When considering a jumpstarter purchase, consider a few points:

1: How much capacity do you need / weight do you want? The “marketing number” seems to be inverter wattage, but the useful number is battery capacity, in amp-hours. A bare minimum for jumpstarting engines should be 12AH, and look for 20AH if the unit’s likely to be cold while you’re using it. (Lead-acid chemistry is *very* temperature-sensitive.) Don’t be fooled by a high-wattage inverter mated to an inadequate battery.

2: Is the battery treated properly? All the jumpstarter packs I checked out at Harbor Freight were discharged, and had probably been that way since they shipped from China. Lead-acid batteries are damaged if they sit for long with less than 80% charge, and anything below 20% for more than a few hours is just murder. Also, does the charger have any sort of regulation to prevent overcharging if you leave it plugged in?

3: Is the battery replaceable? Even treated right, lead-acids in this type of service are only good for 4 or 5 years. The inverter, clip leads, and case will probably last much longer. Make sure the battery is a standard size, and that you can change it without having to glue the unit back together when you’re done.

4: Are the accessories built to last? If you’re looking at a unit with an integral air compressor, make sure the hose is stored thoughtfully. Cramped corners and tight bends will kill cheap rubber hoses, and they’re often a pain to replace. The last thing you want is a bulky, expensive, heavy unit whose bulk, expense, and weight are due to a failed or otherwise useless compressor. Are the jumper cables long enough that if a clip hinge gives out, you can replace the clip and still have some useful length?

5: How are the ergonomics? As this review points out, having the clip leads stored on the unit itself can be nice. Xantrex opts for separate leads that plug in, which is great if you’re primarily using the unit as a portable inverter, but would quickly get annoying if you’re just starting a lot of cars. Personally I’ve always found that the built-in lights are somewhere between useless and hostile, because they invariably shine at my face, rather than my work. Until someone puts a gimballed light in one of these, I’ll opt for a separate flashlight, thanks. I saw one pack with an integrated charger, normally a handy feature, but you needed a special narrow-nosed extension cord to sneak in and plug the charger in. All the weight of a wallwart, all the bulk of an integrated charger, all the clutter of carrying a special cord!

6: What’s the recharge time like? My brother lives in Buffalo, where heavy snow on still-leafy trees recently knocked out power for over a week. (From his own backyard, he could see *several* tree-meets-wire altercations. Multiply across hundreds of square miles and it’s no wonder it took the utility a long time to restore service!) He was running a laptop, a cellphone, and a carbon monoxide detector from his power pack at night, then taking it with him to the office (on a different part of the power grid) to charge during the day. Obviously, the more power he could replenish in 8 hours, the better! If the unit’s AC charger is a wimpy 1A wall-wart, that’s only 8AH, and because of Peukert’s theorem, only about 6AH of that is usable. Charging straight from a high-amperage DC source (like a running car) can be much faster, but is harder on the battery.