Late 2010 D40 Dual Battery System

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Foxbat

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Hi Evereyone, I have a late 2010 D40 STX (140KW) and have been having trouble with the electrical system. The alternator output sits a 14.4V when the engine has just been started but after a few minutes of driving, it drops back to 12.1 and stays there most of the time. Every now and then it will go back upto 14.4 for a few minutes and then drops off again back to 12.1. I have done some investigation into the cause including having it back at nissan twice to find out why.
The alternator on these new models is equipped with a sensing arrangement that reduces the alternator output when the computer feels that the battery has had enough charge. The idea is that the alternator load on the engine is reduced and thus reduces the load on the engine somewhat in an effort to increase the fuel efficiency. The problem I have found is that the battery does not charge to anywhere near full enough. My aux battery was charging to 11.5V as it is connected via an isolator which is only 'on' after the start battery received it's recovery charge. Since the alternator then dropped its output voltage to 12.1, the isolator decoupled and no charge was getting to the aux battery.
The FIX,
The alternator has an internal regulator which is what the computer (CAN command line) controls. This is done by turning 'down' the regulator via the alternator input 'green' wire. Simply cut this wire and there you have it. The alternator is now a constant 14.4V output. Well, if you were like me, you would install and electrical plug that will enable you to convert back to standard wiring if necessary. Now I have done it, I will be watching intently over the next few days to make sure I don't let any smoke out.
Hope this helps somebody out.
Regards to all. Foxy.
 
Very good info mate. I was informed that for this reason it is best to run one of those 12v to 12v chargers as your dual battery isolator. Like the ones c tek have or red arc. Battery world informed me that they have had a few navs with problem dual battery kits.
I was aware that a lot of new vehicles have alternators with this operation and it makes sense that a lot of people would be going thru aux batteries without knowing why they are not getting full charge.

But if ya willing to mod the alternator then problem solved too.

There are other advantages to a 12-12v charger but they are exy.
 
Update

Here's a quick update.

All well so far. Initial charge is 14.4. Volts after start and then settles down to 14.1Volts and stays there all day. Am I happy - s#!t yes.:big_smile:
 
The bonus is that 14.4V won't kill a Gel battery if you choose to use one of those as the aux battery, but a means of limiting the charge current would be valuable as Gels don't like being rushed.
 
Gel's

Yes thanks Tony. I am running a Optima Blue spiral cell as my second and then also link it up to the caravan which runs two 90A/H gels. Plenty of power for camps which are kept topped up with two 80Watt solar panels on the roof of the van. I will bw very happy with the set up next time I go travelling.
 
We only have one 100Ah gel in the caravan, it's supported by two solar panels as well providing about 10.5A in full sun. While driving, we invert the incoming power from the car to 240V and this runs the fridge (Waeco 240/12V auto-sensing) and drives a C-Tek MXS-7000 smart charger to keep the battery topped up regardless of the light conditions (if we can, why not!).

The solar panels are brilliant as long as there's plenty of sunshine. We found during winter that it just wasn't enough, despite the fridge not working as hard, and sometimes in heavily grown forests or deep valleys we also used much more than we gained. Nowadays, a Honda Eu20si generator comes along that supplies that C-Tek if we're not going to drive around.

We have a similar setup in our tub to power the Engel 60L - invert the power, drive a charger to charge the 50Ah deep cycle (standard, not gel) in there.

Travel? Love it. Just took the rig to Uluru. Ours was bought late Oct 09, so it's just over a year old and we've clocked 47,000km.
 
Is this just a 2010 model issue? My June 2008 build STX start charging at 14.4 and then settles to around 14 and stays there for ages (I have 2 x 105 aux batteries downstream of a Redarc isolator and a further 120AH battery in my camper).....I've not had any charging problems at all. I do, however, have a C-TeK fitting permanently mounted to all batteries and give them a top up quite often. When I'm out of town for work - for weeks at a time sometimes - I just leave the bit C-Tek hooked up to the main and it deals with all 3 batteries in the car. The camper battery has it's own C-Tek permanently mounted.
 
Is this just a 2010 model issue? My June 2008 build STX start charging at 14.4 and then settles to around 14 and stays there for ages (I have 2 x 105 aux batteries downstream of a Redarc isolator and a further 120AH battery in my camper).....I've not had any charging problems at all. I do, however, have a C-TeK fitting permanently mounted to all batteries and give them a top up quite often. When I'm out of town for work - for weeks at a time sometimes - I just leave the bit C-Tek hooked up to the main and it deals with all 3 batteries in the car. The camper battery has it's own C-Tek permanently mounted.

