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91
Battery / Re: Lifepo4 charging
« Last post by Caleb on December 11, 2020, 07:28:00 am »
No, it still doesn't work.  I have to be signed up with an account that has access, but I don't have one of those.  I'm trying to avoid Google as much as possible.  :-\
92
Battery / Re: Lifepo4 charging
« Last post by CG on December 10, 2020, 08:02:09 pm »
Try the one above again. Does it work? Google keeps changing things. Drives me nuts.
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Battery / Re: Lifepo4 charging
« Last post by Caleb on December 10, 2020, 07:36:29 pm »
I can't access Googledrive files, but your description is pretty good.
94
Battery / Re: Lifepo4 charging
« Last post by CG on December 10, 2020, 10:15:45 am »
Another solution.
A cheap BMS for series connected cells.
It could be as simple as 6 dpdt switches with their toggles bolted together.
This will charge three cells "IN parallel" which will auto balance the cells. Then switch to "in series" to get higher voltage in discharge mode.

https://drive.google.com/file/d/1jsUqN_ju3MeCcUhk18xyG6ffMNqdyVcb/view?usp=drivesdk

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95
Battery / Re: Lifepo4 charging
« Last post by CG on December 10, 2020, 08:40:09 am »
I've been charging this 3.2v cell with a 7 v power source. Which produces about 280 mA.
The 'cell' itself controls the voltage in the beginning, turning the 7 volts into charging current. But it requires some baby sitting near the end as cell voltage rises and current goes down.
I'm looking for a wall wart supply that will charge the 3.2 volt LiFePO4 cell  with 12 volts. That way I'll get the 1/10th C charging current I need. Just need to turn it off when the voltage gets to about 3.6  volts. (Using the Triac circuit).




To eliminate the cell balancing act using multiple LiFePO4 cells in series, we could just use a single 3.2 volt cell and a dc-dc converter.
My single LiFePO4 cell is rated at 6000mAh and as the link below shows , the LiFePO4 cell has very high discharge rates.

It would be great if they could make the LiFePO4 cell in a 'flat pack ' shape , like cell phone Liion cells.

https://endless-sphere.com/forums/viewtopic.php?t=1773



FOUND IT>>>>>>>>     https://overkillsolar.com/product/lifepo4-cell-100ah/
96
Battery / Re: Lifepo4 charging
« Last post by CG on December 09, 2020, 06:20:59 pm »
So ....after charging and discharging this LiFePO4 cell a few times I'm starting to become a fan.
Not for cells in series though. They still require balancing and if not balanced one cell could be charged backwards. You could use them in series with balancing boards connected.
Still running tests on the one I have.
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Battery / Lifepo4 charging
« Last post by CG on December 07, 2020, 11:22:01 am »
98
Solar energy / Re: Worlds largest Solar farm HVDC transmission ??
« Last post by CG on October 25, 2020, 12:28:27 pm »
1 mile of 0000 copper is 0.2588 ohms, I thought it would be higher.
But copper may be too expensive. 100 miles = 25.88 ohms .724.64 ohms for the 2800 miles.  Aluminum is 0.3985 ohms. 100 miles would be 39.85 ohms.
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Solar energy / Re: Worlds largest Solar farm HVDC transmission ??
« Last post by Caleb on October 25, 2020, 10:48:39 am »
I think inductive losses get quite high when a transmission line is so long like that. 
100
Solar energy / Re: Worlds largest Solar farm HVDC transmission ??
« Last post by CG on October 23, 2020, 09:45:03 am »
I just wondered why they chose to transmit it as DC rather than traditional AC. Can't use transformers on that. But then again the farm would generate the power as DC and then have to be put through an inverter or motor/generator to get AC.
It's a toss-up, I guess.
Pretty big project. I would think they would want to use it themselves, but it may be the "end user" is  just renting the land for "their" project.
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