More 12-volt Tweaks — Computer Power Supply

I mentioned last time that I wasn’t happy with the efficiency of the 12V power supply I installed for running the lights, water pump, furnace, and a few other smaller items.  How bad was it?  Well, putting out 2 amps at 12.3V, it was drawing 52W from the wall outlet.  That’s less than 50% efficiency, and while it isn’t a lot of power being wasted, I expect this power supply to be on 100% of the time–so in terms of total energy wasted, it would account for a pretty big chunk.  At 5A output, it was a little better, but still needed 100W in (60% efficiency).  Could a computer power supply do a better job?

Continue reading More 12-volt Tweaks — Computer Power Supply

Cooking at the HDT Rally

It’s been a while since I’ve posted anything non-technical, and needed to share a few notes from a cooking seminar–geared toward cooking healthy foods in small spaces–I presented at the National Heavy-Duty Truck Rally in Hutchinson, Kansas a couple of weeks ago.

The audience at the HDT Rally seminar.  Credit for this picture goes to Sondra Kahanamoku.

First, let me start by saying that I’m no chef, by any stretch of the imagination.  This is my second time presenting the seminar, but the first was as a stand-in for someone better (John).  The second time was all me, and it probably shows in the more basic nature of what was presented–though I still think it turned out pretty well.  This post will cover some of the recipes and equipment used.  Apologies for the lack of pictures–I was talking and cooking the whole time, and food was being passed around the room as soon as it was ready.

Equipment

 

Anova Precision Cooker with Bluetooth

Before I start talking about recipes, let’s talk about some of the equipment I used.  Obviously, with sous vide recipes, a sous vide cooker was part of the mix.  I used an older Sansaire cooker (about $160 on Amazon now), but you can get a little better deal on the Anova model (with Bluetooth and a phone app, which lets you look at recipes and send settings to your cooker).

I hadn’t really planned to talk about them, but a set of utensils I brought along got quite a bit of attention.  The nesting set hangs from a stand with little magnets in the handle of each utensil, and there’s a ladle, spoon, slotted spoon, pasta fork, and spatula in the set.  They get used all the time, and go through the dishwasher regularly.  At about $20, it’s a pretty good deal.

Joseph Joseph Nesting Utensil Set

Appetizers

This time around, we made two very simple appetizers–a caprese salad and a buffalo chicken dip.

Caprese Salad

What’s a caprese salad? Don’t worry, there’s no lettuce involved.  All you need to get started are a couple of tomatoes, fresh mozzarella, basil, salt, olive oil, and balsamic vinegar.  Slice the tomatoes and mozzarella, arranging them in a row alternating between a slice of cheese and a slice of tomato.  Sprinkle some chopped basil (preferably fresh) on top, and drizzle with a little olive oil and balsamic vinegar.

Buffalo Chicken Dip

This one is pretty easy, but does require some heat.

  • Buffalo wing sauce (I prefer the Hooter’s stuff, as it tends to mix better.  You can get it at most grocery stores, but it’s also a good excuse to go to the restaurant!)
  • Cream cheese (2 8-oz. packages)
  • Shredded chicken (fresh chicken can be boiled, or cooked sous vide, or you can use canned chicken)
  • A bag of Frito’s Scoops

Mix the wing sauce and cream cheese, and either microwave or simmer until the cheese is soft.  Stir together, then add chicken.  Best served warm, and can be easily reheated.

Meats, Sous Vide

It’s been a while, but I’ve talked about cooking sous vide a number of times before (here, here, and here to get you started).  Working with an immersion cooker is really nice in an RV, particularly with meats that you’ve bought and frozen.  I usually keep a full freezer, and it’s easy to pull something out, drop it in the water bath, and walk away while it defrosts and cooks unattended.

At this year’s seminar, we cooked two meats this way–a beef bottom round roast and some tuna steaks.  Cooking this way, you can get a very uniformly cooked piece of meat, and especially with the roast, one that’s very tender without being overdone.  In either case, season as you’d like before putting the meat in a bag.

For the tuna, all you need is 105-degree (F) water, and about 15 minutes of cook time.  For the roast, you’ll cook for at least 8 hours, at about 130F, for a nice pinkish-red all the way through.  If you have more time, it’ll just keep getting more tender, without turning grey.

The only picture I took, after the seminar was over and there was some “clean-up” of the leftovers.

Bratwursts

Cooking bratwursts was a last-minute add-on to the seminar.  The idea came from Gregg (who runs RVhaulers), who bought an immersion cooker after last year’s seminar.

It’s a really simple idea, and makes less of a mess (and less heat) than boiling bratwurst.  Especially if you buy them vacuum packed, drop the bratwurst into 140-degree water for at least 30 minutes or so.  The bratwursts will be fully cooked, and then you can toss them onto the grill or into a hot skillet to brown the outside.  The flavor is richer, and they stay nice and moist.

