Battery causing issues ?
 

Whats up
just wanted some quick opinions before I get a scan tomorrow at my local parts store. The car is a 2008 g37s coupe.

So heres the basics; the car is driven probably once a week or less. The battery was repeatedly dying from lack of starting it so I have been jumping it every week for the past month or so (just never had time in the week to start it and give it life). This past weekend, a jump wasnt working so i took the battery in to advanced auto to get it fully charged since the battery itself is less than a year old.

Once i installed it back in, the car started going nuts. It would randomly shut on and off while driving, take the car into limp mode, not be able to turn off (push to start), etc. This was actually happening on the way back from work so the only way I made it home was driving it for a few miles, then when it would go crazy I would have to pull over and disconnect the negative cable, essentially restarting the entire system and drive again.

In between all this the "service engien soon" light also popped up. Now my guess is the battery is just fucked from dying and reviving repeatedly for so long but I dont have any guarantee as of now. The only reason I am a little skeptical is that once it was fully charged at advanced auto, the guys assured me there shouldnt be any further issue concerning the battery meaning it was holding a proper charge. My only other guess would be the alternator but i've experienced a similar situation with the car going nuts last year and again the culprit was simply a bad battery.

First move would of course be getting it scanned, but as the car is hard to drive proper without repeatedly stopping, id rather try finding a solution online first. Any feedback would be greatly appreciated.

FYI, the car ran 100% last week after I jumped it so there were not any underlying issues prior to this.

Re: Battery causing issues ?
 

So you've said a few things that point toward a possible culprit.

First, jumping wasn't working. This means that even with an external power source from a running vehicle, there wasn't a sufficient amount of power to start the car. If the battery was defective, such as being a dead short or whatever, you would have affected the other vehicle (sourcing power for the jump) visibly as well. If the battery was shorted, you would know immediately if the voltage was tested. A completely shorted battery won't show voltage, because it's shorted.

Then, you got the battery charged, proving that the battery is in good enough condition to be charged, and therefore not shorted, etc.

Through all of this though, you've proven that the alternator isn't the problem. A known-good battery, or a jump start, should start the car. The alternator isn't involved in starting the car, only the battery. The alternator doesn't work until the engine is spinning fast enough to excite the field windings, etc., so it doesn't do anything to help start the car.

So we know the battery is good, and the alternator doesn't matter, but a jump start consistently wasn't working.

We go back to the fact that there is a problem with power delivery.

I suspect that you have a power or ground problem, and being a Nissan product I would first check the battery terminals. I’ve seen a few problems with cracked Nissan battery terminals where the clamps are overtightened and then fatigue, which causes intermittent or high resistance contact to the battery. I had a Frontier where this happened by itself without ever touching the OEM battery or terminals at all. This causes charging problems, and starting problems. This could also cause problems while driving, where the make/break contact can cause big voltage fluctuations in the electrical system. If it's something more global, like a bad power connection to the main fuse block, it can cause all kinds of CELs and funny confusing symptoms like the engine shutting off when you press on the brakes (don't laugh, I solved that exact issue on a Maxima once and fixed it with some fine sandpaper on a main power connector).

It’s also possible that you have a problem with the ground connection to the chassis or block, or at any shared power and ground connections to something like the main fuse block. Nissan sometimes uses a power connection between the battery and main fuse block that can corrode or fatigue. Don’t know if they still use that type of connection for your model year. Connecting jumper cables to the battery posts doesn’t do anything, because the power can’t go anywhere (just like a bad battery clamp).

You can actually track down problems like this with a voltmeter, by checking where you have voltage and where you should have voltage but don’t.

I don’t think this will be a hard problem to track down and fix, although troubleshooting it may be very confusing if you aren’t familiar with how things interact and what you should be looking for. The ideal situation is to troubleshoot it when it won't start, because then it's easy to see where power isn't flowing. Like anything else, it's hard to find a problem when the symptoms aren't showing themselves.

To start with, check that you have power to the fuse block, power to the starter, very low resistance between the chassis and the battery post (not to the clamp, which may be defective), and very low resistance between the engine block and the battery post (again, not to the clamp, which may be defective). You can also check voltage drop between various points during starting, which will be very obvious because of the high current when the starter tries to energize.

This is a good time to have a knowledgeable friend help out if you aren't comfortable doing the tests or interpreting what you're seeing.

Re: Battery causing issues ?
 

I appreciate the input,
you're right a voltmeter would have come in handy at the time but I just didnt have one unfortunately.

But now that you mention it, the negative cable is actually a bit iffy which I forgot to mention. The clamp bolt on the terminal is stripped so i took a screw and screwed it in to tighten it on to the battery to assure contact. Yesterday, after stopping repeatedly to restart the car, i actually removed the screw completely and just let the terminal make contact with the battery even though it was loose because I wasnt going to screw it in and out everytime I had to stop. The funny thing is the first time I removed the screw, it made decent contact with the battery and even the CEL turned off. I drove about 5 miles like that and then it again went in to limp mode.

Is it possible that just the lack of contact from the terminal to the battery is whats causing all these issues? I'm starting to think tahts where I should start ?

Re: Battery causing issues ?
 

Yes. Fix it. Even if it's not the main problem, you can't properly troubleshoot anything else if you have potentially bad contact at the battery terminal. But it could be the main problem right there. Make sure both battery posts and battery cable clamps are clean also, which is as easy as getting a $2 male/female battery terminal brush.

Get OEM parts unless the cable is really simple and can be replaced with something from Autozone. To be thorough, also clean up the contact point where the other end of the cable mounts to the chassis or whatever.

Re: Battery causing issues ?
 

ill be trying this out tomorrow, hopefully it solves the issue
thanks

Re: Battery causing issues ?
 

so I replaced the negative clamp and re tightened both the positive and negative terminals so they fit "snug".
Thankfully most of the issues seem to be eradicated including the limp mode, random cutoff, etc. Car starts right up every time and CEL has also vanished.

After swapping out the clamp and driving for a few miles, the car cut off at one point but turned right back on... in fact it may not have even turned off, the navigation just cut off and came back on, engine was still running fine. Then again after a few miles the same thing happened except the engine cut off, as if it stalled; all electronics and navigation remained on. I started it right back up and drove it about 10 miles home again without issue.

So it seems clear that the prior issue was the contact from the clamp to the battery, but are these symptoms something related to the clamp/terminal contact or something different? To my knowledge, the clamps are fit "tight" around the terminals and are making contact, even while driving. I will check the ground or any lose wiring on the battery tomorrow when i get some time but I am at a loss besides that.

Re: Battery causing issues ?
 

You've likely solved the battery terminal problem, so it sounds like you have a problem somewhere else that now needs attention. It's possible that you have a partially failed fuse or something else that has been electrically stressed by the battery clamp problem, or maybe just a sketchy ground. This one will be harder to track down because it's a very intermittent problem, and will be especially difficult without some a proper voltmeter.. Definitely check the other power connections and ground points on the chassis and block, like you've said..