Thread: DC-DC charger- which one?

Is it possible to do this via a Nanocom Evo?

Sent from my ThL W8 using AULRO mobile app

Originally Posted by RoverLander

It does this for periods of time. Its part of the fuel saving algorithm that the car uses. The car knows the exact state of charge for the battery. So it may let the battery run down for a while in order to save fuel. When you then coast down a hill it will jump back up to 14.7 and recharge the battery back up.

Its only when we connect electrics directly to the main battery or change the total battery capacity by connecting batteries directly to the main battery does the system have a problem.

I believe that most dealers disable or remove the variable voltage algorithm when they see a second battery system installed in the car.

Peter

Hi Peter and again, the D4 operating voltage should never get that low.

To draw a battery, particularly one as large as the D4 cranking battery, down to 12.2v would require a huge current draw and then to try to RECHARGE the battery while driving, to get it to a state of charge that would maintain the battery in a reasonable condition is an impossibility.

As has already been posted, if your D4 is operating at 12.2v then you have a software problem.

Furthermore there is no way a dealer can override or change the Variable operating voltage in any Land Rover.

And another point, how would connecting an auxiliary battery to the cranking battery be any different to connecting a DC/DC device or a set of driving lights or a 3 way fridge?????????????

Originally Posted by ytt105

Is it possible to do this via a Nanocom Evo?

Hi ytt and at this stage, no, there is no way to charge the Variable Operating Voltage settings.

Im regretting getting involved in this discussion.

Other people seem to understand that some cars will operate at low voltage. This from the TJM web site:
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Variable Voltage Alternators

Some vehicles released in late 2010 onwards with common rail diesel and petrol engines have variable voltage alternators that are on the vehicle CANBUS. These alternators vary output based on driving conditions at the time. The range of voltage can be between 12.3V and 15V For this reason, the alternator may not charge a dual or multi auxilary battery bank at all times, and may apply too high a voltage for the auxliary battery chemistry type at other times.

Known vehicles with this style of alternator - Nissan Navara D40, R51 Pathfinder 2011 onwards V6 Diesel only. Hyundai Santa Fe 2010 +, Range Rover 4 2011 +, Ford Ranger 2011 +, Pajero 2012 +, Mazda BT-50 2011 + and Land Rover Disco 4, Isuzu D-Max 2012.
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I dont know if dealers can override the variable voltage capability. A software upgrade definitely can change variable voltage behaviour.

I believe there is a difference between joining two batteries directly together and letting the car charge them rather than a device drawing a current.

Each to their own. Im happy with my setup. Others are happy with a different approach.

Happy to answer any questions about the DC/DC setup.

Peter

There's a huge difference between "happy with a setup" and having one that is optimum, cost effective etc..

What "works" doesn't mean it's the best..

DC-DC units would have to be one of the best for meeting an unnecessary "need"

Persons who understand Electrical and Electronic theory certainly wouldn't fit one in this application.

For example - there is no way for the vehicle to detect how large a battery bank is that is fitted to a vehicle - only draw of current.

Handy when a Fuel Polariser is also fitted (tic)

Little bit of confusion going on here.
Drivesafe is correct (as expected) related to the battery getting down to 12.2V. Not good at all for maintaining charge state. Thing is the battery doesn't/shouldn't get down to that voltage.
RoverLander and subsequently others stated 'the car' gets down to 12.2V. What I think he meant to state is in relation to the variable voltage alternator where the alternator voltage output can get down to 12.2V.

Hi again Peter and that TJM "info" is vague at best.

For a starter, Variable voltage did not start in 2010, Land Rover had the first 4x4s with Variable Voltage in 2005 and Toyota started in 2008.

Furthermore, only one make had voltages operating down to 12.3v and that was/is the Ford Ranger, and as already pointed out, Ford, for the last 18 months, has given their dealers the option to deactivate their system at the owners request.

While a D4 will not operate down to 12.3v under normal use, in Australia, they will go as high as 15.5v and in the UK, over 16v.

So once again, that info from TJM is not accurate.

Also, can you please explain how two batteries being joined together and the current being drawn by the auxiliary battery is any different from say a set of Fyrlyt driving lights drawing 40 amps from the same system?

Originally Posted by Mungus

Little bit of confusion going on here.
Drivesafe is correct (as expected) related to the battery getting down to 12.2V. Not good at all for maintaining charge state. Thing is the battery doesn't/shouldn't get down to that voltage.
RoverLander and subsequently others stated 'the car' gets down to 12.2V. What I think he meant to state is in relation to the variable voltage alternator where the alternator voltage output can get down to 12.2V.

Hi Mungus and your most of the way there.

There have been numerous instances of D4s have a variable operating voltage but run at a constant 12.2v, and this is not the norm.

Now in every instance I have been involved with, the owners have ended up with flat batteries and have had to charge them with a battery charge.

A fully charged battery will have a loaded voltage of no more than 12.7v and as the load increases, the voltage will drop.

So after fully charging their batteries, they find the operating voltage in their D4 is still 12.2v. But the battery can actually be in a higher state of charge but the load being applied to the battery by everything running in the D4, is causing the battery to drop down to the 12.2v, at which point the alternator then maintains the voltage at 12.2v by providing just enough current to compensate the load being applied to the cranking battery.

The problem is that eventually, the cranking battery is still discharged down to 12.2v but by then, the alternator is providing all the current needed to run the D4.

As posted above, at 12,2v, while there may be no load being applied to the cranking battery ( because the alternator is carrying the load requirements ), 12.2v is not suitable for charging or maintaining a lead acid battery.

Ultimately, the condition of the battery diminishes to the point where it no longer holds a charge for any period of time and hence the continual flat cranking batteries.

Toyota went through this same problem yet their lowest operating voltage was 13.2v but this was still to low to maintain the condition of the battery.

About 15 months back, all new Toyotas came with a minimum operating voltage of 13.6-7v.

This slight increase seems to have improved Toyota battery life and charge condition.

Unlike Land Rovers, the low operating voltage of a Toyota is very easily and economically fixed by installing a $50 Alternator Voltage Booster Fuse, supplied by it's inventor in Melbourne.

With Land Rovers, there is a way to get the alternator to run at higher voltages for longer periods, which results in any battery connected to the system, being recharging in a quicker time than when using any device and this is what my isolators exploit.