Tag Archives: planning

batteries, Electrics, school bus RV, Skoolie, Uncategorized

Cold Weather Care and Feeding of Batteries

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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.

 

 

 

164-50, RV oven, RV stove, school bus RV, Skoolie, woodwork

Counterspace

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With the fridge finally in place, I have a firm ‘wall’ to start to build the kitchen in.  I knew for sure that the counter would be at the level of the base of the windows so that we wouldn’t lose visibility, but the actual arrangement of drawers and storage/access cabinets would depend on placement of other things, like the stove and the sink.  If you look on the original floorplan, you can see that there’s a whole lot of potential counter space where things could go.

The stove was easy to place, as my plan was to put it at one of the ’emergency’ windows that can be swung out and give lots of good ventilation if we need it.  As there are two such windows along the counter (colored red in the floorplan diagram), the stove could have gone along either one, but putting it along the fore window would give more ‘working space’ around the sink, which is fairly important when washing dishes and such.  And since we actually had the stove, I could place it so much more precisely than in the floorplan where there’s essentially a 24″ x 28″ space for the (three burner – ha!) stove.

The sink was a more dicey matter in terms of placement.  The window closest to the fridge is ‘sticky’ – there are some scratches in the aluminum frame, and it can make the window hard to close (at least form the inside). My original thought was to put it right in front of that window near the fridge to maximize the available counterspace between the sink and stove, but being able to have fresh air while doing dishes ranks highly, so the sink may move closer.  Actually doing the placement is going to wait until we ‘play’ with the space for a bit.  I had hoped to do this on one last camping trip of the Sprague Brook season, but it just never came to be.

The stove!The first thing I did was take measurements and figure out the placement of the stove.  I was planning for a 24″ deep stove,since I kept seeing that come up as a dimension for newer stoves, but ours is only about 20″ deep, leaving about 4 inches of counter behind it. And while the window comes out to be more than 24″ wide, the stove is only 21″ wide, and that measurement (like the depth) includes 1/2″ of overlap of the trim.

This gave me some concrete information to work with in making the countertop.  While I’ve seen lots of people using some of the pre-made household counters in their skoolies, my wife had shown me an article on how to build a counter that gave the look of thick oak planks and we both liked the look. However, the idea of having beveled edges between the planks seemed to just be an invitation to a continually dirty counter.  So as a compromise, I had decided to use oak to make a counter, with no beveled edges, and as few seams as possible.

It turned out that I had just enough oak in two almost 13″ wide by 1 1/8″ thick planks that, when planed down and jointed, came out to the right length for the counter from fridge-wall to side-facing seat.  These pieces were fixed together with the Kreg pocket-jig and some 1 1/4″ fine-thread screws.   Even with some bowing in the plank, which was fixed with clamps, screwed, and sanded down to fit where the stove would go.

In order to support the counter without actually having counters underneath it, I decided to build in some 2×3″ supports that would hold it up, and just fit the sides of the stove, with allowances for 1/2″ plywood on the inside of the enclosure to help support it.  The 2×3″ supports that attached to the wall rest upon a 2×4″ that is screwed into the wall supports.  I used more pocket screws to attach the horizontal supports to the 2×4″ and then attached the vertical supports to the 2×3″ that was attached to the floor.  The 2×4″ was attached to the wall at a height that would put the 7/8″ thick counter just below the level of the windows allowing for a 3/4-1″ oak backsplash to be added at a later time.

One additional support at the fridge wall and another toward the seat edge, though the one near the seat is back about 10″ so that I could put a small lower drawer and upper ‘bin’ at seat height that would have nice storage space for passengers and the counter above it.

With this all set, I stained the counter and slid it into place, checking the fitting and adjusting the ‘square’ of the stove structural fittings before using more pocket screws to sink things into place.  A 3/4×1 1/2″ edging was affixed to the counter after being rounded with a router and the stove was set in place (the edging had to come up to the trim of the stove.  This was also affixed from underneath with pocket screws.

