Tesla's battery put in the shade by current and cheaper kit A couple more interesting details have emerged about Tesla's “game-changing” home battery, and it remains a moderately limp competitor that's done wonders for market awareness. Courtesy of Bloomberg, the world gets an idea of what the retail from-the-installer price of the battery might look like (rather than the wholesale …
It's just trendy tat to sell to e-hipsters.
Battery storage is supposed to smooth out the spikes associated with PV and wind, but it is pretty inefficient. New batteries will only give you around 80% efficiency at optimal usage. Worse when the batteries get hot/cold/old or the load is not exectly matched.
Pump storage has been used for the same purpose for decades, has similar efficiency to new batteries and has a better ROI.
The scheme I am most familiar with is
http://en.wikipedia.org/wiki/Drakensberg_Pumped_Storage_Scheme. This has been operating now for 34 years with only relatively minor maintenance and has the added benefit of being able too use surplus electricity to pump water into a different watershed for agricultural use.
Ahhhh, who from Wales could forget school lessons about Dinorwig Pumped Storage Power Station
@ Jamie Jones
Not just in Wales either, England too!
I was in a class which had a geography teacher as their form teacher for a few years. Every time it rained and was too wet for us to be turfed out onto the playground for our break, we were sent up to the geography classroom to watch a video. Unfortunately the geography teacher only had two videos. One on Dinorwig, the other on the Milk Marketing Board.
The problem is though, that this “game-changing” technology was lapped up by the technically illiterate media, instead of being greeted with the laughter which it deserves. This is the same ignorance and foolishness that brings us wind farms, solar arrays (hundreds of acres alone in just my local area) and all the other subsidy scams, robbing the poor to give to the rich and not a jot of "Global Warming" prevented. Wrong, wrong, wrong.
Late last year I replaced the battery in the UPS powering this workstation and I started wondering based on that. I'm not going to go through all the figures but to get to 10kWh using those cells would cost ~$2750 even assuming no bulk discount, and top name (Yuasa) batteries from a proper distributor. They'd have a five year life and 200-300 charge cycles so replace them twice as often and double the comparative price to $5500. Add the circutry needed to generate a mains approximation and we're somewhere in the same ballpark as that Tesla unit. You probably could get cheaper using a more sensibly sized battery to begin with but I'm not going to start optimising there, we'll simply leave this unit and lead acid batteries as being roughly comparable on the metrics used so far.
OTOH lead acid cells have quite incredibe power density - that single cell in my UPS can deliver 300W. A bank of 120 to store 10kWh would be capable of delivering 36kW on the same basis. Sure, you'd drain it in minutes at that load but if you need the 8kW shower, the 3kW kettle and 2kW oven all on at the same time for a short period the ability is there. And no, all those batteries wouldn't be absolutely huge, again in rough terms roughly a yard square and seven or eight inches deep - call it the size of a radiator.
This battery seems more of a desperate attempt to find new markets for Tesla's battery tech to cross-subsidise the cars. Sure, it's a nicely packaged solution but it can't cope with real requirements. Proven 1850's tech can for around the same money.
And if you go for some nice deep cycle car or truck batteries instead of the much smaller UPS batteries you absolutely phenomenal capacity.
A lead acid battery rated at 300 amps (not continuous) equates to 3.6kW for a single battery. And at lower power levels you'd get incredible duration.
I've got a small car battery dedicated to a 1.5kW inverter for emergencies. A friend had a black out a couple of weeks ago and it kept their TV and Playstation going for about a day before they got power back. The voltage afterwards was still 12.5v which is roughly 50%.
I was doing the same calculations when the article appeared on Slashdot, and other places.
Basically, it can't compete with a home-brew lead-acid system using established circuitry, well-known and replaceable battery tech (you could literally buy a new battery a week from the Halfords down the road once they start to run down), and something which people will already have in place if they have any kind of home renewable setup. Hell, I was looking at a 3KW mains inverter from 12/24V and they are in the cheap-commodity price ranges now because of all the solar nuts.
Just not sure what they think they are selling that's "new". Sure, different battery tech, etc. but it doesn't seem to add anything. If anything, it takes away (look at those charging cycle numbers, and the max surge output power! It's pathetic!).
I sympathise in that having a company solely reliant on high-end battery technology sucks at the moment. Because we just don't have anything beyond, quite literally, a bunch of laptop battery cells joined together. We just can't compete with that. And the only way forward is to either invent a new battery type that's revolutionary, or make the existing battery types cheaper by producing en-masse. But, sadly, neither option actually solves the problem or gets into the order of magnitude that we actually NEED.
