Battery Drain


  • Battery Drain

    Hello everyone!

    I'm a recently new user to z31performance but I have spent a lot of time on other car forums as well as this one. Rule #1 ALWAYS check for related posts before submitting one. I know for a fact there are A LOT of battery drain posts out there that I have gone through and will do so again to see if I'm missing anything. Some are not the same as mine and some are similar but I never saw a resolution to the post. There may be one that is identical to mine and if you know about, please do not hesitate to direct me in that direction so I don't take anyone's time away. I plan to at least comment when I have a definitive direction I feel comfortable with and will post a comment of the resolution and process so anyone else can use it as well.

    Let me go ahead and get started by saying I bought my first project car that's a 1985 N/A 300zx T Top. So far I love it. Specially with the infinite amount of problems I've been discovering over the past month or so. A little bit of sarcasm with a touch of excitement knowing that ill be proud of where it'll be when I'm done and all the work ill put into it. The beginner mechanical issues I want to address before anything slightly stacked up fairly quickly.
    1. Needs a new Rack and Pinion (Really Bad)
    2. Stiff Brakes
    3. Soft clutch
    4. Bad gauges
    5. Some sort of Battery Drain*

    The battery drain is where I'm having a little bit of difficulty and this is where I need a little bit of guidance. Ill try to be quick and simple for an easy read but I also want to be thorough for anyone willing to help out in order to keep things efficient and less time consuming for anyone. I do want to say thank you in advance. This is my first post so any suggestion are great.


    Issue:
    Almost* any time I start my Z the battery is dead. (* = as long as its been at least a couple days. 2nd+ start of the day it'll work fine almost all the time. MAYBE the next day it'll start as well.)



    If I jump it and sit there in the car, the battery will drain rather quickly. Driving around will help charge it up after about 10 minutes or so and ill be able to turn it off and back on again during that day or maybe the next. If I turn on the AC while driving I car hear the Z take the struggle bus downtown and try and stay alive as best as it can and you can see on the Volt meter that its struggling as well. Now, I've been watching the vehicle at night and checking up on it trying to catch it in the act. and I've been successful. Every now and then the headlight will turn on with out anyone actually flipping the switch to do so. This could easily be a cause for the drain.

    Now, after going through threads, manuals, testing, etc. It's come down to a few obvious issues.
    1. Alternator
    2. Battery
    3. Parasitic Drain
    4. Short somewhere

    The battery should not be an issue. I tested it and made sure were good on cells. My mechanic chose to also change the battery after I told him the issue and informed him not to change the battery cause it will still die by the next morning and that it'll be better to see what causing it to drain. Guess who paid for a new battery anyways? This guy. Guess who's car was still dead in the morning and shocked the mechanic? This guy. Guess who isn't my mechanic? My old mechanic who I've only gone to once and after him having my Z for about 3 or 4 weeks to check 4 or 5 different issues. Two of which he could have been consistently proactive about but did absolutely nothing only change the battery..... I'm pretty upset about it still as you can tell.

    The Alternator I'm leaning on entirely and once I move into my new home at the beginning of May I plan to take it out and have it tested by Auto Zone or some place reliable. If its bad, it'll be replaced but there will still be some form of drain somewhere. Bare minimum, the head lights. But this will most likely solve it have issues charging the vehicle and keeping it charged.

    The parasitic drain I have read up on it when I first got the car as if it was something VERY common, however, recently I've been struggling trying to find relatable forum posts to assist me.

    Recently, I read a comment regarding almost the exact same issue where someone commented a possible short somewhere but never said a resolution or a verification that its a possibility to think about.



    So! Finally to end my novel here, I'm looking for guidance. I don't plan on buying anything until I can trouble shoot further so where and how should I start? The alternator is planned out and ready to execute once I move, but the Parasitic drain and the short being a possibility has never been something I have personally experienced, nor worked on. So, if its reasonable to test for those, how would I?

    The other portion are the headlights. I know it will drain my battery but that does not necessarily mean it will cause my Z to struggle all the time while driving and so forth so I'm understanding now that its not just ONE issue, but more so the possibility of TWO issues related to each other.



