Tesla Motors Announces a New Home Battery • Hacker News Board

Re: Tesla Motors Announces a New Home Battery

#131

Post by it_luddite » Tue, Feb 17, 2015, 3:23 PM UTC

quarterwave wrote: post #57

I have home back-up power based on an inverter charging a lead-acid battery (located in a sheltered area outside the home), which costs about $100/kWh. Usage is about 1-2 hours discharge per day. No matter how well serviced, I've found these batteries don't last beyond four years. Hence I'd pay even $400/kWh for a well-engineered deep-cycle battery that is safe, maintenance-free, and will last at least 10 years. Excl…

check out these _types_ of batteries.

http://www.sbsbattery.com/products-services/by-product/batte...

no recommendation on the supplier, but funny thing, the power companies and telcos have already figured this out for reliable DC power :)

Re: Tesla Motors Announces a New Home Battery

#132

Post by sehugg » Tue, Feb 17, 2015, 3:25 PM UTC

phreeza wrote: post #85

alex-g wrote: post #76

Earlier quoted context omitted.

I wonder if this even needs to be something in the home. Wouldn't it also make sense to install these things, in bulk, in a place where they could service several homes? Say, at the block level. If it is part of power distribution infrastructure as opposed to a consumer product, then that simplifies some of the safety and maintenance issues; concerns like weight or volume are even less important if they are housed in…

This is being done. Power companies have shipping containers full of batteries hooked up to their grids. I have read better stories but the first thing I found googling just now is this http://www.abc.net.au/news/2015-01-07/ausnet-trialling-new-s...

That's still a pilot program, though. The Wikipedia article has a good summary of various tech and installed systems: http://en.wikipedia.org/wiki/Grid_energy_storage#Batteries

Re: Tesla Motors Announces a New Home Battery

#133

Post by GFK_of_xmaspast » Tue, Feb 17, 2015, 3:28 PM UTC

cjslep wrote: post #66

lsaferite wrote: post #61

Earlier quoted context omitted.

I wish sites would add automatic abbr tags to think like FWIW or, in this case, TANSTAAFL so those no in the know can easily mouse over and see what the hell you are saying.

"There ain't no such thing as a free lunch" from Heinlein's The Moon Is A Harsh Mistress , a highly recommended read.

It's most handy as a (weak) indicator of pomposity and / or libertarianism on the part of the user.

Re: Tesla Motors Announces a New Home Battery

#134

Post by maxerickson » Tue, Feb 17, 2015, 3:28 PM UTC

danielweber wrote: post #130

fche wrote: post #68

Earlier quoted context omitted.

A properly wired transfer switch fully cures that risk.

And even though the solution is right there, power line worker remains the ninth deadliest job in America. http://www.businessinsider.com/most-dangerous-jobs-in-americ...

On trip through Minnesota, I watched a helicopter ferry guys up onto the towers to work (they dangled from the helicopter and then transferred over to the tower: http://www.capx2020.com/ ). They were building the type of infrastructure the news says America doesn't know how to build anymore.

I wonder if energized lines are the big problem.

Re: Tesla Motors Announces a New Home Battery

#135

Post by chiph » Tue, Feb 17, 2015, 3:30 PM UTC

evgen wrote: post #101

chiph wrote: post #58

Earlier quoted context omitted.

Not a battery engineer (but my dad was)... Pros: Higher energy density, so you don't need much room for the batteries. They don't emit hydrogen when being charged like lead-acid does, so you don't need safety ventilation. Cons: Not as conveniently recyclable as lead-acid (there's existing infrastructure for this is already in place). The site isn't coming up for me (neither is google cache) but I'm wondering it they…

If you are going to count hydrogen emission as a problem for a lead-acid battery then you should be honest and point out that lithium batteries of all varieties have a habit of failing in spectacularly combustible ways.

Sorry - my last sentence wasn't dramatic enough. "Failure mode more like a fireworks factory burning, than the Hindenburg exploding"

Re: Tesla Motors Announces a New Home Battery

#136

Post by XorNot » Tue, Feb 17, 2015, 3:30 PM UTC

jacquesm wrote: post #73

lsaferite wrote: post #63

Earlier quoted context omitted.

I'd imagine in this case they are looking at the economy of scale they'll be able to gain when producing these out of the gigafactory. I'd be interested to see the $/Wh cost difference once it comes fully online.

