There are a number of factors that you need to consider, but you can get by with a pretty minimal setup if all you need to do is keep a relatively small e-cig battery going for a week. On our camper, I use a "lawn and garden" battery, which is adequate for a small amount of lighting for a weekend. It cost about $20, although I suspect the cost has gone up since I got it.
It is not a "deep cycle" battery, so every time I use it, I am abusing it and causing its premature failure. But at $20, I can afford to replace it every few years.
To extend the life, I have an extremely small solar panel. As long as I keep it pointed at the sun (meaning that I need to move it once an hour or so), it will almost keep up with our minimal use in one day.
If you're going to be near a vehicle, the easiest way to do it is to use your vehicle battery. Of course, be sure to run the vehicle occasionally so that it will start when it's time to go. If you need a USB port, you can get one to plug into your lighter socket for a few dollars. You can also get a small inverter, which will provide you with AC power. As noted above, this is extremely inefficient. Your vehicle's engine is designed to propel a ton of steel down the road at 60 MPH, so it's not a very efficient way to charge a small electronic device. And converting from DC to AC and back to DC also adds ineffeciency.
But since you have the car right there, the inefficiency is not important. You just want to charge your battery, and it doesn't really matter if you waste a few cents worth of fuel in the process. Now, if you are backpacking, then efficiency becomes a much more critical issue, since you don't want to lug along a bunch of dead weight.
If you're not going to be near a car, but weight is not an issue, then the easiest way to do it is to get a "jump start" battery. Again, if you run it down all the way, you are abusing the battery. But the cost is relatively low, so this probably isn't a big issue. Again, you can get a USB port that plugs into 12 volts.
If you're going to be in the deep wilderness, then a more high tech solution might be called for. I've never had occasion to need one, but the small LiIon batteries with a USB port seem to be quite cheap these days. Some have a solar option, which appears to me like it will extend the useful life, as long as you take the time to keep it pointed at the sun. Or just figure out how long each battery lasts, and bring along enough so that you won't need to charge.
Finally, for many applications, the humble disposable battery is a cost-effective option. Use 8 (or 9) D cells in series, and connect a lighter socket to it. Again, it will be more than adequate to power most 12 volt devices (including that cheap USB port). And when the batteries are depleted, you can simply throw them away. This would not be a good option if you need to haul out your own trash, but in many situations, it is extremely convenient.
It is not a "deep cycle" battery, so every time I use it, I am abusing it and causing its premature failure. But at $20, I can afford to replace it every few years.
To extend the life, I have an extremely small solar panel. As long as I keep it pointed at the sun (meaning that I need to move it once an hour or so), it will almost keep up with our minimal use in one day.
If you're going to be near a vehicle, the easiest way to do it is to use your vehicle battery. Of course, be sure to run the vehicle occasionally so that it will start when it's time to go. If you need a USB port, you can get one to plug into your lighter socket for a few dollars. You can also get a small inverter, which will provide you with AC power. As noted above, this is extremely inefficient. Your vehicle's engine is designed to propel a ton of steel down the road at 60 MPH, so it's not a very efficient way to charge a small electronic device. And converting from DC to AC and back to DC also adds ineffeciency.
But since you have the car right there, the inefficiency is not important. You just want to charge your battery, and it doesn't really matter if you waste a few cents worth of fuel in the process. Now, if you are backpacking, then efficiency becomes a much more critical issue, since you don't want to lug along a bunch of dead weight.
If you're not going to be near a car, but weight is not an issue, then the easiest way to do it is to get a "jump start" battery. Again, if you run it down all the way, you are abusing the battery. But the cost is relatively low, so this probably isn't a big issue. Again, you can get a USB port that plugs into 12 volts.
If you're going to be in the deep wilderness, then a more high tech solution might be called for. I've never had occasion to need one, but the small LiIon batteries with a USB port seem to be quite cheap these days. Some have a solar option, which appears to me like it will extend the useful life, as long as you take the time to keep it pointed at the sun. Or just figure out how long each battery lasts, and bring along enough so that you won't need to charge.
Finally, for many applications, the humble disposable battery is a cost-effective option. Use 8 (or 9) D cells in series, and connect a lighter socket to it. Again, it will be more than adequate to power most 12 volt devices (including that cheap USB port). And when the batteries are depleted, you can simply throw them away. This would not be a good option if you need to haul out your own trash, but in many situations, it is extremely convenient.
