Inverter Installation

[Colin_374358138]

Hi,

I'd like to install an inverter into my Bailey Ranger 620/6.

I wondered if anyone has had any experience of this.

I propose to place it behind the battery locker with thick short leads to the 12v supply and then take the output straight 'into' the line that carries the 230v to each of my three sockets in the caravan by means of a simple lighting style junction box.

I'll only switch the inverter on when the caravans not hooked up. All should be well except two things concern me:

1) When hooked up to site mains, the output stage of the inverter will see 230v, although the inverter stage will not be on. Will this fry the inverter ? (of course I could unplug it if needed)

2) When the Caravan is not hooked up and I have switched the inverter 'on' it will take the 12v battery and invert it to a 230 sine / square output. This 230v will be present as planned on the van sockets BUT because its present there, since the whole 230v line is joined together, it will surely be present at the input to the battery charger... therefore the inverter will straight away become maxed out charging the battery its simultaneously draining... if you get my drift... Don't really want to mess about with a switch on the battery charger input if I don't have to.

Cheers, - well done to anyone who has read this to the bottom also.

Colin

 

[Dave_374330759]

Not a clever idea at all. You would need to put a changeover isolating switch between the inverter output and the 240v input to the caravan so that there was no possibility of connecting the AC mains to the inverter output or conversly the inverter output to the AC mains. You would also have to make sure that the inverter output wasn't trying to run the battery charger either.

What size inverter were you thinking of?. You will also have to make sure that anything that got plugged in wasn't higher than the inverter capacity (including the water heater, heating system, electric kettles, hairdryers etc) Don't forget that that even a 300watt inverter would require nearly 30Amps at full load (assuming 80% efficiency)which would totally knacker a 110a/h battery in just over two hours (you only get 110a/h if you discharge it at the 20hr rate = 5.5 amps)

 

[JTQ]

Colin,

Without wishing to be rude only helpful "as you are having to ask , about this potentially dangerous subject then you should not do it"

My Electrical HNC was back in th 1960s but based on what I remember from then you must not do what your proposing.

There is as the way you describe it a risk "your" 230 volts is back injected into the grid and this is I recall illegal as well as bl--y dangerous.

You need to double pole isolate your 230 volts and the suppliers mains from each other onto the vans circuit for starters.

You will need also to isolate the charger from receiving your 230 volts.

Don't do it just use a multiway block like the rest of us and keep safe and insured.

 

[Colin_374358138]

Yes I guess you are right - even if I unplugged the battery charger the 230v would go thru the mains protection switches to the water heater, room heater and the fridge. Not ideal. However if none of them were ever switched on to 'mains' at the same time......

I plan to instal a 600w or 300w inverter and yes am aware of the fact that realistically its only going to run very small appliances. My reason for doing this is cos I am fed up the the inverter danlging around the place whirring to itself when its in use. I want it out of the way and muffled and want to route its output to the existing 230v sockets just cos they are there available unused.

 

[Colin_374358138]

Is it so dangerous though ? Considering these scenarios I am not sure it is:

Not on mains hookup. Battery charger is unplugged and therefore isolated. If the inverter is on and the water heater (for example) is switched on to elec (from gas) then all that will happen it that the inverter will either overcurrent and shut down, or blow its fuse or keep running and heat the water VERY slowly.

On mains hookup - why would I switch the inverter on ? Or even plug it in for that matter ? and so no issue.

 

[Colin_374358138]

must admit to not knowing what you mean by a multiway block. Can you elaborate ? If there's a simple solution then fab.

 

[JTQ]

must admit to not knowing what you mean by a multiway block. Can you elaborate ? If there's a simple solution then fab.

The thing I described as a multi-way block is a short extension lead with say 4 x 13amp outlets. Enough outlets to use your inverter on several tasks at the same time, like charging camera cam corder, laptop and TV in my case.

Not tidy but safe.

Yours is unsafe in that one day someone not necessarily you might hook into the mains.

Cheers John

 

[JTQ]

The thing I described as a multi-way block is a short extension lead with say 4 x 13amp outlets. Enough outlets to use your inverter on several tasks at the same time, like charging camera cam corder, laptop and TV in my case.

Not tidy but safe.

