Tesla Wants to Build a Battery for Your House

[Living Large]

Not my statement, That's Elon Musk's statement. Of course it's not believable. After all, everything he's ever said has been unbelievable right? Paypal, SpaceX, Tesla, Solar City. All unbelievable....

I don't doubt someone placed orders.

What I don't understand is how the batteries for home use will be able to be used, as discussed above in this thread.

Heck, I could have ordered some and put them in my basement when delivered. Then what?

[kwilcox]

Well, it appears that Tesla will (only) have an electrician install the battery. I can't speculate much more than that myself. Better to wait and see what empirical data comes from actual installations. I am intrigued however by the large number of utility scale orders.

[Living Large]

Well, it appears that Tesla will (only) have an electrician install the battery. I can't speculate much more than that myself. Better to wait and see what empirical data comes from actual installations. I am intrigued however by the large number of utility scale orders.

Installation by an electrician, a drunk neighbor, Santa Claus. That isn't my problem. A 350V to 400V battery with 50 cycles a year is what is giving me pause. I don't go to church very often, so I'm not big on acts of faith.

[Willy T]

I A 350V to 400V battery with 50 cycles a year is what is giving me pause. .

That must have come from Sun King.

Tesla, a world leader in the field of electric mobility, is an ideal partner on our way towards being able to use solar power twenty-four hours a day." The two companies have already been working together for some time in the automotive business area: Tesla uses Fronius welding systems for manufacturing its S and X models.

This sounds more realistic.

[Sunking]

10 kwh low cycle, 7 kwh high cycle. Same batteries. Different setup option.

That does not strike you as odd and smell fishy? I don't know of any battery chemistry, especially Lithium family that goes from 3000 cycles @ 70% DOD and drops all the way down to 500 cycles at 90-100% DOD. There are FLA batteries that have better performance curves.

[Ian S]

That does not strike you as odd and smell fishy? I don't know of any battery chemistry, especially Lithium family that goes from 3000 cycles @ 70% DOD and drops all the way down to 500 cycles at 90-100% DOD. There are FLA batteries that have better performance curves.

Does it make a lot of difference if the 500 cycles are over a short time vs a long time (i.e. 10 years)? I guess I'm asking what is the interaction among age, number of cycles, and DOD?

[pleppik]

Well, it appears that Tesla will (only) have an electrician install the battery. I can't speculate much more than that myself. Better to wait and see what empirical data comes from actual installations. I am intrigued however by the large number of utility scale orders.

It doesn't surprise me. Utilities have a huge gap between the cheapest and most expensive power they buy/generate. Customers pay something more like an average.

At the prices Tesla is offering, I expect the utilities will be installing these things all day long. They can save a bundle by charging the batteries from base generation and using the battery power instead of building peakers.

[Sunking]

Does it make a lot of difference if the 500 cycles are over a short time vs a long time (i.e. 10 years)? I guess I'm asking what is the interaction among age, number of cycles, and DOD?

Ian that is the million dollar question as each is a trade-off. Batteries have calendar whether they are used or not. They have cycle life vs DOD and they all over lap. A good example assume you have a battery, any battery with a Calendar life of say 7 years, 5000 cycles to 50% DOD, or 2000 cycles to 80% DOD. Capacity say 1 Kwh to make math easy. What do you do with it? .

Knee jerk reaction is 5000 cycles 50% DOD. But you would be wrong. In 7 years is only about 1600 to 1800 cycles and you are dead. Calendar life bit you in the butt. In that time you only get 800 to 900 Kwh out of it. Take it to 80% and you get the same amount of cycles before the Calendar clock runs out. Difference is you now get 1280 to 1140 Kwh out of it or 21% more energy over the same time period.

No where is what is really fish about Tesla claims. At 10 Kwh 500 cycles. At 7 Kwh over 3000 cycles. That might not sound fish to you, but stinks to me. Reason is you look at any of the Lithium chemistry they all have roughly the same ratios. Example say you get 1000 cycles at 100% DOD, at 50% DOD you only gain 50% or 1500 cycles. So if they claim 500 cycles at 100% DOD, one expects 750 to 800 cycles at 70% DOD not 3000 plus. 1000 cycles or double would be a quantum leap. 3000 is make believe.

It is not just me giving Musk the evil eye, it is the whole battery world calling it BS.

[kwilcox]

Well, I can't speak to the home battery (who can given the dearth of detailed specs), but I do know that the 85KWh battery in the model S is designed to cycle far more than 50 times per year over its 8 year replacement guarantee.

[Johann]

1 ton = 12, 000 BTU of cooling= 1hp
These don't really make sense with today's efficiencies but they come from the early days of refrigeration when belt drive compressors were used.
A 1 HP motor was needed to spin a 12K btu compressor that was now replacing 1 ton of ice.

Where did you get to the conclusion that 1hp=12,000 btu=1ton ?

1hp =745.6 watts
1 watt = 3.41 btu

745.6 x 3.41 = 2542.49 btu

1hp = 2542.49 btu.....not 12,000 btu or 1 ton.

[kwilcox]

It doesn't surprise me. Utilities have a huge gap between the cheapest and most expensive power they buy/generate. Customers pay something more like an average.

At the prices Tesla is offering, I expect the utilities will be installing these things all day long. They can save a bundle by charging the batteries from base generation and using the battery power instead of building peakers.

That's precisely why I'm intrigued because cheap storage will reduce demand charges for renewables. Autonomous grid based energy storage/delivery makes weather related peak generation calculations obsolete and delivers a grid that is renewable friendly.

[Living Large]

That must have come from Sun King. (50 cycles, 350-400V)

This sounds more realistic. (marketing talk)

I haven't drank Kool-Aid in over 40 years.

The 50 cycles per year for the 10kwh Powerwall, 350V-400VDC comes from Tesla, not Sunking.

[Willy T]

I haven't drank Kool-Aid in over 40 years.

The 50 cycles per year for the 10kwh Powerwall, 350V-400VDC comes from Tesla, not Sunking.

Then you know the difference in buying a emergency back up and something your going to use daily to time and power shift. Two different products designed to do two different things, both are for a Grid Tied System.

So why would it give you pause because they offer it for someone that has no use for a daily cycle product ? Thats like being concerned about Ford Motor Co offering other trucks than pickup trucks.

They don't hide the fact they have two different products with two different uses, nice to see some honesty.

Powerwall comes in 10 kWh weekly cycle and 7 kWh daily cycle models. Both are guaranteed for ten years and are sufficient to power most homes during peak evening hours. Multiple batteries may be installed together for homes with greater energy need, up to 90 kWh total for the 10 kWh battery and 63 kWh total for the 7 kWh battery.

[Alisobob]

I still dont get the use, or market for this thing.

Most homes have peak useage, in the evenings, when the family is home. ( Lights on, TV on, oven on, etc..etc..)

So this thing charges during the day.

Wait... Peak POCO rates are during the day.... and cheapest at night.

So when exactly am I supposed to charge this thing, and use it.... to use it effectively??

I also need the device, a AC to DC rectifier to charge it, and a DC to AC inverter to use it, so I'm really buying 3 devices, plus losing efficiency at every conversion step.

I'm sticking with Solar....

[Living Large]

Two different products designed to do two different things, both are for a Grid Tied System.

So why would it give you pause because they offer it for someone that has no use for a daily cycle product ? Thats like being concerned about Ford Motor Co offering other trucks than pickup trucks.

I have no interest in a grid-tied system. End of story. I have my dad's vacuum tube collection - equally useful technology to me.

If I needed a pickup truck, I wouldn't buy a box truck or church van on a Ford chassis.