DEDCHP.THD --- Copyright 1987 by Phil Wheeler An original compilation of Compuserve Model 100 Forum messages for use by Forum members only. Flash!! The Chipmunk population is being threatened by a plague -- of battery failure. This THD file reports and discusses the failure of 'Munks from exhaustion of the NiCad battery pack. Now notes that one member is using a "Captain Video Chipmunk Adapter" to charge his drive. No ordering info, though. **Updated 10/17/87** Message range: 157941 to 157962 Dates: 10/9/87 to 10/9/87 Sb: #Dead Chipmnk Fm: Bill 70126,767 To: All I have one of the original Early-Bird chipmunks that has given me several years of good service. It recently died, and now refuses to charge up. I'm guessing that the NiCads are dead. Has anyone had experience with this problem? If so, please drop me a line and tell me how I can bring my critter back to life. Thanks. Bill Lippard Fm: Tony Anderson 76703,4062 To: Bill 70126,767 Yes, there have been several reports of nicad failure, and that they obtained replacement nicad cells direct from Holmes Engineering in Utah at a reasonable cost, and installed them easily. Nicad life of 3 years is not unusual, they are spec'd for about a thousand charges, which if given every day, or every other day, figures out to about 3 years. (approximately) The nicads are attached to the circuit board with a plug, and if you open the case, and unplug the nicads, you might be able to use the Chipmunk on AC power alone. There have been some comments that the disk drive needs the extra current capapcity of the nicads when it first kicks in, but it's worth a try, it may work with the older Chinon drive; maybe not. Worth a try, anyway... Chipmunks were offered in an AC only configuration at one time. It may be that what's needed for AC only, is a larger power supply; one capable of providing more "kick" when the disk drive starts turning. You might ask about that possibility when you call Holmes. (801) 572-6865. Ask for Glenn Checketts. Fm: Bill 70126,767 To: Tony Anderson 76703,4062 Tony, Thanks for the fast reply. I'll call Holmes on Monday and see about ordering the new NiCads. By the way, how do you get the case open? Bill Fm: Eiji Miura 76703,4311 To: Bill 70126,767 Probably the internal battery is bad. It happned to my earybird Chipmunk in last Dec. You can order battery from Holmes and replace it yourself, or you can send you Chipmunk to them and let them do it. I sent mine in, and the charge was $52 including shipping. It took about three days. Fm: Tony Anderson 76703,4062 To: Bill 70126,767 Remove the four rubber feet on the bottom of the case, remove the screws, and slide the whole unit out the back of the case. Fm: Eiji Miura 76703,4311 To: Tony Anderson 76703,4062 Chipmunk does not work with AC power alone without the internal nicad. Remember you tried it with my Chipmunk when mine (Chinon) died in Tahoe? By the way, Holmes Microsystems' phone number has changed to (801) 975-9929. Fm: Tony Anderson 76703,4062 To: Eiji Miura 76703,4311 Thanks for the new information on the phone number. Yes, I do recall vaguely we tried to get it to work, but not the details. Thanks for reminder, but I do suspect it would work with a larger capacity power supply. Question is, "how large", and where do we get one from. Fm: Mark Lutton 73106,1627 To: Eiji Miura 76703,4311 You can also buy a new Nicad battery pack at a well-equipped hobby shop for about $20. They are used in radio-controlled planes and other toys. The plug is different; you will have to clip it off and solder on the old plug. Be careful not to short the wires -mine came fully charged. Fm: Doug Pratt (ModelNet) 76703,3041 To: Mark Lutton 73106,1627 Hold it, Mark...Radio-controlled planes and other TOYS? Them's fightin' woids where I come from....(smile) Seriously, most sub-C ni-cd packs sold in hobby stores won't fit the Munk. They're designed for use in RC cars, and are soldered into the wrong physical size. It could be done, of course, by buying individual cells and sme heat-shrink tubing. It's also important to charge new ni-cds for 24 hours at slow rate, to balance the individual cells in the pack. You learn that kinda stuff flying toy airplanes! Fm: Mark Lutton 73106,1627 To: Doug Pratt (ModelNet) 76703,3041 Well, tiny computers are toys to some people too .... I bought my replacement battery at a model railroad shop (Charles Ro in Malden, MA). Now I admit the fellow behind the counter didn't really know exactly WHY he had such a battery in stock or what sort of machine it was designed to be used for -- it was unlike most he'd seen for RC planes or cars, and would not really have fit even an OOO-gauge RR locomotive. But it fit the 'Munk perfectly. Fm: Doug Pratt (ModelNet) 76703,3041 To: Mark Lutton 73106,1627 Good for you! Glad to hear your Munk is back among the living. Are you using the Munk charger, I hope? I suspect that there's circuitry that will be damaged if you punch higher charge current through the Munk charging jack. Fm: Tony