The Holey Story Part II -> Searching For 128 Amp Hours
So, 2 days ago (in internet time) we left our intrepid boondockers in a 128 Amp Hour hole, with just the slimmest prospects of getting out. How would our adventurers elude this holey problem and find the amperage they so desperately needed before it was too late? Would Paul be forced to miss his football games? And Nina be forced to endure the prospect of Paul in such a horrifying state? Even our RV was morose and philosophical, throwing out the question “Oh, where are thou Amperage?”….
Well, we got some FABULOUS ideas from our blog followers. Jil suggested a bar (which, though it would not directly close the amperage gap would certainly ease the pain and give the whole problem a much more rosy outlook). Terry suggested hooking up the bikes to a hand crank generator and peddling our way out of the hole (a suggestion I personally REALLY liked, especially with Paul on the bike). And Bob suggested one less football game (which seemed totally logical for me but was, of course, horrifyingly unthinkable for Paul).
Well, having strung out the suspense for as long as I possibly can, I’ll go through our thinking on how finally we solved our dilemma. We had 3 brilliant ideas for the gap, and it turns out the easiest and bottom line cheapest was the best solution (isn’t that always how you want it)?
1/ Go DC On Everything
In every RV there’s stuff that runs directly off the DC current from batteries (lights for example) and stuff that requires you to turn on an inverter to create an AC current (like TV/internet/electronics). But if you look deeper you’ll find that you don’t really need the AC. Look at the back of your computer charger, for example, and you’ll find that although it takes in AC current it converts it to a DC current which is what the computer actually uses (for example the output on mine is 19V, 4.74A DC). So, instead of doing the whole silly DC->AC->DC conversion why not just mount a bunch of DC plugs, run everything directly off your DC batteries and get rid of the need for an inverter altogether? It seems like a great idea, but the numbers will tell you otherwise!
Expected Costs. Costs for this project are waaaay higher than you might expect. Not only do you need to install a bunch of new DC plugs (we’d need 5 in various locations for our TV, satellite, 2 computers, internet router), but you’ll have to run new, thicker wires to those plugs (since the existing wires in your rig are not meant to handle higher DC current) PLUS you’ll need to buy DC to DC converters for all your electronics (since they all need a regulated DC voltage). Even if you do the installation yourself, a typical DC->DC converter costs anywhere from $30-$85 (e.g iGo Laptop Travel Charger), not to mention costs of wiring & new plugs. You’re talking at least $300. Add-in labor time/costs and this number will be much, much higher.
Expected Amp Hour Savings. In this scenario you get rid of your inverter. So savings are inverter usage = 2.5 Amps = 25 Amp Hours over a 10 hour period.
Bottom Line. It’s alot of money and time for very little savings. You use $300 and save only 25 Amp Hours = $12/Amp Hour saved.
2/ Dedicated, Smaller Inverter
We have a massive honking 2000 Watt inverter in our rig. It’ll run everything we have including our super-amp-sucking microwave, but it doesn’t need to be that big if you’re just running electronics. Why not buy a small, dedicated inverter just for the electronics and save some power?
Expected Costs. A small pure sine-wave inverter costs anywhere from $150-$300 (say the Xantrex PROWatt 600). We would keep our old inverter for the big stuff, so we’d need to do some additional AC wiring for this project too.
Expected Amp Hour Savings. Our current inverter runs ~2.5 Amps/hour. The new inverter would run ~0.5 Amps/hour. So, you would save 20 Amp Hours over a 10 hour period.
Bottom Line. Savings are still way too small to make a difference especially if we add-in the costs/time of getting more AC wiring done. At a minimum we use $150 for only 20 Amp Hours of savings = $7.5/Amp Hour saved. Better, but not good enough…
3/ Get a New TV
The new LED TV’s are nice, and as it turns out for this project they are REALLY nice. They’re thinner, lighter and use a ton less power. Could such a simple solution really make sense?
Expected Costs. A new 32″ LED TV costs anywhere between~ $400-$500. Since our old TV had a custom mount, we’d need to buy a new “universal” mount for another ~$50 too. However we expected to make some money by selling the old TV.
Expected Amp Hour Savings. Here’s the shocker of the story. When we looked at the specs we realized our old 32″ Sharp Aquos LCD TV was running a massive ~175 Watts. The new LED TVs, many of which are Energy Star compliant only run ~60-75 Watts. That’s a HUGE savings of minimum ~100 Watts or ~80 Amp Hours over a 10-hour period. Plus there’s no need to run any new wiring and the new TV would fit directly into our old TV cabinet. A little modification needed to add the new mount, but nothing compared to the other solutions out there.
Bottom Line. For ~$450 we could get 80 Amp Hours of savings giving this solution a cost of ~$5.5/Amp Hour saved. Definitely the route to go.
4/ And The Final Results?
Well it turned out better than we expected. At the time we were shopping Costco had a deal going on a new 32″ VIZIO M320VT for ~$400 (all in). Paul got the Peerless PT640 Universal Mount on Amazon for $50 and we saved $120 by selling our old TV on Craig’s List (sold in half a day). Total cost = $330
And the Amp Hour savings? They were….wait for it….10 Amps/hour (as measured by our Xantrex LinkLITE) . Total savings = 100 Amp Hours over a 10 hour period. It’s not quite the full 128 Amp Hours we were looking for, but it’s darn close.
Bottom line we used $330 and saved 100 Amp hours = $3.3/Amp Hour saved. Not bad at all.
And so ends the holey story and everyone lived happily ever after….well, until Paul gets another one of his geeky ideas anyway.
I was in the middle of checking out the power usage of the Vizio LED compared to the ol CRT but you beat me to it. But you could also save more if you would have bought it at Wal Mart for $349 which would make your cost per amp hr cheaper. Good wright up!!!!
