Tag Archives: DC Electrical

Testing out the Backup Camera(s) (Part I, The Parts)

So, with all the cold weather and lack of being able to work on the bus, I pulled out the backup cameras and screen, to test them out.  I had had these for a while, but they were still in the boxes, and I wasn’t sure how and where I’d be installing things.  I ordered all these from Amazon last winter and just never got around to them.

 

So, here are the parts, all expanded out of their boxes:

Here is a relatively cheap back-up camera that had decent reviews, and I thought I’d give it a try, or keep it as a spare if the other camera ended up not working or burning out too soon.  It attaches by way of a hollow, threaded post through which the wiring goes.  It has a small plug/socket set to connect the camera to the DC power/return and the 25′ long RCA cable (which will be a little short for the bus).

There had been some complaints about it not being really waterproof, but it looks good to me, given that the lens and body are all nicely molded together, and the back (with the post) is screwed into it with four small screws, meaning that the only place for water to get in is at the back, which you should be sealing up anyhow.

They included a little pieces of what seems to be a 1/16″~2mm foam tape (which somehow escaped my picture) to put on it, but I’ll use a thin bead of butyl rubber when I go to attach it.


Night Vision Parking Car Rear View Wide Angle LED Reversing CMOS Camera

Night Vision Parking Car Rear View Wide Angle LED Reversing CMOS Camera

This was the ‘fancy’ back-up camera that I opted for.  It’s ‘fancy’ because it has the IR LEDS that kick on when it gets dark enough.  I had figured that this would be the main back-up camera for the bus.

It attaches to the vehicle by the side-flanges, and the wires come off the back.  It has separate plugs for a rather standard ‘+ in’ 12 VDC plug (the red one in the picture) and a female RCA jack for the video.  The camera came with 25′ of RCA cable, but I have a run of 50′ that I’ll use instead.

Like the cheaper camera, the body and lens are all together in one nicely molded piece, with a ‘hatch’ that’s screwed down on the top.  Again, I’m figuring on using some butyl rubber sealant around the seam there to try and keep out water, which I expect to be a bigger deal with this camera, since the opening is up and there’s a bigger hatch.


One of the major complaints in the Amazon reviews about both of these cameras is that the image is backward, and you can’t change it, or that it’s been built wrong.  However, these are really back-up cameras, designed to be installed in a particular way so to give an image that’s going to give the driver a familiar view of a rear-view mirror. And they do that just fine, so I think a lot of the issues in those comments is that people didn’t understand what they were buying.


Lilliput Eby701-np/c/t

Lilliput Eby701-np/c/t

The Lilliput screen is a 7″ touchscreen with a VGA input as well as two RCA inputs and a reverse-sensor that automatically changes the input to a camera’s input when the transmission is shifted into reverse. It had some good reviews as being a reliable and visible screen for vehicle use, able to interface with a vehicle-based computer (which I’m planning on installing).  It runs on 12 VDC, but also came with an AC adapter (which made testing a whole lot easier).

It also turned out to have TWO RCA inputs (Video 2 is the one activated by the reverse sensor), so I’m likely to install both back-up cameras and have them each on separate channels (more on this in Part II). The cables that came were actually in two parts, perhaps in case one didn’t have an on-board computer.  The first connects to the screen and includes the power jack (black), RCA jacks (yellow), reverse sensor (green wire), an audio input (white), and the screw-on secured connector for the other wire which connects to the VGA jack and a USB connector for the touchscreen.

Armed with these bits (and a 12 VDC power source from a USB IDE hard drive connector), I got into actually testing the system.

(Continued in Part II …)

 

 

 

 

 

 

 

Cold Weather Care and Feeding of Batteries

A recent discussion and some questions on the subject of batteries gave me the idea to sum up what I have on the subject in hopes that it will help other folks’ batteries to last longer.  For the RVer who wants to stay quiet, a good, reliable battery bank is the way to keep so many of those systems that make camping life so comfortable going, and most of us can’t afford and don’t want to buy those expensive new batteries often.

There are a number of strategies when choosing batteries for your RV/Camper.  Some people choose one single large battery, like this ‘universal replacement’:  This one has a rating of 200 Amp-hours (It would last for 200 hours under a constant 1 amp draw, or 1 hour at a 200 amp draw) at 12 volts DC, which is the usual power system for your regular vehicle and most RVs.

