Inverter's

[Guest bill]

I notice that inverter's are being written about in mags; Using a laptop computer when parked for an hour etc, with one of these, I assume it would draw lots of power from the battery? -1- Is the battery damaged from inverter use? -2- the user time must be limited? -3- Are some Inverter's better than others? -4- Is there any point at all in using an Invert: -5- Some advertised are very pricey. Bill

[Guest PeteC]

hi Bill We have an inverter which is mainly for use when travelling Problems are (some are from what other people have found) 1 The output is not a true sine wave 2 Tv's even LCD's are very voltage dependent so if bttery Voltage falls the TV Lap top ... will trip out 3 You are changing a 12 V DC into 230 V Ac only to go through a Ac>dc 230V . 12V conversion in the inverter - Very wastefull as each change has its own losses We run our Laptop & Tv on mains only If we dont have mains we dont have them We dont goaway to watch Corrie Laptop is for downloading pictures, writing up our diary, playing CD's, Route Planning, receiving emails of documents When away i dont surf the web or contribute to forums

[Guest Mel E]

Inverters are fine for the purposes you describe. You can also get true sine wave inverters if the equipment needs it (Waeco do a series of different output ones). However, very few pieces of equipment actually need a true sine wave input. Assume that the inverter will consume about 15% more power than it gives out. Thus a TV showing 40 watts (at 240 volts) on its label plate will consume about 46 watts (40+15%) of battery power. Divide by 12 volts and that's just under 4 amps. Thus 5 hours of TV will consume 20 amp hours of battery power. The problem with inverters is when you expect them to drive powerful things like microwaves. Even if you get a big inverter, it can kill a battery stone dead in no time flat (if you'll excvuse the pun). A 600 watt microwave will consume about 1000 watts of power. That's 1000/12 or 83 amps - enough to flatten your standard 85 amp hour battery in little more than 30 minutes.

[Guest Neal]

Bill As ever, it's "horses for courses". Pete's point about changing DC to AC only for the TV to change it back to DC is correct but the balance is that you can use a domestic, mains-only TV in your motorhome that is infinately cheaper to buy than a mains/12V one. Where there is dedicated build-in space for this it makes sense. Then you need an inverter to use it when not on mains hook-up. The talk of flattening your battery would be a concern in small campers with limited battery capacity but, consider the US RV. Some of the larger ones have up to six (yes, 6!) leisure batteries in a bank; that's over 600Ah at their disposal! You will concede that the prolonged use of a large inverter is not going to pose too many problems on the battery capacity, is it? I use a 1000W inverter which powers the TV/VCR unit, the Sky digibox, and a conventional aerial amplifier. I also have some spare capacity - just in case! (This is unlikely as we have a 4.5 KVA generator installed!) My theory is that I want to be able to use absolutely everything that I have where-ever I am camped; site, CL, or field. We also us our motorhome throughout the year so, as January and February have quite long periods of darkness (and inclement weather), we need things to occupy our (tiny?) minds. Regards Neal

[Guest Howard Cutler]

Hi Bill, I agree with most of the comments made. An inverter canbe a good investment and necessary if you don't want a generator or regular mains hookup as we do. I have fitted a second 110amp leisure battery in parallel and connected in a 500w inverter(£69). With this arrangement I can run up to 4 days using lights/mainsTV/DVD/radio/CD/shaver etc but not iron,kettle or fan heater. My inverter is non sinewave but I still get an excellent TV picture.My next investment will be solar panels but until then most m/homes have a high output alternator which is rarely used to full potential and will restore battery power on a relatively short run. regards Howardc

[Guest Clive]

Just to echo most of what has been said above. Inverters do have a place. Most equipment is quite happy with a "modified square wave" type inverter. Modern inverters are probably better than 90% efficient and have a low quiescent current - but its always good practice to turn them off when not in use. Laptops and some TV systems are specified for use on 12 volts, but this 12 volts needs to be accurate and stable. The mains input for such equipment provides this stability as required by the manufacturer of the equipment, it also provides galvanic isolation which could be important in some circumstances. Hence I always run my Laptop using its "mains" adapter from the inverter. The TV also becuase the 12 volt internal inverter within the TV packed up years ago but its fine on Mains! Amps from the battery? About 22 times the amps actually taken from the mains when using an inverter. For example a Laptop taking 50 watts will consume aprox. 5 amps from the leisure battery when running via the inverter. Solar Panels? Like motorhomes, hard to justify but they do make you feel smug when the sun shines! Enjoy

[Guest Bill Haylor]

Thanks to all for the comments, I'm guessing I get more interesting answers on the forum than asking a salesman who's out to sell his product. Bill