,

After reading various threads about battery’s charger and maintainers, I guess there are different opinions on the pros and cons of connection on the hatch directly to the battery or under the hood in the jump post.
For me it’s easier, more practical and safer to connect it under the hood, maybe technically it will be better a direct connection to the battery, but my concerns are:

1 – I’m a very distracted guy and as I always leave my car facing the garage exit, I’m afraid one day I completely forgot about the wire on the hatch connected to the wall!
2 – If you leave the hatch only slightly or totally open because of the charger wire, I think it’s better you manually shut down all the interior lights BUT you can't do that with the small red warning lights on the side of the doors.
3 – If you close it, I guess that won’t do any good to the charger wire.
4 – Under the hood, you can leave it completely or only slightly open with no problem with interior lights.
5 – Even for a very distracted guy like me I guess it’s easier to spot an open hood right in front of your eyes, before "departure"!

It’s just my opinion and what works best for me.
Thanks and regards

inactiveuser1

You're welcome.Thats what I liked about the hookup as it's directly to the battery and not thru the electrical system.I also put an inline fuse right before the battery.

Hilton

The Porsche charger/maintainer is just a rebranded Ctek charger. From looking at one at the local dealership, it was the same as my old Ctek 3600 I ended up buying elsewhere (for less $$).

Identical in fact except it had Porsche printed on it, and it didn't have the convenient end-swapping connector for changing sets of leads (for croc clips, hardwire etc.).


I find that disconnecting the ground strap to plug into the hard-wired connector on the battery terminals also stops me accidentally driving away with it connected I extended the eyelets that came with my charger so the plug-in connector sits up by the ground strap behind the tool panel, for when I want to charge the battery (e.g. if left parked and not on a maintainer for a month or so).

Fogey1

Excellent find! First time I've seen those.

The huge (and I think complete) bunch of extra 928 publications that Jim Morehouse includes on his CDs are worth the price of admission even without the manuals.

Maybe some of those pubs won't be applicable for your specific car, but don't you want another 928 anyway?

928porschemangreg

The main thing is no matter what you get, install the bolt-on leads to good connections. When plugging in, plug the charger into the bolted on leads, then plug in the AC. This way there is no sparking, no surge and your electronics will appreciate it. I had to extend the bolted on leads longer, so they would extend down the side of the radiator and just barely clear the Spoiler area. I connect it and leave the charger outside the front wheel so I (or the wife) cant drive off with it connected. This setup also keeps me from having to pop the hood. Also can be done in the rear, same way through the battery box, and 2 things because I don't trust chargers, 1. Fuse the connection to the car, 2. Keep the charger outside of the car.

depami

Connecting to the under hood jump post should be fine for maintaining.

But, if the maintainer is not well filtered and regulated, serious damage to electronics could occur from inadvertently disconnecting the battery while the maintainer is still connected.

Securely mount one of these to the underside of the rear bumper and wire it directly to the battery with an inline fuse.



Put one of these on the maintainer.



Back into the parking stall and hook up.

Should you forget and drive away, it will simply unplug.

MainePorsche

I have the Schumacher unit.
I purchased at WalMart trailer pigtail electrical connectors. I chose the one that had about 25 feet of pigtail wire. I removed the eyelets from the Schumacher unit and connected the red/black to the brown/green of the of the male side of the long pigtail (chose brown for ground and green for 'go' positive). To the female end of the pigtail I connected to the same colors to the battery direct. Though I could've went to the jumper post, I chose to have less connected there. When I want to charge, I open the rear hatch, grab the the female connector that resides on top the factory carpet but under the Lloyds carpet. I simply plug the male end from the Schumacher unit into it and presto.

dr bob

MainePorsche--

For safety, and if you haven't already, add an inline fuse at the battery end on the positive wiring you put in. Most of that trailer wiring is 16ga, and most charger/maintainers are less than 5 Amp capacity, so no trouble with power from the charger. But the fault current capacity of the battery is hundreds of amps, so fusing at 10 Amps is needed to protect the wiring.

Same logic applies to pigtails installed to the jump post. Inline fuses are very cheap insurance from fire due to rub-through of your aftrmarket wiring bits.

MainePorsche

Thanks dr bob.
Will be done before the sun goes down.
Craig

Hilton

Thanks for that Dr Bob - excellent point and I'm going to add an inline fuse to my hardwired eyelets at the battery terminals. I had to extend the wires a few inches, so I'll cut out one of the extensions and solder in a fuse holder for a 10A fuse (I have a 7A charger).

MFranke

I've used a "Battery Tender Plus!" for the last 10 yrs or more without any issues. The positive lead goes to the jump post in the engine compartment. The negative lead clips to the cross brace mount and bolt.

There are no worries of forgetting and driving off with it connected because the hood is raised.

___________________________________________________
1988 928 S4, Silver Metallic, Black Interior - with me since '93

Alan

This is NOT a wise connector choice for several reasons...quite obvious ones I think...

EDIT: Ahh - sneaky - different pictures now... anyway Audio jacks are not a good choice - they often aren't designed for high current and can short the poles during connection.

There are 2 pole high current pull apart connectors that are designed for this purpose - use those.

Personally I have a schumacher permanantly installed up front, permanantly attached to the front jump post with its 110v input connected via a front grille mounted IEC socket - matched with an IEC plug pigtail. I also have a dummy plug installed to protect the socket integrity when not in use.

Advantages:

I always have the charger with me
I carry a spare IEC plug pigtail in my emergency bag
Its easy to plug in to charge (though I quite rarely need to)
When plugged in at the front its quite visible (I use an orange cable)
If I should forget it just pulls out when I reverse out the garage
(and lets face it - who reverses into their garage...)

I do also have provision for a regular (higher current) charger also. I have a direct fused feed in the hatch area to the battery - supplying a permanently on outlet mounted on the rear quarterpanel. A regular accessory plug pigtail there lets me do a medium current charge via the hatch - but in this case I use a battery switch at the ground strap ground point to isolate the battery.

Alan