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Thread: Flat battery

  1. #11
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    The output current of the Optimate 4 is only 1A when in bulk charging mode so it 'can' handle the so called 'car battery' but just takes ages.
    The battery conditioner designed for the higher capacity battery (like car battery) has much higher current rating.

    It would be nice if you have multimeter to measure the voltage but if not, probably easier if you just take the battery out and have it charged by someone.

    The Optimate 4 can operate as long as your battery can hold above 2V during the safety check phase.

    You should be able to tell at which stage the Optimate 4 decided to quit through the indicator.

    Do you have security/immobiliser on your NSX?

    If the hazard light came on when you connected something, you may have triggered the immobiliser.

    After having the battery charged or getting the new one, wear ear plugs and be prepared with the loud siren as soon as you reconnect the battery.

    Quickly dis-arm the alarm/immobiliser to stop the siren.

    Standard procedure for me so I always have ear plugs nearby while working on the car.


    Kaz

  2. #12

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    Quote Originally Posted by Old guy View Post

    Conventional lead acid batteries are damaged by deep cycling. If the battery has been repeatedly discharged to the point of being flat you have shortened its life and are likely in need of a replacement.

    Not repeatedly discharged as battery replaced last year so first time.

    If 'using leads' meant using battery jumper cables to connect the battery in another car to the jump start terminals in the engine compartment that should spin the starter motor just fine. If the starter motor failed to spin using jumper cables then you have some other problem.
    Sorry, jumper cables yes. I was hopeful here but engine didn't turnover. Perhaps I didn't leave it connected and the donor car running for long enough to get a base charge in the NSX battery? Could I have blown a fuse....or damaged the alternator? I connected to the positive terminal and the spare wheel brace...which got the hazards flashing.

  3. #13

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    Kaz, yes there is an immobiliser fitted. Lights flashed but thankfully no alarm when I connected her to the donor car/battery. Will be ear plug armed when I reconnect for sure.

    As I recall the optimate seemed to show no progress via the lights. I then tried an Oxford trickle charger and it showed the red warning signal. Not even I can get plugging it in wrong so assumed it means battery too discharged to recover

    I'm away from home this week but will roll up the sleeves and investigate further at the weekend.

  4. #14

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    Quote Originally Posted by Bonners View Post
    Kaz, yes there is an immobiliser fitted. Lights flashed but thankfully no alarm when I connected her to the donor car/battery. Will be ear plug armed when I reconnect for sure.

    As I recall the optimate seemed to show no progress via the lights. I then tried an Oxford trickle charger and it showed the red warning signal. Not even I can get plugging it in wrong so assumed it means battery too discharged to recover

    I'm away from home this week but will roll up the sleeves and investigate further at the weekend.
    If you have an immobilizer installed and you didn't even get a click from the starter when you had the jumper cables connected to the other car, I would be suspect that something is up with the immobilizer and it is preventing the starter motor circuit from operating. When you use jumper cables to connect the NSX to another car, try briefly turning the headlights (or the emergency flashers) on the NSX on. They should work fine off of the other car's electrical system. If the headlights won't come on then there is something wrong with the NSX electrical system or you are not doing the jump process correctly. Even with a dead battery, when the NSX is connected to another vehicle you should be able to engage the starter and the motor should run. Once the engine is running, it is theoretically possible to disconnect from the other car and run on just the alternator; but, don't push your luck with that.

    If the charger is giving you a warning light I would treat the battery as 'time to recycle'.

  5. #15

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    Quote Originally Posted by Old guy View Post
    If you have an immobilizer installed and you didn't even get a click from the starter when you had the jumper cables connected to the other car, I would be suspect that something is up with the immobilizer and it is preventing the starter motor circuit from operating. When you use jumper cables to connect the NSX to another car, try briefly turning the headlights (or the emergency flashers) on the NSX on. They should work fine off of the other car's electrical system. If the headlights won't come on then there is something wrong with the NSX electrical system or you are not doing the jump process correctly. Even with a dead battery, when the NSX is connected to another vehicle you should be able to engage the starter and the motor should run. Once the engine is running, it is theoretically possible to disconnect from the other car and run on just the alternator; but, don't push your luck with that.

    If the charger is giving you a warning light I would treat the battery as 'time to recycle'.
    Gotcha, thanks very much for the help, something to do at the weekend....again.

