Solar question

Another vote for Solar4RVs. Expert advice and all the quality gear you could want at very competitive prices.

Lithium batteries and thin, direct stick panels have enabled me to have a system that would have been impossible using older technology because of weight. I'm two years in with the battery technology and it has performed faultlessly.

Skull

Skulldog, can you outline your system?
Keith

Hi Keith,

I have two x 135 w flat direct stick panels feeding into two x 90 ah LiFe Po 4 batteries. I have a battery computer unit that calculates state of charge using a shunt.

The van is a full ensuite 19' Crusader. The system has to run various LEDs, 60 l Waeco fridge, TV, sound system, iPhone, iPad charging etc.

The only 240 v appliance we run is the washing machine and for this I have installed a 700 w inverter.

In terms of performance, I have never seen the SoC below 50 %. And that was after four days of rain in Tassie. Our normal use is down to 85% after a single night and that returns to 100% before midday.

The mains charger remains off even when in caravan parks as it gets enough from the solar system and the manual for the batteries says not to trickle charge them.

The only bit missing from my puzzle is that I don't use the Anderson plug to charge the van batteries from the alternator as I haven't worked out whether there is a need to have some sort of isolator between the alternator and the panels.

I purchased the panels, controller and computer from Solar4RVs and the batteries from Evworks.

When looking at price, they are currently listed at $675 for a 90 ah battery, you need to remember that they weigh half as much, can handle many times more cycles and can be discharged down to 20% SoC without harm.

Now the usual disclaimers -no connection to the firms mentioned. I'm a user not a techo and don't want to be dazzled by the Internet experts.

Hope this helps.

Skull

Thanks Skull. It does indeed help.
That sounds like a very elegantly designed system. As I understand it, your Anderson and your solar can work together, as they will agree on the voltage between themselves. But it's not been easy to find DC-DC chargers for LiPo4 batteries, but Sterling Power now have them - some very big ones too.
Many thanks for your comments.
Keith

Sorry, that's 58 kilos for the battery.
Keith

Keith,

I was typing (below) while you were posting so didn't see your numbers. Strongly agree with your aversion to antisocial gennies, but I think that you can achieve a decent outcome without going to such a big system.

Cheers

John

Keith, I agree with most of your numbers, except the inverter. You will need at least a 2000 watt pure sine inverter, and preferably a transformer based one for off road durability. The cost will be a lot more than $400. Have you tried EV Works, as they were the best value for money when I bought my cells? it is very important to get your charging right, to ensure the life of the battery. Each manufacturer of Lithium has different charging limits, so it is a matter of matching the charging eg MPPT, DCDC, etc so they are all functional.

Thanks Phil
I have not chased down inverters yet and I think the one I looked at was 2Kw with 4Kw peak on eBay. But it did look too cheap to me.
I guess I will need a charger and controller with adjustable output voltage.
The management system that comes with the batteries is a double backstop against overcharging and excessive draw down. But I am a novice at this and really value all of this help. I will look at EV Works as I get closer to buying. Still haven't built the damned camper.
Keith

John,
The inverter will sit right by the batteries and you are right that the cables will be huge (and heavy). I spent a lot of time looking at the 12volt aircon systems that they use in truck prime movers. But, like the Rv rooftop aircons, they cannot offer inverter technology, are a pain to install and end up costing $4,000-$5,000 on their own. And they still leave the basic power supply problem.
The domestic inverter aircons are lighter and more efficient plus are very cheap to buy and maintain.

Rooster is on the money.....

Not sure what state you are in, but I've been away over 200 times and only had approx 2 or 3 nights where it was hot enough to affect your sleep....and I haven't even got a fan.

I'd be spending a fraction of that on some insulation and plenty of ventilation for your build....and setup in the shade !

Hey Gronk,
My wife is going through the hot flushes thing and aircon is apparently not negotiable. I won't stay in caravan parks unless absolutely necessary so a powered site is not negotiable either. Generators are the modern scourge of camp grounds, so they are out too.
So aircon it is.
By the way, a decent "normal" power system with two AGM batteries, 200-300 watts of solar, 12 volt charger, controller, inverter and wiring won't leave much change out of three grand anyway. Plus I'd be buying new AGM batteries every five years or so. I think the big system will pay for itself in about fifty years.
Keith

Running refridge aircon is almost as noisy as a modern gennie.

Yes that is right ,garrycol...nothing worse than a air conditioner going half or some times all the night next door and trying to get some sleep , at least people camping with gennies have usually got them turned off by 9pm or so but not so the aircons in van parks, the attitude of some seems to be we have it we will run it and bad luck for anyone that does not like it. Usually you can not hear much of the noise the aircon is making from the inside of your van but your next door neighbor certainly can.

I agree with both of you.
But a small Fujitsu is just 44dBa at one metre, which is very quiet - about the same as a quiet urban street an night. Even so, I'd camp well away from anyone before turning it on.

Ha ha, my wife is going thru the hot flushes as well.....but she aint getting aircon !!

Bit of a misconception about the lifespan of LiPo batteries....they haven't been around long enough for reliable stats on that.....early reports from USA point to no longer spans than a well looked after AGM..

