Electrical issues.

[lotusolly]

Hi all,

I'm hoping somebody might be able to give me a few tips as to where to start looking for a problem.

What I believed to be an issue with bad batteries appears to be something more in depth. As I have mentioned on a different thread my car is stored in a garage without power so I am unable to connect a battery conditioner, which results in the battery often running flat if the car has not been used for a couple of weeks, which I know is not ideal.
Issues started with the battery starting to loose charge after just a couple of days and then only charging to about 9V. After replacing the first battery I found that the battery didn't seem to be charging properly on the car and had the alternator refurbished. All seemed to be ok for a while but then started to have the same issues again with the battery not holding charge. I replaced the battery again expecting the frequent discharge to be the issue but the problem is again reoccurring.

If I jump start from another car it has no problem starting but now if I try and start from a power bank the voltage is being pulled down so far that it does not start.
Took the car out today and a new issue appeared. A couple of times the engine momentarily cut out, all the dash lights come up as if turning the ignition to position 2 and then cleared back to normal! This was literally a split second thing and I was moving on each occasion but I suspect if I had been stationary the engine would have stalled.

Any body have an idea of what the problem might be?

Thanks

Olly

[NZNick]

Main relay?
Battery connecting cable frayed / twisted?

[Mark N]

Hi olly
Have you checked the battery terminals for clean tight connection ? Then I would checked the earth connection from battery to chassis/ body . I'm no expert mind . Then swoop out main relay . As nznick said.

[nicjwin]

If you let the battery run down to flat it probably wont hold a charge for more than a few hours . Can you run a solar battery charger from the roof to the car . It might help a bit or disconnect the battery.

[lotusolly]

Thanks for the comments.
Battery connections and ground cable good.
I haven't changed the main relay and that may explain the momentary shutdowns but I haven't had any issues starting usually associated with relay failure, just low voltage.
I did buy an optimate solar charger/conditioner but this doesn't seem to generate enough power to maintain the battery charge.
I have a vented bonnet on the car which means the battery is located behind the duct making access to the battery a bit more awkward and certainly not something I would want to have to get to every time I use the car. Extending the positive cable with an accessible switch may be an option.
Thanks

Olly

[WhyOne?]

Hi Olly. Sorry to hear you are having problems.

I have a spare main relay kicking about somewhere (fits my 2001 NA2, not sure if these are year specific?) You're more than welcome to borrow it and swap yours out. (I'm away for the weekend but back early next week). Just shout.

[lotusolly]

Hi Olly. Sorry to hear you are having problems.

I have a spare main relay kicking about somewhere (fits my 2001 NA2, not sure if these are year specific?) You're more than welcome to borrow it and swap yours out. (I'm away for the weekend but back early next week). Just shout.
Hi Ian,

Thank you for your kind offer. My feeling at the moment is that something is putting a high draw on the battery but if I can't find an issue I may take you up on that just to eliminate it.

Thanks

Steve

[Pride]

Looking at what the main relay does all points to curing your problems Steve, anyway good luck.

13670

[NSX100]

Hi Ian,

Thank you for your kind offer. My feeling at the moment is that something is putting a high draw on the battery but if I can't find an issue I may take you up on that just to eliminate it.

Thanks

Steve

I too have had this problem with my NSX since purchase nearly 10 years ago. Even the mighty Kaz was unable to source the problem - there are some old threads on my issues. I have replaced the battery several times and found that the only solution was to keep it on a CTEK all the time. If not, the battery will run flat in several weeks. I have had a car electrics speacialist look at it with no luck. Having said that my car sat motionless in the garage for 6 months over the winter on the Ctek and when I fired it up a few weeks ago it started flawlessly on the first turn of the starter.

I would certainly like to know the cause and if there is a solution.

[Kaz-kzukNA1]

Seems like chasing two or even more issues and all related each other.

Because of this, even you replaced/refurbished something, it is soon damaged again or creating another new issue related to the remaining ones by addressing just one thing at a time….

Q1: What is the measured dark current at the moment?

Q2: Have your battery drop load tested. Result?
Probably dead even if you have replaced it. Going through de-sulphation mode may recover it but the damages were already done.
Remember, although people uses the term '12V system', the ordinary lead acid battery with 100% charge would be around 13.0V.
Anything below 12V is like less than 50% charge state.

Q3: When you managed to start the engine and at idle rpm once warmed up, what is the voltage reading at the dash gauge?
Measuring at ACG +B terminal using multimeter would be better but for now, the dash gauge reading is ok.
Should be around 14.5V.

