95 Lt Waeco running off 2017 Prado

Kali,

Allan is right.

We use 100 plus Ah a day in our power-hungry setup. Power-wise I can afford that, I'm set up for it - I have 360Ah of lithium and I don't have to worry about the 50% rule that users of lead-acid need to consider.

BUT to get that 100Ah back into the batteries I have 440 watts of solar. 200watts of that is fixed on the roof of the camper and can never be 100% efficient as it cannot track the sun, gets a bit of shade, etc. The other 240 watts are portable.
I manually track the sun with those. If the weather is not perfect for solar but just ok, it may take all day to get the consumed power back, or may not make it at all. If the weather IS perfect, I can get it back by lunchtime. I think this is an indication of the size of solar system you will need.

My DC-DC charger is maxed out at 25 amps, so minimum 4+ hours driving time if I'm doing it from the car. Depending on what your vehicle charging system pumps into your batteries, your mileage may vary.

Attached is an Excel spreadsheet that allows you to work out electrical endurance given daily consumption, battery capacity, solar capacity and other parameters. You can change anything in the yellow cells. Don't change anything else.

I have entered your fridge consumption data and a 120Ah battery with 50% daily max discharge. Now play around with various combinations of battery capacity, panel size and numbers and see what you need to give you a few days endurance.

For the more technically minded, I don't think this tool accounts for charge efficiency and Peukerts, so its results will always be an approximation. It will perhaps be more accurate for lithium (LiFePO4) because Peukerts is irrelevant (a factor of 1.0) and charge efficiency is very high (around 97 to 98%, I believe).

Cheers

Yes I understand that, they were in fact given all the details of the fridge etc & what we needed.
I’m of the belief if they could not 100% offer a solution they should not of taken our $$ for something that is of no use to us. Just said they could not help

In light of your reply, then they should have "supplied" or declined the fitting, unfortunately many dealers are focussed on $$$$$$'s more than and end result which drives away into the distance.
As I mentioned, they may know what a battery does and what a fridge is, but not much else. They act intelligent but it is often an illusion portrayed for effect.

Definitely agree!! Lol

Kali, this very much depends upon how clear you were in expressing your needs. If, indeed, you let them know all the details of the unit and indicated you would want to run it on an ongoing basis. they have an obligation to back up their suggested set-up. They cannot indicate something will do a job it will not do (Consumer Guarantee law). However, this may be down to what information you gave them.

The unit has to be fit for purpose, including any verbal assertions made by any salesperson.

Without prejudice,

Take it with a grain of salt from that author, His early work was based on info he asked other people for and he didn't always understand before he passed on the info on his site. It has changed on the site now but once it read before you design a charging system you have to understand how a cars alternator actually works, and proceeded to describe it in detail, unfortunately the detail was incorrect, since then, about 10 years ago I have discarded anything he writes as possibly being incorrect.

I was researching fridges at the time when I found that, until reading that bit I thought I was learning something but then I asked myself how much faith can I have in any of the advice.

Boils down to if your going to explain to the average guy how something works you want to make sure you actually know what your talking about because people that really do know will read it too.

As to your questions about your system, give it a run for a couple of trips and see how it goes, if it is insufficient then upgrade it, and don't be worried about running the battery to below 50%now and then , the energy is there so use it, theoretically it may not be doing the battery any good in the long term but it wont kill it instantly as many make it sound like, when it starts to let you down then replace it with something bigger.

in my opinion no solar system is perfect, if it is critical that you never run out of power then trade off the weight of a couple of extra batteries for a ex10i or something similar.

Yes I do run solar and i have designed my set up to suit my style of usage and it works better than I thought it would, but that's with reasonably new batteries so I know the efficiency will deteriorate with time.

The same set up used by someone that doesn't do what I do when travelling would be a lot different.

You need to taylor your set up to what you like to do when your out and about using it.

I agree fully with qldcampers assessment but would add that some of the advice given by this self-proclaimed guru is downright dangerous.

I suggest speaking with Phil from solar4rvs. He is a wealth of knowledge and only too happy th share it. His prices are also very reasonable.

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......."the other option to consider is the use of a small 1Kva generator to supplement your power options"...

No Baz, no, NO.
He'll be running it all night within my earshot!

I was thinking the same as you Baz,
Before chasing more battery capacity I would be considering whether such a large fridge is required

Same here, that size fridge should be good for 8 people camping. Its a darn big box to cool and recool.
Recheck your real fridge needs.

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Hang on Kali, now there is a "Jayco" in the picture. What else have you not told us?
Then you refer to a "van". What is that? Is it the Jayco?

What is a "good investment at half the cost of doing the Prado"?

There are a number of people on this forum that can assist you but only if they have the full picture. Otherwise we are just wasting our time.

kali,

Are you thinking of having one battery in the car, the other in the van and then coupling them in parallel via the 12 pin for camping and charging?

If so I forsee problems. If you would like more advice from here a sketch of what you intend would be a great help.

Cheers

Yes we have a Jayco Starcraft which at the moment just has the standard set up (battery & solar). Apparently the standard wiring in the vans is not big enough to run the fridge - so a more cost effective temporary solution is to get a second battery coupled to the standard one in the van & thicker wiring run out to a new 12v plug specifically to run the fridge.
Obviously this isn’t ideal as we still cannot have the fridge in the car etc but it solves our fridge issue whilst free camping. Costing around $700 compared to the $1700-2100 we have been quoted to do the car 2nd battery, charger & solar blanket.

All yours Frank.

