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Appliance, Electrics, school bus RV, Skoolie

iLLumi Projections E26 Edison DC 12V-20V LED Light Bulbs *or* Electrics (Part IV)

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Barring the installation of the DC circuit breaker panel that I mentioned before, I went about installing the first 12 volt DC light that would be powered by the house batteries.  The need for this was displayed on a short day-trip we took to help a friend clean out her old family’s house, and the boy was unable to read, and I had some trouble finishing loading and packing the bus because the lights that I had installed were AC, and I hadn’t enough cable to run electric power from the house we were cleaning.  I wasn’t going to just leave the key in the accessory position for the interior lights, because I’m a bit touchy now about running the bus batteries down after our Evangola trip.

Anyhow, I had found two of these lights at Buffalo Reuse, though only one of them had its glass globe, and they both had the original 1920-30’s fabric-coated wiring.  Toward that end, I disassembled the fixture, replaced the old wiring with 14-gauge plastic-coated wire, and installed a new light bulb socket.  (A tip to people who might want to try rewiring such a fixture – use a ball pull-chain as a wiring snake to get the wire through those support tubes.)  In retrospect, I probably could have used 18 gauge wire, but I tend toward overbuilding anyhow.

Unfortunately, the ‘cup’ that holds the globe was lightly cracked and I haven’t been able to find a replacement, as it’s smaller than standard.  It’s a usual thing for such lamps, however, as the older brass gets brittle.  I decided that it would be okay, though, as I was going to cushion the cup anyhow, so I went about that.  I used some vinyl electrical tape to circle the interior of the cup, and then to surround the base of the globe as well, as this would keep road vibration from causing any problems.  I then went about gently scraping all the old paint flecks from the brass and glass.

However, getting the light refurbished was the easy part.  I wanted the light to rest above where the table will be in the cabin area of the bus, and the ceiling there is, of course, curved.  I wanted to have a flat base (parallel to the floor, that is) to mount the light to, and I had the wood to work with, but the curve looked tricky.

The endcap!As a woodworker, I knew the importance of having a jig or template to help and didn’t want to do the ‘trial and error’ method of creating one, until I realized that I had one already – the rear interior endcap!

I used some MDF that I had about, and traced the endcap, and cut it out, making sure to draw on plenty of lines at 90 degree angles to the flat base of the endcap.  These were important, just in case the smaller bit of the template (where the MDF wasn’t wide enough to fit the whole of the endcap might not be exactly parallel to the base) …

So, armed with the new template, I worked out how far from the window edge the light needed to be and set about making a base that would fit the light AND the ceiling.  I had some 7/8″ thick oak to work with and cut it to 5 1/2″ squares, and traced the curve onto one.

Careful cutting on the bandsaw, and then shaping with the bench sander yielded a very nice fitting piece of curved oak.  A 2″ forstner bit cut a smooth access core down through the curved wood, setting the stage for the important attachment bit for the light fixture; the part with the screw fitting on it.

The ‘light fixture mounting attachment’ needed to be sunk into the wood, parallel to the flat base, and this was quickly undertaken with a wood chisel.  Since I was working with oak, and going with the grain of the wood, this wasn’t bad at all.

I put a second piece of oak under the curved one to give a nice solid base for the lamp.  I did this because the thin edge of the curved piece I had cut was really thin.  I was afraid that if I just attached the lamp to it, it would crack or pull the attaching screws right through the wood.  Plus the routing on the bottom would be another nice touch of decoration that would show in the bus.

Using a countersinking bit I put four #10 screws into the two pieces of oak together, and drilled some holes through to the bottom and countersunk from the bottom for the metal pan-head screws that would attach it to the ceiling.  I then gave it a coating of stain and let it rest while getting the rest of the job ready.

 

 

 

 

Loading a drill just smaller than the metal screws that would affix the wood to the ceiling, I pre-drilled one hole, and marked the center of the access channel in the wooden base.  I then switched to the hole saw and cut through the metal of the ceiling to so the wires could be run.

Using a regular wire snake to run the wires, it was a simple thing to get power to the location.  I ran 12 gauge wire from the converter to where the switch was going to be at the windows, then ran the 14 gauge wire from there, as I planned on hooking more lights in on this same circuit.

While I’m really looking to run some manner of dimmer in on this circuit, for now, I just put in a pull-switch.  It was easy to drill a hole in the exposed ceiling sheet metal, and for now the circuit is grounded to the frame.

After that, it was a simple matter of connecting the wires at the lamp, and tightening the screw pole to cinch it up to the wood.

 

 

In trying to make the batteries last as long as possible, I wanted to have the most efficient lighting that I could, and went for some LED lights.  Most of the problems with LED lighting seem to be in that the LEDs only put out light in a relatively tight beam, making them tough to use in a standard fixture.  Toward dealing with this, I found this multi-directional style of bulb, in both 7 and 9 watts:

I have to say that these are SUPER bright on 12 volts, and while they say that they’re rated up to 24 volts, I don’t think I’d want to see them – they’d be way too bright.  As it is, the bulb does stick up over the globe a little, but the upward-facing LEDs provide a lot of indirect light off the bus ceiling (and show the places where it really needs to be cleaned!).

