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.