More worrying, I would think for people who own their cars, is that if the company is really that reliant on batteries, you only need a tiny blip in lithium prices, or for such projects to fail miserably, and all that battery warranty comes to naught and one of the prime components of the cars becomes pretty much unobtainable.
Sucks to be an early adopter reliant on some magical, mystical technology advances that nobody has.
You are onto something, but there is a limit of how many lead batteries you can have in a given area, due to their weight. If foundations (and floors) of your home are not designed to take the weight of lead batteries in little space, you will be risking structural integrity of the building by putting too many batteries in one place. In other words, unless the building has been designed specifically for this, you cannot really make much use of this great energy density of lead batteries. Although of course, you can put these to some use and 10kWh does not seem like unreasonable figure - assuming this is not hung on a wall or put in tall tower on the floor with small footprint.
As for charging cycles, in case of lithium based batteries it actually depends on how much a battery ever gets discharged. If the limit is at 50% (as opposed to standard over 80%) then you can virtually cycle the thing in perpetuity, with only little loss of efficiency (say, 20% as opposed to 50% after 1000 cycles). I do not know how charge cycles are limited in lead batteries though, perhaps someone will enlighten me.
One Powerwall weighs about 100 kg. The solar panels on my roof produce during summer on average 14 kWh a day, with best days bringing in over 22 kWh. Meaning at least 3 Powerwalls of 7.5 kWh, or 300 kg _hanging on the wall_. A house where that kind of weight on a wall is not a problem, will quite likely not risk structural integrity because of a couple of lead batteries reasonably placed on the floor.
What kind of house do you live in where 300kg on a wall is a structural integrity issue? On plasterboard partition walls, yes. On structural brick? They can support the roof and upper floors without problems. 300kg, distributed allong a wall, isn't a serious load.
> What kind of house do you live in where 300kg on a wall is a structural integrity issue?
At least here in Florida all the houses are matchstick & tarpaper quality. I wouldn't trust 300kg on any wall including an exterior one. Hell, the outside siding is having trouble hanging on after only 10 years.
@ Bronek Kozicki "I do not know how charge cycles are limited in lead batteries though, perhaps someone will enlighten me."
I'm no expert but have been doing a lot of reading lately. It seems that lead acid is the same as your lithium batteries. A 50% discharge will give double the life of an 80% discharge and less discharge even longer life span. Apparently a 50% discharge rate will give the best lifespan vs cost. They say that cycle life varies from 500 to over 1000, but that's for premium batteries. I found a page with a good overview. One takeaway for me was this statement:
An important fact is that ALL of the batteries commonly used in deep cycle applications are Lead-Acid.
"then you can virtually cycle the thing in perpetuity"
No, you can't.
Lithium cells store best at about 66% charge.
They start degrading with time as soon as made even if not discharged. For off grid you need to store daylight energy for night time. So cycling is daily and perhaps 1/3rd discharge for new batteries and after a year or two that might be 50% of capacity as capacity reduces with use (and time for Lithium Ion).
I recently charged a New Old Stock 40 year old Lead Acid cell. It's fine because it was never filled with acid. Sadly today shops store Lead Acid batteries pre-filled, so check the date code!
There are really two main kinds of Lead Acid Gel cells. The UPS/ Alarm / Emergency light float applications and the regular cycling (portable lamps and inverters) were it's discharged daily.
They are more for standby or portable use at lower AH than 40AH
Gel types are poor at high pulse currents compared to wet,
There are several flavours of wet lead acid:
General Purpose
High pulse current (for starter motors). These don't like deep cycle. Typically 30AH to 200AH and 12V.
Industrial UPS standby. There may be a generator too. Much higher power than single PC / Server UPS.
Regular deep cycle (i.e. night time on off grid solar). Typically sold as 2V 200AH or larger capacity.
Only units subject to movement / vibration need fibreglass mat spacers.
They have different plate constructions. Life is shorter on all types if the battery is completely discharged. But this is perhaps more true of Lithium Ion. The NiMH in contrast can be stored discharged (better actually!) and don't have a problem with full discharge.
All types technology reduce in capacity with number of cycles, so for off grid night time use double the kWH capacity needed.
There are a number of good reasons why you"d not want to use lead acid (beyond just the weight).
Firstly, if you want to get more than a few hundred cycles out of them you need to limit yourself to not more than 50% discharge (30% if you want 10 years life out of them).
