Ring 300W 12V Inverter Running 230V 8W LED Class I Luminaire

[securespark]

Bit nervous about this.

Need to swap Class I for Class II methinks!

Also, calculated that, at 80% efficiency, my 8W lamp has a load of 0.83A.

So, for a 3 day weekend, that's plenty to run the fitting off a 110Ah and leave spare capacity for other stuff, charging mobiles, etc...

 

[bernardgreen]

The quoted 80% efficiency will be at ( or close to ) full load.

Most of the missing 20% will be the base load of the invertor's control system which will be taken from the battery even if there is no load on the invertor's output.

 

[Aragorn84]

wouldnt you be better using 12v LEDs and ditching the inverter?

 

[securespark]

That's an excellent point.

But:

I need the inverter for other electrical stuff.

I have a 230V LED lamp.

I don't have 12V LED lamps....

Plus, the volt drop won't be good.....

So, assuming I leave things as they are, have I boobed my calculations?

 

[bernardgreen]

I would run the invertor on minimum load and measure the current from the battery and use that calculation in the battery life equation.

Also allow a bit of lee way for the meter reading to be in-accurate as the invertor may be taking current from the battery in pulses or other waveform that the meter cannot measure accurately.

Have you considered using 12 volt vehicle LED lights ?

 

[securespark]

Thanks, Bernard.

Yes, I've considered auto lamps. But there's volt drop again...

 

[ekmdgrf]

What are you planning to use it for?

Very wet finger in the air predicts about 15 days usage.

I once did a test of my 65Ah battery with a 300W inverter and using it to power an Athlon 1400 (just the tower not the monitor) and it ran for 11 hours.

Sounds like you're planning a camping trip. I tend to use a an LED strip, which works really well. Though I usually have 13A power and Gigabit ethernet into the tent, which powers a couple of laptops, GigE swtich, travel kettle, LED lighting, fridge and phone chargers. Works really well.

 

[securespark]

Yup!

Planning camping trip, but just 3 days.

Have got 300W inverter, but don't need fridge or kettle (will build fire for HW!) just power for LED lighting, charging and inflation purposes.

Lighting mostly for tent pitching as we will be arriving after dark to a site without mains hook up.

Have got my 110 Ah battery currently rigged up to the 8W LED lamp now. I just want to see how long it lasts! So far, it has been on 4¼ hours.

 

[bernardgreen]

Lighting mostly for tent pitching as we will be arriving after dark to a site without mains hook up

Many of our scouts (1960's version) could put up a tent in darkness. They learnt the art blindfolded and watching the early attempts was amusing to say the least.

 

[securespark]

They are fine!

This for me, who has poor eyesight in daylight, let alone after dark!!

As an aside, does anyone know of any LED spike floodlights that are Class II: do they even exist?

Lamp been on for 8¼ hours.

 

[Aragorn84]

Surely lighting, charging and inflation can all be run directly from 12v?

If your going to buy another luminare anyway, surely it makes sense to simply buy a 12v one. 12v to USB chargers are ubiquitous, as are 12v air pumps.

 

[securespark]

Was looking to borrow a flood.

The pump I already have: it is 230V.

The inverter has a built-in USB port I can charge the smartphone from.

If I wanted to go 12V, I'd have to buy a 12V flood, a 12V charger and a 12V pump, all of which I don't have!

Plus, I still have an issue with volt drop, as the lamp needs a goodly length of lead on it (10m): no good at 12V.

 

[Aragorn84]

Given its drawing very little power, i cant see 10m of sensibly sized cable dropping all that much voltage?

The calculator here:
http://www.tlc-direct.co.uk/Technical/Lighting/VoltageDrop.html

suggests 1mm flex would see only 0.3v drop at 8w

Not very significant i wouldnt have thought?

 

[securespark]

Hmm. Getting complicated.

Lamps expensive.

12V floodlight hard to locate.