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909
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# Posted: 23 Oct 2023 21:12
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Quoting: Steve_S I have 2x174AH, 1x105AH & now 4x280AH, all work happily & transparently with each other.
What voltage are you running. Are those individual cells or groups of batteries . I have 1 x 100 AH and 1 x 280 AH grouping in parallel to make 380AH but would like to move away from 12VDC eventually and build up to a 48V system.
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Steve_S
Member
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# Posted: 24 Oct 2023 08:25 - Edited by: Steve_S
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I run a 24V System. I build my packs as simple 8S so 8 cells, 1 JKBMS per pack.
Here are a couple of my resources which may be helpful to you.
Battery Building basic guide.
https://diysolarforum.com/resources/luyuan-tech-basic-lifepo4-guide.151/
General LiFePO4 (LFP) Voltage to SOC charts/tables 12/24/48V
https://diysolarforum.com/resources/general-lifepo4-lfp-voltage-to-soc-charts-tables- 12-24-48v.109/
This is my General System Diagram (currently out of date as I will update it when call completed next spring)
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paulz
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# Posted: 24 Oct 2023 08:52
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Quoting: Steve_S Paul, the 4 batteries are actually pretty darn good for being 12 years old. 99.2% SOC with cells at 3.30# is pretty close too, as 3.400 is 100% SOC. I do not see anything there that raises any flags at all.
Steve, thanks so much for reviewing my battery stats! those photos were taken after some charging yesterday. Here is first thing today, after all day and night running of fridge and modem, plus a couple hours of TV through the inverter last night, 13.0 has been the usual lately, will come back some after sun comes up. All batts will be about the same.
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Steve_S
Member
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# Posted: 24 Oct 2023 12:01
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3.25#Vpc should be around 60% SOC.
Grab this quicky chart of mine, might help...
https://diysolarforum.com/resources/general-lifepo4-lfp-voltage-to-soc-charts-tables- 12-24-48v.109/updates
Have you changed or modified any of your stuff ? New TV or other ? Anything new that can have a parasitic load you were not expecting ? Even a new LED TV when off still uses some juice.
Again, to my eye, nothing in that image is unusual or out of place.
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paulz
Member
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# Posted: 24 Oct 2023 20:15
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Thanks again Steve, and for the chart, I’m still in the green!
No recent changes to my daily use stuff; fridge, modem, TV, lights, water pump.. I did add a washer/dryer recently but only use it maybe once a week, and usually run a generator same time.
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paulz
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# Posted: 7 Nov 2023 13:52
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Hey, so I was checking out our TV, the only thing I use the inverter for usually. the cord has a power box that knocks it down to 19vdc. I tried 12vdc direct, no dice. Can I get a 12-19dc step up thing?
Would that save much juice over running it through the inverter?
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ICC
Member
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# Posted: 7 Nov 2023 14:39
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If the TV will operate on 19 VDC, you could use a DC-DC booster converter like this.... https://www.amazon.com/dp/B07VNDGFT6?ref=ppx_yo2ov_dt_b_product_details&th=1. That takes a wide range of input to a wide range of output voltages. The output voltage is user selectable by a little rotary 'pot'. It would likely have less loss than the inverter, but is that so critical that you would introduce another piece of equipment?
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gcrank1
Member
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# Posted: 7 Nov 2023 16:18
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How 'big' is your inverter.
Find the watts used by your biggest draw device; in this case the TV?, and upsize that by about 25%, that will be your inverter 'size'.
Example, for most stuff we are doing fine with a 300W psw inverter. If it fails I will probably up that to a 500W as the inv loss is similar between them. Far less than running a 1500W or more!
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paulz
Member
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# Posted: 8 Nov 2023 08:35
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Thanks guys. My inverter says 2500w, it draws about 25w plugged in. Turn on the TV, adds about 35w, total around 60w. Small potatoes, maybe not worth fussing over.
Neat booster ICC, will get one if helps. We usually have the TV on for 3-4 hours night.
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909
Member
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# Posted: 8 Nov 2023 19:29 - Edited by: 909
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I run a Bestek 500W pure sine wave inverter . It's just enough to run a small fridge / freezer combo , TV , all the lights ( 20 LED soffit lights ) , and charge laptops , power tool batteries, cell phones and tablets. It's small enough so it doesn't consume a lot of energy just being on. And since its indoors a smaller unit makes less noise. You can expect a 10% loss . 90% efficiency.
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paulz
Member
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# Posted: 9 Nov 2023 12:07
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I added 2-18650 batteries in series to a car battery, 20 volts, that runs the TV. Now if I could just figure out how to do that off my battery bank (4 12v in parallel) I’d have recharge..
It might run off 2 12v (24v) in series, haven’t had the guts to try.
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909
Member
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# Posted: 9 Nov 2023 19:58
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You can wire five 18650's in series for 18.5V nominal . Even fully charged you're only at 21V.
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paulz
Member
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# Posted: 10 Nov 2023 10:57
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Quoting: 909 You can wire five 18650's in series
Sounds good but keeping them charged could be an issue.
I understand no one will say it should run off two 12v bats in series (actually (26 Li volts). I may try it anyway, soon as I have a backup plan besides listening to my wife jabber all evening.
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gcrank1
Member
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# Posted: 10 Nov 2023 12:06
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I think in the old days you would stack some resistance to the higher than desired voltage (2xs 12v at 26ish) to bring it down to within tolerance. Nowadays there must be some basic adjustable thingie; like a dc to dc step down?
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paulz
Member
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# Posted: 10 Nov 2023 12:54
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Thought about that.. but I’ve ordered one of the buck converters ICC mentioned, see how that does.
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ICC
Member
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# Posted: 10 Nov 2023 14:46 - Edited by: ICC
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Quoting: paulz buck converters ICC mentioned
The item I linked to is a "boost buck" converter. A combination unit. That is, it can raise voltage higher than input (boost) or lower voltage output (buck). There are probably more plain buck converters than boost or combination boost buck.
-izzy
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ICC
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# Posted: 10 Nov 2023 18:00 - Edited by: ICC
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Oh. It does require some minor assembly. The upper and lower acrylic plates are not fitted when it arrives. Peel off the paper protection and then assemble with supplied spacers and screws. Top spacers are different length from the bottom ones.
-izzy
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Provolone
Member
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# Posted: 20 Nov 2023 07:46
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Sounds like you've got a hefty power supply with that Astron 50A. It should handle your needs well. As for using it with a MSW (Modified Sine Wave) generator, I've heard mixed opinions. Some folks say it's fine, but others recommend a pure sine wave inverter for sensitive electronics.
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paulz
Member
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# Posted: 22 Nov 2023 11:19
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Still waiting for that 12-19v converter, but not too hard.. what I did find was this smaller TV in my junk. Hung it closer to the bed, and surprise, the wife actually likes it better than the big wall mount. Best of all, it’s 12v, no inverter and less juice. Leaving the big one up for now..
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