21/12/2021
The global drive to reduce CO2 and other emissions is proving a powerful incentive for industries to switch to electric solutions for their power needs. Of course, there is an assumption that most of that electricity will be from clean sources. The truth is that we’re still some way from that goal but we are getting there: here are three caravans that rely on electricity for habitation or propulsion
Terry Owen
In the EU for example, in 2019, according to Eurostat, renewable energy sources made up 34 % of gross electricity consumption in the EU-27. Of course, this figure will include some bio fuels, such as wood chip, but it is growing year by year. Indeed, it’s more than doubled since 2004 and the EU could well meet its target of net zero carbon emissions by 2050.
Against this backdrop the RV industry is taking a long hard look, both at its products, and the way they are made. The result is that we are beginning to see vehicles that rely solely on electricity for habitation, or propulsion, or both. In the next three articles we look at three very different products, each of which takes a bold step towards that all-electric future.
Knaus’ E.POWER caravans dispense with LPG in favour of a smart electric solution that won’t trip the electrical supply to the pitch. The result is less weight, simpler operation, and less maintenance. It’s perfect for today’s world and the newcomers to our industry, attracted by the Covid induced boom.
Harvok’s full electric caravans take the LPG free solution a step further by dispensing with the pitch supply in favour of solar panels and a large lithium battery bank. It’s an idea that might not work so well in northern Europe but, in the outback of Australia and similar markets to which this product is aimed, it’s a different proposition. For those not convinced there’s even a ‘try before you buy’ option.
Dethleffs E.Home Coco concept caravan takes the biggest step of all by introducing electric propulsion. The idea is to reduce the load on the towcar and so extend its range. This is something that is really important with the all-electric cars that are set to become our future means of transport.
The additional equipment adds some 600 kg to the weight of the caravan although production versions are expected to be lighter. To convince sceptics that the idea is viable, Dethleffs staged a 380 km trial across the Alps and down to Riva on Lake Garda. The caravan was towed with an Audi e-tron and the combination made the journey with power to spare in the batteries of both vehicles. Of course, self-propelled trailers still have to be homologated into law, but Dethleffs’ parent the Erwin Hymer Group is working on that with other interested parties.
With all that battery capacity on board it should be very easy to power the habitation side of the caravan, and even run air conditioning, for that occasional overnight stop. Exciting times ahead!
The big question is whether the market is now ready for the all-electric caravan. Knaus Tabbert certainly thinks so and has launched no less than 13 layouts in two model ranges – the Sport and the Südwind
Much has changed in our industry in the last few years to make the all-electric caravan an attractive proposition. Firstly, more campsites than ever are offering 10 amp or 16-amp hook ups on their pitches, especially in mainland Europe, where most of these caravans are expected to sell. It’s not so long ago that 6 amps was the norm, with 10 amps if you were lucky.
Many of today’s caravanners want all their home comforts whilst away and this has inevitably led to a demand for more power. At the same time campsites have been standardising on the European 16-amp rated CEE17 hook up connection and taking the opportunity to upgrade to 10 amps, if not the full 16. Secondly, weight has become much more of an issue, especially for the increasing numbers of those who passed their driving test after 1st January 1997. They are limited to train weight maximum of 3.5 tonnes and it’s a figure that can easily be reached, especially if you have a heavy towcar. Weight is also a big issue for hybrid and all-electric towcars, many of which are not even homologated for towing. Thirdly, ease of use. Having to maul and change heavy gas bottles can be a positive chore, especially if you have to go a long way for a replacement. Also, the Covid pandemic has attracted many newcomers to our industry and, if we are to keep them, we need to make using a caravan as simple and easy as possible. Eliminating gas goes a good way towards that. Eliminating gas also means that the fridge can be a much lighter (and less expensive) compressor type.
Two models are offered, 98 litres and 150 litres, depending on the available options. The water heater can be simpler, lighter and cheaper too. Knaus’ solution is to use the Truma Therme, although it’s just used in the 230-volt mode, rather than also taking heat from the blown air system. It’s compact, efficient, lightweight and simple – just what the doctor ordered for this type of caravan. Cooking comes courtesy of a two-burner induction hob. Such devices are light, very efficient and easy to clean – perfect for any caravan where 230-volt power is available. With an all-electric caravan there is always a worry that the pitch fuse will be tripped through overloading. Knaus has thought of that one and has a two-pronged solution. The main consumer of electricity in a caravan is normally space heating. However, instead of a conventional heater, Knaus has chosen the Dometic FreshWell 3000, under bunk air conditioning unit, which can be used for both heating and cooling. When used for heating it is particularly efficient, producing nearly three times the energy (2500 watts) it consumes in electricity. This make it especially useful for those situations where the electrical supply may be limited. The heat output can be further boosted to 3000 wats by using the inbuilt 500-watt heater. The FreshWell comes with a remote control making it very easy to operate. The other prong of defence against tripping is the smart energy control system. All you have to do is set the fuse protection in amperes to that given on the pitch. It then ensures that the electrical devices are automatically controlled according to demand and the available power. To this end they may be regulated, prioritised, switched off or added, to keep the current draw within the set limit. With the best of planning there may always be the odd night where you want, or need, to camp without a hook up. Fortunately, Knaus has thought of this and come up with a rather novel solution, albeit it’s a €399 option, and not offered as standard. In partnership with German power tool manufacturer Einhell, Knaus has produced a power package that runs on a 6Ah lithium battery pack from a power tool. When no hook up is available power is fed from the battery into the 12-volt system. Apparently, there is enough power to supply the lighting, water pump and compressor fridge for one night, hence Knaus is referring to it as the ‘one-night stand system’. When power is restored, the battery is automatically recharged. Another option for caravans up to a body length of 5 metres is electric floor heating. This could be a good choice for those wishing to use the caravan in sub-zero temperatures, when the air conditioning unit will struggle to produce any heat. Alternatively, the Truma E-Kit can be specified. This boosts the warm air system courtesy of two 900-watt electric elements.
