This thread is transferred out of a thread by Iana which was initially started as a general discussion on solar panels, addressing aspects of a split system install were taking the thread off topic, so I have moved it to a separate thread. While initially answering a question from Reed, others are of course welcome to join in.
Reed asked "how much energy the split system required in watts?"
The most accurate measure I have is a Victron BMV 700 which I use to track SOC, it displays the "net" energy flow into and out of the battery. I have isolated everything else by killing my solar, and also my 24V to 12V charger then watched the power consumption when I started the air con on a hot day with the van already hot.
Power consumption was being measured in amps at 24V, and went something like the following:
3 to 5 amps for about 1 minute, with a lot of variation in the range. (70 to 120 watts), The fan was running, but I do not believe it had started the compressor.
The current then jumped to about 15 amps then gradually ramped up from there to 38 amps. (900+ watts) The compressor was now running flat out.
It stayed around the 38amps for about 10 minutes, by then the van felt cool, and the power consumption started to drop, again in 5amp increments.
Once running for mayve 30 minutes the power consumption appeared to have bottomed out and was fluctuating between 8 and 13 amps. (about 300W)
after that I turned the solar and the cross charger back on, and it was nice to see current flowing in to the battery again, yes the air con was still running.
If you have been used to having to start a generator to run a roof top unit, this split systems just seem too good to be true.
It is also worth noting that these power consumption figures include the energy required to run the 3,000w LF inverter.
I have 1,200W of solar on the roof, being 3 strings of 4 panels, with each string on its own set of feed cables. Each string has a theoretical output of 6 amps at 68 volts.
The strings are then joined in parallel just before being fed into the charger, thus the theoretical input to the charger is 18 amps at 68 volts.
The charger is a 50A MPPT charger from MPP Solar (Taiwanese company).
I should mention that the panels are 100w light weight semi flexible panels, the total weight including mounts etc would be around 15kg for all 12.
Battery
I still have the standard 12V house battery, which feeds power to lights, pumps, fridge (Vitrifrigo 12v), TV, radio, etc.
The MAIN battery is a 200Ah Lithium (LifePo4) which is actually two 200Ah 12v batteries linked in series.
Each 12V battery is made up from 4 200Ah lithium cells (nominally 3.2v).
How is it used?
All of the solar charge is directed into the 24V system.
There is a 24V to 12V charger keeping the 12V system alive.
The 240V system is fed through a 3,000W LF (low frequency) inverter (huge, and heavy, but good clean output, with high overload tolerance).
How well does it work?
The solar is a bit disappointing, I have seen it get up around 20 amps into the battery, but it is more common to see it around 10.
I only turn the inverter on when I need it (air con, microwave, mashing machine, or a plug in).
A few hot days I have run the air con through the day, and I still typically get to 100% charged between 4pm and 6pm.
I have set my charger to spend all day in bulk charge mode, with a target voltage of 27.3, and as such my cells stay in balance (typically less than 10 mv diff).
I have run the solar for about 4 hours after dark, and in the morning my battery was sitting on 60+% SOC, so I given how the consumption drops off I believe I could run it all night if required.
That particular night I also cooked for about 10 to 15mins on an 1,800W induction cooker.
I do not have any protection against discharging my batteries too far, and I am still learning how far I can push them.
I think it is safe to say I have gone over the top in my specification. But it does work well.
I have run the solar for about 4 hours after dark, and in the morning my battery was sitting on 60+% SOC, so I given how the consumption drops off I believe I could run it all night if required.
A friend of mine has approx 2kW panels on his boat and runs a 2.5 KW (Cooling capacity not energy consumption) inverter split system, he runs it continuously independent of shore power. He is a solar installer and says that once the room cools down the a/c draws only about 400-500 W. He runs a 24v system with a big inverter. We run a 3.5kW inverter a/c on our vessel with a Yamaha EF2400is generator once the boat has cooled, the genny just "ticks over" to run the a/c. The inverter split systems are a huge advance over the older technology with regard to starting and energy consumption. Unfortunately although we have a/c in the Winnebago I haven't purchased a generator yet and solar powering it is not practical in a motor-home due to roof area and the weight of the batteries. I'm waiting for the price of Li batteries to come down, also they have a reputation for catching fire, the most famous case being in the Boeing 777 dream liner aircraft.
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If we are going to be altruistic I want to get something out of it
You are absolutely correct I should have said Air Con rather than solar.
Migra
I am not at the van at the moment, so I can not read information of the energy rating label, but I wil answer your questions as well as I can:
1.It is a standard 240V home split system.
2.It is a Fujitsu 1.5Kw Reverse Cycle Inverter System (chosen because of compressor size).
3.See 2.
4.They have re modelled the Fujitsu web site, and I am having trouble getting the info, but from memory the maximum start current was listed as 6amps, and from memory that was on heating, with cooling being about an amp lower.
5.Fujitsu, it is the smallest reverse cycle split they make.
6.I assume so, it was purchased retail in Australia.
7.Sorry not at the van at the moment. Expect to be able to get this info on the weekend.
John
The panels are the light weight semi flexible ones, each panel generates about 6amps at 17.2 Volts, the same as a normal household panel. I have increased the voltage by linking them in series.
Muskat55, your experience pretty well matches what we are seeing, where the current ramps up gradually, and only stays up while it actually needs to generate significant cooling, then it drops to a very low current requirement when just maintaining the temperature.
