Hi guys,

2009 Infiniti G37 Sport Coupe

Randomly, I will come home from work and park it at 6pm at night. Next morning at 6:30am I goto start it and the battery is either completely dead or has enough juice to spin the motor literally once before it stops.

The battery is less than a year old. I took it to Advance Auto where I bought the battery (Its one of the big name brand batteries, I forget exactly what name), and the guy brought out his battery tester and told me that the battery was fine, but it was my STARTER drawing power (?!?!) with the car off.

Has anyone ever heard of this, and if this guys diagnosis is correct, what would cause this and what would I have to replace?

Any suggestions appreciated at this point! I'm about to drop it off somewhere to have it diagnosed if this doesnt sound correct.

 

Possibly wrong diagnosis?
The starter main power is supposed to have power at all times. When the starter motor is not engaged this does not become a drain.
The solenoid is what engages it and this is either an on or off part. If it indeed was your starter the car would stay in starting mode continuously.

There is a possibility the main power for the starter has deteriorated and started to create too much resistance while cranking i.e bad connection drain way too much amperage giving an appearance of a weak battery.

The same goes for your grounds, any deteriorated ground will make the starter work a lot harder.

You should get yourself a BT OBD adapter and monitor your battery voltages before turning off the car and prior to cranking in the morning.

 

I actually have one, thanks for the suggestion, Ill do that.

 

I had this on two 2008 G37S 6MTs. Both times it was caused by some a/c valve that cycles thru after the car is off. There's a TSB about it. They replace it w a valve from the GTR and your battery w a battery from an M45 for more CCAs. Google "G37 ITB 10-010b". It should come up. Dealer may tell you your vin doesn't match, but just describe the issue and bring in a printed copy of the TSB. They did it for free for me both times. After the work I never had the problem again.

The very first time that happened I thought it was just a bad battery so I replaced it. It took about nine months for it to start happening. I replaced the battery again and nine months later same thing, and that's when I found the TSB and had a resolved.

 

This is a crazy find so many years down the road. Thank you for this!!!

 

Hell of a find, I wonder up until what year it did this.

Technically the only way this can stay on is if the IPDM commands it. This vent control valve power is shared with MAF 1+2 and EVAP PURGE + which is why the ECM programming might be needed.

According to the TSB:
Does the customer do one or both of the following? • Only make frequent short trips with the car. • Store the car for long periods.

It is possible that the combination of battery drain over systems that require memory and this valve's function will drain the battery over time thus killing it and with this short trips and long stores it doesn't give the car enough time to charge the battery properly.
@MotorvateDIY can also chime in on this. The alternator works at a higher load on a older battery so the combination of all of this does a good number on our batteries, you add this to the deterioration of the one single 8 ga ground wire and you're in for electrical problems.

Fun insight: On my engine stand I do not have an IPDM, I have my alternator charging constantly.
There was a time that I disconnected the connector while running and around 11v the ECM kills power to the throttle relays and I get a code. Pretty rational up until the point that you start having battery issues.

Im really interested in this valve and up until what point the superseded one was done and if it only affects this year.

 

PS. My engine stand though no IPDM or BCM sees about the same engine harness voltages it will stay charged for weeks without being turned on.
This is on a battery that had given me issues in my Sedan ended up being just fine in my stand but in the car not so much.