Battery trickle charging

[sivermee]

I recently bought a lovely 21,000 mile 1991 928 GT.

As it will not be an everyday car, I want to keep the battery on a trickle charger.

I have two questions:

1. The handbook recommends undoing the earth strap whenever the car is on a charger. I am not entirely sure why - could someome confirm / explain?

2. The battery is rather inaccessible. Are there any other points where I can attach the leads to a charger? Otherwise my best option is to permanently connect one end of the CTEK charger (using the eyelet connectors) to the battery, and then just plug it in when needed.

In any event, advice would be welcome.

Thanks

 

[GAFTON]

Hi!

Congratulations on your new acquisition! Enjoy! (am sure you will)

You will gather from my replies that I am not an expert just sharing my limited experience:
1. No idea.
2. There is a 'nipple' located in the engine bay (left hand side) for jump starting.

My 928 does not discharge the battery just sitting there (I have to say that it will not have been left without at least a walk in the park for more than 2 months). Have never had it on a trickle charge. I have had a battery go bad (half the cells dead on a 1.5 year Porsche battery) but I do not think this was related (at the time the car was being used regularly). Have now replaced it with the Bosch A6 battery (recommended by Bosch for the 928 and guaranteed for 6 years)(bought it online and it was delivered next day all ready to go) - it feels better and has never failed yet. And, it's cheaper than the Porsche battery . By the way my 928 has the factory fitted alarm system always on when the car is parked so there is some battery use.

Best wishes,



I have no doubt that somebody with more expertise on here will provide you with better replies.

 

[EU53UUX]

Hi,

Lucky you buying what must be a pristine GT!

Interesting question - I faced this dilemna with my 1988 928 S4. I originally thought that I could use the cigar lighter (cigars in a 928 not cigarettes). However it turns itself off with the ignition as you have no doubt found out.

A friend gave me a female cigar socket which he got from Maplin I think. I worked out what was positive and negative and hard wired it to the battery with some two core wire. It comes out from under the carpet just beside the rear seat so I plug my trickle charger in there. The danger with this approach is that is shorts out on the car. So you should use a thickly insulated wire, and when not in use I have found an old port cork fits beautifully into the socket!

As Gene said my car is happy for long periods without the charger - except in winter when it gets less use and the charge depletes rapidly in the cold. However if you have tracker fitted it will drain much more quickly even in summer.

Greg

 

[sivermee]

Many thanks for the advice, most helpful.

Cheers

 

[Lancerlot]

Hi,

Disconnecting the earth strap is a safety measure to avoid a chassis short circuit in the event the + terminal from the charger slipping off.

Try your cigar lighter with the ignition off. If it still works, you can use this to plug in your Ctek.

Hope this helps.

Regards,

Clive.

 

[ball]

This is probably too late, but you can simply charge your car using the jump start nipple located on the right hand side of the engine compartment and connecting the negative to a screw head holding the torsion bar. I regularly use a trickle charger as in winter time the alarm quickly drains the battery.