Battery Change

  • Mike1210
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29 Dec 2010 23:09 #2560 by Mike1210
Battery Change was created by Mike1210
I have a garaged 1988-928S4 in excellent condition except that it won't start if left to set in the current cold climate for only a couple of days. Therefore, I have two questions regarding changing the battery:

1. What battery/brand is recommended? (The current Interstate battery was installed by the previous owner- I don't know when).
2. Are there things I need to do or be prepared for (?), or do I just remove the current battery, put in a new battery and I'm then good to go?

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30 Dec 2010 02:50 #2561 by srshaw3
Replied by srshaw3 on topic Battery Change
The problem may be more likely to be an electrical drain, so you should consider having the battery tested before replacing it.

A simple suggestion I found, is to disconnect the battery cables, and reconnect after the same number of days it normally takes to drain it. If the battery is ok when reconnected, it is a drain, not the battery.

Sorry, I don't know the correct battery offhand, but height is critical if you want to be able to close the battery box cover and not make contact with battery terminals from a metal cover :)

Electrical drains are all too common on the 928. There are many thoughts on pursuing this, if you find the need.

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  • the flying scotsman
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30 Dec 2010 08:22 #2562 by the flying scotsman
Replied by the flying scotsman on topic Battery Change
The battery is easily replaced although its not common because of size and how the positive and negative posts are positioned. Buy a battery from a reputable manufacturer with a good guarantee. I use a Delco battery which has lasted well and has large dealer support which is important when travelling far from home.

The reason why your battery is losing power is either the battery is old and perhaps wasn't maintained or there is a drain (known as parasidic) from one or more of the many circuits in the 928.

My advice is that batteries are relatively cheap so if theres doubt as to age and maintenance of the current battery replace it.

Once you have a good battery clean the cables, check cable continuity and install in the battery box using the battery hold down clamp. Connect the positive cable. With the negative cable still disconnected and using a good digital volt meter set on the largest amperage position read the current draw between the negative post of the battery and the negative/ground cable ensuring all electrical systems are off. The resultant reading on the DVM is the parasidic draw on the battery.

Should this measurement be high (over 3mA) report back and we'll troubleshoot some more.

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30 Dec 2010 12:32 #2583 by pcar928fan
Replied by pcar928fan on topic Battery Change
If the battery is more than say 5 years old, I just replace the thing and not screw around with it. Rarely have I had batteries last longer than that in a 928 that isn't driven regularly. 928 S4's and GTS's have LOTS of little electrical things that never seem to fully turn off and thus can flatten a battery pretty quickly. Never seen one do it in 2 days, but if the battery is weak to begin with then sure...2 days.

I just call up Auto Zone and tell them what year and model my car is and they tell me if they have a battery in stock. No biggie. They will know what you need.

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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30 Dec 2010 13:00 #2584 by Mike1210
Replied by Mike1210 on topic Battery Change
Thanks. I don't think there is a parasitic drain (though I will try checking), probably just an old battery. This past summer (when I purchased the vehicle) and autumn I would go a couple of weeks without running it and it would then start right up.

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30 Dec 2010 13:33 #2585 by pcar928fan
Replied by pcar928fan on topic Battery Change
That sounds like an old tired battery to me...

James
78 Silver / Black-white #295
84 Ruby Red / Black AO84
88 Dark Blue / Linen-Black
92 Polar Silver / Dark Blue 92EURO
93 Arrow Blue / Black

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30 Dec 2010 14:14 #2588 by Kiln_Red
Replied by Kiln_Red on topic Battery Change
Mike, do you have access to a good working volt meter? I would check the parasitic draw now and trace any drains before putting another battery in. Anything above 30MA will fry a new battery pretty quickly.

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30 Dec 2010 16:38 #2594 by 928mac
Replied by 928mac on topic Battery Change
I installed a deep cycle battery found here but I bought mine at NAPA

www.dcbattery.com/optima_yellow.html

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