500w inverter

[pands10]

can anyone tell me would a 500 w inverter have much of a drain on a 90ah battery?


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[Dave1258]

Hmmmm.. A Big depends..what do you want to use it for?
A sine wave inverter of 500w is on the small scale of inverters which have direct Battery connection as CLOSE as possible.
Modern inverters are not now "life sucking" drainers of Batteries as most people seem to think. Long gone are the days of heavy transformers and low quality transistors.
Do you have any other means of 110/24ov i.e. shore power, solar energy etc.?
Mastervolt do an excellent range of inverters, will have to do a search on the website tho' Regards Dave

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[steverow]

Dave is right, they are much better these days than they used to be thanks to modern semiconductor technology. Most modern units also incorporate a CPU type cooler fan which helps the efficiency.
They are usually not true sine wave devices rather modified square wave devices.
The 500 watt refers to the maximum permitted AC load, although unfortunately in my experience the chopper circuit often refuses to start with anything approaching max load. Better to start the inverter then apply the load rather than the other way round.
I have a 350 watt one fitted to my boat. I keep the 2 inverted mains sockets separate from the shore power sockets and labelled as such. Simply attaching the output to your existing mains ring is a bad idea. Keep the DC circuit as short as possible with the largest dia of cable you can reasonably install.
I use mine to run only the navigation laptop and LCD telly for SWMBO. Everything else is either 12 or 24v battery driven.
Try and avoid using using it for mains lighting and heavy duty motor applications, or for anything that might expect a 50Hz timing pulse from the mains to derive a clock frequency ( like early LED alarm clocks).

Cheers

Steve.

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[[2574]]

Simple maths tells me that a 500w inverter (running at max) will drain 2.1 amps from your battery. So a 90 AH battery, assuming you would not want to draw more tham 40% of it's reserves (to avoid damaging the battery), would suggest that the max "on time" for the inverter would be 17 hours.

That's my theoretical knowledge - it would be interesting to know from a "teccy" whether this stacks up in reality.

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[boatone]

Ouch....bad arithmetic.....

watts is pretty much watts at whatever voltage you are taking the power so a 500watt invertor running from a 12volt supply will be sucking around 40 amps when under full load (12v x 40amps = 480watts). That means your 90AH battery will only really be up to supplying around 45 minutes - assuming 30% of battery capacity is good working practice before recharging.

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[[2574]]

Re: Ouch....bad arithmetic.....

Not bad arithmetic - bad understanding! I always thought VxA=W and that was a fact. So my (erroneous) thinking was that 500W delivered at 240V must (by maths!) be 2.1A. (2.1A x 240V = 504W). I didn't know this "cardinal rule" was flexible - but then I always was crap at Physics!

Thanks for putting me right.

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[Geoffs]

Re: Ouch....bad arithmetic.....

Ah but its 500watt from 12v, so as Tony says 45+ amps from the battery. But you are right, its 2.1 ish amps to the load.

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