944S2 battery replacement.
Thread Starter
Racer
Joined: Dec 2016
Posts: 343
Likes: 134
From: Svedala, Sweden.
944S2 battery replacement.
Hi,
During the Summer I noticed my voltage gauge to be showing just over 12v at start and then while driving (with headlights always on, as law in Sweden), the voltage slowly drops to around 11v or just below. I could leave the car parked for a few days and it started again no issues, but then the gauge only read 11v or thereabouts. Now parked up during the Winter, I leave the car on a 5 amp trickle float, and just before I start it, the gauge shows around 13v, but then drops to 12v once running.
Upon further inspection, I see that the battery currently installed is only a 4 cell 44ah (no other markings). Would this be the cause of low voltage reading at the gauge? I have read that the car should have at least 60-70+ah, but no info on the right CCA... so if I buy a new battery, what do people recommend... running now well in an S2?
My car also has the factory alarm, so I am guessing disconnecting the battery for replacement with the car unlocked does not affect the alarm?
Maybe the alternator is also suspect... an easy way to check this? (I imagine you need to check while the engine is running).
Thanks,
Andrew.
During the Summer I noticed my voltage gauge to be showing just over 12v at start and then while driving (with headlights always on, as law in Sweden), the voltage slowly drops to around 11v or just below. I could leave the car parked for a few days and it started again no issues, but then the gauge only read 11v or thereabouts. Now parked up during the Winter, I leave the car on a 5 amp trickle float, and just before I start it, the gauge shows around 13v, but then drops to 12v once running.
Upon further inspection, I see that the battery currently installed is only a 4 cell 44ah (no other markings). Would this be the cause of low voltage reading at the gauge? I have read that the car should have at least 60-70+ah, but no info on the right CCA... so if I buy a new battery, what do people recommend... running now well in an S2?
My car also has the factory alarm, so I am guessing disconnecting the battery for replacement with the car unlocked does not affect the alarm?
Maybe the alternator is also suspect... an easy way to check this? (I imagine you need to check while the engine is running).
Thanks,
Andrew.
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Joined: Mar 2002
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From: Boulder, CO
Sounds like a standard alternator test would probably indicate it is not charging, or charging very little. You may just need brushes and possibly the voltage regulator which are easy to swap into an S2 alternator even with it in the car.
Brushes can be replaced with volvo or merc parts for a few krona if you have a big soldering iron. Likewise the regulator is a common part and new ones come with new brushes attached, I have been using Huco regulators spec'd for Mercedes lately.
I run Group 48 batteries AKA H6.
Cheers,
-Joel.
Brushes can be replaced with volvo or merc parts for a few krona if you have a big soldering iron. Likewise the regulator is a common part and new ones come with new brushes attached, I have been using Huco regulators spec'd for Mercedes lately.
I run Group 48 batteries AKA H6.
Cheers,
-Joel.
Thread Starter
Racer
Joined: Dec 2016
Posts: 343
Likes: 134
From: Svedala, Sweden.
Sounds like a standard alternator test would probably indicate it is not charging, or charging very little. You may just need brushes and possibly the voltage regulator which are easy to swap into an S2 alternator even with it in the car.
Brushes can be replaced with volvo or merc parts for a few krona if you have a big soldering iron. Likewise the regulator is a common part and new ones come with new brushes attached, I have been using Huco regulators spec'd for Mercedes lately.
I run Group 48 batteries AKA H6.
Cheers,
-Joel.
Brushes can be replaced with volvo or merc parts for a few krona if you have a big soldering iron. Likewise the regulator is a common part and new ones come with new brushes attached, I have been using Huco regulators spec'd for Mercedes lately.
I run Group 48 batteries AKA H6.
Cheers,
-Joel.
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Joined: Mar 2002
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From: Boulder, CO
I'm part Scandinavian, or so I am told. I mostly spend time in Norway where I have some friends but I did enjoy visits to Sweden and Denmark.
I do not know the electrical specs of the batteries. The ones I have bought have been more than adequate.
The alarm does not mind battery changes but if you may have issues with the airbag light, which is resettable without special tools unless you have a 1991.
I do not know the electrical specs of the batteries. The ones I have bought have been more than adequate.
The alarm does not mind battery changes but if you may have issues with the airbag light, which is resettable without special tools unless you have a 1991.
Thread Starter
Racer
Joined: Dec 2016
Posts: 343
Likes: 134
From: Svedala, Sweden.
I'm part Scandinavian, or so I am told. I mostly spend time in Norway where I have some friends but I did enjoy visits to Sweden and Denmark.
I do not know the electrical specs of the batteries. The ones I have bought have been more than adequate.
The alarm does not mind battery changes but if you may have issues with the airbag light, which is resettable without special tools unless you have a 1991.
I do not know the electrical specs of the batteries. The ones I have bought have been more than adequate.
The alarm does not mind battery changes but if you may have issues with the airbag light, which is resettable without special tools unless you have a 1991.
