Generators – a quick look

Generators – you either love em or hate em, always provoke lively discussions whenever the topic is mentioned.   It isn’t my objective to give an opinion either way on generators simply to point out MY experiences and thoughts.

Let me start out by saying we have a generator.  We have had it for almost 4 years.  We have used it twice.  If nothing else it provides a good backup “just in case” and is reassurance and peace of mind if all else fails.

There are many types of generators with various outputs on the market and getting the right one can be tricky.  There are several factors to be considered when choosing a generator:-

Portable or fixed, Petrol or gas, Pure sine or modified sine, Output, weight, size and noise and of course Price.

Portable or Fixed – this is largely dictated by available space and depth of wallet.  There are benefits to both.  Fixed are normally electric starting, out of sight and can run from either the existing vehicle fuel tank or a separate tank and are securely fixed to the Motorhome.  On the downside they are also the most expensive.  Typically £3 to 4000.

Portable generators can be located in any available cupboard/locker and they have their own built in fuel tank.  They are vulnerable to theft as they are outside the camper when in use – but they are much cheaper – typically between £200 to £1000.

Petrol or Gas – This really is a matter of choice as most generators, fixed or portable can be purchased as petrol, diesel or LPG or converted afterwards.    Many folks claim that running on LPG is quieter than petrol.  Maybe they are right but the difference is minimal. I certainly would need to think of other benefits before deciding to invest in converting to run on LPG if only noise was the benefit.

Pure sine or modified sine – The decision here is more of what you expect your generator to do.  In very simple terms the difference between the two is that pure sine wave generators smooth out any fluctuations in current that is found in modified sine.  Not very technical I know and I’m sure there are better qualified people than me that can come along and get into detail.   If you simply wish to charge the batteries then modified sine will do the job.  Only older appliances such as microwaves may give you problems and if this is the case then a£30-40 will buy a new microwave and cost much less than the difference between modified or pure sine wave generators.   We have a pure sine generator yet have a modified sine Inverter and I always charge my laptop, phone, camera batteries off the inverter.  I think in this day and age most modern appliances can tolerate variations in voltage without a problem.

Output, weight and size – The most important considerations.  At the outset you must have a good idea of what you want to use your generator for.  Here are a few points to consider.  When you start up your generator and switch it on, the first thing that happens in most cases is the fridge-freezer switches over from gas to 240volts.  The on-board charger kicks in and starts to re-charge your batteries at maximum power.  You need to understand how much power these items take, particularly at start-up.  On start-up most appliances take much more power than their stated running requirements so take this into account.   Then you need to add on the power required for each item of equipment you intend to use.

Here are my requirements as an example:

Fridge/Freezer                             200w

Built in charger                             450w

30amp Pro Digital charger          300w

50amp Pro Digital charger          425w

Total minimum Output required  1375w

Now we have a 1600W generator so have a little flexibility and we can also control either the fridge, or Pro Digital chargers.  So by turning off the chargers we could if needed boil a kettle or run our heating system on 1kw setting.

Output is generally related to weight so the greater the output the heavier the generator so make sure you have the available payload.  If payload is an issue then look at ways to minimise the required load – turn the fridge over to gas and don’t try to boil a kettle: switch off non essential 12 volt appliances as they will fool the charger into thinking the batteries are more depleted than they are.

Size – always measure up both the available space and dimensions of any generator you are thinking of buying.  One friend of ours has to keep their genny in the shower cubicle as it won’t fit in any locker – and its diesel – and it smells – and they have to place a mat on the floor to stop it staining the shower tray.

Price is a no brainer but bear in mind that generator prices can and do vary tremendously.  Even with similar models prices can vary by several hundred pounds.  For example a Honda 20EUi can be found new at around £750 on the internet or £1100 at many garden centres.  Our Kipor 2000 pure sine cost just over £275.  I don’t want to get into an argument over reliability and noise levels as its all subjective and controversial.   If you intend to use your genny every day then clearly the better the quality the more longer its likely to last.  However if like us you use it very infrequently then its more cost effective to go for a cheaper model.

