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Thread: Some Final Thoughts

  1. #1

    Default Some Final Thoughts

    on Batteries.

    Batteries serve two purposes,, as storage to keep the lights and electric blanket on at night;

    and as a buffer during the day when the solar panels are providing their peak output, but the microwave, washer, dryer, compressor,,, welder, planer and table saw,, and everything else,,, are absorbing some, none,, or more than the available output of the panels. The battery makes up the difference, and charges if it's less.

    Day is when you are using your power,, in big chunks.
    Inverter capacity and sizing become critical, as well the the ability of your controller to squeeze every available watt from the panels.

    I spent several hours after viewing Will's presentation re-reviewing lithium battery availability and pricing.. There are indeed a lot of people getting into lithium battery storage,
    at levels that vary from Will tying 8 x 3.3V x 43 AH cells together to make a 24V battery,, to the massive storage installations going online in Australia.

    This is going to put the old time of day metering used by the electric utilities on its head,, where they tried to get you to shift your vacuuming to the evening, away from peak day use. Now,, of course,, the peak power is available during the day,, and the grid is on battery after sundown.

    My best efforts found new lithium to be at least 3x, closer to 4x, more expensive than lead acid pricing. I understand that if you take care of your lithium battery, it has almost unlimited life. And,, you can safely discharge lithium deeper,, so you need less of a lithium battery capacity to equal that of LA. And you don't have the weight,, annoying water usage, and some stinky gassing.

    Will talked about $600 for 2400 wh of lithium; I buy 11,340 wh of Golf Cart batteries at Costco for $800
    I've had very good luck with these,, but I've learned some lessons along the way. One thing,,, keeping the electrolyte level just over the tops of the plates really cuts down on gassing and water usage. I try to maintain a quarter inch cover.
    I haven't added water since December,, and my batteries get exercised a lot.

    Little things: We used to run the dishwasher when we went to bed. Now, we do it in the morning when the sun shines. I used to crock pot beans overnight,, now I do it in the afternoon when I have too much power. We turn the electric blanket on through the afternoon,, turn it off when we go to bed. If you have a dry bed,, you really don't need an electric blanket at night.
    It drops to a bone chilling 62F at night,, pretty consistently. The humidity varies more than the temperature.



    I have two banks of 8 x 6v x 225,, and am going to finish with a third. I will be back in the battery market in 2025,, with luck,, and fully expect that Lithium will have taken over the battery world.

  2. #2
    House SOB Little Corn Tom's Avatar
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    Default Re: Some Final Thoughts

    Excellent, practical analysis.

    BTW that is $70 per KWH for LA vs $250 per KWH for Lithium.

    And then there is the disposal / re-cycling issue. Do they really re-cycle LA in Nicaragua or just dump them in the Lake?
    Life's different here ... It's a whole 'nother pace.

  3. #3
    TRN Science officer bill_bly_ca's Avatar
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    Default Re: Some Final Thoughts

    But what is missing from many of the above is the power density.

    Amp hour to amp hour (as rated on the side or the data sheet ) for the two it would initially appear evenly matched in surface performance with LA 1/4 the cost for the batts.

    BUT

    Once you take the 5000+ cycles (50% discharge) for LiFePO4 vs the 2000 (typical 20% discharge) 700 is cycles (50% typical discharge) for LA. Then you have the agonizingly slow 80 to 100 % charge slope.

    So in essence you do pay 3x to 4x more and get 4 to 5 times the performance and life.

    All it really shows is that you can not buy LiFePO4's for a small scale use that has advantage over LA - (e.g just run lights and a small fridge etc etc)

    So for us to have 24V - 100Ah that is too float 10 AM with a 50% discharge over night would cost us the same to have 2.5X more LA batteries, for the same discharge density to preserve battery life the cost difference is negligible once you figure the maintenance and I can swap out 3.2V cells that are problematic at will rather than tossing the entire 12V cell.

    KWP - Did you price out some of the 80% remaining life batteries Will outlines in the one video? They were pennies per Kwh
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  4. #4
    House SOB Little Corn Tom's Avatar
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    Default Re: Some Final Thoughts

    Bill,

    I simply cannot agree with your math as any thorough analysis will show clearly that the battery life is a function of ionic water exchange due to the mineralization of unanticipated animal discharge (M / UAD) into the hydration of the lead acid (LAH) battery vs. the lithium ion.

