After trying some rectangular switches that didn't fit into the cut-outs, I tried a smaller one that I could insert right into the blank. It worked fine, so bought two more.

One of them controls the underseat/under dash LED light bars. The other one controls a fuse panel I installed on the passenger's side. That powers two 12v outlets that are independent of the ignition.

I have one more spot available, but how can I use another switch?

1. I drilled a hole in the center of the blank.
2. I covered the terminals with liquid tape, just to play it safe.
3. The left switch is for the fuse block, and the other is for the LEDs. Both light up when switched on.

It's very easy to wire the switches and then pop them into the opening. Because of the lack of clearance on the back of the blanks, I used a couple of drops of hot glue to keep the switches in place.

 

 

If you're looking for an accessory to add...I've thought about permanently mounting a 110V inverter somewhere and wiring in a couple of 110V outlets on the dash somewhere, with a remote switch for that. Obviously one would need a relay (and probably dedicated power feed from the battery) for an inverter of any size. I'd probably have one in the 400W range for my uses...plenty for a laptop or a hang-in-a-cup portable immersion heater (to make tea or soup or whatever).

 

Do the blanks just pop out or are they held in by some type of retaining device?

 

That's an idea, although I've had an inverter sitting in its box for years. I guess the idea of a converter appealed to me at the time. So many things run on 12v, that I never needed more.

 

The best way to pop them out would be to reach from behind and squeeze the top and bottom retaining clips. You would have to find a five year old child to do that. There isn't much room back there.

What I did was force a thin screwdriver into the center of the side. It marked it slightly, but the blank comes out easily that way. If you look at the left side of the switch with the amber light (above), you can see a scratch in the left edge. The mounting hole is very deep for some reason.

 

This is really awesome! Well done!

I'm curious, how difficult was it to install the independent fuse box/always-on outlets? THAT is a fantastic idea.

Was it difficult to work a master switch into the floor LED circuit?

...would you be willing to walk a layman with very limited car electrical experience through either or both of these DIYs??

 

It was a bit of a project just figuring out the how and the where. I took some pictures, and I'll get them organized. I'm about to shut down (the computer, that is), so I'll have this ready for you tomorrow.

 

I have a 2k Samlex pure sine inverter mounted under the back seats fused directly to the battery at 40 amps as I don't want too heavy of a load killing the battery. Max it can do is 400 watts (~10ADC for 100Watts AC) If you remotely mount an inverter and run wires to outlets throughout the car, make sure the inverter is a good quality one. Cheap inverters produce conducted RFI on the AC lines that can interfere with the radio, Bluetooth, and other devices.


I also repair inverters on the side too and familiar with the internal workings of them. Inverters are a handy thing when camping and on long road trips. it has to be the right one for the job though. Modified sine wave inverters don't play well with electronic devices. A pure sine wave inverter is more expensive, but the waveform is just like what you get from utility.

 

I like the idea of adding a USB port in the blank switch plates. Then you could plug in a dash mounted GPS/phone without running a wire to the center console. You could also charge a phone that you set in the driver cup holder right above those switch plates.

I have an inverter but I never use it. Back in the 90's I would use one to charge a laptop, but now my laptop has such good battery life that I would never do that. All of the devices we use now are USB powered. So I don't think an inverter would be as useful. If you really need one, just bust it out for that particular case, no need to hardwire it if it is only used a few times over the lifetime of the vehicle.

Awesome job on the switch plates, I would like to do something similar for controlling interior illumination and adding charging ports.

 

I agree an inverter isn't too practical for daily use. For camping or long trips they come in handy. The last time I used it I had a group 29DC deep cycle battery connected to it (not to the car at all) and ran a few LED lights, Bluetooth speakers with an Ipod, and hey cannot forget the all important mixed drink blender!!


I may just wind up taking it out and like you said use it for that particular use. 400 watts isn't much for me anyway. Blender alone is about 900 watts (for a few seconds) and not practical from the Fit's battery.

 

Most electronics these days have switching power supplies that are perfectly happy with MSW inverters; if anything, the MSW is less stressful on the initial rectification and capacitors than normal power. Likewise, resistive loads like incandescent lights and heaters are perfectly happy. Motors and transformers are generally functional but not as efficient or effective as with a sine wave. Things that use phase control such as light dimmers or variable speed tools don't work properly at all. (Microwave ovens typically also don't work too well with MSW inverters, but more because they are very sensitive to the peak input voltage than because they are sensitive to the input waveform. That's doesn't matter for a Fit, though, as the Fit's little battery isn't going to supply power sufficient for a microwave and survive very long at all!)

RFI could be a concern with cheap inverters of any sort, as they all involve high-power, high-speed switching circuits and may have ineffective filters. A well designed and well built pure sine wave inverter will produce negligible RFI, though.

 

I agree with you on all points. Where I disagree is Modified sine wave inverters do not play well with switch mode power supplies that have active power factor correction circuitry inside. In fact MSW likely will damage it over time. If the SMPS has passive PFC circuitry such as a large cap then MSW shouldn't be an issue. However most modern SMPS employ active PFC as part of the ROHS & UL compliance. Sine wave inverters are compatible with everything made these days.


RFI is not generated on the output stage of an inverter actually. Its part of the input boost stage taking 12VDC and stepping it up to around 180-200VDC. The voltage goes from 12VDC to 12VAC through a step up transformer around 50khz boosting the voltage to 180-200VAC rectified to VDC and dumped into a large capacitor that the output stage feeds off of. In a good sine inverter there are RF chokes and filtering components to get rid of all the switching noise, but often cheap ones do not employ it. They make simple power filters like at best buy that negate this RFI.


The Fit battery is way too small to power by itself for too long. The plates inside are too thin. Its meant as a starting battery, providing high current in short bursts. The accessories in the car run off the alternator, which in this car it looks to be a 90 amps, but it may only be able to do say 55 amps continuous. Anything over that rating and the windings overheat. That's why I fuse limited the inverter to 40 amps. Doubtful I'd run anything more than 20 off it for my purposes..