You mention a fear of Lithium batteries catching fire, yes that is true for Lithium Polymer (Lipo) batteries, they are very fragile, however the newer Lithium ferrous oxide (LifePo4) batteries are probably the safest batteries on the market. They do not get hot, they do not give of gas, they do not explode, they do not catch fire, but they are slightly less energy dense than their Lipo cousins.
The batteries fitted by Boeing were Lipos, and I believe they have now changed to a different battery, not sure what though.
The new batteries that are coming are Lithium Graphene, and they will be amazing, but do not expect to see them in a usable package for a few years.
Thanks for the information. I had read around 750 W to run a split/level. Have read about those that are 120 V AC (we are in US), 24 and 48 V DC. We could easily run a 750 W for a number of hours every evening. We actually do such with the 1750 W Dometic to cool the main cabin of the 5th wheel to mid-80s (30 C). If we had something that used 43% of the power, it would be absolutely great.
Reed and Elaine
I was interested in a split system, chatted with a guy in a park that had one installed. I would be worried about tubing runs, and also that the unit itself is designed for static installation. How would a split system stand up to road travel?
Ian, there are hundreds, if nt thousands of split systems on vans, fifth wheelers, and motor homes in Australia, and you hear about very few problems.
Regarding plumbing runs, just keep the curves generous, and mount things well.
I can not speak for other people's vans, but I know our rides very smooth. We have left loose items on the kitchen bench (by accident), and they are still where we left them 200k later.
I think a lot of people are in a situation where they have not had the opportunity to install a split, we planned it in right from the start. Even the company who built our van had no qualms about installing it for us, their only concern was that we keep the compressor and the head unit at the same end of the van to avoid having to run the tubing along under the length of the van un protected.
It sounds as if you have time to make a decision, so ask a few people who have experience with splits.
Plendo don't get me wrong, I'm all for the idea, but I have only seen one installation, they'd had no problems with it, the condenser was mounted on rubber isolators, and covered with a canvas cover when on the move.
I wonder if there are any warranty issues. Be interesting to hear from a split system supplier on this.
The caravan manufacturers would not like the idea, the roof mounted unit looks like a self contained unit that even I could install. They would not want everyone wanting a split type which would push up production cost.
It does however get the weight off the roof, gets rid of that offending unit waiting to be wiped off by a low limb. Allows more solar panels and is probably cheaper to run.
My Fujitsu was fitted new when the van was built almost three years ago, full time on the road never missed a beat and strangely enough actually works as an AC should, even in last years heatwave up to 46C. !
Super quiet, we can sleep easily with it running, super efficient due to modern inverter technology. Mine will run easily from a 1 kva Yamaha.
If you look inside a rooftop clunker, you will see a compressor module and a couple of fans, some piping and electrics, look inside a split same basic components.
All things mechanical/electronic can suffer faults at times so why should a split be worse than a rooftop type.
As said so long as good installation practices are adhered to the split if by far the better system.
And as for warranty issues, the warranty in an RV, is yes a grey area, but if mine failed tomorrow I would fit another instantly and still be ahead money wise compared to a rooftop monolith using outdated noisy technology.
I can buy three splits for the cost of one rooftop unit.
As you've probably gathered after having 3 rooftop pieces of junk in previous vans, I hate them with a vengeance, hate 3 way fridges too! the modern technology is here why not use it.
find out from the manufacturer of the a/c, what is the minimum length of the refrigeration pipe work. Some manufacturers stat a min run of 5M.
Regarding Warranty:
Find out from the manufacturer what the warranty will cover, also obtain a copy of the warranty and read before making any purchase....some manufacturers will not cover warranty in a caravan application.
DO NOT RELY ON THE SELLER INFORMATION........it will not be a problem until you have to claim warranty it is then you will find the seller has short term memory and selective hearing.
General:
I would suggest you ask Fujitsu for a electrical specification sheet for the model you have. This should give you the max starting current (for a inverter model it will be very low) and the max run current.
You should also ask what outside temperature is the max run current calculated, normally it will at 35C, ask for the information at the highest temperature tested e.g. 46C
You should ask what is the max outside air on temperature the a/c is design to operate at.
You should ask the seller what indoor temperature would be reached at what outside temperature. e.g. 24C indoor 35C outdoor
I have not included any questions involving humidity conditions.
The cooling capacity is calculated on a indoor DB/WB with a DB/WB design condition, this information should be shown on the manufacturers brochure.
Also check what type of refrigerant is being used in the system...e.g R410a or some are changing to R600.
my opinion most reasons people go to a split system over a rooftop is cost. I understand there are other reasons including structural reasons, not enough space on the roof.
Beware you must be a qualified refrigeration/air conditioning person to install any split system.
Releasing roof space for more solar was a bonus of flitting a split system, certainly not the reason i did it. I did it because I wanted an air conditioner that worked, was quiet, and that could be used with an inverter without crucifying the battery. My experience with prior systems told me that roof top systems did not really meet any of my criteria.
I did try to talk to Air Command to see if they were going to update to inverter technology a number of times over a two year period, and each time they stated that there was " no advantage" in doing so.
I am happy to accept that I will not have warranty on my household air conditioner installed on a mobile platform, even although it was professionally installed. As stated by Banjo if it fails I would replace it tomorrow. I purchased my unit at the beginning of winter, it cost me less than $500, and I saved more than that when I deleted the roof top unit.
I am not worried about maximum loads etc. It works.
