So maybe 3 months ago i had the Infiniti dealership perform the TSB update on my car which included the new vent valve, ecu update, and a bigger battery. I thought everything was fine as the car has been starting up fine every morning but i recently had to take time off work due to covid. I went to start the car after 10 days and the battery was completely drained. Overnight the car goes from 12.8v to 11.9v. Any ideas on whats causing the drain?

 

Problem is pretty common in these cars. Prior to the update did you ever leave your car off for that long?

 

I don't think the TSB is the cause. Letting the car sit isn't good for it. It stone cold draining put a good hurting on its ability to recharge and I'm betting your battery is a little older so now its just its time.

 

As I only drive my car 1-2x/month (COVID notwithstanding), the battery would often get substantially weak after a fortnight or so (worse in colder weather). I bought a cheap battery tender (actually 3) from and have had zero issues since.

Something to consider, especially if the car is going to be sitting for extended periods of time.

 

Battery is only 5 months old, its the 700cca battery from infiniti. So i spoke to an Infiniti tech and at least he was honest, he said that the car will always have a slow parasitic drain, and that the tsb update just slows the rate that the battery is drained. He advised me to just disconnect the battery if the car is going to be sitting for any longer than 5 days. He also said a trickle charger is an option. I find it kind of stupid that infiniti never really addressed this issue properly, but what can you do. Ive only had the car a year and i like it too much to get rid of it.

 

Just get a tender. Unhooking the battery is going to cause ECU relearns and other issues.

 

All modern cars are going to have some level of parasitic drain due to all of the electronics that are being integrated. It is not solely a Nissan/Infiniti issue.

Like stealthee suggested, get a tender if you know your car will be sitting idle for extended periods of time. I set it and forget it. When I need to go somewhere I just unplug the tender from the power outlet, unclip the harness, and go. Takes all of 30 seconds and I don't even have to open the hood.

 

if the parasitic drain on the battery is more than 100milliamps after sitting for 30 minutes with all doors locked and vehicle electronics in sleep mode it is not normal. obviously if you let your car sit for 10 days without it starting it will cause the battery to drain down to the point where it will not crank. battery voltage is the pressure and amperage is the flow of electrical current. its the amperage that is most critical, meaning you can actually have a 10.5 volt or 11 volt battery as long as you have enough amperage your car will crank and start over.

 

So while looking at the FSM of the BCM. It mentions battery saving function and to test draw on this circuit. Looks like the charging wire to the IPDM keeps voltage upon turning off the vehicle.

 

is there a fix for it?

 

A car should be able to sit for weeks and still start.
That being said, I do use a battery tender If I think I'm going to let it sit for more than a couple of days.
Had a problem with batteries when I first got my G.
I did the home brew grounding kit (making sure not to bypass the amp sensor ring).
Got a high amp batt. Got a deep cycle batt. Almost bought one of those spiral wound ones.
Only thing that fixed my battery woes was the "always charging alternator mod".
Cut one wire, and you can go back to the lighter/cheaper battery.
Basically makes the "smart" alternator into a dumb alternator.
Apparently the IPDM takes up to 10 minutes to "initialize" And I only had a 15 minute commute to work.
Guess there is a slight increase in parasitic drag without the system being active. Maybe 1/3 HP at WOT?
Idk and I don't care, my car starts all the time now. Don't have to worry about getting stranded on my lunch break lol.

 

So THAT is really the conclusion. In my opinion this is one of the ways to increase MPG with the toggling of the alternator. This however impacts the battery by giving it an array of voltages based on what the IPDM determines the demand is.
Other than a software update that can better control the IPDM "charge on" command the only other fix for this is to disable the wire to it. Like previously stated before it will keep the alternator charging manually as analog alternators work.
Draw back might be a very slight power and efficiency loss at the sake of keeping your battery alive and functioning as it's supposed to.

I drive 50 miles round trip and dont go through a slow crank unless I dont use my car for the whole weekend.

 

Wow. First time hearing of this, but if that's true it sounds like a good trade off to me to dump the "smart" setup. Thanks.