Does somebody know what the normal charging voltage of a G37s should be like?
I had some starting problems lately and now I try to figure out what can be the problem.

 

cars should put out 13-14V to charge the battery. i like to put mine on the Battery Tender once in a while to "top it off", as modern cars with all the computers and big audio systems may not get the battery fully charged, especially if you doing a lot of short trips.

clean the battery terminals and connectors, maybe add some ground wires, and go to an auto parts place that will do a free battery check.

you can get a 12V alt/batt voltage plug-in to keep an eye on things:


... or use the Torque app and a Bluetooth OBDII dongle to monitor voltage.

 

Thank you for the information. My battery is less than 7 months old and I think it is still ok. What I noticed was a bit low charging voltage. When the engine is started the charging voltage is about 14,8V then after a while it slowly lowers to 13,2V ~13,0V. So I think this is a bit less but am not sure.
I can measure the voltage already through a OBDII dongle and the Torque app on my phone.

 

Cars should charge at 13.2 to 14.2V. That being said, I have noticed my G do the same thing... It will start out around high 13's then be low 13's 20 minutes into my drive. Mine is a 2012, original battery. Batteries anymore only last about 48mos so if it's beginning to turn over slower... you may be in the beginning of a dying battery or developing a dead cell. You could also check the output voltage of the battery itself if you have a volt meter... My last dead battery was showing sub 12 volts, but would still turn over my 2002 Expedition... but slower and slower until it finally had to be jumped.

 

search the DRL install threads ... there is a module that limits battery charging to give higher mpg's (wtf?!?) that you can disconnect.

 

I do not want a higher charging voltage. I was asking because I want to make sure there is no problem with my dynamo. Partly based on what is told here I don't think the problem is caused by insufficient charging. As the battery is almost new and also my multi meter shows it is workng fine after I charged it.
So I'm gonna measure the electrical consumption when the engine isn't running, to find out if that can be the reason for the empty battery.
Dis anyone know what the consumption might be (in mA)?

 

The two videos show battery V with car off and V when the car is running.
Should I change my battery or should I be worried about my alternator giving out?
Any input would be appreciated.

 

The battery is empty for sure. Only how it became empty is hard to tell only by watching the video's. There are two options
1 it drained empty
2 it isn't charged enough

Normally the charging voltage rises a bit when the battery is empty then it will be around the 14,5V so I put my money on a defect alternator/regulator as your 12,4V is too low.. But when your battery is dead it can also be that the charging voltage is low. Also the G37 has a built in envoironmental thing that you have to drive more than 4 miles in order to let it charge at it's max.
Best is to check the state of health of your battery with a battery tester (when it's ok then your alternator is defective). Or charge your battery with a battery charger and check your charging voltage again directly after a trip of more than 4 miles.

 

Battery Hydrometer

Normal alternator charging voltage

 

Yea I was able to get the battery and alternator tested. They’re both good. The starter is good too. There was bad/loose positive connection. My positive connector is also getting worn out so I might need to change that. Appreciate the inputs guys 🙏

 

That charging voltage looks better. Good find in the connection. You see a good check can prevent to replace non-defective parts.