what can i run on an inverter?

[hogggman]

hi all,
i finally got my leisure battery sorted.it is 85 amps,and i currently run the tap for the sink,occasionally the coolbox,and i have swapped over the circuits for the blinds,stereo,interior lights etc.
i am intending to fit an inverter,but wondered what size i could realistically run from the leisure battery,and what could i run on it, i.e tiny microwave?
thanks
jamie

[Simon Jones]

I think there's been a fair bit of discussion on here in the past (see what the search brings up). It all depends what you are likely to want to run & for how long, or whether you are prepared to run the engine at the same time to keep the battery charged. A cheap 150W invertor is fine for a laptop, or similar small appliance, however running something like a microwave would probably need at least 1000W & you'd probably be better off buying a 12v microwave in the first place. They can be picked up from places like Maplins for £100 - £150.

Similarly, if you do want to run a low voltage item that normally has a mains transformer, then try to find a power supply that does it in one go. For example, Maplins do a 12v - 19v laptop power supply, which is more efficient than converting 12v to 240v & then back down to 19v.

[Trouble at t'Mill]

Ho hogggman.

Hmmm, I don't think so, unfortunately.

I'm assuming by 85 amps you mean an 85 Ah battery - which means 85 ampere-hours. This means is can theoretically deliver 85 amps for one hour before going 'flat'. Or, you could take 42.5 amps in which case it would last 2 hours. Or 1 amp which it could supply for 85 hours... etc.

Unfortunately, when it comes to things like heating - whether for cooking or for keeping warm - a 12V battery just ain't going to cut the mustard.

Let's take a small microwave oven, say 600W. Running from the 'mains', this would be taking just under 3 amps (600/230=2.6). However, if you try and take this many watts from a 12V battery, it would be consuming 600/12=50amps! It wouldn't just be the oven that would be getting hot...

Also, a 600 watt inverter won't be cheap. Also, there would be inefficiencies when converting the voltage, so you'd get even fewer bangs for your buck than this (I do love metaphors...)

And 600 watts is a tiny microwave.

You are pretty limited as to what you can run from a 12V battery, via a mains inverter or not. It can realistically only provide lighting, music, TV, small fridge/cooler, etc.

Sorry...

[hogggman]

now you`ve burst my bubble!i`ll stick with my coolbox and lighting then?
thanks
jamie

[moonshine]

Hope that's a compressor-driven coolbox Jamie. An ordinary coolbox will flatten a battery very quickly, unless you only switch it on while the engine is running or when connected to a mains hook-up and battery charger. Even on my boat which has two 110ah leisure batteries, I wouldn't risk running a coolbox.

[haydn callow]

A 85 amp hr battery will probably give you only a useable 60% of that 85. When the battery drops down to 12 volts it is to all intents and purposes nearly flat. Any decent inverter will cut out at about 11.8volts to save battery damage. Also you are unlikly to ever get the full 85 in there in the first place.
I would forget trying to run a microwave. Even a small fridge drawing say 3 amp hr would be pushing things over night with a light or two and a dvd.

[dandywarhol]

My 1200W invertor will run a 700W microwavebut it can only be used for about 5 minutes (enough for a curry) Thats because the 700W microwave takes 1200W to run it - they're pretty inefficient

I've actually stopped using it for that now as the leisure battery doesn't like being recharged so quickly.