Allan, are you intimating discretion is the better part of valour? :-)

Kali,

Your description is not 100% clear to me, so let me summarise what I think you're saying and correct me if I'm wrong.

After you've spent $700 you are going to have
- 2 batteries in the van
- a dedicated 12V outlet in the van for the fridge, with thicker wiring

To me $700 seems a lot of money to supply and install one battery, a fuse, a bit of cabling and an outlet. Is anything else being done?

To be honest, as I understand what you've said to date I don't think the $700 you are about to spend will fix your free camping issues with that fridge for more than one day.

And without spending significant dollars on DC to DC chargers and adequate cabling (the existing is undoubtedly inadequate, but I may be wrong. I hope I am.) I doubt that your batteries, particularly the van batteries, will ever be properly charged from your car, so even a day's driving will not give you enough charge to last a night.

Before anyone can make any further comment we need to get a proper picture of your system after the proposed work has been done.
- What will be the total amp-hours of the two van batteries?
- How many watts of solar do you have?
- What kind of solar regulator is installed? (Make, model, amps rating)
- When you are driving, how is the existing van battery charged? That is, is there a DC to DC charger in the van or is it just wired from the van battery to the car via the trailer plug?
- The car. Others have already raised issues regarding the low voltage output of your vehicle's charging system. These voltages are NOT sufficient to charge either the second battery in your car or the battery(ies) in your van. In my opinion significant $$$ need to be spent to fix these issues.

Cheers

Yes Frank. I have better things to do.

No they did not just isolator
Which we now know is part of the issue

I assume as its a 2017 its then new 2.8ltr unit, I believe Toyota are supposed to install a standard accessory package for this model that consists of a Redarc DCDC unit, as you have paid good money for a system that will not work satisfactorily I would suggest that you take it back to Toyota and get them to install what they should have in the first place.

A thing to be wary of with this model is that the alternator is now ECU controlled though not fully as with some as other vehicle makes. In the Toyota setup the ECU control is presently replicating the previous temperature controlled alternators though tends to charge around .2V-.3V lower than the previous 150, it does not monitor the charge state of the cranking battery.

Users have found that the charge voltage can vary greatly from vehicle to vehicle in the range 13.2V-13.5, with the occasional vehicle getting 13.8V at the same temperature. The 13.2V is quite low and may cause issues with some DCDC chargers, probably not so much of a problem with an under bonnet install but can be problematic with van installs as you may find the charger throttles back or cycles on and off due to low input voltage.

Before you decide on a charger I would work out what the expected current draw is going to be and see what input voltage your likely to get at the charger and them check the charger specs to see what impact the low voltage will have on the chargers output. In your case I would go for a DCDC charger that accepts a low input voltage, is ignition triggered and doesn't perform throttling on low input voltage.

Hi Kali,

Unfortunately lots of cranky old buggers on some forums, you would think with all the travelling they do they would be more laid back and relaxed:)

Kali,

There ARE people here willing to help, and there will be diffing opinions on their advice. Discussions on 12 volt systems are notorious for getting the sparks flying, so to speak :-)

Don't give up!

If you like to progress from my FollowupID: 887441 above, but not here, send me an email at frankp79 at hotmail dot com.

Cheers

Got to love forums, almost always ends in complete confusion for the OP.
The correct advice usually comes up early in the replies if your lucky, from people that actually know the subject, not just look it up on google and repeat it.

Then the arguments start from the google experts arguing with the people that actually know the subject well enough to engineer a good solution and confuse the OP even more.

I have often called bullshit on posts that are blatantly incorrect in electrical sections only to get labeled a troll, I think warning someone about bad advice is more helpful than offering a solution only to get it pulled apart from guys that have only ever worked on their own set up.

One thing I have said repeatedly is before you act on any forum advice especially if it is going to cost $$$ is to ask the poster their qualifications in the field.

I think what has upset people in this thread is the goal posts keep moving, makes it hard.

As frank said, don't give up, but make sure the advice you choose to follow is practical.

Ill give you an example,

With solar charging systems there are a lot of trade offs, cable size, panel size, battery type(not size) regulator type and so on which pretty much only affect the charging time. People that have had no practical experience with them will strive for the impossible 100% efficiency on paper.

The more efficient the system is usually the dearest and is normally not really needed for the individuals requirements. You could try to install the best system in the world but it will probably cost you 3 to 4 times more than the one you actually need, that's where deciding who to listen to becomes important.

Good luck with your decisions and enjoy your travels.

Kali.
No one has been rude or unkind, simply stating things as they are. Depending on your point of view and understanding of the issues you may feel at a loss, and yes Toyota didn't do their best, but everyone else has aimed things in a positive direction for you.

The battery charging and solar and fridges interrelationship is challenging to absrob and understand if you have no prior experience, but we all started at the beginning.

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Now just hang on a bit Kali.

As has been said ... "No-one has been rude or unkind". There have been many attempts to assist you but you have not been co-operative.

For my own part, I responded to your initial post quite promptly with some suggestions and asked you for more information in order to assist further. You did not respond. Then later I asked again for more information on several points. Again no response from you. If you expect to receive assistance you need to be co-operative. By ignoring those who respond and try to assist, it is you who is being rude.

Please do not feel that you are not welcome on this forum. Just be polite and answer questions put to you and express gratitude to those who try to help you.



I for one do not consider that others who are less experienced are in any way inferior. In fact I am highly motivated to help and educate others of either gender. Please reflect on how you responded to forum members who were trying to help you.