Outer Limits 4x4 Board

Im planning to buy one of these today, as my aux battery just cant keep up with the demand of my Evakool 70L fridge/freezer.
And later this year before Augusts Cape York Adventure, i plan to buy another Engel 40L for food. The drinks can stay in the Evakool.
My aux battery is a Century N70T rated to 75Ah. The fridge goes off on low voltage after about 12hrs running, im stationary longer than this on trips quite frequently. I wanted to buy another battery to put in the system, but it would only take longer to charge both batteries.

Solar looks like the option. I have looked about on ebay, and this seems to be what i need. Unless anyone can school me differently.
Would you buy it?

http://www.ebay.com.au/itm/NEW-120W-Fol ... 336fb1cae8" onclick="window.open(this.href);return false;

I'm no expert but do remember a thread in gen chitchat about the eBay stuff being rubbish. Go a deep cycle dual battery with a higher AH rating and if you are worried about time to recharge get a alternator with a higher output, mine is 180amps vs standard of 85.

stilivn wrote:I'm no expert but do remember a thread in gen chitchat about the eBay stuff being rubbish. Go a deep cycle dual battery with a higher AH rating and if you are worried about time to recharge get a alternator with a higher output, mine is 180amps vs standard of 85.

+1 im looking at a 200ah second battery when I do my car only problem is its a large battery as its mainly used in earthmoving equipment / trucks. But you can get standard n70 sizes up to 150 ah on ebay for a good price too

I would think surely the solar kit would atleast kepp the battery topped up enough. I read a post from a bloke that had actually bought the same kit and he said it was great. But id much rather a couple more positive feedbacks before i bought something like this off Ebay.

Im heading down the High Country 5th March, and i want that trip to be the test trip for the new battery/solar gear. I dont want to get all the way up Cape York and find i still cant keep a fridge running!

Anyone else have any idea? Id rather a solar kit, as the more i discharge a battery, the more it needs to be charged.

stilivn wrote:if you are worried about time to recharge get a alternator with a higher output, mine is 180amps vs standard of 85.

The alternator is unlikely to be the limiting factor in the charge rate for the battery. In most automotive charging systems the batttery is effectively self-regulating - it will only take as much charge current as it wants. A more sophisticated regulator ir more likely to improve the charging time than simply replacing the alternator.

Other notes:
The solar panel, at 17% efficiency, is (IIRC) a middle of the road unit.
You should note that the maximum power (110W to 120W) is at 17V, which is more than a battery can use.
Depending on how the regulator works, you may never be able to achieve maximum power from the panel, even under optimum conditions.
Maximum current out is 7.6A, at short circuit. After regulation, I suspect you would be lucky to achieve 6A into your battery - but this is still more than one fridge will draw, so you would be in front - under ideal conditions.
Depending on where you are, the time of year, and how well you position your panels, you should only rely on the equivalent of 5 to 6 hours of peak output each day (maybe only 4 hours in Victoria in May). So that's somewhere between 24Ah and 36Ah from the panel, and I normally work on something like an Engel using 24Ah per day - if used sensibly. A more expensive regulator (a "Maximum Power Point Tracking" regulator) may be able to improve daily output, but I know little about them - somebody else may be able to provide more information.

I have this exact kit and it works well, with my fridge running I am still in positive charge territory ( 40l engel ). The only thing I would do is to extend the wires to 8m long which allows me to park in the shade and have the panel in the sun.

-Scott- wrote:

stilivn wrote:if you are worried about time to recharge get a alternator with a higher output, mine is 180amps vs standard of 85.

The alternator is unlikely to be the limiting factor in the charge rate for the battery. In most automotive charging systems the batttery is effectively self-regulating - it will only take as much charge current as it wants. A more sophisticated regulator ir more likely to improve the charging time than simply replacing the alternator.

Other notes:
The solar panel, at 17% efficiency, is (IIRC) a middle of the road unit.
You should note that the maximum power (110W to 120W) is at 17V, which is more than a battery can use.
Depending on how the regulator works, you may never be able to achieve maximum power from the panel, even under optimum conditions.
Maximum current out is 7.6A, at short circuit. After regulation, I suspect you would be lucky to achieve 6A into your battery - but this is still more than one fridge will draw, so you would be in front - under ideal conditions.
Depending on where you are, the time of year, and how well you position your panels, you should only rely on the equivalent of 5 to 6 hours of peak output each day (maybe only 4 hours in Victoria in May). So that's somewhere between 24Ah and 36Ah from the panel, and I normally work on something like an Engel using 24Ah per day - if used sensibly. A more expensive regulator (a "Maximum Power Point Tracking" regulator) may be able to improve daily output, but I know little about them - somebody else may be able to provide more information.

Any thoughts on how often you would have to run the car to provide the extra "top up" you might sometimes need? I realise it depends on the weather but what would a sort of average case be - to kick in a few hours' worth of fridge-running power plus recover the power it took to start the motor etc?

chimpboy wrote:Any thoughts on how often you would have to run the car to provide the extra "top up" you might sometimes need? I realise it depends on the weather but what would a sort of average case be - to kick in a few hours' worth of fridge-running power plus recover the power it took to start the motor etc?

