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PowerBook Duo battery replacement
- Thread starter Mk.558
- Start date
Trash80toHP_Mini
NIGHT STALKER
I've got a high capacity BTI Battery Pack for the Duo. It sticks out the front about 3/8" as compared to a Standard Battery, giving a bit of an asymmetrical appearance to the front edge, but not wholly unpleasing to the eye. My guess would be Full Size AAs inside the beast.
beachycove
Well-known member
As I say, I have not tried it, but I do know for a fact that regular tabbed high capacity AA NiMh cells won't fit, and 4/5 AA NiMh cells are hard to find and are very, very hard to fit in there (though it can be done -- I have done it, and if I can do it, anyone can).
The thing is, the original NiMh cells used in 1993-4 were typically rated around 900mA. The PowerBook will not work well with 2000 or 2500mA cells, anyway, as it seems not to know quite how to charge them. We have this behaviour in 540c recelling attempts too. So why not just go with cells with comparable capacity to those used originally, that will readily fit in the ruddy thing, that can be easily replaced by using standard battery holders suitably wired together, etc.? There's method in the madness, and one of these days I will get a round tuit and try it out.
Bunsen
Admin-Witchfinder-General
http://en.wikipedia.org/wiki/AA_cell#Dimensions
The *area* each would take up, laid flat (ie, in a single layer)
4/5A: 833 square mm
AA (tabs): max 726.45 square mm
AA (buttons): max 739.5 square mm
Side to side, a pack of eight (max 14.5mm) AAs would be the same width (116mm) as a pack of seven 4/5As (119mm), and 1 - 2 mm longer.
It *just* might be possible. Easy check: cut out some paper rectangles to the AA size (51 x 14.5mm max), and see if they can be arranged to fit into a Duo cell.
From Trash80's link:
So, an AA is slightly longer, and slightly thinner.
The *area* each would take up, laid flat (ie, in a single layer)
4/5A: 833 square mm
AA (tabs): max 726.45 square mm
AA (buttons): max 739.5 square mm
Side to side, a pack of eight (max 14.5mm) AAs would be the same width (116mm) as a pack of seven 4/5As (119mm), and 1 - 2 mm longer.
It *just* might be possible. Easy check: cut out some paper rectangles to the AA size (51 x 14.5mm max), and see if they can be arranged to fit into a Duo cell.
Bunsen
Admin-Witchfinder-General
Close enough. Amp-hour storage is a measure of how much total energy it can store - unrelated to the max amps of current it can put out continuously. Whatever amount of current (amps) you draw, divide the amp-hours by that and you get the number of hours it'll run for, at that current. ie, a 40Ah battery can run a 40 amp load for one hour, or a 4 amp load for ten hours, etc. Amps x hours ... equals amp-hours. NB: not "amp-per-hour"
The 5x0s use the accursed "Intelligent" batteries, which have an onboard controller IC. The Duos do not. I don't think one should assume the behaviour would be the same.
Trash80toHP_Mini
NIGHT STALKER
IIRC, back in the early 68kMLA day, someone used the the higher rated cells in Duos to good effect.
Re-celling Duo Bats was a big topic back then, here and over on 'fritter.
Back then, a 2300's 640 x 480 wasn't quite as ludicrous in terms of LCD real-estate as it is today. :-/
Re-celling Duo Bats was a big topic back then, here and over on 'fritter.
Back then, a 2300's 640 x 480 wasn't quite as ludicrous in terms of LCD real-estate as it is today. :-/
Bunsen
Admin-Witchfinder-General
http://en.wikipedia.org/wiki/AA_cell#Rechargeable_chemistry_and_capacity
So ... no. Unless you fancy your Duo bursting into flames.
Bunsen
Admin-Witchfinder-General
Archive copy of another page on rebuilding Duo batteries. Contains this image:
*if* the case can handle an extra 2-4mm lengthways (left to right in the image) ten AAs would easily fit sideways in two groups of five (ie, each cell running the same direction as the outer four cells)
Existing width: 2 x 17mm + 49mm = 83mm
5 x AA width: 14.5mm = 72.5mm
Existing length (outer): 2 x 49mm = 98mm
Existing length (inner): 6 x 17mm = 102mm
2 x AA length: 51mm = 102mm
I'm running through some other possible rearrangements, but so far, they all rely on having that extra 2-4mm of wiggle room lengthways. (2mm if using tabbed cells)
Refresh my memory, someone - which end / side of the battery as pictured slides into the Duo / has the contact points?