Q4: While keeping eye on the volt gauge, blip TH pedal several times gently to like somewhere 2,500 - 3,000rpm from idle rpm. 800 -> 2,500 -> 800 -> 2,500 -> 800,…..
Everytime when you blip the TH, does the volt gauge fluctuate like more than 0.5V or does the needle stay almost at the same reading?
If staying at steady reading, is it the same as Q3 or slightly higher?

Q5: Put IGSW into P2 ON. Keep eye on the volt gauge and gently wiggle it towards P3 START position but without activating the starter.
Does the volt gauge fluctuate?

Q6: How did you check the GND cable? Did you check the chassis GND point behind the battery case?
You can't check it without removing the battery case first.
Alternatively, you can measure the resistance between battery negative post and GND point inside the eng bay.


There are other things to check but these are at least enough to start with.

Kaz

[lotusolly]

Seems like chasing two or even more issues and all related each other.

Because of this, even you replaced/refurbished something, it is soon damaged again or creating another new issue related to the remaining ones by addressing just one thing at a time….

Q1: What is the measured dark current at the moment?

Q2: Have your battery drop load tested. Result?
Probably dead even if you have replaced it. Going through de-sulphation mode may recover it but the damages were already done.
Remember, although people uses the term '12V system', the ordinary lead acid battery with 100% charge would be around 13.0V.
Anything below 12V is like less than 50% charge state.

Q3: When you managed to start the engine and at idle rpm once warmed up, what is the voltage reading at the dash gauge?
Measuring at ACG +B terminal using multimeter would be better but for now, the dash gauge reading is ok.
Should be around 14.5V.

Q4: While keeping eye on the volt gauge, blip TH pedal several times gently to like somewhere 2,500 - 3,000rpm from idle rpm. 800 -> 2,500 -> 800 -> 2,500 -> 800,…..
Everytime when you blip the TH, does the volt gauge fluctuate like more than 0.5V or does the needle stay almost at the same reading?
If staying at steady reading, is it the same as Q3 or slightly higher?

Q5: Put IGSW into P2 ON. Keep eye on the volt gauge and gently wiggle it towards P3 START position but without activating the starter.
Does the volt gauge fluctuate?

Q6: How did you check the GND cable? Did you check the chassis GND point behind the battery case?
You can't check it without removing the battery case first.
Alternatively, you can measure the resistance between battery negative post and GND point inside the eng bay.


There are other things to check but these are at least enough to start with.

Kaz

Thank you everyone for the tips.

Honda have replaced the battery under warranty. I managed to take the car for a run this afternoon and everything appears to be running fine at the moment. I do still have concerns at the rate batteries have failed recently though. My storage situation has been in place for quite a while but it is only fairly recently that I have had rapid battery failures!


Kaz in response to your questions,

1: I assume by dark current you mean the current draw on the battery with everything off? I have a multimeter with a fork type current measurement but it only reads as low as 0.1A. With the fork around the cable directly behind the battery terminal it is not registering any current draw.


2: Battery was dead and has now been replaced.


3:Voltage at ACG +B terminal is 14.4v and dash gauge is reading just above 14v.


4:Throughout the checks there was no visual fluctuation in the gauge reading.


5:IGSW in P2, (all the dash light are on). As I turn the key towards P3 I reach a dead spot where all the lights go out and nothing happens until I turn a little further and then the starter engages. Wiggling the key I don't get any chattering like a poor connection, it is either P2, the dead spot or starter engaged. Dash voltage gauge stable at 13v in P2, shuts off in the dead spot and comes back to 14v when started but doesn't show any fluctuations other than switching at specific points.


6: GND cable was checked for resistance with a multimeter and visually with the battery removed.


Many thanks


Olly

[Kaz-kzukNA1]

Hi, Olly.

These loop coil style probe on the handheld multimeter is good for measuring AC but not for DC especially the minute current.
You would need really expensive one for accurate DC current measurement.

Still, we are talking about the dark/parasitic/residual current less than 100mA and in the order of 10mA so best if you connect your multimeter inline/series between the battery negative post and the GND cable.

Before doing so, please double check the current rating of your multimeter.
You may blow its fuse if you have stuck closed power window circuit, AMP relay, etc.

If you have aftermarket security devices, it could be much higher but with factory fitted OEM security or immobiliser, you should see somewhere around 50 - 90mA.