These bulbs are the soft-white version, and the vendor that I got these from indicates that there’s a bright-white version, but these seem very white compared to an incandescent, or even CFL soft-white bulb.  I did light them up when it got dark as well, and got these results:

School Bus, school bus RV, Skoolie, Uncategorized

Electrics (Part II)

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(Continued from Electrics (Part I))

The next step was the batteries. Of course, the bus already had two big batteries wired up to start the bus, so you might ask why we’d need other batteries. The answer is that there are two types of batteries that you’d find in an RV (or maybe even your car), and they each do different jobs.

The batteries already in the bus, and the ones in regular cars, are primarily meant to start the car and store up excess power from the alternator. That is, they are meant to have a high/hard draw of electricity in relatively short bursts. Often these will have ratings of ‘cranking’ amps or ‘cold cranking’ amps to show how much ‘power’ they have compared to other such batteries. Bigger batteries have more ‘cranking’ amps, meaning that they can provide more power to the starter. The bus’ two batteries have a total of 1880 ‘cranking’ amps and 1500 ‘cold cranking amps’. (For a comparison, my pick-up truck has 825 ‘cranking’ amps and 690 ‘cold cranking’ amps.)

 

The type of batteries that I added were ‘deep cycle’ batteries, which are meant to be slowly discharged of more power than the regular auto batteries are.  Thee are rated in ‘amp hours’ which tell you how long they will hold up giving power dependent on how much draw you put on them.

You might be wondering how you would know if you have a battery with enough ‘amp hours’ for your system.  There are a number of different on-line calculators (here’s one from http://www.batterysizingcalculator.com/ ) to make sure you get what you need.  Many RV systems are set up for only 20-24 hours of battery usage, assuming that you’ll be running your generator, plugging into shore power, or be using your vehicle’s alternator to recharge your batteries by then so you don’t overdraw your system.  A system that draws 30-40% of your battery’s ‘amp hours’ in 24 hours will totally drain your batteries in three days of use!  (A great resource on understanding all this is in “RV ELECTRICAL SYSTEMS-A Basic Guide to Troubleshooting, Repair and Improvement” by Bill and Jan Moeller, 1994, Ragged Mountain Press, Camden, ME  which is a little outdated on some of the appliances available but the theories and math are really sound.)

Anyhow, I worked out our system for four days of off-grid usage, estimating for a bunch of appliances and hour-usages, and came up with about 480 amp-hours at 12 volts that we needed.  There are a number of ways to get that.  Some people use a number of smaller voltage batteries (6 volt golf cart batteries are favorites) that can be wired in series to give the 12 volt systems, or several 12 volt batteries wired parallel to give the amp-hours needed, or combinations of series and parallel connections of lower voltage batteries to give the right voltage/amp-hour combinations.  The trick in all these is to use the same type/capacity batteries throughout the system, or the batteries could be damaged through uneven power draw or charging.

Another consideration was which type of battery to choose.  Most car batteries are flooded or wet-cell, which can be ‘sealed’/’maintenance free’ or  ‘serviceable’; the ‘serviceable’ ones being the ones you have to top up with distilled water and have to be sure to give adequate venting to let off the (potentially explosive) hydrogen gas and the sulfuric fumes that can come from charging, while the ‘sealed’ ones have the ‘eye’ that give you a color if everything’s okay, but can still vent gasses while charging.  These have to be mounted upright (or they could spill), and need to be mounted outside of the ‘liviing’ area of the vehicle (or be really well vented in a non-reactive compartment).

Additionally, there are AGM (Absorbed Glass Matt) and Gel-Cell are different in that the electrolyte isn’t simply in a liquid, but rather in a gel held between the plates in the battery, with the Gel-Cell actually being more of a rigid gel with a higher silica content.  These can be mounted in any direction and only off gas is badly overcharged (or with the wrong charger in the case of Gel-Cells), so these can be mounted in a passenger compartment without special ventilation.  The AGMs are considered one of the best at holding charges, and the Gel-Cells are considered very deep cycle (with a very slow recharge time) and have better durability in hot weather.  (Nice info summary and more info here at http://www.batterystuff.com.)

I ended up going with two Lifeline GPL-8DL batteries, each 12 volts with 255 amp-hours, so that when run in parallel we would end up with 510 amp-hours.  These are, however, pretty sizable batteries, each weighing 162 lbs, and being 20″ x 11″ x 9 3/4″ in size.   As big as this is, though, the two of them fit just fine under the rear-facing bench seat behind the captain’s chair, which serves to keep the length of 2-0 line running from them to the convertor (and later to the inverter and solar controller) to a minimum.

To be safe, I wanted to put a fuse in the system, and found a 500 amp surge/125 amp continuous fuse, with a little 15 amp bypass fuse that  would keep small systems running after the big fuse burned out.  In addition, the big fuse could be unscrewed to limit the danger to the batteries themselves.  When you are working with so many amps, even at a seemingly harmless 12 volts, it can be dangerous.

Now, I needed to put in some appliances! (Or at least one …)

Continued in Electrics (Part III)