Battery Charging Problem

[ddmgj]

I recently purchased a 2005 Boxster and don't drive it in the winter. I bought a CTEK Multi US 3300 Battery Charger which is the same brand as the Porsche charger and use the cigarette lighter adapter. It doesn't appear to be charging as the partial charging light indicator light hasn't moved to the fully charged indicator after a couple of weeks of charge. Do I need to do anything else? Can I connect the charger directly to the battery terminals while in the car instead of using the cigarette lighter adapter? Is there anything I have to do to safely charge the battery?

[mikefocke]

How is the fit of the lighter plug in the lighter socket? There are 2 sizes of lighter sockets Porsche used depending on year and country. There is a red plastic adapter I got with my Porsche charger that goes into the socket and allows a solid fit but I do have to fiddle with it a bit to make sure that the male end is into the socket far enough and is seated.

Certainly you can connect to the battery terminals, though that is a bunch of trouble and requires the front trunk lid to be opened or the wires to crimp the rubber weatherseal.

The preferred method is really to use the socket...if it works. Has for me for 4 winters.

[ddmgj]

It has the red plastic adapter and seems tight and the light indicates it is charging but it has been a couple of weeks with no change in the light to the completed stage.

[Lil bastard]

Sounds as if the battery may be at fault. If the battery has been run down in the past a few times (perhaps prior to your acquiring it, and therefore unknown), it's future ability to accept and hold a charge is seriously impaired. And further so with each successive discharge - the effect is cumulative. Also, any battery 4 yrs. old or older has left it's best years behind it. Your '05 could have been produced and sold as early as 8/04, so (assuming it's the original) it's coming up on that benchmark.

Could also be damaged. This happens more often than people think. Hit a pothole or good bump and it's possible to break the fairly fragile lead plates, or crack the case between cells.

Then too, it may have a low or diluted electrolyte level.

Check the battery with a multimeter (battery cables disconnected). It should read no more than 13 volts, ideally about 12.6 (batteries usually contain 6 cells, each producing approx. 2.1 volts). If this is not the range the multimeter indicates, then suspect the battery, especially after already having it on the charger. If the voltage is below this level, suspect loss of electrolyte, sulphating, or damaged plates. If above, suspect cracked case between cells which are shorting internally.

Finally, with the battery connected, car running, all electrics turned ON , incl. High Beams (called a Load Test), check the battery again with the multimeter. This time, it should read between 13.8 - 14.2 Volts - this is the voltage supplied by the alternator. If not, you may have a faulty alternator, most likely the diodes. If below this range, the alternator likely caused the plates in the battery to sulphate. If above, the alternator may have 'cooked' the battery, causing it to boil off it's electrolyte.

If that's the case, you'll need to replace or rebuild the alternator in addition to replacing the battery. Good Luck!

[clickman]

I'm in the same situation: won't go past "charge" to "maintenance".

Any issues with the leaving the battery and maintainer hooked up for the duration, and then replacing the battery in spring?

[JFP in PA]

If the battery is showing signs of not accepting a maintenance charge, pull the maintainer, fully charge the battery with a conventional charger, and then have it load tested (with a real load test unit, not what is described above). The load test is a pass/fail test; there is no ambiguity in the results. If it is good, put the car back on the maintainer; if it is bad, put in a new battery. Leaving the car with connected to the Ctek all winter with a dying battery is not good for the maintainer, and will not recover the battery................

[clickman]

Checked battery electrolyte level, and it was way low.

Filled it with distilled water and put it back on the CTEK. Will check it over the next 3 days to see if it switches from "charge" to "maintain".

I checked the electrolyte level last fall before putting the battery on the maintainer, and it was a bit low, and I topped it up then.

Is it normal to lose so much fluid in one driving season, or is there another problem, like the alternator?

(I was really dumb and had the battery connected up backwards last winter for a few minutes. No codes and the battery voltage checked ok afterwards, like the alternator was still charging ok.)