Please note that Honda branded security/alarm systems on UK model with Thatcham CAT1, etc are dealer fitted and not from the factory.
Thus, they will increase the current drain.

If over 100mA, you have extra devices and if it's like 0.5A or over 1.0A, you have serious drain issue.
Very likely to be the case on your NSX.


From what you wrote, the ACG rectifier and regulator are fine at this stage.


Separate issue but you should consider replacing the IGSW cable.
When in P2 ON, both IG2 and IG1 are active.

The gauge unit is powered through IG1.
In P3, IG1 stays On but not the IG2.

Therefore, depending on the ABS warning circuit, the ABS light may rest when turning the IGSW towards P3 START but rest of the gauge lights should stay On.






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I have seen people using cheap screw type battery isolation switch (like above photo) installed at the battery negative terminal but personally, not recommended.
The contact current rating is just not enough with these cheap models.
Due to the vibration and the thermal shock, the screw type switch gets slightly loose and repeated process will increase the resistance at the terminal contacts resulting in reduced current flow.
Already seen several NSX struggling to start the engine because of this.





https://www.nsxnet.com/img/parts/img8639_1.gif?rnd=1556306193



https://www.nsxnet.com/img/parts/img8639_2.gif?rnd=1556306193
[All photos courtesy of Mr Toyoizumi at T3TEC, Japan]

You really need the race spec spring/pressure loaded switch with enough contact capacity.
Still, it needs replacing at certain interval but far better than the cheap screw type products.

You can find it through Demon Tweeks, etc.

It is designed to be mounted somewhere away from the battery so easily accessed without being disturbed by the spare wheel, etc.
If you know your local automotive electronics or audio shop, etc, they should have thick wire gauge, huge crimp terminal and the crimping tool so ask them to create the required wires/terminals.
You need to be creative on where to mount the SW.

There are several aftermarket products specifically designed for NSX usage as well.
T3TEC has one but not cheap, though better than killing your battery every few months.


Kaz

[NSXGB]

https://www.nsxnet.com/img/parts/img8639_2.gif?rnd=1556306193
[All photos courtesy of Mr Toyoizumi at T3TEC, Japan]


Kaz

Off topic, but what is the deal with the flexible brake lines on the ABS modulator in the picture Kaz?

[Kaz-kzukNA1]

Brake bias adjuster (twin bore PV) for BBK application.
Supplying the parts for them :).

[The King]

I too have had this problem with my NSX since purchase nearly 10 years ago. Even the mighty Kaz was unable to source the problem - there are some old threads on my issues. I have replaced the battery several times and found that the only solution was to keep it on a CTEK all the time. If not, the battery will run flat in several weeks. I have had a car electrics speacialist look at it with no luck. Having said that my car sat motionless in the garage for 6 months over the winter on the Ctek and when I fired it up a few weeks ago it started flawlessly on the first turn of the starter.

I would certainly like to know the cause and if there is a solution.

I've had my car for 7 or 8 years now. My batteries would go dead in 3 or 4 weeks if not hooked to a battery tender. I just assumed this is normal.

[Kaz-kzukNA1]

Ordinary battery doesn't behave like below but for the ease of understanding, just using the simple math.
JIS 5Hr rating for NSX MT battery capacity is 52AH.
You won’t be able to start the engine if the battery capacity (not the voltage) drops to 70 - 80% and ignore the environment effect such as the temperature.
52AH x 0.7 = 36.4AH

Presuming the dark current is at 50 - 70mA, it will consume about 1.7A/day.
So, 36.4 / 1.7 = about 21days for reaching the limit.

Obviously, this is from fully charged healthy new battery condition so if already in use, it would be shorter.
For the clarification, even with the same total power usage, consuming very small current over many hours is much easier for the battery than taking huge current in short period so in real world, it would be much longer than 21 days but again, for the ease of understanding, we would leave thos characteristic.

Although your remote fob may have 'Honda' or 'Acura' badge/text on it, it could be not factory fitted system.
As mentioned before, the H & P security system on UK NSX or Kenwood, etc system on Acura models are all dealer fitted and not from the factory.
In some cases, I have seen nearly 100mA dark current or even more.

So, if your battery is not new but still in good condition and if the dark current measurement is at about 50 - 70mA, then about 2 weeks would be a good reference for connecting the battery conditioner or not.
If using ordinary battery, please try never let the battery capacity drop to the level you can't start the engine.
Even for just once you had to use jump battery, the damage was done and you would most likely never be able recovering the 100% capacity.


Kaz