I had considered leaving the leading corner of the counter as a 90 degree angle, but thought that it would present too much of a chance for a bruise in the close quarters with several people on the bus.  Toward that end, I decided to trim the corner and make it a simple 45 degree angle, which was easy to work with for the trim.

With the counter in place as it is, it looks like a lot of space, though we’ll need to decide where the sink will go, and I was expecting to put in a full size sink as opposed to the RV sink that we salvaged from the trailer.  The salvaged sink is stainless steel and in decent shape, but it’s only 4 or 5 inches deep.  A standard kitchen sink is around 9 inches deep, and a double sink that deep could easily have one side filled with hot water and suds to wash and then use the other side to rinse and thus conserve water while still doing a full set of dishes for four or six people.

One of my concerns right now is that the 29″ height that the counter is at (the bottom of the windows) may be a bit low to be comfortable tpo work at for long periods of time since most counters are at about 35″ height.  That said, I do make cookies and bracciole at our kitchen table and it’s only about 29″ tall, so … time will tell.

 

 

 

 

 

Appliance, Skoolie, Uncategorized

The Norcold Refrigerator 876EG2 *or* Electrics (Part III)

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After getting the AC breaker box and converter installed and working, I set about getting our fridge in place and powered.  The 4-4 1/2 cubic foot fridge that we salvaged from our friends’ trailer was what we wanted in terms of a small three-way unit, but unfortunately, it didn’t work.  First, the controller card wasn’t responding, and even though the ammonia system was sealed and I could force the AC heating element to fire up and run, the fridge just wouldn’t cool.

Now, if you’re only used to our modern, AC, compressor refrigeration systems, the ammonia-based systems of a heat-powered system may seem odd. But they are super-quiet (aside from the occasional gurgle) and great for boondocking.

Here’s a nice introductory video on non-mechanical refrigeration systems:

If watching the video is too long for you, essentially the three-way (two electric heating elements or the LP gas heater) system works non-mechanically (no compressor to force-chill the liquid/gas coolant) to cool the interior of the freezer and fridge through heating ammonia to a gas, then taking advantage of the fact that it will condense back to a liquid and the chilled liquid ammonia will become the cooling factor for the freezer and the fridge.   Ammonia boils (and thus condenses back to liquid) at -28°F, which is more than enough to keep things freezing in the freezer.

Now, in getting a second-hand non-mechanical fridge system, there are some trouble-shooting things you need to do, unless the owner you’re getting it from can demonstrate that it definitively works.  One is to tip it on it’s back for several hours, then raise it up slowly.  This is done as an attempt to insure that all the liquids are back down in the reservoir so that the ammonia can be boiled off, and thus cool the interior of the fridge/freezer.  The other is to bypass the thermostat’s circuit board and put a heat source (like the electric heater that is installed on the unit or an LP source, like a low flame propane torch) to see if the ammonia will boil out and chill the system.

The most important part of the system is the cooling system, and many old fridges can be rehabbed by purchasing a new cooling system (most for around couple hundred dollars).  After I tested the salvaged unit for a couple of days and found no temperature change in the interior at all, I considered this, and started in to do my research, finding out that the shipping charges for these rebuilt/recharged systems can be costly.

It turned out that for us that a (relatively) local seller on Craigslist was selling a 6 cu ft Norcold Refrigerator (model 876 EG2) for about what it would cost for us to get the rehabbed cooling unit for the smaller salvaged unit.  And, the seller had it running and cooling when I came to pick it up, so I knew that it was good.  (He was also the one that threw the converter in for a song.)  This was a good deal, as a comparable new unit like one of these is much more expensive:   

The 876 model is a two-door unit, which was a change from the salvaged one, which had a small metal enclosure for the freezer that helped to cool the rest of the fridge.

The two door unit makes for a much more energy efficient and manageable freezer and fridge in terms of temperature.  You don’t get ice in the fridge area and the freezer stays really cold.

