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Electricity I export to the grid during the day pays me 7.1c. Electricity I use at night costs me 22.4c. How many years payback will I face if I tear apart a Tesla? And what does that convert to as an investment APR? Show your working.
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Mar 23, 2015 13:08
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~Coxy posted:Electricity I export to the grid during the day pays me 7.1c. $101,500 to buy a new Tesla Roadster (why does everyone think the guy bought a car just to get the battery pack but whatever). Let's assume all the other equipment is free. It has a 53kWh battery and let's assume you can use the entire capacity. So every night you charge it from empty for 53*0.224 = $11.87 Every day you sell the power back for 53*0.071 = $3.76 For an annual profit of 365*($3.76-$11.87) = ($2,960.15) Assuming the battery pack will give you 5 years of service in this usage, your amortized cost for the battery is $20,300 per year, bringing your yearly profit to ($23,260.15). At the end of the 5 years, you will have made a profit of ($116,300.75). The payback period is therefore #DIV/0 years and your APY is -22.9%.
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Mar 23, 2015 13:33
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Vanagoon posted:So you could convert it to run the most gigantic combustion engine you can find. The purpose of this is to piss the hell out of the Tesla fan club, of course. Put in a redblock with a gasifier on it and run cedar chips. It'd smell fantastic. 
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Mar 23, 2015 14:46
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DNova posted:$101,500 to buy a new Tesla Roadster (why does everyone think the guy bought a car just to get the battery pack but whatever). Let's assume all the other equipment is free. Nope, I'm dumb, you go ahead. cakesmith handyman fucked around with this message at 22:05 on Mar 23, 2015 |
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Mar 23, 2015 22:03
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Cakefool posted:
I intentionally snarked it up by calling the losses "profit" 
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Mar 23, 2015 22:07
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Cakefool posted:
The brackets fooled me, too. I thought DNova was an idiot, and clearly, while there is a raging moron in this situation, it isn't him.
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Mar 23, 2015 22:46
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Good thing that guy left a paper trail online of his cool battery hack, so when he burns his house down it makes the insurance adjuster's job a little easier.
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Mar 24, 2015 00:25
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I wonder if he hosed with the charging circuitry at all. Li-Ion batteries have a nasty habit of exploding unless you have a ton of very specific and well-tuned circuitry gently stroking it and reassuring it like a cat made out of nitroglycerin.
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Mar 24, 2015 02:32
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It's almost like no one read the thread to see just what amazing, well thought out work he did.
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Mar 24, 2015 02:55
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Yeah you really should be able to tell just from looking at the photo up above that this guy has put enormous attention and thought into the project. The battery is from a totaled car, he didn't pay full price for the car OR for the battery. If you skim the thread for even like just two or three pages you'll rapidly come to realize that dude knows more about electricity and batteries than your average electrician.
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Mar 24, 2015 03:37
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some texas redneck posted:I may or may not have called the Texas Attorney General over one apartment I lived in, along with city code enforcement. I had a very similar conversation with the city when I was living in San Antonio. Fire ant infestation (that they were aware of and didn't treat before we moved in) shorted out the AC at the rental property I lived in. Took our landlord over a month to get around to even looking at it, in July. Even that only was only after we got the city involved and offered to fix it and withhold the cost from our rent.
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Mar 24, 2015 07:56
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Edit: nevermind, didn't notice the amortization in DNova's math, the actual operating profit/loss is smaller and makes my question pointless
Dylan16807 fucked around with this message at 10:43 on Mar 24, 2015 |
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Mar 24, 2015 10:40
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Please note my post was a direct response to the one above it. I didn't review the builder's website in any way.
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Mar 24, 2015 11:10
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Backov posted:It's almost like no one read the thread to see just what amazing, well thought out work he did. quote:Pairs of [battery] modules will be connected in series for 44.4V nominal @ 235Ah. 
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Mar 24, 2015 11:35
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According to the National Grid website, I use between 400 and 800 kWh per month. So he has enough juice in those batteries for 1-2 weeks of power. Less if he's a heavy user. That sounds about right for a fully off-the-grid home, actually.