That's a bit of a "how long is a piece of string" type question, because there are so many variables involved, as I'm sure you understand.

The system we're looking at here, if well managed, should be able to "hold its own" with a single 40l (ish) Engel (or similar). Under ideal conditions, it should be able to sustain the fridge indefinitely. But a few days of poor weather will quickly create problems.

Personally, I would check the battery voltage levels every day or so, and go for a drive as required. I'd be surprised if a drive was required much more than once a week (good weather, well managed for sun etc), but I can't sit around a standing camp for days on end without going for a drive - so a drive (say 2 hours) every three or four days should be ample. Note that I say drive - just idling for a few hours may not run the alternator fast enough to generate as much current as the battery could take, and I don't believe in sustained idling of a motor anyway.

I know that, with my Autofridge and an 85Ah Full River AGM under the bonnet, I can stand for 3 days in warm weather without the fridge cutting out. Unfortunately, keeping a few GPS units and a PC running off the battery will kill it in under a day.

Does that kinda answer the question?

-Scott- wrote:

chimpboy wrote:Any thoughts on how often you would have to run the car to provide the extra "top up" you might sometimes need? I realise it depends on the weather but what would a sort of average case be - to kick in a few hours' worth of fridge-running power plus recover the power it took to start the motor etc?

That's a bit of a "how long is a piece of string" type question, because there are so many variables involved, as I'm sure you understand.

The system we're looking at here, if well managed, should be able to "hold its own" with a single 40l (ish) Engel (or similar). Under ideal conditions, it should be able to sustain the fridge indefinitely. But a few days of poor weather will quickly create problems.

Personally, I would check the battery voltage levels every day or so, and go for a drive as required. I'd be surprised if a drive was required much more than once a week (good weather, well managed for sun etc), but I can't sit around a standing camp for days on end without going for a drive - so a drive (say 2 hours) every three or four days should be ample. Note that I say drive - just idling for a few hours may not run the alternator fast enough to generate as much current as the battery could take, and I don't believe in sustained idling of a motor anyway.

I know that, with my Autofridge and an 85Ah Full River AGM under the bonnet, I can stand for 3 days in warm weather without the fridge cutting out. Unfortunately, keeping a few GPS units and a PC running off the battery will kill it in under a day.

Does that kinda answer the question?

Yeah pretty well for me it does.
The solar kit will mostly come into play when im on the cape york trip in august or a similar trip, when we will be camping at each stop for 3 or more days. And when on tracks like OTT, and in a convoy, no one wants to drive up and down the track, we want to enjoy the spot we are at. Obviously i have the luxury of being able to run the motor to charge the battery, but for less than $850 im happy to pay it for the big trojan i bought coupled with the solar kit and not have to worry about battery levels or starting the engine daily to only surface charge the battery.

Same here, thanks Scott. I guess what I was thinking, and I think you confirmed it, is that if the solar set up is a bit marginal but not too bad, then it's not that hard to compensate for it with the alternator, at least for some types of camping situation.

I'd go back to the start of the problem, my 70L fridgemate gets 3 full days off my duel battery system before it goes to low power mode, I ahve changed the wiring a bit, got some anderson plugs and thicker wiring instead of that long cigarette plug one that has a bit of voltage drop in it. How many volts are you getting at your second battery aswell? might not be getting a full charge in it.

Last time i checked i think the original lead dropped 0.1v from the ciggy lighter plug to the fridge connection. All my power outlets have 4 or 5mm wiring im certain, i just hooked another one up today with 6mm to it. My power box that goes in my canopy has an anderson plug connection going down to the aux battery with big cable.
My alternator is brand new but standard, just checked it and its throwing out 13.9v at the isolator (Projecta 100a electronic), 13.9v at the aux battery, and 13.9 at my anderson plug connector ready to plug the canopy power box into. To me that is normal.

On our Cape trip I ran a 50 and a 40 litre off a 105ah battery, Phirana duel battery system and the standard alt in a TD42.
Both fridges in thermo bags in the back of the ute, uncovered except when parked I put a piece of air cell insulation over them for shade .
I had no trouble sitting for 2+ days at a time.
Only once did I have trouble and that only came about because voltage was low and I guess both fridges cycled at the exact same time, I'm guessing tho.
I was away for 6 weeks.

Try to keep your fridges full, they work less.

i get two days running my 60 ltr engel and associated fluoros, versalite, and twin fluro optilux in the canopy.
for 850 wouldnt it be worth getting another battery wired in/ cheaper.
i myself use trojan as we discussed before... brilliant.
i myself would go the solar setup, but many people run the triple batteries, and have it set up that you just take it out when the trips done, like these plastic case battery packs, not the jump start type.
and i would go this way, as people are mungrels these days. steal anything especially a solar panel!!.