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How much should you pay for batteries ?
#11
You wouldn't fully drain the 2000mah every cycle though would you? because you'll try to extend the lives of cells. so.. maybe 70% of 7.4Wh = 5.18Wh
Developing a sustainable farm and homestead. East coast of Australia
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#12
(03-16-2018, 01:06 AM)Spazmor Wrote: You wouldn't fully drain the 2000mah every cycle though would you? because you'll try to extend the lives of cells. so.. maybe 70% of 7.4Wh = 5.18Wh

Sorta correct. It depends on what you did the test on from low voltage to upper voltage. But, generally speaking, the tests are done from about 4.2V down to 3.2V or 2.8V (depending on the charger and your settings). Then use the voltages from 4.1V to 3.2V as the working voltage. So yeah, you use about 70-80% of the tested capacity. Thats why it's good to have about 1/3 more than what you actually would need.
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#13
Good read, thx all for posting. I’m not entirely concerned with competing with the grid, the environmental bit is big for me. I’m in Miami and I’m bracing for more hurricanes and more flooding, besides the fact that I hate messing with fuels and ICEs, the gas frenzy leading up to Irma was real. I for one love the modular nature of diy cells. I plan on one day converting a car and my boat to electric and I can then move cells around to power whatever I’d be using. The benefits are kinda endless for me.
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Her: omg I want that
Me:I can make that
Her: Dodgy
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#14
In my country, the grid cost is so cheap that it didn't justify to make all this powerwall or battery bank. No matter how you calculate it.

It is just for hobby and interest. And such hobby parts are expensive to buy.
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#15
If your country is subsidising the electricity then this does make your own power wall a difficult proposition. In the majority of other countries where the power cost is representative of the actual cost of production + supplier and distribution margin then pricing is starting to get to the point of being fully economic, for new cells..

Recycling used cells that still have plenty life left in them is a huge win for everyone if done right and the economics of using used cells, if they are cheap or free then this would make even subsidied electricity viable to compete against. Note "cheap"....

If you buy a solar panel at the current market price (wholesale rate) then your energy cost out of the panel is less than $0.02/kWh over the life of the panel. The down side is that if it costs $0.15/kWh to store that energy and release it again then this starts to be difficult to compete with, excluding any environmental consideration.

My belief is that using recycled cells for a powerwall is just as good in certain terms to planting a tree.....
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#16
(04-19-2018, 12:42 PM)completelycharged Wrote: If your country is subsidising the electricity then this does make your own power wall a difficult proposition. In the majority of other countries where the power cost is representative of the actual cost of production + supplier and distribution margin then pricing is starting to get to the point of being fully economic, for new cells..

Recycling used cells that still have plenty life left in them is a huge win for everyone if done right and the economics of using used cells, if they are cheap or free then this would make even subsidied electricity viable to compete against. Note "cheap"....

If you buy a solar panel at the current market price (wholesale rate) then your energy cost out of the panel is less than $0.02/kWh over the life of the panel. The down side is that if it costs $0.15/kWh to store that energy and release it again then this starts to be difficult to compete with, excluding any environmental consideration.

My belief is that using recycled cells for a powerwall is just as good in certain terms to planting a tree.....
My country is subsiding the energy as much as free for usage of not more than 200kwh/month. It mainly for the poor. With my average $0.06/kwh, it doesn't make sense to get into solar and powerbank. 
Mainly as hobby/interest. 
It is a joke in my country where produce 2nd or 3rd most solar panel in the world. We local have difficult to get a panel and the price is expensive.
But such subsidizing lead to people wasting the energy and resource, not creative and country development. 
Getting a new cells here is so tricky where market is floating with fake China product. The recycle cell from the laptop is not cheap too. While people mostly using clone laptop battery that not sure what cell is inside.
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#17
The economics for a powerwall with $0.06/kWh electricity cost would only make sense if it is to cover blackouts/loss of power and you value the lost power highly.

Solar could still work but if you end up exporting more than around 25% and do not get paid for it then it is not viable. Guessing you have a disc based electricity meter, which will spin backwards when exporting, so in theory, you could export the small amount and effectively reduce your bill. The economics at $0.06/kWh would take some time to recover your costs though.... more than 10 years..

That said I am also guessing the local utility would not allow this "if" they knew it was heppening.....
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#18
(04-20-2018, 11:48 AM)completelycharged Wrote: The economics for a powerwall with $0.06/kWh electricity cost would only make sense if it is to cover blackouts/loss of power and you value the lost power highly.

Solar could still work but if you end up exporting more than around 25% and do not get paid for it then it is not viable. Guessing you have a disc based electricity meter, which will spin backwards when exporting, so in theory, you could export the small amount and effectively reduce your bill. The economics at $0.06/kWh would take some time to recover your costs though.... more than 10 years..

That said I am also guessing the local utility would not allow this "if" they knew it was heppening.....

It is pretty efficient for energy supply here as average blackout occur once a year. At most twice. Only last 2-3hr. Which mostly happen during summer where people using aircon a lot. 

In my calculation if you save the solar system investment money in the bank, the pay dividen is much more higher than the investment. Nothing to worry and maintainance free. We do have grid tie solar program. But it not profit anymore and more favor to solar farm. Blame the utility company monopoly. 

Yes, it is illegal to supply energy back without proper authorities certified. For safety reason. I have done that before. It like reduce my bill most 7%/month. But as hobby/interest, that is nothing much to play around if put it into grid.

No matter how I calculate and reason, it is not economics to invest on it. Can't paid back at all. Unless some drastic $/kWh up and solar equipment price cheaper.
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#19
(03-11-2018, 03:36 PM)DarkRaven Wrote: That's what I've been saying almost from the start. And it's even more complicated because how do you value your time? How do you value the ecological impact? It's not easy at all to make a sound calculation that gives you a result that you can use to make up a definitive yes or no.

Paying for used batteries is already a bad start. You have to get them free or for a very low cost, we're talking about cents per piece. If you don't and pay the insane prices some people ask for then you have to increase the value you see in using reclaimed cells because otherwise this is already a bad economical decision before you have even started.
And then, if you decide to do it, you have to price in your work hours. Reclaiming 18650s is a very inefficient way to get cells to build some energy storage.

You can buy big cells today at 1.00 to 1.50 EUR per Ah that can be assembled into a battery in a matter of minutes and will give you thousands of cycles.

Could you share a link for such cells.
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#20
This makes me realise that although i spent about 4-6 weeks looking for cells, i found 180 laptop packs brand new in boxes unopened with an average of about 7 cells per pack (some 6, some 9, so 1260 total cell, at 2300mah each) for 300gbp! A bargain...! (so less than 24p per cell!)
have had very few dead cells (maybe 7 in 100 as an average so far)...

i think i need to find more at this price! seems buying in bulk is the way to get deals, too many people on ebay are selling 10's or 20's of cells for way too much.

the time aspect hasn't really been much as testing i have just been swapping batteries in the morning/evening and charging/leaving, the thing that takes time is pack building more than testing IMO.
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