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Mar 24, 2015 14:44
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I wish I only used 800 kWh a month.  I think our low record in the winter is about 900 - that's with a gas furnace, LED/CFL lighting in the entire house, very conservative thermostat settings, etc. Don't forget losses due to conversion. A really good inverter might top out around 85-90% efficiency when fully loaded (and dropping to 50% or less while lightly loaded), plus you're looking at a square sine wave instead of true with most inverters. Anything with a motor in it will draw more power than it would when on utility AC, if it's getting power from a square sine wave. This may also throw off anything that relies on a true sine wave for a clock (so a lot of AC powered clocks may be a bit off, especially an oldschool clock with a motor instead of electronics).
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Mar 25, 2015 07:33
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some texas redneck posted:I wish I only used 800 kWh a month. Are inverters STILL that bad? I looked a couple of years ago and there were plenty of smallish inverters (5-30kVA) that output 64-step sine waves with less THD than utility power, 95-96% efficiency at full load and 90-95% efficiency at light load. fake edit: Yeah, these things are still around, and the efficiencies are even better now, with cleaner sine waves and better frequency control. 98.8% max eff, with 93% weighted eff, 20kVA.
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Mar 25, 2015 11:41
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babyeatingpsychopath posted:Are inverters STILL that bad? I looked a couple of years ago and there were plenty of smallish inverters (5-30kVA) that output 64-step sine waves with less THD than utility power, 95-96% efficiency at full load and 90-95% efficiency at light load. Yeah I think some texas redneck has either only used car inverters, or solar inverters 5-10 years ago, both of which put out poo poo "modified" sine waves (IE square waves with a notch in them) and were 80% efficient at best. Good, long-term use installed inverters are much better now, though the lovely ones you buy for your car are probably still poo poo.
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Mar 25, 2015 15:50
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Old non power factor corrected computer supplies should actually run more efficiently on square wave inverters than sine or step, but motors are going to loving hate you for that poo poo and you shouldn't abuse them with square wave if you can avoid it in any way.
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Mar 25, 2015 16:14
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Yeah, you can run 120V DC into a lot of cheap PSU's and they won't even notice. Switchers are switchers. They don't need the 60hz for anything unlike linear supplies. That battery project is super impressive. We are fulltime RVers and have a somewhat middlin-tier battery bank, buncha 6v's in series parallel for 12V 440 AH. His poo poo dwarfs ours pretty hard, plus his engineering is top notch.
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Mar 25, 2015 18:03
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Some older units that run a 400VDC chopper input stage and use a bridge rectifier in normal mode for 240 and in doubler mode for 120 may get a bit pissy about that since the duty cycle will be real far from optimal on the chopper and/or buck boost converters, but yeah it will likely work. A square wave should work on any non PFC unit, and probably most intelligent active PFC units as well as long as they aren't assuming a sine in their power factor correction circuitry. on topic poo poo: I was hanging with my brother Monday night and he told me some stories of his ghetto apartment in Manchester NH. The place was wired for three and four way switches for the living room light, but some chucklefuck maintenance handyman had replaced them all with regular switches and swapped wires till it worked. As a result there were 3 switches that ran the light, and any of them would turn it off but they all had to be on to turn the light on. The best part? They didn't all face up when on and most weren't marked. It took quite a while to figure out how to turn the light on and why there were so many "dead" switches that "did nothing."