Conclusion
Removing LPG not only makes for simpler operation and maintenance it creates more space and allows for a greater payload. It’s also very much in tune with today’s drive to reduce CO2 emissions. Knaus could be onto a winner with its E.POWER models. Time will tell.
If you live somewhere like Australia, with its abundance of strong sunshine and opportunities for wild camping, the idea of a solar-powered caravan that needs no LPG makes an awful lot of sense
In this scenario the challenge is to be able to harness and store enough electrical power for all your needs - including cooking, refrigeration, air conditioning, and so on. It’s a challenge that stirred the mind of an Australian caravan engineer who decided to focus on a high-tech battery and solar solution for caravans. His objective was that users should ‘Never compromise on power, comfort and technology again’. As a result, Harvok Co. Ltd was established in 2018 in the Hubei province in China as a joint venture between Australia and China. The resulting Harvok Eco-Factory is both a centre of manufacturing and R&D, and is built to manufacture full electric motorhomes and caravans. The site covers some 130,000 sq m (32 acres) and is operated by Australians to a world class standard. It is one of the largest sino-foreign venture RV manufacturers in China with production capabilities of 2000 plus units per year. As well as Australia, the company is also exploring international markets. Australian customers are served by Harvok Pty Ltd, a subsidiary of Harvok Co. Ltd. that operates from a brand new 3000 sq m warehouse in the Melbourne district of Dandenong South. Interestingly the Chinese factory has a 150-metre-long automated testing line with a rain penetration test, visual inspection and sterilisation system. In addition, 32,000 sq m (8 acres) of green land is set aside for camping trials. It is covered by more than 30 kinds of plants and 200 trees. Plans are also afoot to build a testing ground for road trials - indeed, the company has recently invested some $4m in test facilities. It seems Harvok is determined to find any issues before its user do! For off-road use all touring caravans are built on a rugged steel chassis with an electrophoretic coating to resist corrosion and rust. The suspension is rated at 3.6 tonnes and is coil sprung with twin nitro gas struts and 16-inch mud terrain tyres. An aluminium upper frame provides both strength and rot resistance. The floor is made from a single piece honeycomb composite for rigidity and to avoid rot. As you might expect the roof of the caravan is covered in solar panels. For ultimate toughness these are marine grade flex panels and come as standard with a rating of 1000 watts although up to 2000 watts is possible. In common with many modern cars, the main electrical system runs at 48 volts, to better handle the various power requirements.
This is then transformed into 12 volts or 230 volts as required. The lithium batteries are rated at 300 amp-hours, 48 volts, which gives up to 14.4 kWh of power. This should be enough for most needs, especially if the sun is also shining. (By way of comparison Tesla’s Powerwall 2 home storage system is rated at 13.5 kWh). To turn all that power into a more practical 230 volts, a 3000-watt inverter is fitted. This allows for the use of a water heater, induction hob, refrigerator, washing machine, air conditioning, coffee machine, hair dryer and much more. Being able to use all these appliances whilst off grid, and without a generator, is something of a game changer for off-road caravans. A 1200-watt DC-DC charger is also fitted to give a fast recharge when on the move. It does so by taking power from the towing vehicle’s alternator and feeding it directly to the lithium batteries at a maximum current of 100 amps. Should a mains hook-up be available, for example when back home, a 30-amp multi-stage charger ensures the lithium batteries can be topped up in a gentle way. Two internal layouts are available, each with a length of 19’ 6” (5.8 m). One is a luxury two berth with a front bedroom, end washroom and rear door. The other a family friendly model with a front door and three bunk beds plus washroom at the rear. The power is controlled by a patented Smart Power Management System (SPMS) with a central panel for easy electronic management of things like the zoned lighting and electric awning. The display panel also provides much useful information, such as the state of charge of the lithium batteries and the estimated the number of hours left. You can also see the amount of solar power being produced.