ETA:
*if* the case can handle an extra 2-4mm lengthways (left to right in the image) ten AAs would easily fit sideways in two groups of five (ie, each cell running the same direction as the outer four cells)
Existing width: 2 x 17mm + 49mm = 83mm
5 x AA width: 14.5mm = 72.5mm
Existing length (outer): 2 x 49mm = 98mm
Existing length (inner): 6 x 17mm = 102mm
2 x AA length: 51mm = 102mm
I'm running through some other possible rearrangements, but so far, they all rely on having that extra 2-4mm of wiggle room lengthways. (2mm if using tabbed cells)
Refresh my memory, someone - which end / side of the battery as pictured slides into the Duo / has the contact points?
ETA:
From tyler sable's guide:
ETA: this - http://en.wikipedia.org/wiki/List_of_battery_sizes
beachycove
Well-known member
4/5 As or bust. The battery arrangement is also not always as generous as the image suggests (Duo batteries differ inside).
Higher capacity cells will take a good charge, but as far as I can determine, they will not take a full charge. Thus you will typically only get the battery life (2.5 hrs or whatever) originally projected for a Duo battery from a recelled unit; you will not get 3 times the battery life originally projected (7.5 hrs. or whatever). It seems to me that the charging circuitry is geared to lower capacity cells. Because of the memory effect in NiMh technology, this then has a degrading impact on the cells. I have had several batteries in which this happened.
However, it is still worth doing, and the new battery will last a good while, but it is not a long-term solution. Matters may be improved by soldering/ welding differently, and conductive epoxy would be one way to go. However, there is a fair bit of twisting and flexing involved in getting the cells into the case, so you'd need to work very methodically and precisely if using epoxy, which is not going to be as robust as a proper solder joint.
Higher capacity cells will take a good charge, but as far as I can determine, they will not take a full charge. Thus you will typically only get the battery life (2.5 hrs or whatever) originally projected for a Duo battery from a recelled unit; you will not get 3 times the battery life originally projected (7.5 hrs. or whatever). It seems to me that the charging circuitry is geared to lower capacity cells. Because of the memory effect in NiMh technology, this then has a degrading impact on the cells. I have had several batteries in which this happened.
However, it is still worth doing, and the new battery will last a good while, but it is not a long-term solution. Matters may be improved by soldering/ welding differently, and conductive epoxy would be one way to go. However, there is a fair bit of twisting and flexing involved in getting the cells into the case, so you'd need to work very methodically and precisely if using epoxy, which is not going to be as robust as a proper solder joint.
Trash80toHP_Mini
NIGHT STALKER
That being the case, so to speak, an external charger having all new circuitry with sensing and the appropriate power supply for a current battery technology hack would be the way to go for any really effective re-celling hack.
Can the Power Manager be hoodwinked into using these hypothetical modern cell batteries without charging them when hooked up to the Duo's AC Adapter? Mistakes will happen, somebody (an idiot like me, for argument's sake) will certainly plug in the AC Adapter w/o removing the hacked BatPack.
How would a current 12v (DeWalt for example) Lithium Battery Pack and Charger Unit do for the basis of such a hack? Such packs are more than likely designed for periodic high output rather than a continuous supply of power, so duty cycle incompatibility may be problematic. However changing the battery cell type might be a workable fix, sort of like the difference between a deep discharge automotive vs. a continuous (?) discharge marine battery. They're both lead/acid but very different in the way they're designed for their specific duty cycles (?).
I'm no expert on the Power Manager, power supplies or battery technology by any stretch of the imagination, but something along these lines seems to be well worth exploring to me.
Can the Power Manager be hoodwinked into using these hypothetical modern cell batteries without charging them when hooked up to the Duo's AC Adapter? Mistakes will happen, somebody (an idiot like me, for argument's sake) will certainly plug in the AC Adapter w/o removing the hacked BatPack.
