Making an external batt pack for my camera

My Panasonic DMC-FZ50 uses a little proprietary battery, which looks like it holds a pair of 16340s in series. I've had this camera for a little over a year, and both the original batt and the no-name spare I bought on eBay seem to have less capacity than I remember. I don't know if they're actually losing capacity or if it's just my perception, but it's no fun. The DC adapter is only available from Panasonic for something like $70 or thereabouts, so that's out as well.

However, I've got a multi-voltage DC adapter with various and sundry plugs, and I've found that one of them fits the camera's DC jack, other than being a little too narrow to make contact with the negative outer terminal. So, I'm going to add some bulk around that plug and make it easily swappable between that multi-voltage adapter (which can indeed power the camera) and a big ol' batt pack, like 6D NiMHs or something. Muahaha.

When I had your problem I used aluminium foil around the negative terminal to increase its thickness.

In your place I'd gut the pack that has less runtime, remove the existing cells, solder wires to the connections, make a hole in the casing, let the wires through and glue the thing shut. Then I'd connect two 18650 cells to the wires for very long runtime. If you need super-ultra-moster runtime you could go with Kai's D-sized LiIons instead.

Unless you're an extreme user, a year is a bit too soon to be experiencing problems. Do you leave the camera on for extended periods that it's not being used? Do you take advantage of the auto powering down feature? I set mine for 5 minutes or less.

I shoot bands every weekend for 3-4 hours at a time and I never run out, but I've got a spare just in case.

5-6 years ago power consumption on DSCs was a problem, especially if you were using the LCD. Today it's improved so much, you're hard pressed not to get at least 100-150 shots off of a single charge.

It's not worth it to be tethered to a power cord. Make sure your charger is OK (or get another one) and replace the batteries if necessary. I just got a FZ8 and picked up two no names off of eBay for $14 shipped. They seem to work as well as the original.

I strongly suspect that it's just your perception or that you're doing something that's a real power hog. If you leave it on and don't use the power saver mode and spend a lot of time looking at your shots and showing them to others, then that's the problem.

You'll be much happier popping in another battery than loosing your freedom staying hooked to a cord.

Well, one battery that I could've sworn I had charged not more than a month or so ago had gone pretty much flat stored in my camera case (the manual warns against this, but doesn't specify how long it takes). I alternate between the original pack and the eBay one. I was taking some pics yesterday, and it seemed that a full charge wasn't lasting more than 0.5-1h, and I was turning off the camera between shots (a few minutes).
The charger was apparently charging each pack in 15m-0.5h, while the manual says a full charge should take 2h. It also gives an estimate of 360 pics over 3h, which is nowhere near what I was getting.

Perhaps this weekend, I'll charge up both packs, then test them out to see how long they actually last. Hopefully, yesterday's poor performance was a fluke. Regardless of the results, however, I'm still going to make an external pack, because that's my idea of a good time. If necessary, I can even make a holder for the batt pack that attaches to the hot shoe.

Low capacity, high internal resistance, high self discharge. Yup, your packs look dead as doornails.

My guess is that you've had the bad luck of buying a digicam that had been sitting on the shelf for a while, so you got one with a battery that was already degraded. You also had the bad luck of getting a dud spare cell.
Both problems in one instance are a bit unlikely, but hardly impossible.

Either that or you've got a defective charger, but that seems unlikely to be the case as (as far as I know) all digicam packs have protection circuitry built-in that would prevent overcharging.
Edit: perhaps you left the packs completely empty for some time and they were overdischarged by the circuitry? It should disconnect itself completely if a dangerous voltage is reached, but I wouldn't be surprised if it still kept drawing a tiny amount of current.

There's also the possibility that you're a very hardcore user who's already gone through both packs' estimated 500 cycles.

As for the external pack: I think attaching it to the tripod thread mount would be a better idea. You want the heaviest part of the digicam to be under it, not on top of it, for stability reasons. Make it symmetrical and you'll be able to rest the digicam on it.

It would kind of suck to have two dead packs. Maybe I just need to cycle them a bit, or something. The FZ50 was introduced around September '06, and I bought it in December of the same year, so I don't think it was sitting around for too long. I haven't cycled them that much, either - less than a dozen times each, I'd say. I'll see if a few quick cycles can revive them.

Pack under the camera - sounds good.

Not sure if this is the original Panasonic one but the battery can be found here for $ 19.99 + S&H

These guys have good batteries and prices:

http://www.diamondbackbatt.com/panasonic-2.aspx

I don't think he wants another pack identical to the original two...