I own a Fluke DSP-2000, a cat5 network certifier. It's a great little machine, I bought one as I do some networking work on the side and I'd used one at work. It works well, except the people who designed it apparently didn't know a thing about batteries. It takes proprietary NiCad battery backs, BP7217's, which cost about $130. I suspect they consist of 6 AA batteries, they look about the right size, and produce 8.4V, though are marked as 7.2V.

What happens is that if they are left to their own devices, like all rechargeables, they discharge. When they're empty, the fluke refuses to charge them. Since they're proprietary, you can't just put them in a different charger.

So, my question is, how do I trickle charge these myself to get them to the point where the fluke will take over charging? Between myself and work, I've got four dead batteries, so it's about a $500 question. The batteries have five contacts. From left to right, they're labeled -,T,G,C and +. On a good pack, minus and T both read 8.4V differential between C and plus. G is at zero relative to all the other contacts. I don't have a bench power supply, so I'm hoping for something a bit more inventive.

Am I completely wrong in assuming that all these need is a trickle charge to get them started?

Matthew

A charger with movable pins or aligator clips will do the trick. Maha has such a charger with support for both Nickel and both Lithium chemistries.

It will charge almost anything.

http://www.thomas-distributing.com/mh-c777plus.htm

I think your best bet might be a Dewalt Power Tool charger. These are high-quality current-sensing NiCd chargers for *any* NiCd pack size from 7.2V up to 14.4V (or higher, depending on the charger model).

Just use aligator clip leads to jumper from the charger to the contacts on your batteries. Do not touch the contacts at any time while the charger is powered --120V may be present.

Of course, you still have to work out which two contacts are for charging.. maybe by probing the charger unit you have ?

Cheers

Ok, I took one apart. They're not AA's, they're slightly larger, and cost about 5 bucks each for exact replacements. Interestingly enough, the newer version of the pack weighs a lot less, so I suspect it uses actual AAs. I left it at work though, so I'll have to check details tomorrow. They're pretty much in series with one resistor between two of the positive contacts, who's purpose is lost on me.

I've got a battery charger that has a spot for 9 volt batteries. Can I just hook that up to the positive and negative contacts? I don't mind if it's not great for the batteries, I suspect I just need to get them slightly charged.

Matthew

Ok, I decided I'd try my 14V cordless drill battery charger on them, as that seemed to be close to Mark and Stew's recommendations. I tried to hook it up, and the charging light would come on for five secconds and fade away. At first I thought this was because I wasn't making good enough contact, but eventually discovered that it was just what the charger did.

At this point, I threw it back in the fluke, and plugged it in, and it started to charge. Had I left it hooked up long enough for a bit of charge to build up? Had the higher voltage shocked the dendrites out of it? Did I just get lucky and it decided to work again? I'm not sure, but I've got a few more of these to try, so I'll let you know if it's reproducible.

Matthew