Secondly you lose power during charging lead acid (ignoring the losses in the charger circuitry) to the tune of about 15%
Thirdly you need a three stage charging circuit, and for the top 20% you need to trickle charge otherwise you knacker your battery life (as does NOT giving it a 100% charge).
The cost of a lead acid system may be lower in the short term, but it's more over the 10+ year lifespan we're talking about and produces some fairly noxious ewaste into the bargain.
produces some fairly noxious ewaste into the bargain.
Lithium Ion recycling, Oddly not Lead Acid, Most Lead Acid Batteries in Europe are easily recycled as new Lead Acid Batteries. The Lead can be essentially reused easily forever. Lithium batteries are far more energy intensive to recycle and don't last as long.
I can't find the site, but this week I read a fantastic analysis of the Tesla solution which included life, cost and carbon impact. It compared existing battery techniques vs some other solutions. The most notable thing was that they said the cycling of Lead Acid vs Lithium effectively gave you double the life. The carbon impact was less but it wasn't ground breaking. The basic thing is that Lithium batteries can be cycled more deeply than Lead Acid, that depth of charge means you need fewer of them for a given demand, because of the better cycling performance you can also make them last longer. So, Lithium ion gives you twice the life, a fair bit more expensive, but a good carbon footprint.
I further did my research and found I could build the Tesla system for the same or less. I might build it because I have an off-grid project, but it isn't a trivial build.
Using expensive, fiddly, light weight lithium batteries in an application like this where weight just isn't an issue is nuts. It's the kind of thing you sell if you can get away with it, or if you have got too many lithium cells not being used in your original market.
Using cheap, simple, any size you like, well understood, easily serviced, easily charged and recyclable lead acids makes much more sense.
"And the other 38% comes from"
Well if you can't be a***d to read the ref !
Nuclear, gas, biomass, hydro. ( I've got a German neighbour here in Switzerland and he often spouts off about how much cleaner German electricity production is " Mostly wind and solar" )
Greek bonds might well be biomass
I think find it hilarious (In the German meaning) that coal power plants emit magnitudes more radiation into the atmosphere than nuke plants...
It makes me so angry that some corrupt energy execs in Japan running crappy Gen II plants built in the 60's have ruined nuclear energy for everyone. Especially since those plants would have been safe if they even did something as minor moving the generators to the top of the hill, built up the seawall to match the plant further up the coast, or even just had a couple of truck-mounted generators stored in a safe place that could've been brought in. None of these would have cost all that much, probably about $1.5-2 million for the whole complex of four reactors, but they didn't want to spend it so the whole world is doomed to use fossil fuels to generate the bulk of our electricity...
They filter out all the nuke derived electrons at the border so that the volk only have untainted leccy.
This is done with a filter made from crystals ground up and suspended in pure mineral water. The nuke electrons have a different vibration and bounce off the crystal particles and go back to France.
This is the same technology Apple uses to ensure that they only use untainted sustainable leccy from the CA grid.
Well, that's what you get for having a wobbly coalition government. Decomming all the nuke plants to keep the leaf-munching luddites on message[1].
Looks like we might be about to get a taste of this arsehattery.
[1] A very strange leaf-munching luddite requirement that involves choosing lignite (brown coal - dirty as it gets) as your power source of choice. Makes you wonder which foot the German greens are going to shoot off next time they get their sticky paws on the levers of power.
50 load cycles a year??? Forget about price, forget about the 2kW max output. If this battery is supposed to store solar-energy during the day, and provide off-the-grid power at night (that's the way it was announced), then 365 load cycles a year would be required. Even an on-the-grid scenario where you only want to smooth out the peaks, in a location with lots of dark winter days, easily could require 200 load cycles a year - meaning you'd have to buy four times the capacity!
The bloomberg article states clearly that the intended use of the 10kWh is as a backup and not for daily use, hence the comparison with the generator. The 7kWh battery is the one designed for daily use...but it's not available yet since it currently doesn't make financial sense...so yeah...um...nvm
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Indeed , a decent gen set , the transfer panel , emergency panel , installation ( muffler , gas / diesel tank / natural gas/propane tank + electrical work ) , decent vibration damping and possibly a remote emergency panel will cost a heck of a lot more than 3699 $
The 2kW max load is not a problem if all of your domestic devices added together draw less than that.
(this is from the mirror so I won't include the link)
'The average power of a vacuum cleaner on sale in Europe is 1,800 watts. This will have to be halved within the next three years, as the limit of 1,600 watts will be reduced to just 900 watts from September 2017'
Hoovers will still suck.
