Using a generator/ electrical component protection

[Anseo]

A reply that Parksy made in a comment earlier today gave me reason to ask the following (cheers Parksy B) ).

If using a non sine wave petrol generator (2 stroke or 4 stroke), can I obviate any damge to any and all installed caravan electrical components?

My thought being:
Hook up the generator to the battery direct as opposed to hooking up the caravan to the generator via an EHU connector cable.

Would generator direct to battery connection smooth out any electrical surges etc. ?

John

 

[Woodentop]

I am confused. Do you have a generator with a 12V output, or do you mean you have a 240V generator and a charger of some sort to charge the battery?
Generally speaking a generator will provide stable-ish output but they are prone to spikes and other things and the output voltage will vary with generator speed (not that that is too much of a problem.) Certainly the gen output will be good enough to drive a charger to charge the battery assuming a 240V supply.
However the spikes from the gen can be quite large and could damage anything electronic within the caravan from the 12V caravan PSU/charger to your phone/tablet/laptop chargers to your TV.
An invertor generator as with yours will generate an internal voltage which may or may not be 240V which then drives a pure sine wave invertor to give you a true, stable, and most of all clean 240V output.
I know what I would do. Oh, and modern gens especially the Honda 400W inverter units (of which I have experience) are amazingly quiet.

 

[Damian]

Non sine wave generators are very prone to large spikes and need very regular maintenance, with 2 strokes being the worst.

Most generators do have a 12v output which can be used to charge a battery but it is always recommended that the battery is charged alone, in case of problems with the genny.

Depending on what you want to power dictates what size genny you would need, and from my own usage to operate the mains in most conditions you would need at least a 2KW unit, and pure sine wave output, but a bigger one if you have the newer 3Kw heaters.

 

[ProfJohnL]

A reply that Parksy made in a comment earlier today gave me reason to ask the following (cheers Parksy B) ).

If using a non sine wave petrol generator (2 stroke or 4 stroke), can I obviate any damge to any and all installed caravan electrical components?

My thought being:
Hook up the generator to the battery direct as opposed to hooking up the caravan to the generator via an EHU connector cable.

Would generator direct to battery connection smooth out any electrical surges etc. ?

John

With such a wide array of different models and manufactures, and in particular the plethora of cheap models and the many blatant copies of well respected makes, many of which are very poor imitations in terms of reliability and performance, one has to err on the side of caution.

As Damian has suggested the 12V outputs are principally for charging an isolated battery. On several I have seen the 12V output is also very limited current wise, so you would not get the full power capability of the generators 230V out put, so you might be left wanting. Whilst a battery in good condition would filter most of the electrical rubbish these things can produce, there is another problem in that the 12V charging has no smart control, so it could and probably would damage a battery if left on charge for too long.

Not withstanding the antisocial nature of generators if you are on a regular caravan site, small portable generators are very inefficient, and costly to run, It might make more sense to look at solar panels.

If generators are the only solution for your needs, then save up and go for good quality 4 stroke inverter generator.

 

[Guzzilazz]

A reply that Parksy made in a comment earlier today gave me reason to ask the following (cheers Parksy B) ).

If using a non sine wave petrol generator (2 stroke or 4 stroke), can I obviate any damge to any and all installed caravan electrical components?

My thought being:
Hook up the generator to the battery direct as opposed to hooking up the caravan to the generator via an EHU connector cable.

Would generator direct to battery connection smooth out any electrical surges etc. ?

John

I'm adding to this because I don't think the other replies directly address your question.

Firstly, the "pure sine wave" question ONLY applies to alternating current, i.e. 230v Mains voltage... Grid provided current (i.e. EHU) is a pretty pure sine wave output. Other sources such as generators, or inverters (devices which convert 12v direct current from the battery to 230v alternating current) may not produce this "pure" wave, and it is this output that may cause some devices not to work properly. These are generally things with motors or electronic devices.

A portable generator SHOULD NOT be connected to a 12V battery, the normal connection would be to plug a battery charger into the generator, and for that charger to connect to the battery. With the response you have given I recommend you get someone knowledgeable to discuss in detail with you, and to demonstrate to you on your caravan, how to use a generator.

 

[ProfJohnL]

I'm adding to this because I don't think the other replies directly address your question.

Firstly, the "pure sine wave" question ONLY applies to alternating current, i.e. 230v Mains voltage... Grid provided current (i.e. EHU) is a pretty pure sine wave output. Other sources such as generators, or inverters (devices which convert 12v direct current from the battery to 230v alternating current) may not produce this "pure" wave, and it is this output that may cause some devices not to work properly. These are generally things with motors or electronic devices.

A portable generator SHOULD NOT be connected to a 12V battery, the normal connection would be to plug a battery charger into the generator, and for that charger to connect to the battery. With the response you have given I recommend you get someone knowledgeable to discuss in detail with you, and to demonstrate to you on your caravan, how to use a generator.

I fully agree about the benefits of using a pure sine generator with a inverter controlled output. But your last statement ignores the fact that many generators do have a dedicated 12V DC connection for charging batteries. The question is if it is safe to use on a caravan battery whilst it's connected to the caravan?

I suspect some would be fine but others could be dodgy, and because of that uncertainty it's best not to do it whilst it's connected to the caravan.

Socially and ecologically it's wise to consider alternatives to using a petrol generator.

 

[ProfJohnL]

The idea of using a portable generator for 230V ac powering a caravan has raised its head again.

To put it bluntly small petrol generators are horrendously inefficient and expensive to run. If you look at whole life costs, some alternatives do make a very strong argument and should be considered.

To establish the efficiency of system you need to know the ratio of the input to the output. In the case of a generator we need to know the energy in each unit of fuel, and the amount of useful energy produced at the output of the generator for each unit of energy input.

The most common fuel used in portable generators is petrol, and most of it is purchased at filling station prices.

Petrol (Gasoline) has approximately 8.75 kWh/L (heating power per Litre)

If we consider one of the most popular suitcase generators by Honda the EU22I which according to honda's website

https://www.honda.co.uk/content/dam/local/uk/brochures/industrial/EU22i Generator Launch Leaflet.pdf
It has a fuel tank capacity of 3.6L and a stated runtime of between 8.1H (I pressume no load) to 3.2H (on full load) Honda also claim a 3.6H run time @ 1.6kW continous loading.

At its rated its rated output of 1800W it will consume 3.6L of fuel in 3.2 hours. That is 1.125L per hour. That equates to 8.75kw/L x 1.125 9.84kW of fuel to produce 1.8Kw = 18.2% efficency

But at no load it continues to run and your electrical efficiency is zero! and as most caravans do not consume a constant amount of power due to thermostats turning load on and off the efficiency of the generator will in practice be less and closer to 10%!

To put it another way you are wasting about 82 to 100% of the petrol you are putting into the generator! You are also paying road fuel duty which is not actually applicable for non motive power applications.

But that isnt the end of it, There is of course the purchase cost, other consumables such a engine oil, and the costs of regular servicing required to maintain its efficiency.

To offer a comparison, by law all gas appliances have to be a minimum of 70% efficient, so for things like space heating gas is a far better option than running a generator. Even though gas may cost more per unit its still more cost effective than using generator power.

There are some appliances that cant use gas, things like TV's, so the alternative to a petrol generator would be to use an 12Vdc to 230Vac inverter or choose a 12V operated TV. Recharging the battery is possible using solar panels, which are coming down in price. Over an equivalent time looking at lifetime costs Solar panes will be much cheaper than running a generator, and much more convenient and reliable.