Skillet Macaroni

  • 1lb lean ground beef or turkey
  • Onion (either chopped part of a fresh onion, or a couple of tablespoons of dried onion)
  • 1 can of stewed tomatoes (do not drain)
  • 1 can each of black and dark red kidney beans (drained and rinsed)
  • 1/2 of a packet of taco seasoning
  • 1 cup of elbow macaroni (whole wheat preferably)
  • Serve with sour cream and cheese on top.

In a large skillet, brown the ground beef and onion, but don’t drain off the grease.  Toss in the tomatoes, with all of the liquid in the can.  Add the rinsed and drained beans, taco seasoning, and the macaroni.  Cover, and simmer for 15-20 minutes, or until pasta is tender.

Serve in a bowl with a bit of sour cream and shredded cheese on top.

What else?

Hopefully there’s something here that interests you.  I’m planning on doing the seminar again at next year’s rally, so I’m looking for ideas and suggestions.  The goal is to present things that are a little different and fairly healthy, but easy enough to make in a small kitchen with ingredients that can be found just about anywhere.

 

More Electrical Changes

Last time I talked about this project, I left you hanging with the lead acid batteries from the old house power system gone, and the generator connected to the chassis batteries.  But I didn’t have anything hooked up to power the remaining 12V house loads–things like the furnace, water heater, water pump, slide out motor, and a few lights.

There are lots of ways to approach this, but first it’s worth knowing how much 12V power I really need:

  • Water heater: just control logic here, no actual heating.  It isn’t enough to worry about.
  • Furnace: about 8 amps running at 12V.
  • Water Pump: 4 amps just before reaching the high-pressure cut-out (in other words, when it’s under the heaviest load)
  • Slide out motor: 30 amps while in motion, more at the beginning when it’s sort of stuck in place.
  • Lights: since they’re all LED, not more than 10 amps.
  • Awnings: Just control logic here, and from what I can tell the only reason they use 12V at all is to power the on/off switch.  I may be able to eliminate the need for 12V at some point in the future.
  • A couple of power outlets (10A max each), an antenna amplifier, and a small sound system.

Other RVs may have other considerations:

  • Leveling jacks: I have them, but they’re driven by the chassis/starting batteries.
  • 2-way (LP, 110VAC) refrigerator: The control board runs on 12V on these.  Very little power needed, but the refrigerator doesn’t run without it.  If you have a 3-way (LP, 110VAC, 12VDC) refrigerator, you’re using 12V power not just to control the other two, but also to provide cooling–which is a significant demand.
  • Generator: Most RVs are configured to start the generator from the house batteries.  I talked about why I don’t like that setup here.

When you look at the list of things that need 12V DC power to run, almost all of it is stuff that only needs to run for short periods of time. So while it might work, I really don’t want a big DC power supply running all of the time.

I’ll admit I didn’t have it all settled when I pulled the old batteries, but I had enough of a plan to get by.  The slide-out was the biggest thing to deal with, and while I could in theory have wired it to run off of the chassis batteries like the generator and jacks, power for its motor and all of the lights in the slide out were fed in together–I didn’t want to try getting another set of wires into the slide out.

So the short term solution was pretty crude, but it’s still working just fine.  I picked up a cheap 12V lithium jump starter, that’s able to be charged while the main leads are energized.  It’s also not one of the ones with the smarts to limit current until the car’s battery is charged to a certain point, so it’ll work with no other battery in the system.

To test it out, I clipped the leads and connected them directly to the slide-out’s controller:

Battery jumper pack connected to slide out wiring.

This configuration has no trouble running the slide out through its full travel multiple times.  It’s micro USB charging port is more than enough to charge it and run the few 12V LED fixtures in the slide out.

For the rest of the 12V stuff, I’m using a 300W adjustable power supply.  I’m not quite happy with it, as it’s not nearly as efficient as I’d like, so there’s not much point in dwelling on it at this point.  It works fine, but I’ll post back when I have something better in its place.

With an extra set of leads, I now no longer carry the bulky SLA battery pack as insurance against a dead toad battery.  It just isn’t necessary any more–the lithium jump starter does a better job.

Which batteries should start the generator?

Ok–fair warning up front: this post is probably going to sound like a little bit of a rant. 

One of the high-current 12V loads I needed to figure out how to power as part of the 48V lithium-ion project was the generator, and if you’ve been following the lithium house battery project, you already know that I resolved the issue, at least for now, by connecting the generator to the chassis batteries.

While it may seem like an obvious solution in my case, it remains that most motorhomes are configured with their generator powered by the house–not chassis–batteries.  I’ve never liked that configuration, and I thought I’d take a few minutes to discuss why.

Continue reading Which batteries should start the generator?