Restricting the maximum load of a device will force designers to improve efficiency (at least at the enduser point).
Restricting the amount of fuel you can buy for a pound (by punitive taxation) has lead to the increase in mpg of vehicles.
My kettle is rated as 2.5kW, it boils a cup of water reasonably quickly but watch what happens when you turn it on, hot bubbles form around the element, detach and rise to the surface releasing some of their heat on the way up but most of the heat is given up to the atmosphere.
Any water left in the kettle cools quickly due to lack of insulation.
It can't be beyond science to have a 1.25kW kettle boil the same amount of water in a similar timeframe, if you restrict kettle elements then someone will find a way (and make some money in the process)
Neccesity (natural or artificial) is the mother of invention.
"My kettle is rated as 2.5kW, it boils a cup of water reasonably quickly but watch what happens when you turn it on, hot bubbles form around the element, detach and rise to the surface releasing some of their heat on the way up but most of the heat is given up to the atmosphere."
Most of that is dissolved air coming out of solution, and nothing to do with the heating.
"Any water left in the kettle cools quickly due to lack of insulation.
It can't be beyond science to have a 1.25kW kettle boil the same amount of water in a similar timeframe"
As James Joule convinced us many years ago, it takes a fixed amount of *energy* to raise the temperature of water to boiling, so twice the *power* takes half as long - assuming a perfectly insulated kettle, and that's the real point. A crappy uninsulated 1.25kW kettle will be no better than a crappy uninsulated 2.5kW kettle and probably worse because more heat is lost in the longer time to boiling. If you want rules about kettles, make them apply to the insulation, not the heating power.
Instead of restricting power to a specific input amount, would not a more sensible approach be to rate devices on the usable power, i.e their efficiency?
e.g. for a kettle, how much of the energy into the device, goes into the water, and is still there once the heating cycle competes? (i.e. Takes into account losses due to poor insulation).
Then set a minimum efficiency threshold. Say 75% to start with, then later 85%, then a few years later again 95%
That way people could still have their 2.5KW kettles, but their increased power simply boil the water faster, but with no more wastage than a same efficiency rated 1.25KW kettle.
I suspect the primary aim here by 'them upstairs' is not actually an increase in efficiency, they just want to reduce the peak load times when the advertising breaks kick in on the TV and everyone goes to make a tea/coffee.
I think you tend to hit a ceiling with efficiency. Physics dictates you can only transfer energy with so much efficiency given the properties of the materials used in the construction of the heat source and container. Trying to improve these probably falls into the realm of diminishing returns due to the need for ever more exotic materials for the heat transfer plus potential reduced safety. I mean, a metal kettle will conduct heat throughout its metallic body, and at least some of this heat will be lost to the outside air through convection and radiation (thus why the sides of the kettle tend to still be too hot to touch even if not directly exposed to the heat).
1. The bubbles are comprised of mainly air coming out of solution, these form around the element first and so are heated most and being less dense than the water surrounding them rise to the surface and escape into the atmosphere taking some of the heat with them.
2. In a fully insulated container a heating element of twice the power will boil the water in half the time (all other things being equal). I could boil the same amount of water in one tenth of the time by using a 25kW kettle.
Great except it would have lost a lot of its heat by the time I have located and rinsed a mug, put in sugar and teabag etc. It seems a 2 to 3 kW uninsulated plastic jug kettle boils water in the right timeframe.
I could change the order of the process but people have been doing it this way for years hence the phrase 'i'll put the kettle on' rather than 'I'll find some cups'.
I could use a lower power element in the current design but it would take too long to boil so if I can't increase the load (due to an external constraint) I will have to redesign the kettle.
3. As the OP points out it is a loading issue. (we're talking 2kW load here)
At the moment there is sufficient extra capacity in generation to let me use any amount of domestic power I like (subject to wiring/fuse constraints), this spare capacity that might never be used costs everybody to keep available.
If it wasn't available then I would soon learn to live within the limitation or provide my own when I want it.
If I never need it then why should I pay for all this infrastructure just in case you do ?
Did these people not even bother to read the press kit? The 10kW battery is designed for BACKUP ONLY and specifically says that it is optimised for WEEKLY charging - the 7.5kW battery is designed for DAILY charging. The comparison to the generator is laughable - because it's running off fuel - why even bother - that's like saying Solar panels are prohibitively expensive and it would be cheaper to run from a generator - well guess what - it would be even cheaper just not to bother with renewable energy at all and just take your electricity from the grid.....
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