How would a current 12v (DeWalt for example) Lithium Battery Pack and Charger Unit do for the basis of such a hack? Such packs are more than likely designed for periodic high output rather than a continuous supply of power, so duty cycle incompatibility may be problematic. However changing the battery cell type might be a workable fix, sort of like the difference between a deep discharge automotive vs. a continuous (?) discharge marine battery. They're both lead/acid but very different in the way they're designed for their specific duty cycles (?).
I'm no expert on the Power Manager, power supplies or battery technology by any stretch of the imagination, but something along these lines seems to be well worth exploring to me.
Trash80toHP_Mini
NIGHT STALKER
I was thinking more along the lines of having the sensor contacts on the battery pack tell the Power Manager that the Battery is at full charge, but your way sounds better in terms of protection and charge level monitoring during use.
. . . but then again, I'm far from being knowledgeable about even electronics in general.
. . . but then again, I'm far from being knowledgeable about even electronics in general.
Bunsen
Admin-Witchfinder-General
Trash, I think your safest bet for a modern battery hack would be to use a completely external* pack running into the rear power socket @24V. That would bypass the power manager altogether and allow you to use any cell chemistry and charger you desire. If you are using lithiums, a current limiting device inline between the pack and the power socket would be a good idea. Come to think of it, I have seen lithium cells for sale on evilpay that have tiny button circuits mounted on one end for individual-cell level protection.
* I mean, electrically external. One could in theory pack them into a Duo battery shell, and bypass the internal connectors straight to the rear. With an appropriately placed internal plug, your new pack could be plug & play swappable with genuine batteries. Lithium cells are 3.7V, so one would need six or seven of them to reach an appropriate voltage level. Six would be 22.2V, seven would be 25.9V. My personal thought would be - test the lower voltage on a Duo with a lab bench supply - with current limited to the same as a real PS - and see if it operates OK. If not, shoot for the higher voltage and mount an inline voltage regulator to limit it to 24V. Either voltage would leave open the possibility of using a pair of 12V (nominal - in truth variable around 15V) solar panels in series to charge the pack, but that might be more successful with the lower voltage.
* I mean, electrically external. One could in theory pack them into a Duo battery shell, and bypass the internal connectors straight to the rear. With an appropriately placed internal plug, your new pack could be plug & play swappable with genuine batteries. Lithium cells are 3.7V, so one would need six or seven of them to reach an appropriate voltage level. Six would be 22.2V, seven would be 25.9V. My personal thought would be - test the lower voltage on a Duo with a lab bench supply - with current limited to the same as a real PS - and see if it operates OK. If not, shoot for the higher voltage and mount an inline voltage regulator to limit it to 24V. Either voltage would leave open the possibility of using a pair of 12V (nominal - in truth variable around 15V) solar panels in series to charge the pack, but that might be more successful with the lower voltage.
Trash80toHP_Mini
NIGHT STALKER
The problem I see with that approach would be the same, bypassing the sense contacts on the internal battery means no battery strength indication. Back in the day, I was going to use this config for the DuoBoomBoxDock™ hack. The two DeWalt Charger/Separated Stereo Speaker units would have been powered by 12v Battery Packs and a PTO circuit for the Duo would be 24v to the AC Adapter Jack.
Personally, I'm leaning more toward, a more modern NetBook or ancient ToiletSeatBook approach, using just the face of the Duo's BatPack to conceal a non-interchangeable Battery system. Given an adapted Micro-SD chiplet HDD replacement, the HDD Bay becomes "mostly" available for additional cells. However, I'm reserving that space for the 1400's Card Cage or an EtherNet->WiFi Box kluge.
Then there's the BTI BatPack to hack as well, for another Duo. }
Personally, I'm leaning more toward, a more modern NetBook or ancient ToiletSeatBook approach, using just the face of the Duo's BatPack to conceal a non-interchangeable Battery system. Given an adapted Micro-SD chiplet HDD replacement, the HDD Bay becomes "mostly" available for additional cells. However, I'm reserving that space for the 1400's Card Cage or an EtherNet->WiFi Box kluge.
Then there's the BTI BatPack to hack as well, for another Duo. }
Mk.558
Well-known member
There's another problem with using Lithiums: the Duo's battery meter won't properly register the capacity remaining. AFAIK the discharge curves for NiMH and Li batteries are very different.
Using the smaller AAs may be better for multiple reasons: 1) the capacity is more likely a match or close match to the original total amp-hours, 2) the slightly smaller size means refitting should be slightly easier, 3) should be less expensive AND 4) more likely to get solder tabbed variants.