I bought a battery today... Banner 72Ah and 660CCA - Immediately I could tell the crank over was much more spirited upon start up. Fits snug in the compartment though (as I have the factory alarm horn next to it). No airbag light to worry about, as no airbag in the EU spec '90 S2s
The next worrying part is, upon the new battery install, the voltmeter is under reading. I won't know if I have an alternator issue until I can drive it more, but think I will replace the voltage regulator and brushes anyway (as it is not a big cost - just never done it before)
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From: Boulder, CO
You already know it's not charging, you should see like 14V until the battery is topped up and then 13.5V or so otherwise.
The gauge can be off though, it's good to check with a DMM.
Check the wiring, the 944 also suffers from some deterioration of the starter/alternator wiring and there can even be a short near the starter that can cause it to run unexpectedly. I have also seen insulation go missing from the main alternator to battery wire for a distance behind the alternator. So there could be some bare wire there which can short while working on the alternator in situ with the battery hooked up (not a great idea). I used a little ratchet screwdriver to get the voltage regulator bolts.
That thing next to the battery might be the vacuum canister, careful not to disconnect the vacuum to it when changing batteries.
Cheers,
-Joel.
The gauge can be off though, it's good to check with a DMM.
Check the wiring, the 944 also suffers from some deterioration of the starter/alternator wiring and there can even be a short near the starter that can cause it to run unexpectedly. I have also seen insulation go missing from the main alternator to battery wire for a distance behind the alternator. So there could be some bare wire there which can short while working on the alternator in situ with the battery hooked up (not a great idea). I used a little ratchet screwdriver to get the voltage regulator bolts.
That thing next to the battery might be the vacuum canister, careful not to disconnect the vacuum to it when changing batteries.
Cheers,
-Joel.
Thread Starter
Racer
Joined: Dec 2016
Posts: 343
Likes: 134
From: Svedala, Sweden.
Yeah, saw the vacuum canister... was very careful with the install. Thanks anyway for the heads-up.
Upon thinking more, I don't think there is anything wrong with the alternator... as last year when I bought the car, I immediately drove it 700km straight, with A/C on, headlights on, stereo on. There was no drop in voltage, with the gauge always hovering around the 11.5-12v mark, so the car was getting enough to run, regardless of the very old and small battery that it had in it. And then when doing shorter drives (approx 1.5hrs) the voltage was similar.
So it could be that the voltmeter is under reading from years ago, due to bad earth or contact. I could, if inclined, take the dash apart and check all the gauges - doubt it has ever been done in 29yrs. But at this stage I will wait until Summer and a few drives to see how it acts. Meanwhile is there an easy way to test the voltage coming directly from the Alternator while the car is running (sorry for my ignorance on this, as new to this type of electrical stuff)? I have heard about starting and disconnecting the negative at the battery and then measuring with multi meter... but unsure exactly.
Upon thinking more, I don't think there is anything wrong with the alternator... as last year when I bought the car, I immediately drove it 700km straight, with A/C on, headlights on, stereo on. There was no drop in voltage, with the gauge always hovering around the 11.5-12v mark, so the car was getting enough to run, regardless of the very old and small battery that it had in it. And then when doing shorter drives (approx 1.5hrs) the voltage was similar.
So it could be that the voltmeter is under reading from years ago, due to bad earth or contact. I could, if inclined, take the dash apart and check all the gauges - doubt it has ever been done in 29yrs. But at this stage I will wait until Summer and a few drives to see how it acts. Meanwhile is there an easy way to test the voltage coming directly from the Alternator while the car is running (sorry for my ignorance on this, as new to this type of electrical stuff)? I have heard about starting and disconnecting the negative at the battery and then measuring with multi meter... but unsure exactly.
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Thread Starter
Racer
Joined: Dec 2016
Posts: 343
Likes: 134
From: Svedala, Sweden.
Now I will check the ground cable, as I have read the fuel and voltmeter gauges under-read if the ground is bad on the firewall. I read it is located behind the engine block... but don't have any user manual to identify it. Can I access from above?
Drifting
Joined: Apr 2006
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From: Dallas, San Francisco, Tampa
Off topic...about how many people live in Malmo? You, perchance, wouldn't happen to know a Linda Groenlund, would you?
Thread Starter
Racer
Joined: Dec 2016
Posts: 343
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From: Svedala, Sweden.
No, I don't know Linda. I know a few Porsche owners living in Malmö, but not sure they are on here.
Racer
Joined: Jun 2001
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From: TOMS RIVER, NJ
Cleaning all of the grounds and even replacing the thick black negative wires that all connect to the battery negative side, the alternator negative side and the thick ground wires that connect to the bell housing and chassis can make a huge improvement in the entire system. The car runs better, the lights are brighter. Personally, I install an adjustable voltage regulator on the alternator. I usually set it at 14.4 volts. It works wonders