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Mar 25, 2015 18:38
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kastein posted:The place was wired for three and four way switches for the living room light, but some chucklefuck maintenance handyman had replaced them all with regular switches and swapped wires till it worked. As a result there were 3 switches that ran the light, and any of them would turn it off but they all had to be on to turn the light on. That's logic-puzzle level crap there. I was an electrican's helper-for-hire for a little bit before I got my license, and I showed up on a jobsite as they were trimming out. There were a couple other guys there. One guy professed to have his license, but the guys running the job didn't check. It was a hotel, and the job was to hook up all the room entryway lights. The door opens and there's a 3-way light switch, a small coatroom, and a bit of a partition with a 3-way light switch on the back of it. Both switches ran up to the light fixture above the coat-hanging area. All the wire was run, drywall up and painted, just waiting for devices and fixtures. The group of people that showed up were divvied into groups. One group would put in the entry 3-way, one would do the partition 3-way, and one would do the light fixtures. We started at different spots so we wouldn't be in each others' way. Lunch comes, and everyone's done, so we gather around for our paychecks. First, though, they had to check the lights. To the breaker panel they go, and click, clicPOW.... click, clicPOW. Every other breaker pops as it's energized. All the rooms on one side of the hall are shorted. WTF. Turns out the guy "with his license" had only EVER done control voltage work (AC/HVAC/Intercom) and had NO IDEA how to wire a light fixture. The back of the fixture was all NM cable, so the two travellers had to go together, the power had to go down to one switch, come back from the other switch and hit the light, and the neutral from the power had to go together. This guy had just twisted all the "colors" together, then put a red and a black wire (seemingly at random) on the light fixture. So black, red, blue, green were all jammed under wire nut, white unconnected to anything and folded back into the box, and a random red and black wire connected to the light. Note that green is one of those wires. Yep. He'd shortwired power to ground through switches (or not) in EVERY box. Needless to say, we all got an afternoon's work fixing that guy's stuff, and he was allowed to leave without a paycheck.
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Mar 25, 2015 20:57
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kastein posted:I was hanging with my brother Monday night and he told me some stories of his ghetto apartment in Manchester NH. The place was wired for three and four way switches for the living room light, but some chucklefuck maintenance handyman had replaced them all with regular switches and swapped wires till it worked. As a result there were 3 switches that ran the light, and any of them would turn it off but they all had to be on to turn the light on. But every day you get to feel like you're living inside a 90's-era bullshit Sierra adventure game!
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Mar 25, 2015 21:05
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Parallel Paraplegic posted:But every day you get to feel like you're living inside a 90's-era bullshit Sierra adventure game! I would honestly not be surprised if there was a Sierra game that included a puzzle of having to turn on the lights (so you don't trip over an end table and break your neck, thereby causing a game over) where the light switches made no goddamned sense and in fact were laid out in precisely the least intuitive fashion possible.
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Mar 25, 2015 21:33
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TooMuchAbstraction posted:I would honestly not be surprised if there was a Sierra game that included a puzzle of having to turn on the lights (so you don't trip over an end table and break your neck, thereby causing a game over) where the light switches made no goddamned sense and in fact were laid out in precisely the least intuitive fashion possible. Now all we need to do is find a way to re-wire the switches at random whenever you leave the house and we'll have the perfect lovely adventure game experience!
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Mar 25, 2015 21:38
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I don't know about that, but there was a Sierra game where your Clapmaster breaks and leaves a prong in the socket, and you have to find a safe way to remove the broken prong without killing yourself in the process. Everything I need to know about outlet safety I learned from Roger Wilco.
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Mar 25, 2015 21:44
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Another fun day at work. No idea how or why this car wound up down a dead-end alleyway behind some South Phila rowhomes, ending up at my insured's house.  Car's been sitting there, stuck in the house, since early February. The 2-tons of deck on the roof might be a reason.
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Mar 26, 2015 05:12
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Half Life had a ton of game-ending electricity puzzles, guys.
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Mar 26, 2015 10:19
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Wasabi the J posted:Half Life had a ton of game-ending electricity puzzles, guys. They mostly made sense, and it loving quicksaved and let you save at any arbitrary point with a key so I forgive it  (sorry for the videogame derail)
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Mar 26, 2015 14:24
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Wasabi the J posted:Half Life had a ton of game-ending electricity puzzles, guys. It also had a ton of scenery like this: Well, HL2, anyhow.
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Mar 26, 2015 14:39
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Bad Munki posted:It also had a ton of scenery like this: Bet there's a medkit up there... 
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Mar 26, 2015 14:51
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Wasabi the J posted:Bet there's a medkit up there... Time to figure out the physics puzzle, I guess.