Noise – most generator manufacturers publish a decibel rating for their generators and its usually quoted at a 7 mtr distance away from the unit.  many of the quality manufacturers also quote a minimum load output level.  Occasionally some dealers misquote this by quoting the noise level at minimum load to favour the one they want to sell you.  All generators are noisy but there are ways to minimise the noise level in say a crowded area where you may want to keep the neighbours happy.  The biggest effect on a noise level is load.  For example our Kipor will almost double in noise level if we switch on all the chargers or boil a kettle.  Many reputable generators have a throttle control that controls the speed of the engine depending on load.  (usually called auto throttle) these devices do make a big difference.  Cheap generators without throttle control will run at maximum revolutions at all loads and are therefore noisier.   Suitcase type generators are quieter than open frame models.

In my experience generators are not used very often and form part of the “kit” we all carry as its kinda expected.  I know folks who carry a 30kg generator yet only ever stay at sites with EHU yet they know they exceed their maximum payload.  When generators are used they are not always used to best advantage.  For example – most folk buy a generator as a method of re-charging their batteries when camping “off-line”.  One problem here is that vehicle manufacturers tend to fit 14 to 18 amp chargers and even these are not always digital.   Just do the maths – 1x 110ah battery has to supply power for lights, water pump, heating unit, small inverter for phone charging and TV etc. and in winter, excluding LED bulbs, it is easy to use 40 plus amps in a 24hr period.  To fully re-charge the battery will take up to 3 hrs as the charger will reduce output gradually as the battery voltage raises – and you need to do that every day you are off-line.

Answers – well one answer would be to boost your charge rate.  Basic chargers can cost from as little as £15 to over £500 depending on how deep your pockets are.  The advantage is that by recharging at say 45amps ( 18 + 30) then it reduces your generator running time by almost 2hrs.  A big saving.  We had a total charging capacity of 110amps and if there was no sun or light, could re-charge our batteries every three days or so – all 650ah,  sufficiently in around an hour or so.

TIP:  Many generators will also have a 12 volt output that will allow you to charge your leisure batteries at around 8 amps  – if you rely totally on the on-board charger to replenish your batteries then by using this 12 volt outlet you can increase your charging rate by a further 8 amps during the same operation thus reducing the time you need to run the generator.

Another would be to turn off the fridge or switch to gas only before starting the genny as an hour or two without power would not affect the fridge temperature much, particularly in winter.  Remember that the fridge will automatically switch to mains electricity as soon as it detects a supply if its AES fridge.

Conclusion:  Generators can be very useful and have their place in our camping world, but you need to fully understand what you expect it to do and consider if it fits in with your style and they need to be used efficiently.  An extra battery and an invertor with a supplimentary charger can reduce the running time considerably.  The best answer though may be to look at ways on conserving power in the first place.  Converting to Led’s, turning off unnecessary lights, using reading lights instead of roof lights all can seriously reduce your consumption and hence the frequency and time needed to re-charge the batteries.

Just a point on Gas Generators

There are two basic types of gas generator around.  There is the petrol generator with an LPG conversion and there is the pure LPG generator such as the Self Energy EG20.  The former is a cheaper method of running a petrol genny, giving more flexibility.

The EG20 works quite differently from a petrol/gas generator mainly because it is usually fitted underneath the body or in a locker or attached to the chassis where practical.  Its different in that its output is 20amps at 12 volts so no 240 volts.  If you still want to boil a kettle or charge your phone you will need an inverter.  The EG20 can run automatically day or night and starts up when its electronics detect a drop in battery voltage or you can operate it on the manual control and only use it when required.  On automatic it is designed to prevent your battery from getting low in the first place and will keep cutting in and out accordingly.    The EG20 is much quieter than the petrol equivalent.  Its not quiet though.  The EG20 is cheaper than a built in petrol generator but still costs over £2200

For further information see my article on Power Management before making any decision on buying a generator.

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