General info & tips


On Tuesday (20/12/2022) we started packing our caravan ready to take to our daughter’s for Christmas. 

As a precaution I decided to check that the heater and hot water were working. 

When I turned on the heating (Truma combi manufactured around 2017/2018) I got an error code W255 H. A look at the manual advised that this suggests a loss of the 12 volt source. 

I took off the top half of the cover to the circuit board and checked the power to the unit and measure 12.8 volts, thus suggesting a different problem.  Until the error code is cleared the heating will not operate,  so another look at the Truma website suggested a reboot. 

This can be done in one of two ways according to the year of manufacture. One method is to disconnect the 12 volt supply and leave it disconnected for about half an hour but on the more recent models there is a reset button,  but to access that you need to remove the lower cover. 

I spoke to a caravan service technician and he said that when the lower cover is removed with the 12 volt supply connected,  there should be a flashing led which goes steady once the board has been reset.  Horror of horrors,  no flashing led but loads of water. 

I spoke to the techy again and he said that he wasn’t surprised about the water and that it would stop the circuit board working.  He said that with a bit of luck if it is dried out carefully it should be alright. I put a fan heater in the caravan on a low heat for 3 hours and when I went back to check,  to my amazement and delight the circuit board was dry and the led illuminated and the error code clear.  It seems that what happened was associated with the rapid change in temperature from -6 degrees on Monday to 14 degrees on Tuesday,  the body of the heater cooled down and then the warmer air caused the condensation to form.

I am offering this advise in case anyone else has a similar problem.  I was surprised that this happened as we keep a dehumidifier in our caravan which runs for about 4 hours every night. 


Some of you maybe aware that for quite a while I have been investigating Lithium Leisure Batteries. The main reason has been, that our caravan heating system which is a Truma system, has a power hungry fan which puts quite a drain on the battery when compared to the water circulation fan of an Alde wet system.

Last year we finally purchased a 100Ah Lithium Iron phosphate battery. We chose the 100Ah battery as that is the largest that we could fit into our battery box.

The company who supplied the battery are based in China and have a number of Lithium Leisure Batteries in their range and several associated accessories such as Lithium Battery Chargers, Solar Panels and Solar Controllers compatible with their Lithium Batteries and Solar Panels, Inverters and the like.

For most caravans, the largest of the batteries that will fit in the standard battery box is a 100Ah battery and the company manufacture 3 batteries to suit differing needs and price bands. The lowest priced 100Ah battery which we currently have is a standard battery with blue tooth connectivity enabling certain features of the battery to be monitored using a Smart phone, such as voltage, charge/discharge rate, capacity and percentage charge and temperature. This retails at around £460.00 to £480.00. They have two other batteries in this size, one of which has a self heating function and retails at around £520.00. The third battery which retails at around £500.00 and is suited to parallel connections.

We have been using our battery since early November of last year and when at the EY Centre bonfire rally, operated for 5 days without requiring any charge and with 40% charge left when the rally closed. We used all of the caravan facilities including the heater and television through that period.

The great benefit of these batteries compared with the lead equivalents is that until the battery is around 95% discharged the voltage does not drop appreciably whereas with many lead acid batteries the voltage drops significantly and at around 60% discharge drops to a point when certain facilities in the caravan start to shut down.

One other benefit that we noted is that the battery weighs only 60% of the weight of our down-rated 85Ah lead acid battery which equates to a few more pairs of shoes for guess who!

Regarding the Self-heating function, this was developed as below 6 degrees centigrade it is more difficult to charge a Lithium Iron Phosphate battery and below 0 degrees I understand that they will not charge, so the self heating function enables the battery to be charged at low ambient temperatures. Once charged, the batteries can discharge to the caravan services at sub-zero temperatures.

I am currently in touch with an agent for the company in China and am looking to negotiate discounts if there is sufficient demand. Please contact me if you are interested in a purchase or obtaining more details to allow you to make an informed decision. You may need to consider changing your battery charger or solar regulator, or purchasing a DC to DC Lithium charger.

Regards  Ron Warner  Contact me on

Refrigerator Problems by Ron Warner

Towards the end of last year  the Dometic refrigerator in our swift caravan started playing up. It had never been the most reliable Caravan refrigerator that we had used, but basically when set to the maximum on gas,  it would not adequately cool things in the freezer part.

There were no warnings to alert us of any problem and when we checked the exhaust,  it was warm and we could faintly hear the gas burning.

When we had the caravan serviced a fortnight ago,  at the end of the service the caravan was given an ‘All clear’ apart from a tyre warning. We asked the service technician whether the fridge was OK and he said that it appeared to be but asked why we were concerned.  We explained the problem and he did a further check and confirmed that everything seemed to be in order and that the freezer part was cooling down   but a check with a fridge thermometer showed that it wasn’t as cool as it should have been after an hour on maximum.

He took off the exhaust cover and inlet cover to the refrigerator and examined the gas flame and was surprised that not all of the jets were supporting a flame. We turned off the refrigerator and he blew the jets out with a compressed air line and then we relit the burner.  This time all of the jets were supporting flames.

It seems that soot from inside the flue drops onto the burner ‘jets’ when towing.

So if you get this problem don’t be fooled into getting a new circuit board until you have had the burner checked to make sure that it is clear of blockages. Ron Warner

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