Tesla batteries retail for $30K@85KWh, so approximately $350/Wh, Lead-acid deep discharge is about $10000/100KWh, so approximately $100/Wh. That's a pretty large gap.

Might want to check your numbers there. $10,000 / 100 kWH == $0.10 per Wh.

Which you absolute cannot get in any market. If you could, everyone would do it because the supply cost per kWh including replacement would beat regular power company power.

EDIT: Just went back over my old calculations for this. The basic problem is that you trade off against the cost of peak electricity, not your solar.

So you can essentially assume off-peak and shoulder power is used for charging, and then you use that to offset your most expensive period. The question is then "how efficient is charging" and "how many cycles do you get from the battery before replacement".

Even at $100/kWh, the math is a near miss rather then a clear win as far as I can tell still.

Re: Tesla Motors Announces a New Home Battery

#137

Post by mtrimpe » Tue, Feb 17, 2015, 3:32 PM UTC

jacquesm wrote: post #119

brudgers wrote: post #105

Earlier quoted context omitted.

Such regulations provide several types of protection to the public commons. Another group of people who are protected are firefighters. In a typical residential installation the power meter also serves as the service disconnect. Response protocols include pulling the meter before many other life saving and property preserving operations. Live equipment and conductors operating from a second source downstream of the m…

And last but not least: when disconnected solar panels are 'open circuit' and the voltages will rise very rapidly. You can arc-weld with two fully illuminated 48V panels in parallel.

It's also not a theoretical concern for disconnected panels either; my late father was consultant in a lawsuit where a small mechanical design flaw in the solar panel connector boxes combined with rough installation procedures caused farms all across France to go up in flames.

It's also not that strange considering the farms would often have 20+ panels generating multiple kVs worth of electricity. Afterwards he refused to put any panels on our home without having a proper micro-inverter installed.

Re: Tesla Motors Announces a New Home Battery

#138

Post by freehunter » Tue, Feb 17, 2015, 3:33 PM UTC

lsaferite wrote: post #92

freehunter wrote: post #87

Earlier quoted context omitted.

PLMATTMETJSOW. People Like to Make Up Abbreviations That Take More Explanation Than Just Spelling it Out Would. SMH.

Hahaha. I love how you end this with another one I had to look up.

Every time I see SMH (shaking my head) or MFW/MRW (my face/reaction when) or a handful of others, it makes me feel really old. If people didn't say it during a Quake match, it's not in my vocabulary. Darn kids these days.

Re: Tesla Motors Announces a New Home Battery

#139

Post by balabaster » Tue, Feb 17, 2015, 3:35 PM UTC

brudgers wrote: post #105

headShrinker wrote: post #60

Earlier quoted context omitted.

Also many municipalities don't allow battery 'grid-tie' with the option of 'off the grid' living. For example, Connecticut has laws which don't allow houses to have batteries that would allow a house to be self sustaining and have a connection to the grid. This is because if you have batteries which cause a back flow during a power outage to the power station, an electrical worker could get shocked down the road. The…

Such regulations provide several types of protection to the public commons. Another group of people who are protected are firefighters. In a typical residential installation the power meter also serves as the service disconnect. Response protocols include pulling the meter before many other life saving and property preserving operations. Live equipment and conductors operating from a second source downstream of the m…

Am I missing something?

When you trip the breaker, the power is still on as far as the box in your house - unless it's shut off by the power company, it's just off inside the house. When you have alternative energy sources that include batteries, the same thing applies. The power from your batteries still runs through your box/breaker (via an inverter), and onward into the house. If you shut the box off, the power is off inside the house, regardless of where the power is coming from.

What's the difference?

Re: Tesla Motors Announces a New Home Battery

#140

Post by phkahler » Tue, Feb 17, 2015, 3:37 PM UTC

When will homes be built with sensible electricity distribution? So often they put the breaker panel in the basement. I want a small utility room or closet where I can install inverters or this battery. I want to be able to run 220V to my stove, laundry, garage (car charging), battery storage, and AC relatively easily - none of these is in the basement (except the laundry in some home I've lived in). Also, if a basement floods, how is one supposed to go down there to access the panel without risk? And it's darkest down there too. It just seems to be the stupidest place to put it. What's up with that?