    Thank you to anyone who has taken to time to read this huge post, as well as those who are willing to guide me in the right direction. Any links to other posts are more than welcomed as you know. As promised, ill keep my end up and make sure I end the post with a comment stating the direction I'm going, troubleshooting process, as well as a final result so if anyone stumbles upon this post in the future they can use it for direction as well. Thank you - Oliver

  • #2
    I have had the headlight switch go bad. Then turn on the lights randomly in the middle of the night. Definitely check your wires for resistance as well!
    "Its the s12's sexy over weight step daughter, the z31"

  • #3
    Make sure your headliner bulb isn’t grounding out and your door switches are working properly. I’ve never had this problem but take a volt meter and check what fuses have power when the key is off and check related things like door switch and lights etc. after.

  • #4
    Thank you nismopu and Dayton570. I just bought a Volt Meter yesterday on my way back from work. Ill check for both the fuses and testing out if there's any resistance from the wires as well. Will update later today.

  • #5
    I've had two battery drains on mine in the past… First was the alternator. When I took it to Auto zone, it tested good. However, I believe at least one of the diodes was bad, causing a waveform in the charge current. This caused the battery not to charge and I would need to charge the car every few days. I was driving about 20 miles per day at the time. Be on the lookout for that when you have it tested.-- you can put the voltmeter on AC to check for this-- if it reads more than half the DC voltage while running, that's an indicator that there's at least one diode within the alternator. DC voltage should be in the 14-14.5v range (while running) just like every other 12V car out there. The second is when the brake light grommet crumbled into dust as they are known to do.
    --------------
    Legal stuff:
    **Nissan Employee**
    Any information shared is simply my own opinion and NOT the opinion of Nissan

    not legal stuff:
    '88 300ZX 2+2-- driving… just details left
    '22 Q60RS-- I tell the wife it's hers…
    '87 Chaparral bowrider-- the next project
    '00 Corolla-- kids car.
    '14 E-350-- Gotta haul those kids in something.

  • #6
    **Update**

    Unfortunately I was not able to run any trouble shooting yesterday as promised. Due to rain and not having a garage right now, I was not able to jump my Z in order to start testing anything. Today should be a better day but Ill update when I get the chance to run some tests.

    mwolvinm
    Yeah, once I jump it I'm going to disconnect the terminal from the battery when I'm not driving. Cant drain the battery if the circuit is open! This way, following the next couple of days I can verify if the Alternator truly is having issues as well. Luckily, I don't need to charge the car or at least don't believe I do right now but it could always start happening when I go through these tests. When I end up testing the Alt, ill be sure it be on the look out for it. Thank you!

  • #7
    this will take some time, but remove 1 fuse at a time and see what happens to the battery. If it discharges, put that fuse back in and take out another. Sooner or later you will find the fuse that is killing the battery. Checking the alternator is easy with a DVM. While the car is running, the alternator should be putting out over 14VDC. If not, it is probably bad.

    the first fuse to remove should be the brakes. I had a problem with the brake petal plastic buttons falling out and causing the brake pedal to not press in the light out switch, a very common problem. Next would be all the headlight and marker light fuses. Headlight switch issues are a very common problem with the Z31
    Last edited by FlyingT; 04-25-2019, 06:00 PM.
    Restore it, Don't crush it. They don't make them like this anymore.

    Scott
    85 Turbo, original owner, restored
    93 NA Babied



  • #8
    while you work on the problem get a disconnect :

    https://www.amazon.com/Post-Battery-…s%2C230&sr=8-3

    I think in some cases the drain is from the ecu itself … I have a disconnect on both my Z''s If i'm away … It's easy … and no ones driving your car without a battery

  • #9
    ***UPDATE***

    I've been doing some trouble shooting over the past few days. Tuesday, I went ahead and checked some fuses to make sure they weren't bad. Nothing came up bad but I'm going to double check today after work. I jumped the car, drove it around for two minutes, turned it off and turned it back on without an issue. I disconnected the battery to leave the circuit open and the next day reconnected it only to find out I couldn't start it. I repeated this process on Thursday by driving it around for a total of 2 hours or so and Friday I was barely able to start it with a struggle. It took about 2 or 3 tries.