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Mar 26, 2015 14:53
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Delivery McGee posted:At least they did something. My previous landlord took a week to get somebody out when the A/C crapped out in the middle of summer in Texas. Luckily I moved out a couple weeks ago before the place fell on my head. I own my new house (a 16x80 trailer, but it's been taken care of). There's only one small problem with the new place, the back stairs will loving kill you: They're steep because they are upside down. The good news is it won't take more than a couple hours and not more than $20 to fix. You'll need some construction hangers from Home Depot and another length of pressure treated 2x4 or 2x6 to run between the 4x4 supports, but you already have some sort of concrete footings there for the step down to the ground. At least that is what my rough eyeball math tells me. Worse case scenario is you have to buy (or make) some four step stringers and install them the correct way. How did they attach what they have there though - wood screws into the stepping surface on the inside edge of that top stair?
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Mar 26, 2015 15:31
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Antifreeze Head posted:They're steep because they are upside down. The good news is it won't take more than a couple hours and not more than $20 to fix. You'll need some construction hangers from Home Depot and another length of pressure treated 2x4 or 2x6 to run between the 4x4 supports, but you already have some sort of concrete footings there for the step down to the ground. At least that is what my rough eyeball math tells me. Worse case scenario is you have to buy (or make) some four step stringers and install them the correct way. He'd also end up with a really drat tall top step, or need to buy new, longer supports. Way it looks he'll need a couple more steps if he orients it right. Could be that there's some setback req's or something for the deck(?) and whoever built it didn't quite measure poo poo out, then bodged in the stairs at the last second. E: And yeah, looks like top step into side of deck. What is fulcrum  Meantime, it's probably a bit more of a crappy tool tale, but I ended up buying a piece of lend with a deck on it a while back, and....that thing is built like a loving tank  As in, you could probably park a couple Abrams on it and it wouldn't creak. Had to take a part of it apart, and in the process of pulling it apart, the floorboards would bend crowbars before giving way. We ended up with 3 of them bent at about a 30* angle by the time we were done. Quality wood held together by loads of 5-inch nails. Entire lot was left unattended for 15-20 years and that thing is still solid as a rock.
Naturally Selected fucked around with this message at 15:55 on Mar 26, 2015 |
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Mar 26, 2015 15:48
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Naturally Selected posted:Meantime, it's probably a bit more of a crappy tool tale, but I ended up buying a piece of lend with a deck on it a while back, and....that thing is built like a loving tank Don't buy your wrecking bars at Harbor Freight. I mean, I'm not just saying that as the usual "LOL HF" schtick. Really, HF wrecking bars are actual poo poo.
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Mar 26, 2015 16:09
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Bad Munki posted:Don't buy your wrecking bars at Harbor Freight. Didn't buy a single one of them, so didn't give too much of a poo poo.  Found a full demo set under the deck itself (2 bars+sledge+pickaxe), and bought one at a yard sale for a buck. I was just not expecting "35+ year old, neglected deck in the mountains" to be holding up that well.On the subject, though-I don't get the HF hate. I wouldn't trust them for tools that need precision or that get a lot of use, but having a shed full of HF crap just in case you need to do something once a year seems to be working out just fine. Hammer/drill/dremel, sure, I bought decent stuff. Reciprocating saw that I'll maybe use once in the next 2 years? I'll take the HF chinesium any day.
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Mar 26, 2015 16:24
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Yeah I have HF tools for the occasional home repair project and they work acceptably well. I will never buy drill bits / blades / etc from there though, the last time I needed to drill some holes in concrete, the cheap-rear end HF bit literally wore down to a nubbin in the FIRST hole.
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Mar 26, 2015 17:24
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Wasabi the J posted:Bet there's a medkit up there... You forgot one crucial detail: 
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Mar 26, 2015 17:57
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killhamster posted:You forgot one crucial detail: 
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Mar 26, 2015 18:37
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killhamster posted:You forgot one crucial detail: Took me a while, was expecting G-Man.
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