I believe so Pete22. Nissan advised me that they have just received the information regarding this and that is why when I first took the car to them (Nissan) they stated that all was well but could not explain my problem. After checking the system out, armed with the new info, it definately affects the 2010 STX facelift version.

I checked my aux battery this morning after driving to work and it is now sitting on 13.5 volts which is heaps better than the 11.5 I had before. I recon I have gained about a 70% increase in reserve capacity of battery charge.
 
Should add to the thread title, "alternator wiring mod" and include a pic of the appropriate wire that needs cutting.
I'm sure this thread will help out a lot of forum members in the future.
 
Hey TAC,

Unless anyone else can shed any light, I believe it is the 2010 series 4 STX's only. Who knows what the 550 NAV will have. So far I have had no issues with mine since modding about two weeks ago. It appears to be running like a 'normal' 12 volt system should.

When I get the time I will add the details and pictures into the 'D40 modding section'. Bit busy at the moment though.

Regards
 
Hi Guys
i too have a "series 4" brand new, swapped over my surepower isolator and fridge from my d22 and hitched up the caravan, headed off to Sydney. only trouble is the fridge wont stay running, although it runs after just starting the car.
i guess i have the same problem.
i also have my two 100amp batteys in the camper connected too the second battery, to keep the fridge in the van running on long "playground" stops forr the kids.
my question has to be can the FIX really be this simple??
i may do what you have done but run a wire to a switch in the car so i can test it?
can you give us an update on yours.?
was this a "memo" to all Nissan dealers?
Should i bother to ask or just do it?
lots of questions i know sorry!!
Nick
 
Update on the post 2010 "green wire cut" I've been running it now for 6 months and all is well, before the mod my Redarc isolator wouldnt even connect the 2 batteries let alone charge, cut the wire and it acts just like it should. Has had no ill effects on the factory battery etc. I thought about putting a switch on this wire but haven't bothered, will just leave it permenently like it.
 
ALTERNATOR Mod

Just to allay any fears you guys may have. I am still running my alternator with the green wire disconnected. No fault codes and no problems. The car gets it regular, albeit expensive, services and no issues have cropped up at all. I didn't expect that it would and I am glad to hear that it has helped someone else out.:rock:

Cheers.


Foxy
 
Does this affect other models ?

Hi guys,
I'm just about to add some charging infrastructure to my 2011 D22 and thought I'd check if you know whether or not I'll run into the same issues as discussed here ?

Thanks heaps,
Paul
 
prob will mate, most new cars have this problem. I just fitted a 40amp redarc 12v-12v charger to mine, cost $425 and acts as an isolator as well.

If you cut the wire, you still need some sort of solenoid, the redarc one which is most popular is around $150.

I have a redarc solenoid that I paid $170 for plus fitting that I will sell for $90, had it installed for less than 2 weeks before I changed to the charger

pm me if interested
 
more questions

Thanks Jason, I may well be interested in the next couple of weeks if you still have it.

So can I just run an isolator to protect my main battery, from the output of the isolator power a DC-DC charger, then from the DC-DC charger's output run long cable to the towbar and terminate in an Anderson plug to be used for charging the battery in my camper trailer ?

And will a CTek DC-DC charger (not sure what model I need) intelligently charge whatever battery I have in the camper, regardless of it's state (apart from dead !) ?

Thanks for the help guys.
 
Oops

Actually I think I got that the wrong way around.

Connect isolator to main battery so it doesn't discharge. From the isolator output run (via a fuse) long heavy cable to the towbar terminating in an Anderson plug. On the van have an Anderson plug at the tow connection, wired to the DC input of a DC-DC charger inside the van, whose outputs connect to the van battery.

Does that sound OK ? And with a DC-DC charger I don't have to worry about having the right type of battery as it will auto-sense and charge correctly ?

Cheers
 
It should do.
I took the cheapest way out and and went for the Super Cheap Autos DC-DC charger only charges at 10 amps. max. but does sense any type of Bat. Use a Century marine pro 720 (100AH) with a small Engle fridge and it seems to keep up although it's only used for overnight and weekenders. So far so good.
 

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