Current sensing Variable Voltage alternators in NW...

[skwiz05]

While waiting for my new NW to be delivered, I started investigating a dual Batt system.

Pirhanna tray, Century marine Batt, easy choice.
Then I discover upon advice from ARB, that the new Paj NW has a new fandangled Alternator thats "smart" and stops charge during acceleration and when crank batt is charged, effectively causing the system voltage to potentially drop below 12.7v, thereby turning off any charge to your auxillary batteries. This means it could take ages of driving to pump a charge back into your aux, or that it may never reach fully charged.

Solution; DC-DC charger. Its a Redarc product, (noting nearly everyone has the redarc relay type parrallel system.....).
I found another good system that uses the CTEK Smartpass and D250S charger as well....

Any one with a newer type alternator had issues, or encountered this info before;

And any one got either installed?

[pauld]

I'd test that myself before I believed it. Connect a voltmeter to cig socket & see if it does actually do as they say.
The idea of dropping voltage whilst accelerating is I assume to stop the alternator load on the motor to give max power but IF it was putting out 100AH (unlikely) that is about 1400W, why bother it's not even 1% of the power output of the car. Likely to be far less than 1400W so definitely not worth the trouble. If this is true, surely it is only on heavy or full acceleration & if so not sure it would matter much anyway. Doesn't mean they haven't done it but I would be verifying what Mr ARB said before I parted with $600 of CTek gear.
DC-DC units are good, they have their place - I have one to charge the batteries in the back. The Redarc 40A unit does the job for $400 (40A model).
Also, with a basic isolator the batteries are in parallel after startup, both batteries would need to be charged and drawing less current before the clever alternator dropped the voltage on the basis that the batteries were charged, so no problem on this front - ie. the alternator sees the parallel batteries as 1.

[skwiz05]

I went to Chadstone mitsubishi straight after Mr ARB, and the techs out the back verified that thats what the "new" alternators do....

Its written up in the REDARC brochure as well......

[securegsm]

If you were to keep you low beam lights on while driving, then your main battery is kept under load receiving slow discharge preventing it from being fully topped up at all times. That's approximately 10A payload, not much at all, but will outsmart that smart alternator and will keep it going for as long as you need your aux battery being charged. I see no problem in driving with low beams on as this is perfectly acceptable during day light hours and even enforced in many European cities where traffic conditions are heavier than in Australia. You need only couple of hours to fully charge 100AH aux battery anyway. Just my 2c.

[pauld]

Yep, just did some searching and Hyundai certainly have one. But, it's smart enough to charge 1 battery properly by measuring the current, so no reason why it can't charge 2 when they are in parallel, it doesn't know the difference, same as if your single battery was low on charge. The comment was also that they actually charge the battery better by monitoring the current rather than just flat voltage based charging - this is one of the arguments that DC-DC manufacturers use as a reason for using one of their units.
Fuel savings of 1-2% in Hyundai, $15 per 10,000K in diesel Paj.
The power increase won't be noticeable under acceleration.
I guess only thing to check would be exactly what the voltage drops to in practice, if lower than 12.5 (unlikely) then it may disconnect the isolator until the voltage came back up. I say unlikely because if it did then current would actually be flowing out of the battery to run the car.
Interesting, suspect this will lead to a lot of discussion over time. I think in a lot of ways this negates the argument for a dc-dc for non long cable run installs.

[likatiger]

Hi Guys, this is freeking me out.

I am not very cluey when it comes to vehicle electrics and am in the process of installing my dual battery system that is actually a transfer to my NW from my sold NP.

My system includes a Pirana battery management thingy that, as I understand it, ensures that the crank battery is charged prior to the 2nd.

So does what Skwiz05 has discovered make my management system redundant?

Cheers
Larry

[pauld]

which Pirhana unit is it?

[pauld]

This article suggests that the voltage is dropped to 13.5 based on under bonnet temperature.... http://www.redarc.com.au/news/are_ec...rs_causing_yo/
Only one way to know, get a voltmeter and watch it over a few days to see what happens.

[likatiger]

Thanks Paul, I will look at it's code when I get home and get back to you.

Larry

[sharkcaver]

Didn't know the NW went down that path, but if so, I'm not surprised. I've read a bit about it in the past. I think these are a fix

http://www.ebay.com.au/itm/DUAL-BATTERY-ALTERNATOR-VOLTAGE-BOOSTER-PRADO-HILUX-ABR-/390458558533?pt=AU_Car_Parts_Accessories&hash=item5ae924c845

Not sure if it is suitable for the NW. Drop Derek an email to see what he says on the matter.

[G Potter]

I have an NW with a TJM IBS dual battry system, went on a 14 day holiday witha 110 litre evercool fridge/freezer in freezer mode. The dual battery system worked fine in charging the second battery. Only time th voltage got low was when didnt drive the car for a few days.

Greg

[pauld]

Didn't know the NW went down that path, but if so, I'm not surprised. I've read a bit about it in the past. I think these are a fix

http://www.ebay.com.au/itm/DUAL-BATTERY-ALTERNATOR-VOLTAGE-BOOSTER-PRADO-HILUX-ABR-/390458558533?pt=AU_Car_Parts_Accessories&hash=item5ae924c845

Not sure if it is suitable for the NW. Drop Derek an email to see what he says on the matter.

Very clever, that's obviously the feedback wire to the alternator, put the diode in and drop the feedback voltage by a bit driving the alternator harder.

[skwiz05]

More info here listing known vehicles with Temp Compensating or Variable voltage alternators....

http://www.tjmproducts.com/products/dual-battery-systems

[skwiz05]

Very clever, that's obviously the feedback wire to the alternator, put the diode in and drop the feedback voltage by a bit driving the alternator harder.

Might NOT be a fix too, considering im just learning that the alternator in the 2012 NW is now on the CANBUS......I think that diode fix is more for Temp compensating rather than Variable voltage aternators....

Gee im learning lots fast here......Think im leaning toward the REDARC BCDC1220/IGN as the dual batt system for the 2012 NW.....

[skwiz05]

And the issue is popping up on other car brand forums as well, with the Variable voltage alternators: below is an interesting description of whats happening to someone...

"just a follow up on my low alternator voltage output. After posting on this forum and searching google i can say my alternator i functioning as designed (not as i would like it though). just a bit more info on what it does, on start up 14.5 v, stays there until engine has some temp then varies between 12.02 to 13.0 v whilst driving, if you remove your foot from acc pedal volts will jump to 14.5 until you touch acc pedal again then volts start to drop again. Alternator output is controlled by the ECU , and is dependant on engine load (not electrical load) eg no load on engine, coasting down hill, full charge to batt. Problems this causes on my car, very poor headlights, dual battery solenoid will only open for a very short time, so after a 5 hour drive my 2nd battery in camper trailer wil be nearly flat running 3 way fridge as it would have received very little charge. Solution to the problem is described in the link to the nav forum, which is to cut the GREEN wire going into the alternator, which i did, problem now FIXED, voltage now sits on 14.4 plus or minus 0.2 all the time(have not checked with camper on yet).My mate has a series 4 st and his car sits on 14.2 all the time, nissan tells me his car is built in Thailand (STLs in spain) and is different to mine. New prados have a similar problem but fixed by replacing a fuse with a diode. If you do this mod DO NOT cut wire near the alternator as it is in an awkward spot, the wire comes up the loom which comes up the front of the engine and is very easy to access. I will post back if i have any problems in the future relating to this modification. Please note this is a problem ONLY APPLYING TO SERIES 4 pathy and navara" ....