  6. #16
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    I don't know how good the spare wheel holder/brace is as the GND point when you tried jump starting last time.

    In fact, one could accidentally create short circuit by jump starting at the battery especially when the spare wheel holder is in one's way.

    Also, seen many NSX with its battery holder bracket in the wrong orientation that the battery positive cable clamp is too close to the metal holder bracket.

    The bracket is coated from the factory but by now, most likely peeled off and the metal exposed.

    You can't even crank the engine so not directly related but just double check that the 120A fuse inside the same main fuse box in the video/photo below is not blown.

    If short circuited or reverse voltage applied, it will blow.







    Can you access the Engine (Eng) bay?

    In order to prevent the short circuit, there is a proper jump start terminal there on our NSX.

    Also, the starter is at the Eng bay so this is the shortest circuit length.

    Very old video but provides you with some idea.









    You can also use that location for the battery conditioner.

    Positive cable at the +B jump start terminal inside the main fuse box and the negative side at the intake manifold.

    Depending on the spec of the TH body, the shape of the GND point on the intake manifold is different but you should see negative/minus [ - ] marking nearby.









    If not heavily corroded, you can also use the metal tube of the brake booster vacuum line as the GND point.




    On my NSX, I wanted the permanent installation for the battery conditioner so wired up in a way to be able to connect at the battery or at the jump start terminal inside the Eng bay.

    This will allow me selecting the connection port depending on how I park the car and keep the security/immobiliser armed.

    In order to prevent me from moving the car without first disconnecting the battery conditioner, I just cover the shift knob with a glove and big notice board at the steering wheel.




    Next time when jump starting, keep eye on the volt gauge.

    Turn IGSW into P2 ON, just one position before the cranking.

    If the volt gauge doesn't move, you haven't connected the donor electrical power supply properly or you have other issues.

    You should see about 12V or above depending on the power source of the jump starter.


    Turn IGSW to P3 START (cranking).

    Normally, you would see about 10V even during cranking and must hold at least 8V in order to fireup the engine.

    If you saw voltage at P2 but no cranking at all (not even slow cranking) at P3, something is preventing the starter circuit.

    If slow cranking and no fireup, something is consuming the energy of the donor power source.


    Kaz
    Last edited by Kaz-kzukNA1; 16-03-2022 at 01:34 PM. Reason: extra info

  7. #17

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    Bloody brilliant Kaz, it's precisely an idiots guide that I need to fault find. Thanks so much.

    I did find an old thread on the forum that talked about it being better to jump start via the engine bay but then someone said they'd done it many times direct from battery. Given the "proper" way requires me pushing the car out the garage, and back in again if I am unsuccessful, I opted for popping the bonnet (front) instead. I have an inkling a may have popped a fuse tbh. Consumable and easily replaceable I assume? Spare already hidden away in the fuse box by chance?

    Another dumb question, a Golf R is man enough as a donor right, or X5 a better option?

  8. #18

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    Jumping the car from the jumpstart terminals in the engine compartment is 'better' because it is usually easier. It eliminates the need to remove the spare tire and reach down and try to clip on to the battery terminals. It also has the advantage that if the cable connections at the battery (including the chassis ground) are in bad condition it eliminates that as a factor. If the cable connections in the car are in good condition you can jump start from the battery location without issue.

    a Golf R is man enough as a donor right, or X5 a better option?
    I assume that refers to the source for jumping the NSX? Either car should suffice as long as they both have the original style battery - i.e. you have not installed some tiny lithium ion battery.

    There are a number of fuses that could disable the NSX starter system. These include the big screw in PAL style fuses like shown in Kaz's photo of the engine compartment main fuse box. The #29 50A PAL fuse in the main relay box (up front) will kill the starting system. However, there are other small fuses that can also kill the system. If the car won't start using the jump cables start turning on stuff (headlights etc) to find out what works while it is connected to the other car. That may give you a clue where to start looking.

  9. #19

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    Thanks oldguy, will try that if I get that far. Problem #1, opening the bloody fuse box.

    It looks like there’s at least 3, perhaps 4 tabs to push in and the one facing the cockpit/firewall, and the one facing across the engine bay (if there is one) look bloody difficult to access. Any tricks or hacks as the kids would say? Thanks.

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