(MONEY Magazine) – Our gadgets just keep getting smaller, faster, cheaper and better. Cell phones now have color screens and take pictures. Cameras have gone digital and can fit into an Altoids tin. MP3 players easily hold thousands of songs in a package about the size of a deck of cards. Even the cheapest laptop has more computing power than a supercomputer from just a couple of decades ago. But for all this progress, there's one key technology that hasn't kept pace: batteries. Five years ago you couldn't buy a laptop that could go a whole day without a recharge. And in 2004...you still can't. Simply put, batteries are the weakest link in most consumer electronics.

The problem isn't just that our gadgets run out of juice too quickly (and always at the worst possible time). Increasingly, they also rely on proprietary batteries that are expensive and often difficult to replace. So what can you do about it? For a start, when you walk into Circuit City or Best Buy, be prepared to ask as many questions about battery life as you would about megapixels or memory. But each kind of gadget presents a different kind of battery problem, with different solutions. On the following page, we'll show you how to get the most juice for your buck with digital cameras, MP3 players, cell phones and laptops.

Cameras When bulky is better

Canon's compact PowerShot S400 regularly tops the charts at Amazon.com. It packs 4-megapixel resolution into a body a mere 1.1 inches thick. The downside: It uses a proprietary battery. If you plan to travel with your camera or take lots of snaps, you'll want a spare. That costs around $45.

If buying a spare puts you over budget, don't be afraid to downgrade to a less expensive camera with, say, 3-megapixel resolution. The best camera is the one you'll use, not the fancy one that's out of power. Or if having a really small camera isn't so important, consider one that does not use proprietary batteries. For example, the Canon PowerShot A80 also has 4 megapixels. It's bulkier than the S400, but it uses cheap, rechargeable AA batteries sold at most drugstores.

Canon PowerShot S400

PRICE: $350 POWER ALERT: Want to carry a spare battery? It will cost you around $45. Alternative: The Canon A80 runs on AAs.

MP3 players The $99 surprise

Say you've had your Apple iPod for a couple of years, and you use it a lot. One day you discover it won't turn on. You charge it and charge it, but nothing happens: The battery's dead, and there's no way to pop out the old battery and pop in a new one. You'll have to send the iPod back to Apple to replace the battery, at a cost of $99.

The iPod battery isn't that great even when it's working--it needs a recharge in about eight hours. That's lousy for cross-country drives or long flights. Serious road warriors should consider the Dell Digital Jukebox, which is listed as having a battery life of 20 hours; some reviewers found the battery lasted nearly 23 hours before needing to be charged. If you just can't get over how slick and pretty the iPod is, Belkin offers a (bulky) booster pack that can run an iPod on AA batteries; it costs about $50.

Apple iPod

PRICE: $299 to $499 POWER ALERT: The price of one of the most expensive MP3 players on the market doesn't include the $99 you may have to pay if the battery dies.

Cell phones Read that manual

Think you pretty much know how a phone works by now? Read the instructions anyway--at least the part about how to maximize battery life. Different batteries have different, often quirky, requirements. For example, before you first use Motorola's MPx200 you're supposed to let the phone charge for a full 24 hours, and then let the battery completely run out once before hooking it up to its charger again. (This "trains" the new battery.) But with my new Treo 600 smartphone from PalmOne, the battery should never be completely discharged.

Improper recharging can easily shorten the battery life of any gadget. I once destroyed a $250 laptop battery by recharging it the wrong way; don't do the same to your cell phone.

PalmOne Treo 600 PRICE: $449 POWER ALERT: Unlike some phones, this one's battery should never be completely discharged. So make sure to read the instructions first.

Laptops Wireless? Ha!

You can watch DVDs on most laptops these days, but what manufacturers don't mention is that there is a good chance that the battery will conk out before the final credits. Laptop batteries keep getting better (usually by about 10% a year), but with every advance there's something new--like brighter screens or Wi-Fi cards--to suck up those improvements. In general, though, if being truly unwired is your top priority, look for laptops that use Intel's energy-efficient Centrino technology.

Perversely, the smallest, most portable laptops are also the ones that need to be plugged into the wall most often. But there are some exceptions: Toshiba's lightweight Portégé M100 runs nearly four hours, compared with two or three hours for the similarly sized Gateway 200XL laptop.

Gateway 200XL

PRICE: $2,030 POWER ALERT: It fits on the little tables at Starbucks but may go dark before your third latte. Alternatives: The $1,749 Toshiba M100. Or a bigger laptop. Note: Prices are recent offers from national retailers.