*You’re around C/30 which should be on the high end of capacity. Lower load usually means a little extra capacity out of the battery. I realized that sentence might have been ambiguous.
From: dmmoff...@gmail.com <dmmoff...@gmail.com> Sent: Tuesday, August 15, 2023 6:56 AM To: 'AnimalFarm Microwave Users Group' <af@af.afmug.com> Subject: RE: [AFMUG] battery nerd question You can do the whole thing in Watts. 12V * 150ah = 1800 Watt-hours 1800Wh / 50W = 36 hours If they’re telling me 95% efficiency, I’d assume 50W out needs 53W in (50 / 0.95). There’s usually an efficiency curve for the device based on load and temperature so it wouldn’t be 95% in all circumstances. Your system should be drawing less than 5A off the battery, and if your multimeter has a 10A fuse like most do, then you could put the meter in line and actually measure the amperage before and after the converter. Then you’d know for sure. And the battery’s total capacity will have a curve based on C-rate so there’s some variability there too. Usually it lasts longer when you’re drawing lower amperage. You’re around C/30 which should be on the high end. Age and maintenance of the battery affect runtime as well. If I want 6 hours of runtime then I plan Ah for 12 hours runtime. When my batteries are halfway toasted I’m still getting useful life out of them. From: AF <af-boun...@af.afmug.com <mailto:af-boun...@af.afmug.com> > On Behalf Of Steve Jones Sent: Monday, August 14, 2023 9:57 PM To: AnimalFarm Microwave Users Group <af@af.afmug.com <mailto:af@af.afmug.com> > Subject: [AFMUG] battery nerd question Just trying to cipher runtimes I have on hand 150ah 12 volt batteries, so thats what id be looking to use. Excluding the conversion loss of a 12v to 48v step up converter is the math correct here? 12v 150ah=1800 watt hours 1800 watt hours at 48v = 37.5ah 50 watts of radio running 48v = 1.04 amps 37.5ah @ 1.04 amps = 32.77 hours runtime does a step up that claims 95% efficiency mean 95% of the watt hours?
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