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Sadly, that is normal. 996 Porsche's are the only car i have ever owned that regularly run below 14. Get a DVM and check it at the battery to be sure, gauge seems to read low.
Your regulator is going same issue. After replacing the regulator the voltage went from what you are seeing just shy of 14 volts with no accessories on, drop to about 13.5 when ac and light are on.
Easy to replace the regulator! Cheaper than replacing the alternator. The regulator is on the backside of the alternator.
I suggest you put a voltmeter on the battery terminals while the engine is running warmed up. Just to verify your dash reading.
I have hundreds of trip logs from my 2003 Turbo and the battery voltage seldom as in almost never drops below 13 volts.
Have to point out the gauge is displaying battery voltage and not alternator output. The low reading is a sign the battery needs no electricity that it is fully charged up. The voltage reading can start out "high", at close to (by the gauge at any rate) close to almost 14V. But as I drive the car I see the voltage reading decline over time over usually 15 to 20 minutes as I drive as the alternator tops up the battery to replace what it has lost sitting for a few days and what it lost in starting the engine.
When I turn on extra electrical loads like the lights, A/C, the reading drops and looks "low" but it is not. The car's electrical needs are satisfied just fine. I have driven hours and hours with the lights on and the A/C on and all the while the gauge reading less than 13V (at least going by what the gauge displays -- the actual voltage level is higher) with no problems. The gauge is not intended to show what the alternator is putting out, which can vary quite a bit. Far and away the most common problem is a weak/failing battery, not a bad alternator voltage regulator. This is why the gauge shows battery voltage.
Macster, did you hook up your own voltage gauge to arrive at that conclusion? Just curious. My experience certainly jives with what you describe.
With A/C and everything on, I'll sometimes see as low as ~12.4 on the factory gauge. I've got a new regulator sitting in the box whenever I have some free weekend time, but wondering if I should even bother.
Macster, did you hook up your own voltage gauge to arrive at that conclusion? Just curious. My experience certainly jives with what you describe.
With A/C and everything on, I'll sometimes see as low as ~12.4 on the factory gauge. I've got a new regulator sitting in the box whenever I have some free weekend time, but wondering if I should even bother.
With everything on mine doesnt go below 13.4 volts. Normal running with no ac its at 13.8.
My readings were like yours until I changed out the regulator.
The volt meter definitly shows charging or not. Just turning the key to on you should see over 12 volts, optimally 12.6, shows full charge. Starting the car you see it drop, then when started and the alternator kicks in it should show above 13.6. Watching the guage at idle then just rev the engine you will see a very minor jump up. You have to watch it closely to see the very small increase.
So the voltage guage is definitely an indicator of charging.
Put a voltmeter on the battery terminals to verify the guage.
This is all predicated that the battery is in tip top shape.
Macster, did you hook up your own voltage gauge to arrive at that conclusion? Just curious. My experience certainly jives with what you describe.
With A/C and everything on, I'll sometimes see as low as ~12.4 on the factory gauge. I've got a new regulator sitting in the box whenever I have some free weekend time, but wondering if I should even bother.
No voltage gauge was hooked up.
Both of my cars have an OBD2 data/trip logger connected to the OBD2 port and one of the parameters I have the devices set up to log every 5 seconds is the 12V power signal at the OBD2 port.
This question came up before on some other formum and I pulled the hundreds of trips from the device in my Turbo and did a search through the data. I seem to recall very very rarely seeing the voltage dip to under 13V but it never remained there more than for 1 5 second sample duration.
The rest of the time the voltage level was above 13V.
The low voltage level reading especially when some heavy electrical loads are active can be a bit troubling. With my "new" Turbo I was on my first road trip with the car and stopped at Elko NV to fuel up. After I left the gas station I happened to glance at the volt gauge reading and it appeared to be "low".
It was so low I called the SA at the Porsche dealer back home and asked him about it. One of the two most senior Porsche techs happened to be at the SA's desk and the SA put him on the phone.
After I think asking me a few questions probably regarding any odd behavior from the engine or the car the tech assured me the reading was ok that it was not a sign of pending electrical problems.
I drove around town a bit just to be sure -- if the car broke down I wanted to be in town vs. out on the freeway -- and the engine was fine the voltage level didn't drop any further. I probably experimented with turning off and on various electrical loads and noticed how the reading was affected.
After a while I left the safety of Elko and continued with my road trip driving east on to eventually MO and after some few days there drove the 2K mles home. The car was fine. The battery was fine.
The alternator and voltage regulator are original. I've never had either one replaced and my research into the car's servcie/maintenance history didn't find any signs the orignal owner had to have either of these items replaced so the alternator/voltage regulator are 14+ years old and have covered nearly 160K miles and except for a couple (3?) batteries over the years there have been no electrical problems of any kind.
If you have a new voltage regulator and want to swap out the old with the new that's up to you. If you can start the engine and the car continues to run fine and the battery gets topped up after some engine run time that's a pretty good sign the alternator/voltage regulator are ok. As I mentioned before a battery by itself can't power a Turbo for more than a few minutes.
Based on my experience with what readings you are seeing but absent any other symptoms or signs of inadequate alternator/voltage regulator output or control everything is normal.
But replace the voltage regulator if you want. if it gives you the peace of mind you need the effort is worth it.
Here is a shot of my dash last night after a 170 Mi. trip home. Idling in the garage lights and Ac on. My 99 C4 was the same before and after i replaced the alternator.
Here is a shot of my dash last night after a 170 Mi. trip home. Idling in the garage lights and Ac on. My 99 C4 was the same before and after i replaced the alternator.
I agree with Kevinmac, especially using a voltmeter on the battery to verify. It seems low given it should be in a charge mode. At 2.1v per cell and 6 cells you should see 12.6v on a fully charged battery, especially being you have a new one. Looking at your gage, 13v is halfway and it's not even there. Charge mode should exceed 13v. Before changing regulator make sure the tension on your belt is correct and it's not slipping. Mine typically exceeds 13 v at idle and pushes around 13.8 under acceleration.
If you are seeing the needle consistently below half-way, just change the voltage regulator. It's cheap and you get to spend some quality time with the car.
Shot of all accessories on and shot of all off except park lights. Sorry for the bad resolution, u get the idea! Reg replaced about 3 months ago
The gauge is displaying battery voltage and the voltage level is "high" because the battery is being supplied a higher voltage to recharge it.
The gauge in my Turbo behaves the same way after an engine start and for some times/miles after engine start.
But after a drive of some distance -- it happens on my 30 mile drive to/from the office -- the voltage level drops as the battery becomes recharged.
If I wanted the battery voltage gauge in my Turbo to display nearly 13V or higher all the time I'd have to avoid driving it enough to recharge the battery so every time I started the engine -- as long as the battery lasted from this abuse -- the charging voltage would be high and remain high.
However, I like to see the battery voltage level drop over time. It tells me I'm driving the car long enough after engine start that the battery is being recharged and it and the alternator are healthy.
If the battery voltage reading remained high even after some 15 minutes or more of engine run time I'd be concerned the battery was not that healthy that the alternator was dealing with a battery that had collected sulphur on its plates. The sulphur coming from the battery acid. If this condition becomes too advanced -- the sulphur hardens over time if left on the plates -- recharging will not cause the sulfur to leave the plates and the battery will not regain a full charge.
10-31-2017, 05:17 PM
Voltage Issue?
