911SLOW

I have a Li-ion battery *Voltphreaks on a 04gt3 that has the same generator like a '08GT3. (superseded part)

Porsche for the 2010GT3 removed the current control regulator from the generator, and put it on the newer generation DME controller that the 2010 cars have. So, it's impossible to retrofit the 2010 generator to a 2008 or a 2004. This is what they told me when I tried to order one.

I believe that this change maybe has to do with the fact that the newer optional Li-ion batteries will get the adequate volts in order to be properly charged. Older generators have a nominal output of 13.6v plus minus 0.2. Li-ion batteries would not charge with 13.4V, whereas a conventional battery would.

The ECU's ability to control the power output of the alternator also suggests that it might be able to recognize when the Li-ion battery is installed (for example from its unique characteristic of discharging in a steady higher voltage than a conventional battery and namely around 13+ vs. 12+) and alter the voltage cut-off points of the generator.

With that said, it probably comes down to the individual car. Mikymu doesn't have any trouble with his Voltphreaks battery in the 2008RS. I did have problems with mine when my original 6Gt3 alternator was dying.

It would be interesting if some of you guys, with the 2010 cars, could take some measurements of the voltage output with the car running to verify or dismiss this theory.

Jon70

^ Thanks for that ifo John. I was completely unaware of that. Assuming my car cannot recognize the Lion battery as such, and my car is using the older generator, does this mean the Lion battery will only partially charge? Anyone know if the standard Porsche battery tender is the same regardless of battery type?

911SLOW

^
My car pumps 13.9volts , my friend's gt3 13.4, both for Porsche's standards are fine but if both were running a Li-ion battery they would get completely different results..mine would charge, his wouldn't.
It comes down to the individual car, that's what Tony from Voltphreaks told me. Interestingly enough, they seem to have problems with P cars more than with any other car manufacturer.
Porsche runs the alternators fairly lower than others, probably to extend their battery life. Just guessing.

Therefore, if one is to buy a Li-ion for a 2008 or 2004 car, I would suggest they check their voltage output first before buying it.
Some cars would even benefit from a change in the positive and negative cables that go from the alternator to the starter or chassis. Cost is about 100eur. I changed mine and got even better cold starts.

BTW you can use same charger for the Li-ion battery.

Jon70

John, Thank you once again.

Now I am assuming my Lion battery was just losing its power over the past 2 months and now has finally signaled its dying message. After 24 hours plugged into the charger, the battery still isn't charged and likely never will be based on your information. Maybe that is why they only specify the battery for the 2010 GT3, RS and Spyder. At least I have a spyder I can put it into. I'd rather have my $ back.

If the battery completely drains, is it gone forever?

911SLOW

Sorry to hear this.

I don't know a lot of details about the oem one re: features and specs but, Li-ions usually have a circuit inside that prevents total discharge. In the Voltphreaks, IIRC it’s set at 11.5V or 9.5V depending on the features. If it didn't have that and it got completely drained, the battery would be unusable.

For your case, better check the battery's manual, and maybe your charger is not working?

Jon70

I suppose its possible the charger when bad, but doubt it. I was at VIR last week and did have an 'off'. Maybe I jarred loose wiring from the alternator? Once I get off work, I am buying a multimeter to check the output.

Carrera GT

Sounds like it's working fine according your experience. The dealer has been researching the battery, but there's no bulletin on it for any problems. He has noted differences in the 997.1 and 997.2 charging system and a bulletin on some mistaken alternator replacements because techs didn't realize the changes meant different voltages. I don't have the details yet.

Jon70

You are right, it must have been charging from the alternator or it would have died long ago. Maybe my alternator is bad or something else.

vph_tony

Tony from Voltphreaks here. John is correct about the lower alternator charge voltage of some Porsche cars. Most users never see this issue. I'm not sure if it was done on purpose or not, or if some Porsche alternators were below spec (but still acceptable for a lead-acid), but in any case, we've had a very very few cases of GT3's not charging the lithium battery because the voltage output by the alternator was only 13.2 to 13.6V or so. This is enough to just partially charge a lead-acid battery, but it will not charge a lithium battery.

- Tony

Jon70

Update on the battery issue: the lion battery did charge using the wall charger. The voltmeter read 13.54v. In a 2010 car should this charge to 13.9v? I am going to monitor the voltage this week to see if it continues to drop.

911SLOW

Jon that doesn't say much the Li-ons have a rather flat voltage output throughout their discharge until they almost reach the empty state so I wouldn't bother with this measurement 13.54 can be full or half full.. what is interesting and will reveal if the battery charges properly is what the voltometer reads on the battery poles when engine is running and idling and:

1. Ambient temperature 20 C
2. Engine Temperatures 90 C
3. All loads switched off

The nominal value for 996/997 .1GT3 for voltage on the battery terminals as tested with the Porsche Tester (or with a voltmeter) is 13.6V + - 0.5V.
Some cars will output more and some cars less.
It's a lucky shot..

Maybe the 2010 guys will also perform voltage readings so that we can see how Porsche manages (or not sometimes : ) ) to charge the Li-ons on the 2010 cars running the new alternator regulator.



John

deputydog95

I was seeing 13.5 today on the multimeter, at the terminals with the engine idling and AC on full tilt.

Is this too low?

Carrera GT

12V is fine, 13V is "nominal" when charging, 13.5 is perfectly healthy. If you're seeing voltage change as load changes, the alternator is working, if you're seeing the battery voltage drop below 12V after any amount of "sitting" (say a weekend or a week) then the car has a parasitic loss (radar detector, cell phone charger?) or a sick battery. This is based on a 2010 GT3 RS 3.8 with the factory li-ion battery -- I had one fail and never beep, the replacement works fine and has beeped when it reached 12V at the terminals.

Be sure to get a good ground to check voltage or "gouge" the test probes into the lead of the battery terminals directly.

There's a lot of good posts here on the lightweight battery topic.

deputydog95

Talked to the dealer today. They said I should be seeing at least 3.8 to the battery terminals. Was contemplating a LI batt, but didn't want to the trigger until I knew for sure I wasn't going to have a charging issue. Bringing it to the dealer tomorrow to have the charging system checked.

I've been reading most of the posts. Good stuff.