120v only lights in slide- convert to 12v?

BFL13 wrote:

ScottG wrote:

BFL13 wrote:
I posted a while back that I get that 1 DC amp draw via inverter with the CFL, using my 3000w inverter.

I posted that the small inverter idea was a scam because they usually have a long thin wire situation which adds to their amp draw, but the big inverter has short fat wires with little loss.

I got more DC amps draw from that same 120v load with a small 300w inverter in the Winegard 12v socket than the 1 amp draw using the 3000w inverter up front close to the batts.

It is not the size of the inverter, it is how it is wired to the batts that counts.

The size of the inverter counts. Big ones have many more (active) components to handle that higher power capability that even at idle draw some power.
The wiring in a RV will have no problem supplying enough current to power 15 to 18 watts of leds via an inverter.
A small, MSW inverter uses less standby current because it has fewer active components.
So in short, a 60 watt MSW inverter is not going to take more power running the same load than a 300 or 3000 watt inverter.

Now could you purposely set up a circuit with grossly undersized wiring for the smaller inverter and cause it's regulators to work under their thresholds in order to cause them to draw excess current? Of course but one would have to do far more than draw 1 or 2 amps though a 16 awg wire (typical in RV's) to run a couple of LEDs in order to do so.

What I did as a test was plug the 300w inverter into the Winegard socket and then bring the shore power cord around with an extension into the trailer and plugged that into the 300w inverter.

ISTR it was 4 ? amps draw (it is in the archive somewhere) to run that one CFL bulb as seen on the Trimetric. It was 1 amp draw for the same lamp with the shore cord plugged into to 3000w inverter

That proved (to me) that it is all about DC wiring to the batts. Also the "stand-by" draw of the inverter has little to do with what the draw is when the inverter is under load it seems. It is not standby plus load, it is less than that. I don't have exact numbers handy.

I ASSume if the 300w inverter were installed up front by the batteries with short wires of sufficient Gauge, it would come out at least even though.

My point is that small inverters in RVs are not usually installed to best advantage, but instead use their skinny wires into 12v sockets, so they draw higher DC amps even with small loads.

Try it out and see what amps you get as a Dc draw.

I will try and find that old post to confirm the amps numbers.

I cant see how the smaller one would take 4 amps to run a CFL where the bigger would only take 1A. The math and the electronics just dont equate unless the wiring were too small.
My small inv takes less than 60mA to run anything from my LED lighting of 14 watts to my TV which IIRC is about 40 or 50 watts.
For the smaller inverter to draw 4 amps to work would probably burn it up. I have seen where discrete components were forced to work with insufficient current source and ultimately overheated and were either weakened or died outright.

Good discussion!