750W Generator what will it run?

[Gareth111278]

Hi

I've bought a little cheep genni [35 quid!] Does anyone how many watts the 3 way fridge needs in 240volt mode?

i've heard a lot about the quality of the out put of cheep gennys , will the fridge be fussy about this?

I also have a flat panel TV , do we think this will need a better output than a cheep genni will give?

i assume the battery charger won't be fussy?

i guess the water heater will pull more than 750W?

help this is new to me!

Gareth

 

[Rod_5041370]

There is no way that I would plug this generator into the mains input of the caravan.

If your charger is a "switched mode" one, it will almost certainly be damaged as would any of the more delicated devices.

If your fridge is on a seperate mains plug you could run this by connecting it directly to the generator without it being powered via the caravan AC input socket.

These cheapie generators are intended for running power tools such as drills, saws etc.

 

[Damian]

Gareth,

The fridge will want between 125 and 135 watts depending on model.

The water heater needs 850 watts for the Ultrastore heater.

Thats the good news., The rest is bad.

With a cheap generator you "may" get a very fluctuating output which is not healthy for modern technology items such as flat screen TV's and caravan 12v supply modules and chargers.

If you really need a generator, which would only be if you cannot hook up to the mains, you really need to be looking at the type with invertor technology built in which will give a smooth output.

The generator you have , if it has a 12v take off, be ok for charging the leisure battery on its own in emergency situations.

 

[Gareth111278]

Hi

Thought i'd be no good for the delicate stuff. i think i can pull the breaker on the battery charger this should leave just the fridge on line.

I'm now thinking of 12v-240v invertor so i can charge the battery off the 12v output of the genni, then run the TV off the invertor, basicly use the 12v system to damp the current. am i looking a at megga bucks invertor?

Gareth

 

[Damian]

Gareth, why do you even think about generator charging, unless you are not using site hook ups?

This has to be the most expensive way forward , with petrol at over

 

[Gareth111278]

Hi Damian

I'm just wondering what i can run , when we're working on it at its storage location, I'm off to the grand prix with it too, no hook up there, be nice to have cold beer and watch TV!!

I know what you're thinking [gas fridge] never found it that good,I'll start a new thread on that!

So any invertor should be smooth enough? just get one with enough umph?

 

[ProfJohnL]

Hello Gareth,

The small generators are at best only about 10 to 12% efficient at converting fuel to electricity, so it is both noisy and expensive to run.

By comparison, the gas system in your fridge must be at least 70% efficient, so using gas is far more fuel economic and a lot quieter. The same can be said of your heater, and also use gas to boil the kettle.

As for TV's, some of the recent LCD types use a mains plug in converter to bring 230Vac down to 12Vdc. Some TV's (not all) will work happily on the 12V battery so that can reduce your need for a generator.

Several other correspondents have warned about the stability of the generators output. Some equipment in the caravan might not like the wide voltage swings the generator produces especially when some power hunger appliances switch off, the generator may over speed and produce much more than the 260Vac that moat appliances can with stand.

The generator may be suitable for fairly constant loads that don't change much , such as battery charging, but consider that most caravaners can last a full weekend with no problems on a fully charged battery- so you might get away with out needing the generator.

 

[Rich]

If you need a generator look at ones which have an inbuilt inverter which will put out 240 volts but it has a digital sine output so you do not have problems with voltage spikes. Kipor do some which are quite cheap compared to a Honda generator but as they say you get what you pay for.. And I am not sure of how reliable the engines are but I do know a few people who use them for racing and to run digital tyre warmers and they have been OK for a couple of years. They have one which is 1.6 KVa and costs about

 

[JeremyClarksson]

There is a risk to the more delicate equipment but when I have run mine I make sure it is running another load like the water heater, this will help in stabilising the voltage and has the added benefit of making the genny quieter as 2 strokes run smoother under load.

If you do a lot of non EHU sites you could run 2 batteries and charge the 2nd battery with a stand alone charger when running the genny as well.

 

[Gareth111278]

Hi john, i think my TV runs off a 12V transformer so i'll use the fridge on gas and use the genni to top up the 12v battery. The Sky box is 12v anyway, water is gas. so we'll be sorted!

I have the genni already thought it'd be handy to run the boiler at home during power cuts too!

 

[Gareth111278]

There is a risk to the more delicate equipment but when I have run mine I make sure it is running another load like the water heater, this will help in stabilising the voltage and has the added benefit of making the genny quieter as 2 strokes run smoother under load.

If you do a lot of non EHU sites you could run 2 batteries and charge the 2nd battery with a stand alone charger when running the genny as well.

good idea re. having water heater on as a sink load might try that.

 

[ProfJohnL]

'I make sure it is running another load like the water heater'

Doing this will not stabilise the generator, for two reasons, firstly Gareths Generator is a 750W design, and most water heater elements are rates at 600 or 800 Watts. The 600W will mop up most of the available power, and the 800W will overload the generator.

The second reason is, a thermostat switch controls the water heater. As soon as the water reaches the switches setting the switch will open, which will suddenly unload the generator causing the engine to over speed and produce more volts than normal, and with the element switch open there is no stabilisation load on the generator so you are back to square one.

 

[Gareth111278]

'I make sure it is running another load like the water heater'

Doing this will not stabilise the generator, for two reasons, firstly Gareths Generator is a 750W design, and most water heater elements are rates at 600 or 800 Watts. The 600W will mop up most of the available power, and the 800W will overload the generator.

The second reason is, a thermostat switch controls the water heater. As soon as the water reaches the switches setting the switch will open, which will suddenly unload the generator causing the engine to over speed and produce more volts than normal, and with the element switch open there is no stabilisation load on the generator so you are back to square one.

Good point there,

I think i'll keep the genny for emergency topping up of the 12V battery!