battery vs powered devices

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thehardway
thehardway Solar Expert Posts: 56 ✭✭✭✭
in Energy Use & Conservation #1
Hey folks, since I haven't hung out here a lot in the past this may have been discussed before, so if it was, just point me in the direction of the right thread.

When trying to cut back on electrical loads, there seems to be a instinctive desire to run things on battery you would normally put on grid power. What appliances and devices, of any, is it cost effective to run on battery vs AC power.

I'm thinking about things like clocks, cordless tools and appliances, etc. For example, beyond convenience, is it more efficient to run a corded power drill for 30 min or use a Li rechargeable cordless drill? Is a battery powered clock more efficient due to the lack of transformer than an AC powered clock? What is the annual cost to run an AC powered clock vs purchase of a disposable battery or a rechargeable.

Is using rechargeable batteries more efficient and cost effective than disposable batteries for the items you use batteries in? Share what you have on battery and what you power directly that could be battery powered.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #2
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    Re: battery vs powered devices

    It all depends. :D

    If you can get exactly the same performance from a DC device as from its AC equivalent and you can leave the inverter off then DC is the way to go.

    But if you're talking about having an inverter on anyway, it makes sense to avail yourself of its power since the self consumption is identical whether its loaded or not (standby mode not withstanding).

    As for battery vs. AC tools, if the output power were identical (mechanical HP) then the AC would be electrically more efficient because it removes the losses associated with charging/discharging the batteries. Again that is assuming the AC is there anyway. If it isn't, then it's like using a generator: starting it to recharge the batteries is more efficient than running it all the time so that the power is available when it is needed.

    You didn't think it would be simple, did you? :p
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  • icarus
    icarus Solar Expert Posts: 5,436 ✭✭✭✭
    #3
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    Re: battery vs powered devices

    For clocks I think it a no brainer. A rechargeable pen light battery might run for 6 months or more on a clock. I can imagine it BR cheaper on AC. The thing about cordless tools, the ease of use, especially for drills votes in favor if cordless, unless you have lots of heavy drilling, saws I have found not so much. The advantge of the cordless is that you can also load shif the charging to use what would ithe wise be excess PV. I keep a rack of batteries and on good days, charge as many as I can while the batteries are nearly full.

    Tony
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