However, the 876 is taller and slightly deeper than the salvaged unit, which threw a bit of a wrench into my plans.  As you might remember from my floorplan, FloorPlans2 there was a covered window behind the fridge, as the fridge needed air space for the cooling vents, and for the heat and exhaust to be vented  outside in order to function.  One of the major reasons why absorption refrigerators don’t work has to do with insufficient ventilation and blockages in the heating system.

With the smaller, salvaged fridge, I had expected to cut vents into the skinned window and not have to cut the roof, even with the fridge sitting up over the wheelwell (I had expected to use the seat-rail as a support).  However, with the much larger 876, I would have to cut off the seat-rail, and rebuild the wheelwell cover in order to lower the fridge as much as possible, and then cut a vent hole in the roof.  I had also planned to cut vent holes in the floor to gain air flow and O2 for the LP burner, but with the depth and base construction of the 876, I wasn’t able to do that, so I would have to also cut into more of the skin of the bus in order to get good air flow (and I was nervous about both of these cuts, since I hadn’t done anything to the exterior up to this point!).

Now, I knew that the fridge cooled nicely on 12 VDC, and wanted to verify that it would run well on AC, and was upset when I plugged it in and got no response! But that was because the thermostat circuitry is all 12 VDC, and must have power to run so the AC can kick on the heating element.  Once that was rectified, I confirmed that the fridge would automatically switch from a DC source to an AC source (and back) when the AC was available for the heating element.  This is kind of a big deal as the electric heating elements are not as efficient as the LP burner, and when available, shore power is your friend for cooling.  The DC power is important for while you’re driving (and perhaps for regular running when all the solar panels get installed), and the LP is good for extended boondocking.

But before I could check and see if the LP worked, I had to replace the gas line from the solenoid and, as it turned out in dis-assembly and cleaning, a new burner.  The new burner was easily available  (though it used to cost less than it does now!) and needed a new compression fitting at the end of the tubing.

Luckily, I had bought a really nice set of tools for flaring compression fittings to redo the brake lines in my wife’s Daewoo, and it turned out that the gas line was a 5/16″ line that I had a bunch of, so I cut and formed up a new line that sealed up nice and tight, and all worked well.

Unfortunately, as the 876 had been pulled from an RV that had been sitting unused, it was from a unit that had been built in the late 80’s or early 90’s, and had this horrible beige padded covering that stuck out and made the fridge even that much bigger.  I had examined the doors and found that the hinges could not only be moved to the right side (from the left where they had been), but also that with the removal of one of the edges the padded facing could be easily removed and replaced with some stained oak plywood, which fit a lot better with our overall look.

I trimmed the existing wheelwell covering and removed the pieces that held it up.  Some 2×3’s built up a new floor for the fridge and then I could measure for the area that it would need for the air venting intake and then the hot air exhaust.  These presented some problem as the opening I wanted to cut would have gone right through one of the rub-rails.  I wanted to preserve these as much as possible so that the bus would keep as much of it’s structural integrity as possible.

To deal with this, I cut the skin between the rub rails to get the opening necessary for the air flow.  This was reckoned from the venting salvaged from the old trailer.  I ended up cutting down the locking casing for the smaller area so that I could get in and clean out the burner, then cut the vents so that the upper area could be screwed in place and sealed.  This makes it removable if necessary, but not with the ease of access of the lower area, yet also keeps the rub-rails intact.

For the top, I, with no small amount of trepidation, cut into the roof.  Three cuts allowed the roof to spring up above the reinforcing plates inside, and two triangular metal pieces for the sides created a nice opening for the heat to exit the bus and create a nice draft to pull cool air over the cooling fins of the fridge.  It has window screen over it to keep insects out, and will (eventually) get a nice sheet metal cover to keep the rain out.

Inside, the air was channeled to the outside by some wooden ducting, sealed with weatherstripping and screwed in place.  The actual flue from the LP burner would run up against the metal, keeping the burning hazard at a minimum, and allowing for plenty of air movement.

Wires were run for the DC and AC power sources and the fridge now runs like a top, even bringing some pop-ice sticks to a frozen state within a few hours.