Reed Hoffmann is a freelance digital photographer in Kansas City, KS and a founding member of Blue Pixel, a digital consulting group.
Recently I was able to save a friend US$100 with a 9-volt battery and a little experimentation. The problem was that he had a Kodak DCS NiMH battery pack that wouldn't take a charge. A few seconds after being placed in a charger the yellow light would start flashing. That's bad news, because it means the charger thinks the battery is no good, and so won't charge it.
Kodak DCS NiMH battery that refused to take a charge
My quest for a solution began with a bit of searching in the forums on this site. I was able to find several threads about Kodak batteries refusing to take a charge. Aaron Monello of Kodak Professional Digital Support in the US posted a message saying:
Unfortunately, the NiMH batteries do not like to be drained too far (as you found out). Please call us directly (800-235-6325) and we will be happy to accept any of your batteries that have "died" and will try to revive them. If any of them is under 90 days old then please send a proof of purchase (copy is fine) and we will replace the battery if we cannot revive it for you.
What's happening is the battery is dropping below a certain voltage that the charger wants to "see" in order to charge it. This will happen if you leave the battery in the camera for an extended period, as the camera always has a drain on the battery as long as it's in the camera. Leave it in too long, and the voltage drops below the level the charger wants to see.
Aaron's post was followed by another where a person (sorry, lost their name) described using a 12-volt charger and an inline 220-ohm resistor to give the DCS battery a "boost," giving it enough voltage so that the charger would "see" it, and therefore charge it.
Now I admit, the smart thing would be to send the battery in to Kodak and let them take care of it. Being impatient, though, I thought I'd try to do it myself. I make no guarantees on the following procedure, and if you're in the US you may well want to take advantage of Aaron's offer of Kodak assistance. If not, then plunge on ahead.
Not having a 12-volt charger (or a 220-ohm resistor, for that matter), I decided to try something a bit simpler that I hoped would work. What you're trying to do is bump up the voltage in the battery to the point the charger will recognize it. Here are the steps I took:
First I placed a pair of paperclips into the terminals at both edges of the battery:
Sliding the first of two paper clips into the DCS NiMH battery's terminals
Next, I used a voltmeter to test that the positive terminal was indeed positive, the negative negative, and that the battery indeed did have some juice left in it:
Testing the battery terminals
CAUTION – anytime you're working with wires (including paper clips) coming out of positive and negative terminals, be very careful not to let them touch each other. You'll at the very least get sparks, and at the worst destroy the battery or even burn your house down.
Once I confirmed that the Plus side was indeed positive and the other side was negative, I now proceeded to the riskiest part of the operation: swiping a 9-volt battery connector out of one of my kids' toys without them knowing about it. I stole mine from an old walkie-talkie they no longer used. I soldered the two leads from that connector to the ends of a pair of paper clips.
Putting a 9-volt battery onto the connector (and being careful not to let the two paper clips touch each other), I then pushed the paper clips into the two slots I'd identified as positive and negative before. The goal was to use the 9-volt battery to give a bit of a charge to the DCS battery.
"Charging" the Kodak DCS NiMH battery
Now came the really hard part – waiting. I let 15 minutes pass before disconnecting the 9-volt battery and checking the voltage on the DCS battery. Eureka, it was higher than before! Now when I placed it in the Kodak charger, it charged normally and has worked fine since then.
My 11-year-old son asked "Why doesn't Kodak just make the charger so it won't do that." Sounds simple enough, but there's probably a good reason they don't, or it's just too much trouble. Whatever the reason, I'm just glad there's a simple fix, and my friend's happy to have saved US$100. Of course, he'll be buying my kids new walkie talkies if they read this story.