    I drove it around Friday all day, if it starts today, I know its charging the battery. If its struggles then starts I know its charging the battery but slow enough to the point that it doesnt reach enough charge to start the car. If its dead It will lead me to the two possibilities below and that the second trial with it starting may have just been lucky.

    1. The battery is being kept alive while running but cant charge/save enough juice to pump out that little extra bit to start the car. Easy test to see if that's the case and will test it today after work. The battery is less than a month old so I hope there isn't an issue with that.

    2. The alternator is only putting out enough charge to keep the battery alive enough to run the car but gets the extra juice to start from jumping it.



    ***The Next Step***

    I'm going to first follow up with mwolvinm and flyingt's advice on testing the ALT while running. (Why I didn't do this the past few days blows my mind. I just spaced on it for some reason.) If it hits 14v then of course that's a good sign.

    I'm also going to entertain that idea of testing my battery even though its brand new. If its bad, Ill replace it but continue trouble shooting on the old battery since it'll die faster if any cells are bad. This way, I don't use a new battery just to watch it die 5,000 times.

    then, since I have time to spare over the next couple of days, I'm going to implement FlyingT's advice regarding unplugging the fuse to solidify what is draining the battery. Although, its relatively clear its the headlight draining the battery, I heavily believe there could be something else as well and this will help out to discovery what is doing it in an excitingly slow process.

    For the sake of future purposes as well, Ill probably end up getting a disconnect that dbruce suggested. through out the trouble shooting process it wont be used, but I want to be able to go through the steps and see whats happening in case I ever need go through something like this


    Last edited by Project_85; 04-27-2019, 09:03 AM.

  • #10
    *** UPDATE ***

    I ran some tests on the battery with my Multi meter, (Should have done this forever ago but the electrical parts of the vehicle is something I've never dealt with before and is a new field I'm learning.) and it does shows that the Alternator is pretty bad.

    I attached the Multi meter to my Battery while it was turned off. It read above 12 Volts, letting me know the battery is good. I turn it on but it sat at about 13.67 Volts and as I turned things on to place a load on the battery, it started to drop to the low 13's in Volts. This explains why it struggles to be turned on as well after being disconnected all night.

    Alternator is ordered and on the way. Ill most likely replace it after the 3rd since that is when ill be moved into my new home and will have the convenience of a garage to beat the weather.

    *** The Next Step ***

    With the Alternator being one half of the issue and having been verified it has an issue, the next step is to figure out whats causing the battery to die all the time which will be a lot of the fuse pulling over night.

    I can confirm the headlights are killing the battery, but there could be other issues involved. So to test this out, I'm going to pull out the fuses related to the lights, then test the battery the next day and see what is draining it. If there isn't an extra drain then the job gets kind of easier. I need to figure out afterward what is causing the Driver side headlight to kick on by itself randomly in the night and why it the slightest touch of the stick will kick on the head lights as well (no twisting involved to actually turn it on).

  • #11
    What is causing the headlights to come on by themselves is the headlight switch, which eventually goes bad on all Z31's. Either the contacts in the switch don't make contact or make contact when you don't want it to. You are lucky, the headlight switch is still made for the 84-86 Z, so you can buy it new . You can try and clean the old one, or buy a used one. Just be careful pulling off the steering wheel so that you don't pull it into your face when it finally breaks free. That can leave a mark. Leave the steering wheel nut on a few threads until it breaks free.


    A great source of used no longer available parts:
    Used http://www.300zxpartsforyou.com/

    The best place to get new:

    New https://www.thezstore.com/page/TZS/P…c10e05/45-4063
    Restore it, Don't crush it. They don't make them like this anymore.

    Scott
    85 Turbo, original owner, restored
    93 NA Babied



  • #12
    Make sure you disable the stock alarm by pulling that fuse. I pulled mine 15+ years ago, definite drain from that.