Powering a inverter off of a D4 alternator

[TerryO]

I seem to remember that D4 alternators are different to earlier alternators and on a D4 they mainly charge the battery when the car is not accelerating or on the throttle, is this correct?

The reason I ask is if that's correct then would that mean there would not be a constant strong enough charge while driving along the highway etc to provide enough power to run a inverter that is powering a 3-way fridge on 240v?

[drivesafe]

Hi Terry and first off, why not just run the 3 way fridge on o 12v.

Next and most inverters have a low shutoff voltage of around 11.0v so it is not a problem powering an inverter from any alternator.

[101RRS]

Firstly why have a 3 way on 240v and not 12v?

Secondly you should not use an inverter when driving as there is a small chance of someone getting zapped with 240v if there is an accident. The so called experts say it cannot happen but it has in the past.

There endeth that lesson now to your question.

Your battery provides a buffer between the alternator and appliance so if the alternator is not generating there required power at a particular time the steady power is being applied by the battery. The same issue would also apply to a compressor fridge on full freeze on a hot day.

Most 3 ways pull about 110-140w so on 12v about 10 amps - not enough to really cause an issue on a running car. Last weekend I travelled from Canberra to Albury with a 3 way running on 12v but didn't realise it was not taking power from the car and was running off the van battery with no charging - no issues temp remained good at about 3 degrees and the ice creams remained frozen in the 3 way freezer. Battery was only about 1/3 down after the run.

For the safety aspect have a think about not using the inverter in a moving vehicle. Most 3 ways will work on 12v ok and can be left for a few hours running without draining a good 12v setup.

Garry

[drivesafe]

Secondly you should not use an inverter when driving as there is a small chance of someone getting zapped with 240v if there is an accident. The so called experts say it cannot happen but it has in the past.

Spot on the money but I now carry Sterling Inverters fitted with RVDs.

This makes them safe for use while driving.

BUT it is still far more efficient to run a 3 way fridge off 12v.

[TerryO]

Thank you for the lesson guys and I am happy to respond to your various comments.

There is no inverter in the D4, it's located approximately 12" away from the fridge and when powered by the D3 it is powered straight off of the ignition via an Anderson plug, so no engine running no power to the inverter.

Why 240 and not 12v? ... If you owned a caravan with a reasonably large 3-way then like the majority of 3-way owners you would know they are hopeless on 12v when driving for long distances especially in summer. Whereas 240 just about holds its own.

Now back to my original question, will the D4 alternator supply enough power to power up a inverter, or does it charge differently to the earlier D3 alternator as I read some where else on here if my memory serves me well.

By the way this is a fairly common mod done by people who do big trips in their caravans and who have 3-ways.

[ytt105]

I never thought I'd disagree with Drivesafe, BUT (certainly old) 3 ways on 12v is a waste of time and dollars.

One of the advantages of using 240 is that most 3 ways work via a thermostat on 240 but not on 12v.

On a 6 week trip through QLD a couple of years ago, I found that 12v did nothing. The fridge temp was the same after lunch as if I'd just turned it off the gas in the morning. And yes it was wired with THICK wire the whole way to the alternator, this was in my P38.

In my van the inverer is mounted to the timber interior so presumably no 240 zappies possible.

YMMV

[drivesafe]

Hi again Terry and I was aware of the location of the inverter, but as Garry has already pointed out, this is just too potentially dangerous a type of set up.

As I also posted, I supply the Sterling inverters fitted with RVDs, and have been supplying these inverters for about 18 months now, for the very reason you have setup up your system but with a twist.

These inverters are fitted with the new safety device, the RVD, and in this case, the RVD-EI units.

The RVD-EI units convert both inverter and generator outputs to a FLOATING circuit.

There is no MEM/EARTH NEUTRAL bond.

Which means there is no way to create an earth return and get yourself, or anyone else, electrocuted.


But the RVDs will also protect against electrocution in wet work areas. Something RCDs can not do.

Now, if you want to set up the bast charging system for your house batteries and run your fridge properly, and all off one single twin supply from the tow vehicle, this is what I supply.

You run up to 25mm2 from the cranking battery, via a solenoid controlled by one of my ABG-FRIDGE units.

The 25mm2 twin goes to the inverter in the van or camper trailer, via a set of 175 amp Anderson Plugs. Or in a motor home
without the need for the Anderson plugs.

The inverter then powers a Promariner battery charger. These chargers have three separate isolated outputs and are available in different charge capacities up to 60 amps.

So if you have a large 3 way fridge and large battery bank ( or lithium house batteries ) you can supply up to 25 amps to a large three way fridge and still have anything from 35 to 50 amps for charging your house batteries.

This system works very well and I have already supplied a couple of these to D4 owners, and they are having no problems running everything in their caravans.

Back to your question, and based on actual installations that I have carried out in D4s, yes it will work.

[stray dingo]

Thanks for the suggestion!
I'm fed up with the 3 way not maintaining coolth on a long drive running on 12v. I'll look at an inverter in the van instead

[drivesafe]

Hi Stray, it’s not just a simple case of fitting an inverter and job done.

If you do set up an inverter, you need to run decent cabling because the thinner the cabling, the higher the current draw of the inverter.

Some of the inverters on the market are so poorly designed that they will pull as much as 90+% more current ( watts ) in than they supply.

To help reduce the voltage drop ( saving watts ) the positive supply needs to come directly from the cranking batteries positive terminal, via a circuit breaker or fuse, and the neg off a good earth point in the engine bay.

But you will also need a means of turning the inverter off when the ignition is turned off otherwise it will very quickly flatten your cranking, because most inverters do not shut down till the supply voltage is 11.0v or lower.

And as pointed out above, this is potentially a dangerous setup and the reason you never hear about it is because the people who work for the different emergency services have continually frowned upon it, on many different forums, when it has been bought up over the years.

[TerryO]

Thanks Drivesafe, regarding power in our van other than the power to the fridge when driving we don't get any power from the tug for anything else including to charge the Vans house battery's. They are charged exclusively from the solar fitted to the roof of the van and with our set up it has never come close to running out.

I was after a convenient and cheap 240v system for the 3-way when driving which I now have and so far it does the trick.