Some folks like to use golf cart batteries, as they can be obtained used, and even as 6 volt batteries, can be hooked up in series to make a 12 volt output and are often fairly cheap, like these (new): These, hooked up as two sets of series connections by a parallel connection would yield 140 Amp-hours at 12 Volts DC.

Now, the ones above are AGM (Absorbant Glass Mat) batteries. This technology became popular in the early 1980s as a sealed lead acid battery where the acid is absorbed by a very fine fiberglass mat, making the battery spill-proof, and means that it can be mounted in any direction. These batteries have very low internal resistance, are capable of delivering high currents on demand and offer a relatively long service life, even when deep-cycled.

AGM batteries are maintenance free, provide good electrical reliability, and are lighter than the flooded lead acid type (which I’ll mention in a moment). They stand up well to low temperatures and have a low self-discharge, but the major advantages are a charge that is up to five times faster than the flooded version, and the ability to deep cycle without ruining the battery. AGM batteries offers a depth-of-discharge (DoD) of 80 percent, while flooded batteries are specified at 50 percent DoD to attain the same cycle life.  The downsides are that they tend to be heavier/bigger per Amp-hour and higher costs than flooded batteries.

A flooded battery might be a cost- and weight-effective choice, looking something like this one: This battery would give 150 Amp-hours at 12 Volts DC, but with a smaller, lighter battery.  The downside of this battery is that you have to make sure the battery is topped up with distilled water, as it will off-gas explosive hydrogen gas and other corrosive gases (so it has to be placed in a vented compartment). You can get around some of the work of topping your battery(ies) up with an automatic system like this one which makes it a simple job with a a hand pump to fill once you install the hose to each of the cells of the battery(ies).

Another problem with flooded batteries is that a full discharge (50%) causes strain on the battery, and each discharge/charge cycle permanently robs the battery of a small amount of capacity (Unnoticable at first, but each subsequent discharge takes more capacity from the battery). Most of the flooded types will have a life of about 200-300 cycles, while the Lifeline batteries that we got are rated for 1000 cycles.

When it comes to cold weather, AGM batteries have another couple of advantages over flooded batteries in that they are much more likely to survive a freeze intact, and loose less of their charge over the same length of time.  This last is probably the most important of the two, as the trick to keeping a battery healthy over cold weather is keeping it charged.

As the weather gets colder, the effective Amp-hours in a battery drops, while at the same time, its voltage capacity rises.  This means that your charger has to be able to cope with this.  There are a number of ‘Smart Chargers’ out there, like these: 

or as units built into converters like this

The thing about these ‘smart’ chargers is that they will automatically detect the charge that your battery has and adjust their output to give your battery what it needs, from ‘bulk charging’ (up to almost 90% charge) through the ‘absorption charge’ (to charge the last 10-15% of the battery) to ‘float charging’ (which keeps the battery full at a constant lower voltage) and even the maintenance cycle of ‘equalizing’ charging (which highly charges the battery to prolong the battery life by removing sulfur from the plates).  A regular charger like you might have in the garage for your  car generally has settings for either a ‘starting charge’ (lots of amps you use to try and get the car started with a dead battery), a ‘bulk charge’ (To bring the battery to a full or near full charge), and a ‘float charge’ (to keep the battery full), though it doesn’t pay any attention to the battery that it’s connected to and continues to do what the switch is selected to, which can easily over-charge a battery and leave you with sulfur corroded plates.

Some people winterize their system by removing the batteries from their RV/campers, and keeping them warm. This is a perfectly acceptable way to winterize, but for batteries with larger Amp-hour capacities (and especially those that are heavier AGM batteries or built into specialized compartments) this can be a lot of work. You still have to remember to keep the batteries charged, or you might lose a cycle of life through discharge as they sit.  Also, if you have the flooded batteries, taking them out is a great time to top them up, and pay more attention to keeping them charged, as they’ll discharge faster than the AGMs.

Also, if you’ve heard that you can’t store your batteries on concrete over winter, as long as your batteries are in a plastic case, you can disregard it.  This adage comes from the time when batteries were produced in wooden cases, and the wet wood sitting on the porous concrete meant that the concrete would slowly leach away the water from your battery.  The only concern with modern batteries is if you can get your fingers underneath to lift them back into their places so you can get going again in the warmer times of the year.

 

 

 

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

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: