Is the same behavior with nimh as with NiCAD? On Sat, Mar 16, 2024, 6:46 PM Brian K. White <[email protected]> wrote:
> One problem with batteries for sure is you can't tell a junk future > leaker by just looking at it. Even if the actual cells are stamped with > a quality manufacturer name, they could be fake or they could be real > but rejects, or they could be illegitimate extra production "after hours > runs" from the same plant in china or wherever that makes the real ones, > or real but aged-out old stock repackaged and sold as new etc. > > And there is essentially no way to detect or prove any of that by > examining the battery in your hand. If it's visibly corroded or doesn't > take a charge or something, you can tell that obviously, but if it > visually looks perfect, and functions within spec, that doesn't prove > anything except that it looks good and works today. It could be utter > garbage that dies and leaks in 1 year or 5 years. > > The only hope that it will actually last the promised number of years > before starting to leak, is to buy it from a source that you can trust > to be very careful with their own sources. No ebay, no amazon, certainly > no aliexpress, it must be someone who will actually care if any > customers ever start giving them a bad reputation. > > I guess all that is true for caps too really, so maybe no difference on > that front. > > -- > bkw > > On 3/16/24 21:21, Doug Jackson wrote: > > Every time I see one of those evil NiCad batteries, I replace it with a > > 0.5F supercap. > > > > I have never had an issue with my M100, or with the Olivetti equivalent > > (number escapes me at the moment) > > > > Having said that, the oldest would have been 8 years ago, so I don't > > have the same 30years of experience regarding leaking characters. > > > > Doug > > > > On Sun, 17 Mar 2024, 11:44 am Brian K. White, <[email protected] > > <mailto:[email protected]>> wrote: > > > > You can run plugged in to the wall for all normal random on/off > > operating times without worrying about it too much, IE, all day long > > for > > 8 to 12 hours or whatever, and for multiple days in a row, if > unplugged > > when turned off. > > > > And you can leave it plugged in turned on or off overnight for one > > night > > to a few days. > > > > And you can even get away with exceeding those pretty badly once in > > a while. > > > > What you want to avoid is plugging it in and leaving it plugged in > 24/7 > > for weeks or months or years, whether it's on or off. > > > > The harm is the charging circuit that charges the internal nicd > battery > > soldered on the motherboard. The battery is not a lead/acid or gel > cell > > that has a float value where it can just stay floating at a certain > > value forever, and the charging circuit is not a smart modern battery > > manager that knows how to stop charging when the battery is full, it > > just keeps on supplying a bit higher voltage than the the cells own > > voltage, and current just keeps on flowing backwards through the > cell, > > and sooner or later this kills the battery by a couple different > > possible mechanisms from plain heat & pressure making it leak and > cook > > off all the electrolyte, to things like the electrolysis process like > > electroplating, eating away all of one plate and building gunk up on > > the > > other. > > > > It's pretty forgiving so you don't have to be super careful. You can > > *mostly* never even think about it, and a normal random usage pattern > > will just naturally be fine. Just don't plug it in and forget about > it > > for a year. > > > > It doesn't touch the AA's and it doesn't matter if the machine is > > turned > > on or turned off. > > > > Now that you make me run through it all like that, I realise this > might > > finally be be an actual valid useful reason to install a supercap > > instead of a new nimh cell. > > > > Mostly there is no point, because both a cap and a battery will only > > last about the same number of years, and both will start to leak > > corrosive juice after about the same number of years. A cap is not > > harmed by being allowed to go all the way dead (which a battery is), > > nor > > by being allowed to stay dead for a long time (extra especially bad > for > > a battery), but even a battery that has been so badly treated still > > supplies more standby time than a brand new perfect cap. All in all, > no > > point. > > > > But one difference that matters, a cap should not be harmed by the > > crudeness of the charging circuit. A cap will just charge up and stop > > conducting and won't care about the charging supply at all. No > current > > will keep flowing through the cap, no cooking or electrolysis etc. > > > > I have always been very much not in the supercap camp, but this is > one > > real thing. > > > > -- > > bkw > > > > On 3/16/24 16:33, Will Senn wrote: > > > Wow, Brian! Super clear. Now, I want a REX# :). > > > > > > When you say that leaving it plugged in will kill the battery, do > > you > > > mean that I should run it off AA batteries most of the time and > > not my > > > 6v 200ma adapter? And the battery you're talking about killing is > > the > > > nicad on the board, right? > > > > > > Thanks, > > > > > > Will > > > > > > > > > On 3/16/24 3:21 PM, Brian K. White wrote: > > >> I summarize REX as: "An on-board software-controlled option rom > > >> library and ram image library." > > >> > > >> That's the shortest way I've found to say what it does, but > > that's not > > >> the same as saying what it's good for or why you want one. > > >> > > >> Because of the particular features and limitations of a M100, > > probably > > >> the single most life-improving thing you can do to one is to have > > >> TS-DOS in ROM. > > >> > > >> That one thing addresses a few different pain points. > > >> > > >> The biggest pain points of a M100 are: > > >> > > >> - Battery-backed ram only storage. Very little storage, and > easily > > >> erased or corrupted, either by dead batteries or a software > crash. > > >> > > >> - The way in manages machine-language software. How they all > > want to > > >> run in the same place in ram, yet the OS does not provide very > > much in > > >> the way of automatically moving programs into and out of that > > spot, so > > >> software is always clobbering other software, or you limit > > yourself to > > >> just having a single machine language app installed, or you have > to > > >> figure out the arcane way to hack the binaries to relocate them > > to run > > >> at different addresses side by side, or you have to keep double > > copies > > >> of binaries so that the running copy can get clobbered and later > > >> replaced from the ram file copy... > > >> > > >> - The main rom provides no binary file transfer other than the > > >> cassette. And no *convenient* file transfer even for text. > > >> > > >> These things combine to make life kind of difficult. For > > instance you > > >> want some better file transfer app, but since you have no binary > > file > > >> transfer to begin with getting the file transfer app itself > > installed > > >> is a pain. Then once it's installed, it consumes precious ram, > > and is > > >> easily broken because of the way machine language apps are are > run, > > >> and the simplest way to address that is to have a 2nd physical > > copy in > > >> ram, which uses up yet more of that precious 32k. etc. > > >> > > >> Having any tpdd client at all installed in any form makes > > transferring > > >> files a breeze, including binary files. This somewhat alleviates > > the > > >> small ram problem because you can easily put files away and get > > them > > >> back, as long as your tpdd software stays working. > > >> > > >> Even better is having a full featured tpdd client like ts-dos > > instead > > >> of teeny, and having it in rom instead of ram. > > >> > > >> That alleviates all kinds of annoyances. > > >> - It consumes almost no ram. > > >> - It doesn't require a pain in the neck bootstrap/loader process > to > > >> get installed. > > >> - It isn't subject to being clobbered and needing to be > reinstalled > > >> because of some other software writing over it or crashing. > > >> - It isn't lost after a hard reset or dead batteries. > > >> > > >> With TS-DOS in rom, you can pick up a totally dead machine, or > > totally > > >> kill your machine with a hard reset on purpose, or suffer a > > total ram > > >> corruption from buggy software, and with just "CALL 63012" you > > are up > > >> and running again, connect to a computer and pull down files. > > >> > > >> But even though this makes a lot of things a lot better, this > still > > >> needs a computer and serial cable. The tpdd client just makes it > so > > >> that you can effortlessly connect to a pc and move files back & > > forth, > > >> and having it in rom just means you can effortlessly always have > > the > > >> tpdd client regardless of crashes or dead batteries. > > >> > > >> That still leaves a couple things that could be better: > > >> - If you had a plain ts-dos option rom, it means you can't use > any > > >> other option rom because the single socket is occupied already > > by ts-dos. > > >> - You still need a serial cable and pc (or a real tpdd drive or a > > >> Backpack or PDDuino) to actually get the files from somewhere / > put > > >> them somewhere. > > >> > > >> REX gives you ts-dos in rom just for starters. It gives you > > ts-dos in > > >> rom which just that right there alleviates several things above, > > but > > >> also: > > >> > > >> - all other options roms besides ts-dos > > >> - full ram image backups > > >> - all on-device self-contained with no computer or serial cable > > needed > > >> (after initial loading) > > >> - impervious to dead batteries or resets or crashes > > >> > > >> And although you do need a computer to install option rom images > > onto > > >> the rex one time, ts-dos in particular is pre-installed, so that > > >> single most-needed one never needs even the initial one-time > > install > > >> from a computer. Only all the other roms need to be loaded from > > a pc > > >> once. And the loading process is easy, because REXMGR uses tpdd > > >> protocol internally to pull the rom images from a pc. No > > >> bootstrapper/loader procedure. > > >> > > >> The other option roms give you mostly a few different office > > software > > >> kits, ie spreadsheets and word processors, and a few other > > things like > > >> there is