Originally Posted by cordelli
I'd opt for the second battery instead if it was cheaper. I find that way more useful then a power cord I can only use on an airplane.
Depends on where you're going. My next-to-last flight was NRT-ORD, 11 hours, and came too soon after SIN-NRT, 7 hours, to recharge the ones I would have used up on that leg. LAX-SYD, which I've flown both ways, is a few hours longer - and that return came right after CNS-SYD, again with no time to recharge at SYD. I'd hate to have to carry, to say nothing of pay for, enough batteries for anywhere the OP might go, now or in the future.
If your longest flight is a North American trans-con, which you can probably do on two batteries with reasonable energy conservation settings and shutting down during mealtimes and such, I'd tend to agree.