HELP! Battery/electrical issue - car keeps dying.
 

So about a month or so ago I was out somewhere for about 45 mins, came back outside to leave and my car was dead. It wouldn't turn over, kept dying until it wouldn't try to crank at all. This was even while on jumper cables. Eventually the next morning we left it on the cables attached to another car for 20 mins and it started, and was fine after that. I changed my 6 year old OEM battery to an optima yellow top just to be safe, but I still wasn't quite convinced that was the problem. Also, as a side note, about 2 weeks prior I had changed my transmission/clutch. I went back over all the bolts and plugs to make sure everything was tight and/or plugged in and everything checked out.

So fast forward, about a month later I go to start the car... same thing. Car's battery was just dead this time. I went to charge it with a portable jumper this time, tried turning over and died, then after being left on for a good 15 mins or so it started. It's been fine since then, again... but now I'm lost as to what could be causing this issue. Anything else I should check from here?? Thanks everyone

I suspect you have an electronic gadget (cam, radar detector, stereo, etc) that is not shutting off when you shut down the car. I'd check power wiring to all added electronics.

no detector/stereo, etc... I had the CJM secondary fuel pump installed a couple months before, but I haven't heard any issues with that (wouldn't make sense to be drawing off the battery while it's not on).

Could be corroded cables, or a poor ground connection.
Are you checking voltage on battery,when the problem occurs?
Fully charged battery should read 12.60 volts; even after sitting a few days,,,there are some modules that may be staying awake & draining battery.
Just unsure if it’s dropping in the 11’s,10,9,etc...
Could have a leaking diode in alternator or other substantial parasitic drain.
Oem battery is a lead acid battery & can corrode terminals; Optima batteries are AGM & do not corrode at the terminals....if corrosion is present/ it’s from the previous battery & was not fully cleaned.
That would be my 1st starting place-remove cables & clean internally w/wire scrubber,pocket knife or large diameter round file....then clean external part with wire brush.
Hope this helps & check charging system as well.

Have the Alternator tested, sounds like it's not actually charging and running off the battery.

A simple way to check is get the Z running and disconnect the positive terminal and notice if it either idle goes up charging or it simply dies which would point to an Alternator issue.

IF your charging okay then like it's been mentioned something is drawing power and depleting the battery

Check your ground cable where it mounts to the frame. That can cause some issues.

Since you just changed your clutch. Look for a loose bolt on a ground or a pinched wire.

Disconnecting the battery in any car with an alternator is a bad idea. Generators create power without power, alternators need power to create power. Disconnecting the battery can create power surges through the entire system. There are also vehicles that this "test" is not foolproof as disconnecting the battery will kill the vehicle even with a working alternator.

Generally it would be better to just measure the voltage at the battery with the car running. While I've come across alternators that put out voltage and no amperage this pretty rare. If the OP has a multi meter, this would be best. The battery sitting there should be, 12.2-12.8 if its charged (after it settles), while cranking / starting it shouldn't drop below 10.5 volts, and running the car should be over 14 volts but anywhere between 13.5-15 is fine. If you don't have a meter, most parts stores will test your battery and alternator for free.

I've done this with older cars. Never with a newer one. If the voltage drops below 9.5 volts. Most ECU's will shut down.

Yeah its one of those things we all used to do, but on modern cars with all the electronics its a really bad habit. It sends spikes through the electrical system. I know Chrysler / Jeep systems are bad examples of this, many of these will go to 20 plus volts, some just sit there at this voltage with bad batteries (or missing batteries).

Have an '08 Power Wagon. I know when the battery starts going bad. Even tho it's showing about 10.5 volts. The dash lights will go crazy at times and the stereo acts up. With the 3G Rams. This is common. :icon14:

Thanks for the suggestions everyone! I still think it's odd that it's SO intermittent (and with a new battery as well?). I'll definitely have the alternator tested and check a couple grounds just to be sure.

The intermittent part sounds like a bad wiring connection somewhere. Grounding is a good place to start. If grounds are good, I'd next check the charging system wiring. Wiring diagrams, wire colors, etc are in the FSM (link in my sig).

I had a similar issue
 

So my Z would die without any real cause and I replaced the battery, and alternator. Turns out the Navagation had corrosion due to when the screen was cleaned with some liquid. Underneath the factory navigation there was some connectors that were corroded. Once they were clean my Z had no more issues, hope that helps.

anyone having this issues? battery keeps dying, granted I hardly drive the z. maybe once a month...

OEM or aftermarket battery?

A battery in good condition and well-charged should keep the car in sleep mode for a month.
Check:
1) Condition of battery. If it's not a sealed unit, check/replenish electrolyte level. Use only distilled water to top off any low cells. Most auto supply stores can check your battery - often for free.
2) That system is charging properly. Should have about 14-14.5 volts at high idle if it's trying to charge the battery.
3) For too much drain when in sleep mode. Check any non-OEM parts to make sure they either auto-off or are on a switched supply.

Sorry about the thread rez from the dead but I am having similar issues. '11 with ~80k miles. I replaced the ground strap and that helped for awhile but it's back to a dead battery after just a few days, lights are on but won't crank. I'm thinking it might just be time to get an alternator. While the miles are relatively low it's 12 years old. When I replaced the ground strap the last time I couldn't pin down any specific high draw areas but I wasn't too through, checked the audio amp circuit and overall draw. The amp circuit didn't draw any load and the overall drain while a bit high wasn't too off from the "normal range 50-80ma" from what I remember.