a FORTH rom and an assembler/debugger/renumberer. > > >> > > >> The ram image backups give you essentially more copies of 32k > > ram. It > > >> helps a few different ways: > > >> - you can physically hold more than 32k of apps or data. > > >> - you can recover from a dead battery or reset or corrupted ram > > from > > >> crashed software by restoring a ram image. > > >> > > >> There are something like 30 or so available slots, and each slot > > can > > >> be either an option rom or a ram image. That's a lot. > > >> > > >> All without a computer. In the coffee shop, on the train etc, > just > > >> recover from dead zero in a few seconds. Just "Call 63012" and > away > > >> you go, all interactive app and menu driven after that. > > >> > > >> So that is why you want a REX of any stripe, REX Classic, REX#, > or > > >> REXCPM. > > >> > > >> Now for REXCPM in particular.... > > >> > > >> Those particular advantages are something the REXCPM is less > > good for. > > >> > > >> REXCPM does give you all of that, but only as long as the M100 > > >> internal battery is not dead and the REXCPM and bus adapter board > > >> remain installed in both sockets. > > >> > > >> You can recover from software crashes that scramble the ram, and > > from > > >> intentional hard resets that wipe all ram (ctrl-break-reset), > > but not > > >> from dead batteries or switching off the memory power switch on > the > > >> bottom for more than a few minutes, or removing the device from > the > > >> m100 for more than a few minutes. > > >> > > >> If the M100 internal battery runs out, or you uninstall it for > more > > >> than a few minutes (you do get a pretty good grace period of > > several > > >> minutes, maybe even over 10 minutes) then you have to reload the > > >> REXCPM from scratch as you just experienced. If you had a REX > > Classic > > >> or REX# instead of REXCPM, all you would have done is type "call > > >> 63012" and you'd be all back up & running. No pc, no "37 easy > > steps". > > >> Done. And to remember "call 63012" just write it on a sticker or > > >> label-maker on the bottom. Put it on the underside of the option > > rom > > >> or battery cover if you want to hide it but then you have to at > > least > > >> remember that it's there. > > >> > > >> I did make a "UPS" for REXCPM that should keep it alive for a few > > >> years, but it's pretty involved to build and ultimately hard to > > justify. > > >> I don't pretend it's practical for most people, but it does work > > and > > >> exists. > > >> https://github.com/bkw777/REXCPM_UPS > > <https://github.com/bkw777/REXCPM_UPS> > > >> > > >> You have to buy the parts from digikey or mouser etc, order pcbs > > from > > >> elecrow or oshpark etc, and then it's a pretty fiddly soldering > > job, > > >> and it ends up costing as much or more than the rexcpm itself > > just to > > >> give it a battery. And for all that, I think I only estimated 6 > > months > > >> per cell x 4 cells = 2 years, but that's after the M100's own > > >> batteries run out, and if you have fresh alkaline AA's and a > > charged > > >> internal battery, the M100 itself can last anywhere from a few > > months > > >> to a year. So maybe up to 3 years? > > >> > > >> A better long-term solution would be a keeper. You remove the > > rexcpm > > >> and plug it in to something with socket and a big battery. But > that > > >> doesn't help with one that's installed in a machine. You'd need > to > > >> remove it from the machine to put it in the keeper. Plus the > molex > > >> sockets are no longer made. There are a few around available > > still but > > >> this would be a wasteful way to use one up instead of keeping > > them to > > >> repair machines. Really, for the long term like over 5 years, > it's > > >> probably more practical to just let it die and reload it. With a > > >> convenient bootstrapper and tpdd server on a pc, it only takes a > > few > > >> minutes to reload a rexcpm from scratch. It's several steps that > > >> requires a cheat sheet to follow, but none are very difficult or > > long. > > >> The hard part is just deciphering the original directions to > figure > > >> out what actually are the steps you need to do. > > >> > > >> So all in all, I'm not sure how necessary the ups is. It's > probably > > >> more practical to just do 2 things to live a happy life with a > > REXCPM: > > >> > > >> 1 - Keep it installed in a machine. And keep that machine > charged. > > >> (Unfortunately, you can't just lave the machine plugged in to > > the wall > > >> 24/7 for months, that will cook the internal battery.) > > >> > > >> 2 - Get good at reinstalling it. It's several steps, but it's > > possible > > >> to write a little cheat sheet that is easier to follow than the > > full > > >> original documentation. And none of the steps are very difficult > or > > >> long. You don't even need the cheat sheet after a few runs > through. > > >> > > >> If you aren't specifically wanting to run CP/M then I always say > a > > >> REX# is far more practical. REX# is an nvram device that acts > > like a rom. > > >> > > >> Instead of ever needing to recover the REX, the REX is what > > recovers > > >> your M100. > > >> > > > > > > > -- > > bkw > > > > -- > bkw > >
