A great debate! Hubby vs wife

Lol if we were the arguing type I don't think we would last on the road for nine months together. We will both eventually get round to an idea. It's not about who is right but what is going to be the best system so it is easy on the road.
Cheers

Hi Ryder

What about a larger alternator? The son put one in his Datsun rally car when he put an array of lights across the front. They must be around. That would help with charging the batteries whilst driving.

Phil

The last thing they need is an inverter when they don't know if they will have enough battery power. Also you don't need an inverter to charge phones and cameras, this can be done with 12v, so creating 240v just to do this is inefficient. They need to be able to re-charge 240AH on top of the car battery so access to 240v with a battery charger or some really big solar panels would be required. On the alternator that is worth looking into, every little bit helps.

VK1DX or Phil
A young chap i know has put two alternators on his old Ford to keep the batteries full.

By the look of the one on the Datto, its off a ford truck. A bloody big one.He has 600 watts of driving lights and another 400 watts of high beam. It's got a fuel injected 2.4 to kick the little 1600 body along.

The standard one was useless. We used to take extra batteries until he found a big one to fit.

Phil

Yep I know even if e make modifications along the way!
Thanks.

oops does it look like the debate is swaying my way???
Thanks for that info
Carreen

Definitely need a multi stage charger like a Ctek 25 amp or something similar, Ctek is my preference, can't beat the quality and safety features imo.

I do not know how many times I have posted it. The be-all and end-all is BUY A GENERATOR! No mucking around with batteries, no invertors, no voltage regulators no worrying about looking for sunshine, and, if you buy a reputable brand - no worries. The oonly downside is, if you are driving a diesel (sad-face) you need two lots of fuel.

Brian, That is not the only downside. You forget to mention generators are not allowed in many areas, they are noisy. Otherwise yes they are an essential item permitting.

With all due respect in 99% of the cases your comment is invalid. If you are in a caravan park you just plug into the mains. Elsewhere you can stop on the side of the road for lubch and chargeup. I tended (I am now too old and ill to travel) to bush camp. Far from the madding crowd and away from noisy drunks and screaming children. Caravan parks were for the weekly shower and laundry then I left!!

Not true Brian, there are many camp sites without power that do not permit generators. On top of that many people go camping for the serenity and generators can sometimes spoil that. You might like to Google the subject, very valid old boy..

A case of "Do not confuse me with facts. I have made up my mind"?
The post requested opinions. You have yours. I have mine. I would never, ever have travelled without a generator. 1500 units make little noise and are light and practical. I kept one in the back of my Range Rover and found it very handy. If you really want to attend places where there are squillions of people I fail to see why you leave home. AND THAT is my opinion too.

Gee Brian no need to get wound up. I have 2 x generators . I dont disagree with you, merely pointing out the downsides. Take care..

That was a great read Peter.

I know almost zero about such matters but thanks to you I now know a little more.

I'm going to scan this and add it to my collection of information.

Cheers - Wayne

Thanks Peter,
The Penny just dropped!! When I said a multi stage charger I thought I was meaning the thing connected to the whole system in the car etc. and not a seperate item you only use on 240v. Otherwise what would be the point of that when you are bush camping with no power for a week! You cannot use it to charge the batteries then if they go flat. So what I meant to say is we need a DC-DC charger. By the way what is a BC-DC charger and what does it do?
Thanks, Carreen

welcome Carreen,

DC/DC chargers allow a battery connected to them to reach a higher charging end voltage, thus fully charging them in a reasonable amount of time.

Some popular models can reach a charging rate of 20Ah/hr (max charging current of 20A). Some others claim even higher charging rates.

Whether or not they can sustain this current regardless of ambient temperature, is another question, because the voltage conversion process generates heat.
There are internal temperature sensors which signal to the controlling circuitry to reduce the charging current to protect itself from the effects of high operating temperature.

Remember you may need to find a way to put back 80Ah of charge into your batteries on a daily basis (actually a bit more due to battery inefficiency).
So that would mean you'd have to run the motor at least for 4 hours (4hrs x 20A=80Ah) - this is just a rough estimate because there are other factors.

Now compare this with the alternator:
it is capable of delivering charge at the rate of 60Ah/hr (60A current) or even higher.
The only problem with the alternator is that its voltage isn't quite high enough to get the batteries to 100% state of charge within a reasonable amount of time. So the alternator will quickly push the SOC up to a level of around 80% and from there on things will go really slow.
But it doesn't matter if the batteries only get charged to 80% SOC, as long as you top them up once per week, or fortnight by using a proper multistage mains powered charger.

In a nutshell, the alternator gets the batteries to 80% SOC faster than any DC/DC charger, provided the wiring between alternator and batteries is adequate.
And the battery capacity needs to be sufficiently high as well, in order for them not to be overwhelmed by the high charging current - but your proposed 2x120Ah batteries are good for a charging rate of 60Ah/hr no probs.

One major drawback of DC/DC chargers is that they tend to over-charge the batteries because they generally have difficulties handling the absorption/float switch-over well enough.
A dedicated multistage mains powered charger is easier to use because you can actually observe what's going on by simply connecting a multimeter across your battery during charging, and intervene if necessary (not easily done with a DC/DC charger while cruising).
The above is even more valid for concurrent loads like fridges which can confuse the charger quite easily.

May I suggest again to do the following:
check the alternator voltage if it's in the range between 13.8~14.0V (multimeter across starting battery, motor on fast idle).
Ensure this voltage is actually kept up by checking again after 15 minutes, don't turn off the motor during this 15 minutes wait.
If ok, get a good sized pair of wires like #6 for the connection between starting battery and house batteries. There should be a 80A rated fuse at both ends of the wire connecting the two batteries' positive terminals.

And buy a good robust battery charger, and a pair of 125Ah quality deep cycle AGM batteries - preferably from one and the same dealer who happens to know his stuff. Stops the blame game in the unlikely case something goes wrong.

regards, Peter

Hi Mother Hen,
Isn't a car just a bigger metal box? A lot of fridges are housed in boxes on the camper trailer draw bars aren't they? I will check it out-thanks
Carreen

Hi John,
I get your point but we will be disconnecting the car a bit and in some places we may travel without the car such as up to the Mitchell Plateau. Thanks for the information.
Carreen

Hi Carreen,

Yes, there is a downside! BTW, it's a long hot walk to the Mitchell Plateau without the car!!!!!

Cheers, and have a great trip.

John