Anderson 76703,4062 To: Doug Pratt (ModelNet) 76703,3041 Uh.... um..... er..... nothing happens if you "punch higher charge current through the Munk charging jack". ... In fact, speaking from an electronic point of view, it doesn't matter what the source _capacity_ is, a device will only draw as much current as it requires. For example, you can have a four amp power supply, and if your device only draws one amp, the other three won't be used -- they aren't "pushed" into the device; they're just "available". The device will still only draw one amp. Now in the case of nicad charging, the cells present a resistance to the power supply voltage, and in accord with Ohms Law, as the supply VOLTAGE increases, the amount of charging current going into the batteries also increases. If the 'Munk normaly operates with a 6 volt (nominal) AC supply, which is rated at 1 amp (for example), if you replace the supply with one rated at 10 amps (still supplying 6 volts), there will be no difference in the amount of charge going to the batteries. You are undoubtedly aware of the differences between "normal" nicads, and the "fast charging" type. Electrically, the fast charging types are simply capable of handling higher charging voltage; which, because of fixed internal resistance, equals higher charging current. However, with the larger power supply, there is more "surge current" available, and this might be a consideration in converting a Chipmunk to AC only use. It's been demonstrated that the Chipmunk won't operate on the AC power pack alone, if the nicads are removed. The disk drive needs the extra "kick" available from the nicads to come up to speed. Interestingly, it appears the main purpose of the AC power supply with the Chipmunk, is to keep the nicads charged; the drive operates principaly from the nicads. Fm: Doug Pratt (ModelNet) 76703,3041 To: Tony Anderson 76703,4062 Right. I'm aware of all that. What I meant to say (albeit clumsily) is that I'm not certain what circuitry there is between the Munk charging jack and the battery pack. If someone acquires a pack in a hobby store, which sells many different chargers that are capable of chargng a 6 or 7-cell sub-C ni-cd pack to capacity in 15 minutes by punching in 5-6 amps until it detects a voltage peak, said person might think, "Aha! Now I can fast-charge my Chipmunk!" I meant to express my belief that it would NOT be a good idea to provide 5 amps of current to the Munk charge jack. (You realize you're dealing with someone who thinks Ohm is what a Tibetan monk chants all day long?) Fm: James Yi 73327,1653 To: Bill 70126,767 Bill, it's possible that those batteries can be ZAPed back to life. Nicads develop internal "whiskers", which can short the battery, but they can be zapped away with pulses of high voltage. I saw devices that do that advertised, but I forget where(in one of those electronic gadget catalogues). Unless they really have reached their life span, they can be revived this way. Don't know if it's worth it, but I thought you might like to know this. Fm: Tony Anderson 76703,4062 To: Doug Pratt (ModelNet) 76703,3041 Of course, Doug, I KNEW that you KNEW all that... just pulling your leg, and taking the opportunity to (once again) explain some of the basics of dealing with nicads. My Great Aunt was an "Ohme"... She used to sigh, and say, "Oh me, Oh my!" (grin) Fm: Tony Anderson 76703,4062 To: Doug Pratt (ModelNet) 76703,3041 Oh yes, there is nothing between the charging jack and the nicads except the plug at the circuit board. In other words, the nicad stack is connected directly to the charging jack. Fm: Tony Anderson 76703,4062 To: James Yi 73327,1653 BNF Enterprises is one source. They sell lots of gadgets, surplus, electronics and nicads. Among their miscellaneous offering is a nicad "Zapper/Charger/Tester" kit. $9.95, Catalog # D85D0297 from catalog # 873E, the Summer Sale catalog. They have a toll-free number, (800) 832-2321. Fm: Mark Lutton 73106,1627 To: Doug Pratt (ModelNet) 76703,3041 Yes, I'm using my Official Captain Video Chipmunk Charger. I don't want to take any chances -- of course if I do bust the new battery, I know where I can get another one. The 5-cell nicad pack is relatively rare; you have to find a well-stocked hobby store. Fm: Doug Pratt (ModelNet) 76703,3041 To: Tony Anderson 76703,4062 Really? Then you could fast-charge the nicad pack if you wanted to. Running an amp of current into the charge jack for 3 hours should give you a full charge after flattening the pack out. Hmm. I might try it if I run the batteries down...I have some pretty sophisticated charging gear around this workshop. Fm: Tony Anderson 76703,4062 To: Doug Pratt (ModelNet) 76703,3041 Only works if the electrolyte gell inside the nicad can take the increased heat involved in passing more current (from a higher voltage) through the cell. That's hard to tell with "generic" battery packs. But go ahead and try it, and tell us if it works, or how much a replacement set of nicads costs (grin).