Battery light on after i Inflated my tires?? electrical help please

Submitted: Friday, Jan 04, 2008 at 07:47
ThreadID: 53098 Views:2925 Replies:8 FollowUps:11
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Hi guys --- this problem pertains to my Nissan patrol 4.2 TDI (99 )

spent a nice day at stockton beach yesterday - and before i left -- inflated my tires with my own pump ( which did not miss a beat )

Done one side off my AUX battery ( 2 tires) then the others from my main battery - I had My accessories on ( motor off ) but not ignition on - so the radio was playing.

Well , when i jump back in to leave - start the beast up - Battery light is on - water in fuel filter light is on and Subtank light is on. i dont have a multimeter with me so i home i go ( 2 hour drive ) and made it easily .....( sub tank was not draining and everything was working - even subtank when i did turn it on)

Now , i have just tested all the fuses in the cabin ( all 20 or so , of them ) all the ones under the bonnet - and have continuity through them all --

quick check from earth to alternator + shows only 12.2 v ( exactly the same as battery ( main ) and when i pull the power off the battery - motor cuts out - also indicating i have no power from alternator.... -- now is there a charger relay somewhere that controls the alternator? and i find it hard to believe that just pumping up my tires with my pump would burn out the alternator even when motor was not running -- anyone care to shed some light for me as i don't want this happening to me in a few weeks time when i am out in the middle of nowhere for a week ...



P.s yes in the future i will only use the aux battery for pumping up my tires
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Reply By: Member - Roachie (SA) - Friday, Jan 04, 2008 at 08:02

Friday, Jan 04, 2008 at 08:02
G'day mate,

Quick lesson: the alternator is under no load etc when you are using the batteries with the motor turned off.

I would suggest that you check/replace the regulator. This is the black "box" on the back of the alternator. I had to replace mine a few months ago....various dash lights coming on for no apparent reason.

Will cost you about $60- for a new one and they DO wear out.

Just as an aside, I tend to leave my motor running when I use my compressor.....however, mine is permanently wired to 3rd battery and I have "plumbing" right through vehicle, so I can plug-in the air hose on the bullbar and at the rear of rig too.

Cheers mate

AnswerID: 279692

Reply By: Ozboc - Friday, Jan 04, 2008 at 08:04

Friday, Jan 04, 2008 at 08:04
Just like to add also - before anyone tells me to go to the Nissan Forums -- i have been waiting for permission to post in that forum now for well over 6 months -- i have asked for authority about 7 times now without a single reply --- so i have given up on that site ..... and no i have not been previously banned --- the webmaster just does not bother to read his emails or reply to them ....
AnswerID: 279693

Follow Up By: Member - GeeTee (NT) - Friday, Jan 04, 2008 at 09:19

Friday, Jan 04, 2008 at 09:19
I haver a similar problem. Been waiting since June to be able to post to threads. Sent them a couple of emails to the administrators with no result. Looks like a "closed shop" ! !
FollowupID: 543862

Follow Up By: Member - Roachie (SA) - Friday, Jan 04, 2008 at 09:26

Friday, Jan 04, 2008 at 09:26
Are you blokes referring to this forum:

Patrol4x4 forum

If so, I have seen other new members logging on for the 1st time recently with (apparently) no hassles..... Not sure why you blokes would be having trouble.....

Hope you can get it sorted with the moderator/s soon


FollowupID: 543863

Follow Up By: Member - GeeTee (NT) - Friday, Jan 04, 2008 at 09:37

Friday, Jan 04, 2008 at 09:37
Roachie, I can log on OK, it recognises me and my password but will not allow me to do anything.
FollowupID: 543864

Follow Up By: Ozboc - Friday, Jan 04, 2008 at 09:37

Friday, Jan 04, 2008 at 09:37
yup , same one --- it has been many months and many emails for me now --- just not worth the effort - i had some information to help other users - but could not contribute ....

how many emails and months should it take to get access???


FollowupID: 543865

Follow Up By: Kev & Darkie - Friday, Jan 04, 2008 at 16:27

Friday, Jan 04, 2008 at 16:27
Sounds like a typical Nissan HQ problem, in that they think there is no problem LOL
So why wouldn't the Missan Forum be the same LMAO

Cheers Darkie

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FollowupID: 543912

Reply By: Member - Bucky (VIC) - Friday, Jan 04, 2008 at 08:14

Friday, Jan 04, 2008 at 08:14
You obviously made it home ok , and with lights on everywhere you would be a little pysed off. So would I ...

have you tried to do a cold re-boot,, ie disconnect battery's for at least 1 hr,, hook them up and re-start,,
See what happens !

should work ,, but there are no guarantees of course !
may need to do it overnight !
Hope you get it sorted

Cheers Mate
AnswerID: 279697

Reply By: furph - Friday, Jan 04, 2008 at 08:26

Friday, Jan 04, 2008 at 08:26
Definately an alternator problem, as Roachie suggests the electronic regulator has given up the ghost (although they are very reliable) but could also be the field brushes worn.