    The conclusion should be obvious to the most casual observer.

    LCT

    Life's different here ... It's a whole 'nother pace.

  5. #5
    TRN Science officer bill_bly_ca's Avatar
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    Default Re: Some Final Thoughts

    This is what I was getting at.. Even if you used DI water 100% pure and blessed by the pope you still have to deal with this...



    This is for a Renesola rebadged LA battery - But all the other manufactures who post charge / discharge cycle data for their batteries (many do not) they are similar to lead me to believe it is a function of of the technology and not the brand or construction.
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    Para aquí para acá Jonh's Avatar
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    Default Re: Some Final Thoughts

    The geek talk is getting thick in here...

  7. #7
    TRN Science officer bill_bly_ca's Avatar
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    Default Re: Some Final Thoughts

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    Para aquí para acá Jonh's Avatar
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    Default Re: Some Final Thoughts

    Yeah, that.

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    Viejo del Foro Daddy-YO's Avatar
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    Default Re: Some Final Thoughts

    This was a very interesting discussion (up to a point).
    Bill, your cycle life vs depth of discharge chart is for 20C. How would that change for tropical temp's, like 35C? I suspect LA would look better and Li worse.

    All seems to boil down to upfront cost. One advantage to going cheap upfront is that in 5-10 yrs battery technology will have improved and be more economical. Buying time, as it were. https://www.wholesalesolar.com/blog/...ium-batteries/ has an excellent table comparing LA vs Li costs for solar power.

    KWP - an electric blanket just to dry your bed? Would a outdoor rack to dry the mattress in sunshine serve? Or, if raining, wrap in plastic - if dry when you get up - til you sleep again?

    And an electric dishwasher? Mine is Nicaraguan and has a Christian name. She's rarely what I'd call electric.

    Today every homeowner wants to get off the grid. It's become just another tax. The best first step to dodge these power brokers is better efficiency and conservation.

    An excellent recent article comparing all the Li-battery technologies out there is found at https://qz.com/1588236/ Check out their circular charts comparing energy, power, safety, Temp endurance, lifespan, co$t of the different types.

    IMO, high-temp liquid metals/molten salt batteries will be the future solution to grid problems, allowing smooth entry of renewable energy sources, into towns, cities, and nations. And a chance to redeploy most of that high tension copper cable.


    I never met a Semite I didn't like.

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    TRN Science officer bill_bly_ca's Avatar
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    Default Re: Some Final Thoughts

    Quote Originally Posted by Daddy-YO View Post
    I suspect LA would look better and Li worse.
    Yes - That is why meander on about the underground bunker - Although they _seem_ quite happy to 35/37... When they dug the shitter I threw a thermomometer down when they were at the 3 ' level and it was 68 f.


    Quote Originally Posted by Daddy-YO View Post

    And an electric dishwasher? Mine is Nicaraguan and has a Christian name. She's rarely what I'd call electric.
    If not the winning-est comment on the net I have read today, it is up there..
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  11. #11

    Default Re: Some Final Thoughts

    Quote Originally Posted by Jonh View Post
    The geek talk is getting thick in here...
    Starting to feel like NicaLiving . . .

  12. #12
    TRN Science officer bill_bly_ca's Avatar
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    Default Re: Some Final Thoughts

    Quote Originally Posted by KeyWestPirate View Post
    Starting to feel like NicaLiving . . .

    Solar with domed concrete
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  13. #13
    Para aquí para acá Jonh's Avatar
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    Default Re: Some Final Thoughts

    Not even close, KWP! No one’s claimed Marxism should provide free power to the people!

  14. #14
    TRN Science officer bill_bly_ca's Avatar
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    Default Re: Some Final Thoughts

    And in a Google twist my entire Google ad train is now Solar panels, charge controllers, batteries, 0ga cable crimps and heatshrink for 0ga cable this morning...
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    Default Re: Some Final Thoughts

    As I explained to my brother back in civilization "my dishwasher has boobs".
    Quote Originally Posted by bill_bly_ca View Post
    Yes - That is why meander on about the underground bunker - Although they _seem_ quite happy to 35/37... When they dug the shitter I threw a thermomometer down when they were at the 3 ' level and it was 68 f.




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