Newton Battery FAQ Table of Contents 1. *Admistrivia. 2. Can I use non rechargeable lithium batteries? 3. What about Renewals? 4. Are there lithium ion (LIon) batteries available for the MP? 5. What about Nickel Metal Hydride (NiMH) AA batteries in my MP? 6. NiMH AA batteries? Where do you get those? 7. *What about Nickel-Cadmium (NiCd/nicad) batteries? 8. How long will my batteries last (per charge)? 9. *Can I charge batteries in my MessagePad? 10. How many cycles will my rechargeable batteries/battery pack endure? 11. What if I want to use a modem or other high power device? What's best? 12. *What happens if I leave my batteries out of my MP2k for a long time, like several weeks? 13. What are some other tidbits of battery information you have? * Questions that have changed since the last posting to Usenet. 1. Admistriva This FAQ started with a Usenet post by Joseph N. Hall. His preamble was: OK, here's my very brief stab at a MP2k battery FAQ. This message is hereby consigned to the public domain. Someone please pick it up and fix all the booboos and incorporate it into a real FAQ some day. -- Joseph N. Hall Eric Damien Berna turned it into an HTML document residing at and is maintaining the FAQ. Please email him at damien@thiel.com with any additions, corrections or comments. In addition we have received help from Mark Crocker, Andrei Chichak, Dave Howell, and Merijn Broeren. Tetsuya Iinuma has translated the FAQ into Japanese, added some Japanese specific information, and posted it at . The scope of this FAQ is restricted to batteries for Newton devices and associated hardware. Battery specific software for the Newton OS is excluded, because properly including questions and answers on software is an order of magnitude more work for Eric. Of course the standard disclaimers apply. This information can only be used at your own risk and no party involved in producing this document is responsible for damage or loss due to use or misuse of the information in this document. This document is in the public domain. Last update: 12 January 1998 2. Can I use non rechargeable lithium batteries? Anything that produces 1.2+ volts should work. Lithium batteries such as those from Evereadys will last 2-3 times as long as alkalines and are also noticeably lighter. Although the charge indicator will not be accurate, they will work fine. 3. What about Renewals? Sure, these will work, but you get a limited number of charging cycles (10?) and diminishing performance with each cycle. They may be a reasonable choice if you never run a modem off batteries, but otherwise their disadvantages are considerable. The Renewal documentation suggests frequent charging with the claim that Renewals "like" recharging. This suggests that if you deep cycle Renewals, they're not likely to last nearly as long. So, if you only need to run the MP for short times between access to an AC adapter, this might be the ideal solution. 4. Are there lithium ion (LIon) batteries available for the MP? Even though LIon batteries and the like are available in AA form, their nominal voltage of 3+ volts would preclude using 4 of them in a power pack. A 2 cell pack could be constructed but it would have about the same lifetime as a NiMH pack. Perhaps a pair of higher-capacity prismatic (rectangular) LIon or Tadiran lithium batteries would be feasible. 5. What about Nickel Metal Hydride (NiMH) AA batteries in my MP? Yes, these will work. Once again you have the charge indicator problem. You should probably carry a spare pair of batteries since NiMH batteries roll off in voltage somewhat faster than alkalines and you may not have very long after a low battery indication before your unit goes dead. 6. NiMH AA batteries? Where do you get those? Joseph has some Toshiba NiMH batteries and a separate wall charger. The batteries were about $5 each and the 10 hr slow charger was reasonable, $30 or so. You should be able to order these from a specialty battery store. 7. What about Nickel-Cadmium (NiCd/nicad) batteries? Sure, these will work too, although nicads have less capacity than NiMH batteries. They have an even steeper voltage rolloff as they wind down, so the low battery warning might come only moments before the unit goes dead, or if you are using a high power device like a modem, not at all. Dave tells us that regular (650 mAh) nicads can't deliver high current bursts after a couple hours, so look for high capacity (850mAh) nicads. He also tells us that Radio Shack has the high-capacity batteries, and a nicad recharger that does a one-hour deep discharge followed by a two-hour speed charge and auto-shutoff for around $30. 8. How long will my batteries last (per charge)? Hard to say. 24 hours of run time with the backlight is a reasonable rough estimate for alkaline batteries. NiMH will be somewhat less, nicad somewhat less than NiMH. Lithium batteries should last 2-3x longer than alkaline, but at $10 for 4 they add up after a while. 