If you can get an aircon unit that will only use 40A running ( don't forget start up current, which can be up to 6x run current ) and you use it for 8hrs ( 320 a/h ), your batteries are down to approx 20%.....what happens if you wake up to rain ?? You'll need to run the gennie for at least 6+ hrs.. even in ideal sunlight ( you'll have to move the panels during the day ) 800W will take 8hrs, which you'll be lucky to achieve most days.

I know KK do aircon units for their campers, so a look thru their site might give you some ideas !

No batteries equals no aircon and we can get a quick charge of 120 amps or so from the big alternator on the tug to keep body and soul together.

Do you know anyone that gets a constant 120A from an alternator ?

If you can.....there is 3 hrs of run time from the vehicle ??

Sorry to sound pessimistic, but you have a big problem to solve....get it wrong and you have spent a lot of money for nothing !

I have been looking at these alternators for my 200 series. 220 amps claimed at idle. There are quite a few USA suppliers of similar alternators.
http://www.m2kinc.com/pdf/174-brochure.pdf

Thanks Scott
I did mention the Rencool earlier, but not by name. It is very expensive a bugger to install and uses a lot of power.
I have spent the night thinking about the idea of using ice from the fridge to power and aircon and the engineering is starting to make my head hurt.
Keith

http://outdoor.companionbrands.com.au/index.php?p=caty&sid=1407281381&l=

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Thanks for all the replies.
I am still very anti-generator Robin as they give me the heebie jeebies whenever I have to camp near them.
The evaporative coolers are great but aren't so good in high humidity.
I guess I'll keep my options open till the time comes to make a decision next year - in the hope that the equipment will get cheaper, which it seems to be doing all the time. Chassis and air suspension are done, but I am still at the floor and water tank stage of the build and am about to start on the walls. So there's no rush.
If it the camper comes out looking like a home made crappy job, I'll ditch the aircon idea altogether.
Keith

Actually Keith I have been going heavily thru the planning stages myself for a homemade camper thats fits my requirements which are a bit different than most ( I insist on solid axle for stabilty , under 600kg built so no brakes required , steel so I can weld broken things , no gas bottles, no spare wheel - uses car one , and so on).

I will probably use a genny which I have never used before because it will in nett save weight/space.

Critical things that effect comfort were control of air flow over sleeping area with oversize vent fans to reduce noise and limit the uncomfortable time down to less than an hour per day which would eliminate extra cooling.

For me though I need to carry a dirt bike so that makes it extra difficult , as to make it all work I neeed basic covering to be approximately 4mm marine ply with no insulation, and this requires good airflow control because its not like fully enclosed box.

All fun - good luck on your project , I'd like to hear more one day.

Robyn
Like you, I am also using a solid axle, but with Landruiser disks and wheels and a five link air suspension with dual shocks on a 1650 mm track. The solid axle gives you a much higher roll centre than these silly trailing arm things that everyone insists on using these days and is much stronger for the weight.

More interesting. I have decided to use 15mm Polycore for the body over a gal steel chassis. It's a 1mm epoxy glass sheet around a plastic honeycomb sandwich, which is very strong and weighs just 4 Kg per sq metre, with good noise, heat, impact and fire resistance. It's a bugger to work with and you have to do a lot of epoxy fibre-glassing and fairing, plus it's not cheap.

But my camper (if I ever get the damned thing finished) will have a pullout queen bed, hard roof, 33 inch spare, separate shower and toilet, 350 litre water capacity, 70 litre grey water, 220 litre fridge, diesel heating and cooking, internal kitchen and dining for four, plus the big electrical and aircon system - and, God willing and the floods don't rise, should come in at under 1,300 kg.
That's light enough to tow over the Simpson. Do post some progress shots or PM them to me during the build. I'll do the same if you are interested.
Keith
http://www.polycore-australia.com.au/

For the record, I have no relationship with Polycore which may have looked the case in the post above.
Keith

Who cares Keith , its a great product .

Thank you Leisha
That post of yours is breath for fresh air. The naysayers were getting me down a bit.
I already have a 175 amp Anderson plug direct from the alternator and a voltage controlled relay is easy to add.
Can I ask: What batteries and solar panels are you using?
Keith

As on the model number Elisha. I found it on a different website.
Low power and reverse cycle too! Looks like the one to pick over the Fujitsu.
Keith

We have 300Ah @ 24v (Our truck is 24v) and we're using 4 of the LG Neon 300W panels on the roof , with 4 x 100W flexible from Solar4RVs (excellent service from these guys) as the portable panels.

We have no gas or diesel appliances, everything (HWS, induction cooktops, convection oven, AC, etc) is electric and only powered by the Sun.

The reverse cycle functionality works great, although it does use a bit more power. We had a 1c morning in June and the AC averaged 370W to keep the interior a toasty 28c

We've been on the road full time since May and not plugged into 240v since leaving home.

That's fantastic Leisha. Looks like the equivalent of 600AH and 12 volts plus 1600 watts on the roof.
Keith