That Walmart deal is a good one! They weren’t offering it in our area at the time we looked (and the 32″ was “out of stock” on their internet site). Costco was base-price $369 at the time we bought, rounding out to ~$400 with tax. Unfortunately even the Costco deal is out of stock now too.
Nina
Sorry forgot to mention we also found a 26″Vizio LED at Wal Mart to switch out the bedroom CRT for the supper price of $189 last year. So our TV’s really save us a bunch of power.
Wayne
VERY nice deal! It doesn’t look like Walmart is offering that size anymore unfortunately. Everything below the 42″ “sweet-spot” is becoming harder and harder to get.
Nina
the formulas he will come up with just to upgrade the TV…
I know…unbelievable isn’t it 🙂
Might as well have been reading French. Maybe someday I will gain one tenth of your knowledge. Until then, three words…Full Hook Up!!
LOL…many would agree with you, I’m sure 🙂
Nina
I have no idea about all this talk about AMPs, but I do know a good job when I see one. GREAT job, Paul. That TV is so big, you will feel like you are at the stadium watching the game. Enjoy!
Thanks. He was rather proud of it…as you can tell 🙂
Nina
I read the whole thing with my head, but you lost my heart at “football.”
For me too…but the geekiness just sucked me right back in…:)
Nina
This is the geekiest rationalization for getting a new kick-butt TV to watch sports that I have every heard! – I love it!! Now, can you guys work on a similar geeky rationalization for a new margarita blender, please!!
I have to admit I DID think it was a rather sneaky way to get a new TV. I’m such a push-over for a good geek arguement.
Nina
OK so, I was a little “off the mark” with the “one less football game” suggestion. I thought it made total sense. Should have clued in to the big gaping hole in the mill-work though. Duh.
Anyway, NICELY done. Good fit. Looks great. And OH, you forgot to somehow calculate fuel savings by all that weight you saved! Ya right. Whatever.
So while I’m on a roll here….I just have to comment on the price of TVs these days. It blows my mind how cheap they are!
I recall many years ago (would have been maybe in the seventies) my dear ole Dad feeling the need for a new TV, and feeling all good about getting a 27 inch Magnavox (I think). It was a fine television and lasted for years.
But here’s the thing. He paid over a thousand dollars for that TV!! This was in like, 1975! That’s what, about a million bucks now?? OK, maybe I’m exaggerating, but not by a whole lot. Even though it was a CRT, this was still a TV you could pick up with one hand. (Well, so long as you weren’t a frail 90 pound weakling of course. But still, not a big TV.)
I think I pooped a little when I saw the bill.
It ended up being part of my “inheritance” when the ole man died, but that’s another story.
It IS amazing how the price (and size) of electronics has come down. Remember those huge “brick” cellphones too? Much has changed in just a few years.
Nina
Yay!
Where there is a will…..there is a way…..and if there is a way….you will find it:)
You guys are a total hoot! Thanks for the incredible tale of “Holey”
LOL
Hec
Glad you enjoyed the tale 🙂
Nina
I’ll have to admit, one of best ideas for getting a new tv! Now if I buy 3 tv’s, will I save 300 amp hrs per day?
Well as Einstein so famously taught us…it’s all relative. If you’re running three 32″ LCD Sharp Aquos TV’s (all on at the same time for 10 hrs) and you switch to running three 32″ VIZIO LED TVs (all on at the same time for 10 hrs), then yes indeed you’ll save 300 Amp Hours 🙂 Then again, unless you’re a MASSIVE football fan and have managed to squeeze said TVs into your rig, then you’ll likely save less.
Nina
Well done … although way above my geek understanding. Would you not also have generator power to help top off your battery needs.
Well we do have a generator, but we call that cheating. Our goal is always to run 100% off our solar. For the sheer geekiness of it, you understand 🙂
Nina
Hehe! Not only informational, but well written and entertaining as well. Thank you Nina for brightening my day. 🙂
All the lingo meant nothing to me, but Wayne understood it all! We’re not solar powered yet, but plan to when we go full-time. We also plan to buy a new TV for the 5er this year, so thanks for the heads up on the LED TV! I love all the details in your posts, I feel like I’m taking a class!
Nina, I saw your comment about microwave failures over on Technomadia and decided to respond in this post because it touches on some of the same issues.
You definitely do not want to run microwaves on MSW inverters. Some other things that will either not work or will be destroyed by MSW are induction cooktops and electric blankets. Some wall-warts will get warmer than normal. Lastly, anything with an induction motor in it, such as a household fridge, air conditioner, or some air compressors and power tools will use more energy and have shorter lifetimes on MSW power.
By contrast, most “electronics” such as computers, TVs, network routers, etc. (and basically anything else with a switching-mode power supply) do just fine on MSW power and do not need pure sine. So in reality, you are better off having a pure sine unit for your large inverter, and a small MSW unit to run your electronics if you don’t want to leave the large unit powered up all the time.
On this last point, I will also note that larger inverters will very small loads are more efficient than small inverters with large loads. So if you need to run, say, 300 watts of electronics, you might find it uses less battery power to run them from your 2kW inverter than from a little 300-watt unit. All inverters are different, of course, so the only way to be sure is to measure the DC draw using a quality ammeter.
HTH,
-Sean
(aka “that electrical guy” on the bus conversion forums)
Thanks Sean,
I was pretty convinced it was the inverter that had fried our microwave, and you’ve just confirmed it. Good to know.
By the way…interesting coincidence…I spent a few hours last night catching up on blogs and was at your site for most of it. Realized you guys are on the West coast shopping for boats. Exciting stuff!
Nina