9. Can I charge batteries in my MessagePad? Officially, other than the rechargeable battery packs? No. The battery pack for the MP2K has some contacts on it that let the MP2K know it's got a NiMH battery pack inside it. The pack also includes a temperature sensor, which is critical for fast charging. You can use all kinds of batteries but the only thing you can charge in the MP2K is the MP2K battery pack. Merjin tells us that there are instructions on converting the alkaline battery holder for the MP2K at (these instructions are in German). After remodeling, the MP2K will recognize it as a rechargeable battery pack and charge batteries in the MP2K. Mark and Andrei tell us that they do recharge nicads in their MPs. The MP110, MP120, and MP130 don't have the temperature sensors and extra contacts for charging the Apple Battery Pack for these models. Instead they have a small switch in the battery compartment that tells the MP the batteries can be charged. This switch is activated by the casing of the Apple Battery Pack. Mark uses an old dead pack's case to hold his batteries and depress the switch. Andrei wraps the two center cells in cello tape to press the charging switch. If an old Apple Battery Pack is not available, other materials would have to be used to fashion a part to depress the switch, such as Andrei's solution. 10. How many cycles will my rechargeable batteries/battery pack endure? With a properly functioning charger (fast or slow), 200 or so for NiMH, more perhaps for nicad. Don't worry about "memory effect"--it is not necessary to deep cycle modern rechargeable batteries. However, a partial charging session wears down a battery nearly as much as a complete charging session. In other words, to get the maximum life out of your batteries, you should discharge them as much as practical before recharging. The easiest way to do this is to buy two sets of NiMH or nicad batteries and carry a spare set with you. When your unit dies, swap the batteries and recharge the dead ones. 11. What if I want to use a modem or other high power device? What's best? What's best? An AC adapter. The old MP100-130 adapter is the most portable. The newer high-tech 9W adapter is OK, too, but you don't need all that oomph to run a modem card. Otherwise, alkaline batteries are definitely the WORST for this application. If you are running your unit on half-discharged alkaline batteries and fire up a modem, don't be surprised if your unit shuts off instantly from lack of juice. Any other type of battery will work better for high power drains. Nicads are known for their low internal resistance (you can start a car with 8 fully charged nicad D cells), but NiMH and lithium batteries are also superior performers. 12. What happens if I leave my batteries out of my MP2K for a long time, like several weeks? According to Joseph, when your MP2K ships from the factory it is in a deep sleep, an ultra-low power consumption mode. It is not truly "off." Why? Well, there is some critical configuration information stored in *volatile* RAM in the unit. This information is programmed at the factory by special whizzy equipment that is not (so far as I know) available elsewhere. There is a teeny internal battery that powers RAM when the super capacitor runs out of charge--10 to 20 minutes after you yank the battery pack. Once this battery goes dead, and consequently your RAM gets corrupted/erased, your unit is hosed and has to be sent to the factory for recalibration. It's easy to avoid the problem--make sure the unit has fresh batteries in it even if you aren't using it. According to Merijn, this is untrue, and as far as he knows, fast becoming an urban legend. True or not, Eric isn't willing to put his MP2K aside for long enough to find out. 13 . What are some other tidbits of battery information you have? This material was gathered hastily off the net, working mostly from manufacturer's claims so it should be taken with a grain or two or ten of salt. Volumetric Maximum Rate of Battery Type Capacity Capacity Charging Self (milliamp-hours) (watt-hours/liter) Cycles Discharge* Alkaline 2850 100 NA 5 YSL** Lithium 200 NA 10 YSL RAM*** 2000 100 10-25 5 YSL (initially) Lithium-Metal 300 250 1-2%/Month LIon 220-250 500-800 1-10%/Month NiMH 1200 100-190 300-500 25%/Month NiCd (high 850 80-125 500 25%/Month capacity) * Discharge is much higher at higher temperatures (days or weeks of life for NiCd at 90F vs. weeks or months at 70F). ** Years of Shelf Life. *** Reusable Alkaline-Manganese Alkaline batteries have high internal resistance and poor pulse performance. Lithium batteries have reasonable pulse performance and a fairly flat discharge curve. Reusable alkaline-manganese batteries have high internal resistance, poor pulse performance, and no memory effect. Lithium-metal batteries are a product of Tadiran, have a flat discharge curve, and no memory effect. Lithium ion batteries have no memory effect, can be damaged by overcharging or overdischarging, and have a sloped discharge curve. Nickel metal hydride batteries have little to no memory effect, can be damaged by high charging currents or overcharging, and their lifetime can be shortened by pulse discharges near battery rating. Nickel-cadmium batteries allegedly have a memory effect, are generally not damaged by overcharging, and have the best pulse performance.