I generally figure about 10% loss for each conversion. Some inverters
and some power supplies will be better and/or worse.
So converting from DC to AC, you have roughly 90% of what you started
with. Going from AC to DC you'll end up with 80% of what you started with.
If you want 70 watts for 4 hours, or 280 watt hours, you will need ~~
560 watt hours of battery for a DC solution. That roughly equates to
700 watt hours for a UPS solution.
If you're using 12 volt batteries, your UPS could use anything over 60
AH per battery.
If you go with DC-only, you could get by with 47 AH per battery.
Your best battery choice is AGM. They can be discharged deeper than
most of the other types (gel, wet).
bp
<part15sbs{at}gmail{dot}com>
On 1/20/2015 3:50 PM, Josh Luthman wrote:
This will be indoors. I'm aiming to get 280 watt hours (70 watts, 4
hours) of run time. Is there any idea as to the inefficiency of the
whole AC/DC/AC/DC process?