Yours is unsafe in that one day someone not necessarily you might hook into the mains.

Cheers John

I cant fathom how you will charge your battery unless you do at sometime, so isolation is essential. It might be onto a reversed polarity supply so it must be double pole isolation.

 

[Rod_5041370]

I cant fathom how you will charge your battery unless you do at sometime, so isolation is essential. It might be onto a reversed polarity supply so it must be double pole isolation.

Colin,

The method I have used is:

1. 300 watt inverter installed next to the battery.

2. Output cabled to discrete mains sockets in the appropriate places.

3. The new mains sockets are white as opposed to the originals which are brown.

I only use these for the lcd TV, digibox and micro-stereo system.

 

[Rod_5041370]

Colin,

The method I have used is:

1. 300 watt inverter installed next to the battery.

2. Output cabled to discrete mains sockets in the appropriate places.

3. The new mains sockets are white as opposed to the originals which are brown.

I only use these for the lcd TV, digibox and micro-stereo system.

NB. Posted as a comment in error.

 

[Colin_374358138]

I cant fathom how you will charge your battery unless you do at sometime, so isolation is essential. It might be onto a reversed polarity supply so it must be double pole isolation.

My battery is charged at home from mains and then solar when on site. I never to go sites with mains hookup. Even if I did go to a site with mains I'd do it with the inverter unplugged.

Nobody else will plus it in except me, my wife does not touch the electric components.

If I ever sold the caravan it would be no problem for anyone else because I'd remove the inverter prior to sale to put in the next caravan.

So it would appear that the only thing I need to verify is whether the inverter can 'see' 230v on its output stage while the converter stage itself is inactive. I know that this will be OK safety wise because the inverter must have an isolation barrier in it to get TUV approval. Only concern is the possible damage to the output schottky's. I also have a higher education in Electronics.

All that said a simple extension lead may be a good compromise.

 

[Colin_374358138]

Like it Rod, another possible - at least this way I can be 100% sure of safety.

 

[ProfJohnL]

Hello Colin,

I think that Rod's solution is by far the safest. It avoids the remote possibility that you accidentally have the inverter exposed to mains supply, and of course that the inverter will be trying to power the water heater, battery charger or fridge etc.

As a general guide, What ever current (Amps) you use at 230V The inverter will draw roughly 20x as much from the 12V battery.

This usually precludes using even quite modest mains equivalent on an inverter and definitely not for a long time. Avoid motors, which tend to have funny power factors (the way the current and voltage wave forms are synchronised) These can upset some inverters.

Proper mains supply is in the form of a sine wave (ignoring interference which for the most part is insignificant) this has the characteristic of a very smooth transition between voltage levels without any square shoulders. Most of the low cost inverters produce what is called a modified sine wave output. This is where the output wave form is a set of square wave forms that resemble a coarse sine wave

This is not a problem for pure resistive loads like a light bulb, but the sharp transitions between voltage levels can some times upset more sensitive equipment such as transformers and induction motors. The appliances may hum than normal, and they may actually consume more power than specified.

There are more elaborate inverters that claim to output a true sine wave. These have the down side that they tend to be less efficient than the modified sine wave inverters.

Most inverters have a low battery voltage detector and will shut off if the terminal voltage falls below about 11V.

 

[Colin_374358138]

Yes I am aware of the relationbship between Amps and Volts in a Wattage calculation. I have a higher eductaion in Electronics. They'll only draw current when switched on of course so....

Still tinking EXACTLY what the best engineering soltuion is: lots of pros and cons in many ways.

Thanks all.

 

[SBS]

My solution was to fit two auto distribution blocks and run 4 gauge cable from the battery (tight for space with a 110 AHr battery)then run the cables for the inverter, mover and caravan supply from the blocks. The inverter is mounted next to the battery box and a 13amp plug takes the power into the battery box and a blue plug to plug into the EHU. This has the advantage of being unable to plug in the mains cable when the inverter is plugged in and, mains power is available throughout the 'van. Drawbacks are that the charger and all other mains appliances need to be switched off.

There was a very elegant solution using mains relays in MMM last year but was easiest to fit when the RCDs etc, EHU inlet and battery were all together.

Hope this helps.