If there is a slight excess of room, foam could be used to fill the gaps. In any case recelling is for the sport of using the Duo like it was originally far longer than it's lifespan (same with using C64s or // models for webhosting).
I'd like to pry open a battery when the SpericallyCorrectedDuo2300 arrives
Using the smaller AAs may be better for multiple reasons: 1) the capacity is more likely a match or close match to the original total amp-hours, 2) the slightly smaller size means refitting should be slightly easier, 3) should be less expensive AND 4) more likely to get solder tabbed variants.
If there is a slight excess of room, foam could be used to fill the gaps. In any case recelling is for the sport of using the Duo like it was originally far longer than it's lifespan (same with using C64s or // models for webhosting).
I'd like to pry open a battery when the SpericallyCorrectedDuo2300 arrives
With a project like this, I'd say it's best to keep it as simple as possible.
I vote for using the regular 4/5 A cells at the highest amp-hour storage you can find them. Then, just put a diode so the battery can't charge in the duo. You'll be sticking with NiMH, so the discharge curve should be near the same, allowing the battery meter to work without any modifications.
Less modifications = less possible errors.
I vote for using the regular 4/5 A cells at the highest amp-hour storage you can find them. Then, just put a diode so the battery can't charge in the duo. You'll be sticking with NiMH, so the discharge curve should be near the same, allowing the battery meter to work without any modifications.
Less modifications = less possible errors.
Trash80toHP_Mini
NIGHT STALKER
In that case, what will you be using for the external charger to get your bats up to the full charge?
I don't have an answer for that question.
I'm just going under the assumption that it would be easier to make/modify some sort of charger than to try and modify the duo or the battery's circuitry too heavily. As mentioned, I'm not good with this stuff, but in the case of trying to build a piece for compatibility; it would make sense to make it as compatible with the old as possible and make the new reach back rather the old reach forward.
...if that makes any sense.)
I'm just going under the assumption that it would be easier to make/modify some sort of charger than to try and modify the duo or the battery's circuitry too heavily. As mentioned, I'm not good with this stuff, but in the case of trying to build a piece for compatibility; it would make sense to make it as compatible with the old as possible and make the new reach back rather the old reach forward.
...if that makes any sense.
)
Mk.558
Well-known member
What is wrong with charging the Duo recelled batteries? Further, is the Duo's charging circuit a smart one or a dumb timed one that guesses at the time charging based off battery voltage?
Let's start filling this out:
Voltage of original batteries: ______
Voltage of replacement 4/5 AA: 1.2v typical each
Voltage of 4/5 AF size true replacements: ______
Voltage of Lithium SuperPack: __________
Capacity of original batteries: each ~ 900mAh, total _______
Capacity of 4/5 AAs: each ______, total ______
Capacity of 4/5 true size replacements: each _____, total ______
Capacity of Lithium SuperDuperCapacityPack: _______
Kinda odd we're still talking AAs:
Or...We will need to drill holes in the front on the battery pack (use a mill with a 3mm drill bit...kinda odd I guess but...Or you could just lay the holes out...) and stuff 10 LEDs and rig up a (LM3965 is it? The IC that can drive 10 LEDs in bar or guage fashion based on voltage input) circuit for battery gauge.
Fancy.
Let's start filling this out:
Voltage of original batteries: ______
Voltage of replacement 4/5 AA: 1.2v typical each
Voltage of 4/5 AF size true replacements: ______
Voltage of Lithium SuperPack: __________
Capacity of original batteries: each ~ 900mAh, total _______
Capacity of 4/5 AAs: each ______, total ______
Capacity of 4/5 true size replacements: each _____, total ______
Capacity of Lithium SuperDuperCapacityPack: _______
Kinda odd we're still talking AAs:
If we are not going to be charging the battery in the Duo then why not just use Lithiums? Battery gauge could be hacked, not my realm but someone here should be able to (or not).
Or...We will need to drill holes in the front on the battery pack (use a mill with a 3mm drill bit...kinda odd I guess but...Or you could just lay the holes out...) and stuff 10 LEDs and rig up a (LM3965 is it? The IC that can drive 10 LEDs in bar or guage fashion based on voltage input) circuit for battery gauge.
Fancy.
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