However, a very big NO NO is disconnecting the battery with the engine running. This is a sure fire way to destroy the alternator diodes or blow the bum out of the regulator. The alternator, without the battery to provide the voltage reference, can instantly develop voltages in the order of 150/250v.
Have done it myself so learned the hard way!

AnswerID: 279699

Reply By: Mike Harding - Friday, Jan 04, 2008 at 10:25

Friday, Jan 04, 2008 at 10:25

A DC motor (your compressor) is, electrically, an inductor and when you abruptly switch off the current flowing through an inductor the voltage across the inductor rises a lot – maybe 200+ volts – the exact value depends on lots of factors.

One possible issue which may have occurred (although I have never heard a proven case of it happening) is that when you disconnected/switched off the compressor a brief spike found it’s way into the vehicles electronics and has destroyed something, perhaps this was “helped” by the ignition being in the accessory position? Vehicle electronic designers go to a _lot_ of trouble to protect the electronics against spikes but a big enough spike will destroy things.

A “back EMF” diode across the compressor will remove the spike but it would need to be a big-ish diode and would be awkward to fit, I suspect.

Most times, _if_ the compressor is connected directly to the battery, the battery would probably absorb the spike but there are no guarantees…?

Let us know what the final problem is please.

Mike Harding
AnswerID: 279718

Reply By: JTPrado - Friday, Jan 04, 2008 at 11:59

Friday, Jan 04, 2008 at 11:59
You may have got some sparking disconnecting the pump. The spike generated has probably blown one or more diodes in the alternator. Was the pump running while you disconnected it by any chance?

AnswerID: 279730

Follow Up By: Ozboc - Friday, Jan 04, 2008 at 16:20

Friday, Jan 04, 2008 at 16:20
HI there , nope the pump was turned off at the switch before i disconnected it from the battery ( no load )

pump ran fine with little effort

FollowupID: 543910

Follow Up By: Mike Harding - Friday, Jan 04, 2008 at 16:29

Friday, Jan 04, 2008 at 16:29
Turning off at the switch is no different to disconnecting from the battery. There is a period of time, maybe 20mS or more, where the switch contacts are "bouncing" and interrupting the current flow. It is during this time that large voltage spikes _will_ occur.

Mike Harding
FollowupID: 543914

Follow Up By: ob - Friday, Jan 04, 2008 at 18:20

Friday, Jan 04, 2008 at 18:20
Reading your threads you seem to have a pretty good grasp on things electrical. I,m posing this as purely a question. does the battery act as some type of capacitor in the above situation and absorb voltage spikes to a degree?
FollowupID: 543949

Follow Up By: Mike Harding - Friday, Jan 04, 2008 at 18:37

Friday, Jan 04, 2008 at 18:37
Hi ob

Exactly so - the battery looks like a damn big capacitor to spikes and seeks to absorb their energy - whether and/or how well it does so is dependent upon many factors which are too variable to calculate. Most times it'll do the job but... occasionally...?

Mike Harding
FollowupID: 543955

Reply By: Sand Man (SA) - Friday, Jan 04, 2008 at 14:33

Friday, Jan 04, 2008 at 14:33
My guess is a diode or something has gone open circuit in the alternator.

Measure across the primary battery terminals with the engine running and if you are not getting around the 14.1 volt mark, your alternator is sick.

I always run anything extra from the auxiliary battery. After all, that is what it is for. In a dual battery situation, with the ignition off and the engine not running, there is no electrical path back to the alternator or primary battery, as it is "isolated", by the dual battery controller.


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AnswerID: 279758

Follow Up By: Ozboc - Friday, Jan 04, 2008 at 16:24

Friday, Jan 04, 2008 at 16:24
HI there , i have a Redarck isolator , so both batteries are in parallel until the Main ( primary ) battery falls bellow 12.6 v ( or somewhere near that ) only then does the 2 become isolated from each other, so i think there may be a path back to alternator.. --- and vice versa -- second battery will not begin charging untill the main is at full voltage

someone please correct me if i am wrong ....


FollowupID: 543911

Follow Up By: GerryP - Friday, Jan 04, 2008 at 22:21

Friday, Jan 04, 2008 at 22:21
Yes you are correct Ozbloc. To "force" isolation with the Redarc simply put a small toggle islolating switch in the small black wire. Breaking circuit on the black wire will disconnect the circuit connection between the batteries. Note that it does not require a beefy switch.
FollowupID: 544010

Reply By: blown4by - Saturday, Jan 05, 2008 at 18:14

Saturday, Jan 05, 2008 at 18:14
Mate I cannot help you anymore than the others have already suggested but if everyone will beg my indulgence I have to say reading these posts is a damn honest to god pleasure and just illustrates there are some very learned people out there, especially Mike whose posts I have had the pleasure of reading in the past. Just reading this I have learnt heaps and hopefully retain some of it in the memeory bank for future personal use or to assist others.
AnswerID: 279956

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