New car - Old battery

[vracer]

I just bought an '89 with a six year old battery on it's last legs (there was some alternator overcharging). The battery shop recommends a 'top up' charger for periods where it won't be used often because 'these cars' leak electricity like oil. My thought is that this might be true for a 964 or 993, but the earlier 'analog' cars shoud be fine.
Your thoughts?

[Rot 911]

It is always a good idea to keep your battery on some kind of battery tender if you aren't driving your car on a weekly basis. Don't need to buy and expensive one. I have everything from a the real $35.00 brand name "Battery Tender" down to a Harbor Freight $5.00 special and they all seem to work just fine at keeping the battery charged.

[Wil Ferch]

Pre 89 cars have a stand-by loss of about 16mA and the later 964/993 cars more like 64ma or more ( hmm...per hour?). Anyway, same time basis of measurement.

Also, many cars, regardless of model type, also have improper "Always Functioning" power windows. Power goes thru a relay and you should only be able to raise/lower windows ( after you shut down after a drive....while still seated)...as long as you don't open/close the door. Once you open/close a door, you should not be able to raise/lower windows on a car that is "off". Some guys' cars do this all the time....and it's wrong if it does. Usually traceable to a bad door switch. Anyway...when this happens, the PW relay is always energized and now your standby draw goes very high.... >100mA/hr draw.

Your battery shop is making sweeping generalizations, these cars don't "leak like oil"....only the defective ones do, like any other defective other brand name of car with modern electrical loads .......

Lastly....most cars don't get driven every day, and even a few weeks at normal stand-by draw can deplete a battery. Use a "chipped" or "smart" battery tender that turns on/off automatically as the battery voltage drops a little during standby. Schumacher and "Battery-Tender" are 2 brand names.

[vracer]

Originally Posted by Wil Ferch

Pre 89 cars have a stand-by loss of about 16mA and the later 964/993 cars more like 64ma or more .

Thanks Will, great answer, but don't forget '89 included both 911s and 964s.

[Wil Ferch]

Correct on 89...but in the context of the question, I didn't think it was necessary to make a hard delineation. That was the reason I say 964/993 as being the more modern....more electrically challenged series compared to "early" cars......but good catch, yes.