Conclusion
The Harvok full electric caravan is one serious piece of kit for a specialised market segment. Its beefy chassis removes the need for compromise on the weight of things like batteries and solar panels whilst providing a true off-road capability, albeit you need a decent tow vehicle to do the job. As technology advances, we may see this type of power solution appear in more general use, and even be used to propel the vehicle, be it a caravan or motorhome. It will be fascinating to see.
It was a few years in the making but, as previously reported in an Aboutcamp BtoB news item, a Dethleffs electrically powered caravan was successfully towed some 380 km across the Alps by an electrically powered car without recharging either. On reaching the destination, both car and caravan had some reserve in their batteries.
It was at the Caravan Salon Dusseldorf back in 2018 that we first saw the Dethleffs e.home Coco, electrically powered caravan. The idea was to enable caravan trips with electric cars without loss of range. To this end Dethleffs partnered with others in the Erwin Hymer Group and also transmission specialist ZF Friedrichshafen AG.
It is well known that many electric cars are not rated for towing and those that are can suffer significant reductions in range when towing. With electric cars set to become the norm it was clear that something had to be done for those who wanted to tow. The concept of the electrically driven caravan was therefore born.
At the time the considerable extra weight and complication of the e.home Coco over a standard caravan seemed contrary to its goal of assisting the towcar, but the developers were convinced they were on to something. That’s when we first heard of plans for a ‘big test’, towing it over the Alps and down to Lake Garda.
The following year, 2019, the Coco was back at the CSD but with some significant modifications under the floor. The two 40 kWh batteries (more than many all-electric cars) were retained but the motor generators moved inboard and with a slightly lower rating of 29 kW each.
The extra weight over a standard caravan remained at 600 kg. The updated unit was declared ready for the ‘big test’.
The next step was to choose a suitable towcar and, for this, the Audi e-tron was selected. The selected model has a maximum braked trailer weight of 1800 kg and a range of 393 km (WLTP). The route would therefore have been a challenge for the car solo without recharging, let alone towing a caravan. However, Udo Gillich, project manager for the e.home project at ZF, was optimistic: “We are very well prepared and have carried out many representative journeys in advance. Based on our calculations and our experience, it should work.”
With all batteries fully charged the outfit set off from Dethleffs factory in Isny, southern Germany, one early morning in July. Performance details were recorded from around 800 sources and other journey data.
The positive effect of the electrically powered caravan was immediately apparent with acceleration like a solo vehicle, stable cornering due to the low centre of gravity, and excellent straight-line stability. The latter is aided by the fact that the towing linkage remains in tension, even when driving downhill.
Strong headwinds were encountered, putting in doubt the objective of reaching Lake Garda without re-charging. Nevertheless, the team pressed on with speeds up to 84 km/h on the autobahn and an overall average speed of 62.3 km/h.
The Fern pass was reached after 100 km, which represented a little over one quarter of the total distance. At this point the charging status for the e.home caravan was 76.7 per cent and the Audi e-tron 71.2 per cent. By the time the Brenner pass was reached 200 km later, both the caravan and car batteries were still more than 50 percent charged. With just 180 km to go things were looking hopeful.
Six hours and twelve minutes after setting off, and with some and 380 kilometres of demanding alpine driving behind them, the e.home caravan team finally reached the centre of Riva on Lake Garda. Despite the headwinds, this was achieved without the need to recharge, even once. Indeed, there was residual energy in the batteries of both vehicles. Measurements showed that 82 kWh of energy had been consumed by the towing vehicle and 74 kWh by the e.home caravan.
The result represents a clear triumph for Dethleffs and it partners within the Erwin Hymer Group and ZF. According to Dethleffs MD Alexander Leopold “The ranges of the current electric vehicles and the current status of the European charging station infrastructure are designed for solo vehicles and do not take into account the requirements of towing operation, for example with a caravan. Dethleffs has always seen itself as a caravanning pioneer. We have therefore identified the challenges of electromobility early on and – together with our partners – are developing solutions that will make this individual way of travelling possible in the future.”
Stephan von Schuckmann, responsible for electrified drive technologies on the ZF board of management added “The e.home caravan is an attractive application that we support with our experience and our portfolio for the electrification of all vehicle types. This corresponds to our claim: ‘We electrify everything’. In addition, the electric caravan is an application in which we can fully bring to bear our competence for system integration and comprehensive electric drive solutions, to achieve more efficiency and therefore longer ranges.”
Of course, a few hurdles remain to be overcome before the concept can go into production. One of these is the additional weight of the running gear and batteries and Dethleffs plans to reduce this to about 400 kg through smaller batteries and other changes. Another hurdle is the formal recognition in law of the self-propelled trailer for road going use. To this end Erwin Hymer Group has been member of the BEM (Bundesverband für Elektromobilität, or Federal Association for Electro-mobility) since summer 2019. This body has the objective of improving the legal framework for the expansion of electro-mobility in Germany.
Conclusion
The development team have done an amazing job in bringing this concept to fruition. With the internal combustion engine set to be phased out for new cars this could be the only way many of us will be able to tow a caravan.
