Tesla Motors Announces a New Home Battery • Hacker News Board

Re: Tesla Motors Announces a New Home Battery

#101

Post by evgen » Tue, Feb 17, 2015, 2:35 PM UTC

chiph wrote: post #58

PanMan wrote: post #37

What would be the advantage of these LiPo batteries over traditional lead-based batteries? In car's, I understand weight (and volume) are really important, but for stationary usage these seem way more expensive / Wh stored?

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.

Re: Tesla Motors Announces a New Home Battery

#102

Post by CapitalistCartr » Tue, Feb 17, 2015, 2:35 PM UTC

I'd love to have a self-contained electrical system for my house. I'd preferentially wire my home with a DC grid alongside the AC, but there's no standard. Do I run 120v, 240v, 5v, 12v? Which interface do I use? Barrel connectors, USB, cigarette lighter? If we have a large-scale movement to household DC, we'd have these things hammered out without me rewiring every appliance.

If these obstacles were overcome, almost everything in my house could run on DC. Most stuff either converts to DC internally, or doesn't care.

Re: Tesla Motors Announces a New Home Battery

#103

Post by jacquesm » Tue, Feb 17, 2015, 2:37 PM UTC

lsaferite wrote: post #86

jacquesm wrote: post #73

Earlier quoted context omitted.

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.

Fair enough. But the pros/cons of each tech would need to be balanced against the $/Wh cost. Once the gigafactory is fully online I thought I'd read they were shooting to drop the pack cost in half? If that were true then it'd be 175 vs 100 and the pro/con list would be much more important, right?

No, the costs are better expressed in terms of price divided by total KWh stored and subsequently recovered over the lifetime of the battery.

So even if they can get the 'installed' price down to All in all this is extremely exciting because manufacturing batteries at this scale will surely lead to economies unseen before but Lead-Acid has an 80 year head-start and is very hard to beat when weight and density are not a major factor.

After all the one reason why we have Lithium-ion is because of weight and power density.

Laptop and vehicles have a lot in common that houses versus laptops and vehicles do not.

Re: Tesla Motors Announces a New Home Battery

#104

Post by jacobr1 » Tue, Feb 17, 2015, 2:39 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.

But presumably cost will be lower when the new factory comes on line right? Otherwise why built it?

Re: Tesla Motors Announces a New Home Battery

#105

Post by brudgers » Tue, Feb 17, 2015, 2:39 PM UTC

headShrinker wrote: post #60

brudgers wrote: post #23

So, where does lithium come from? It comes from the Earth, of course, but it doesn't require strip mining or blowing the tops off mountains like other resources do...most often, lithium is found in briny underground ponds. The liquid is pumped out and left to dry in the sun. TANSTAAFL https://duckduckgo.com/?q=lithium+pond+photos&iax=1&ia=image... Mining is mining. There isn't a "green" form. Tearing holes in the ear…

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 meter are a serious hazard to fire fighting personnel.

Solar panels are a particular hazard because the sun doesn't have a disconnect, many firefighting operations involve working on the roof, and fire burns upward. A collapsed roof may bring a tangle of live electrical parts down into the building and create a hazard that persists long after the fire has been suppressed.

In addition, miscellaneous loads applied to a grid can bring it down. In the Northeast US, much of the infrastructure is old and therefore less robustly engineered than elsewhere.

Re: Tesla Motors Announces a New Home Battery

#106

Post by rasz_pl » Tue, Feb 17, 2015, 2:39 PM UTC

headShrinker wrote: post #60

brudgers wrote: post #23

So, where does lithium come from? It comes from the Earth, of course, but it doesn't require strip mining or blowing the tops off mountains like other resources do...most often, lithium is found in briny underground ponds. The liquid is pumped out and left to dry in the sun. TANSTAAFL https://duckduckgo.com/?q=lithium+pond+photos&iax=1&ia=image... Mining is mining. There isn't a "green" form. Tearing holes in the ear…

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…

> because if you have batteries which cause a back flow during a power outage to the power station, an electrical worker could get shocked

What is the difference between Battery backup and a wind turbine/solar? Somehow you are allowed to have solar and pump back to the grid, but not battery, geee wonder why that is.

Re: Tesla Motors Announces a New Home Battery

#107

Post by [deleted] » Tue, Feb 17, 2015, 2:42 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.

[deleted]

Re: Tesla Motors Announces a New Home Battery

#108

Post by buckett » Tue, Feb 17, 2015, 2:42 PM UTC

Maybe having a battery pack like this at home would mean you could recharge your Tesla car much faster as you're not limited by the grid supply to your home? A bit like having your own Supercharger station at home?

Re: Tesla Motors Announces a New Home Battery

#109

Post by jacquesm » Tue, Feb 17, 2015, 2:44 PM UTC

davegardner wrote: post #99

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…

The same issue exists with grid connected solar panels. My solar panels are designed to stop working whenever there is a power outage. This is a legally mandated requirement here and is very annoying when it happens on a beautiful sunny day. A solar panel installer told me that if I add a battery backup to my installation, then at least it'll still charge the batteries during a power outage.

There are some ways around that limitation. The reason it exists in the first place is so that the power company can safely power down their lines without installations such as yours feeding power back into the lines that are supposedly safe. This on the off chance that you'll end up electrocuting a line-man, which makes good sense.

Of course, since your puny little solar installation is incapable of powering a substantial portion of the grid this usually only really becomes a problem when the section that is islanded is small enough.

Some electrical codes allow you to resume powering your own circuit if you physically lock-out your connection during such an outage, and re-configure your inverter to non-grid connected mode.

You will also require a battery in such a case since the stabilizing properties of the grid (it's a very large load and acts as a huge flywheel or capacitor with basically endless capacity from the point of view of your installation).

And of course when the grid outage has been dealt with and you wish to feed power back into the grid again (or consume when the sun is down) you're going to have to undo all of this.

When I built a solar / wind power installation in Canada I decided that the net metering laws and price of power produced by renewables was so low that I scrapped the whole grid connectivity portion and invested the surplus into a much larger battery.

It felt pretty good to have power when the island was down which happened many times every year.

Re: Tesla Motors Announces a New Home Battery

#110

Post by vidarh » Tue, Feb 17, 2015, 2:44 PM UTC

lsaferite wrote: post #91

skrause wrote: post #38

Earlier quoted context omitted.

All those are good reasons to also have your own power. You'll get your independence and might even save some money. But even then it's still good to be connected to the grid. It will serve as a backup line and if you produce more enery than you can consume, you might be able to sell something back to the grid.

And THAT is a primary reason utility companies are fighting grid-connected consumer solar right now. If you are grid attached you are part of the cost of maintaining the grid that is normally offset by your revenue to the utility. If you are just using it as a glorified battery backup by feeding in excess during the day and pulling during the night and you are a net zero to then company then your per-customer revenue…

Or you negotiate with whomever licenses you to be allowed to change your charges so that the maintenance is covered by a connection/subscription fee and usage is billed separately.

This is increasingly how utilities are structured in Europe: You have connection charges, and usage charges, and they may be due to different companies (though are often billed together via the provider you pay usage charges to).

This has come as part of breaking up utility monopolies so that people can e.g. pick "their" electricity provider (of course in practice this just means the providers settle overall relative supply between each other).