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PowerBook 1400 cells
- Thread starter steve30
- Start date
Bunsen
Admin-Witchfinder-General
AA NiMHs may be too large, but AAA NiMHs might both fit and still be cheaper and easier to find than the exact match cells to the originals. I think they are 4/5 AA or 4/3 AA, one or the other. Don't quote me on that. I've looked in to 1400 recelling, but it was a long time ago. Try a google search on site:applefritter.com
wally
Well-known member
I have disassembled one PB1400 battery pack and it contained eight Sanyo Twincell NiMH cells of size 4/3FAU (unsleeved measurements, excluding tab thickness were 66.7mm L x 17.4mm D). In the US, Digi-Key part number SY136T-ND for the solder tabbed version. But these are expensive as in $10.88 per cell! There is plenty of room for you to rig up some improvised spring loaded tubular holder for using eight economical AA sized (50.4mm L x 14.35mm D) NiMH cells of lesser capacity, length, and diameter. The battery pack internal label says 9.6V, 4000 mAh. Unfortunately I haven't come up with a way to fit 16 AA cells in a series/parallel configuration into the space available.
See
for a look inside. Those green plastic tubular sleeves each contain a pair of 4/3FAU cells in series. There is a Klixon thermal breaker, and both Polyswitch current limiter in series with what I think is a fuse all in series with the battery. The green PCB strip contains on the hidden side a DS2401 serial number device and a temperature sensor, each accessable to the PB1400 power manager. On the bottom of the battery assembly case is a brown colored insulated copper heat spreader which brings the green PCB strip close to the average temperature of all cells, probably for the use of the temp sensor that looks for the temp rise associated with charge completion. Your improvised battery holder should not excessively thermally insulate the replacement cells from that heat spreader. So any space filler material should go above the cells, not below.
I also recall a very tight squeeze but workable situation for button end and solder tabbed replacement AA cells, but this was for PB500 series batteries. In the PB1400 there will be 30 mm to spare in the length dimension if you use eight AA cells.
See
for a look inside. Those green plastic tubular sleeves each contain a pair of 4/3FAU cells in series. There is a Klixon thermal breaker, and both Polyswitch current limiter in series with what I think is a fuse all in series with the battery. The green PCB strip contains on the hidden side a DS2401 serial number device and a temperature sensor, each accessable to the PB1400 power manager. On the bottom of the battery assembly case is a brown colored insulated copper heat spreader which brings the green PCB strip close to the average temperature of all cells, probably for the use of the temp sensor that looks for the temp rise associated with charge completion. Your improvised battery holder should not excessively thermally insulate the replacement cells from that heat spreader. So any space filler material should go above the cells, not below.
I also recall a very tight squeeze but workable situation for button end and solder tabbed replacement AA cells, but this was for PB500 series batteries. In the PB1400 there will be 30 mm to spare in the length dimension if you use eight AA cells.
wally
Well-known member
Should not be a problem as long as the cells contact the heat spreader with no more insulation thickness than the existing cells' sleeving. The batteries run and charge cool until the very completion of charge when the cells start to get quite warm. The power manager is looking for this temp rise over ambient as a signal (one of several, the manager is also monitoring voltage and keeping some running estimate of charge state from a time and current drawn/delivered standpoint) for switching from high rate charge to trickle charge. I think the heat spreader is not for heat sinking, but rather sampling the temperature of all of the cells and bringing this sample over to the strip PC board where a temp sensor is seeing the temperature of the air near two adjacent cells plus the temperature conducted to it from the heat spreader to the PC board to the sensor leads. Whatever cells you use should come with insulating shrink sleeving and can be taped down onto the heat spreader. Then, to help hold down the cells, small foam strips can be put on top to fill the gap to the top cover. Or, there's even enough room to put an inverted homemade springy battery socket thingy that incorporates the original safety overcurrent/overtemp devices and makes contacts to those economical retail store tabless cells. There has been forum discussion elsewhere on the merits of not soldering directly to tabless cells, and some have even built spotwelders using big caps like those used in monster car audio stiffening applications. Leave the vents of the cells and case unblocked in the event gases need to be vented.
One unknown is whether the smaller AA cells will have sufficiently low internal resistance to handle the PB1400 worst case current draw which I am guessing is hard drive seeking plus spinning up a CDROM. Wouldn't be good to get a low battery sleep from this. I have read somewhere that the very highest capacity AA cells get this by trading off internal resistance. Some experimentation, or even better browsing in the RC forums for test results, would be good. The remote control and robot wars people push their cells very hard indeed on both charge and discharge, and I have seen, somewhere on the net, results of comparison testing of cell vendors. In fact they push the cells so hard that many of them just solder direct, figuring that any seal compromise is irrelevant since they plan on wearing out the cell's plate material and insulator integrity before they dry out from seal leakage.
steve30
Well-known member
What kind of capacity should the AA cells have?
Currently, the total capacity of the battery is 3500mAh, so if the AAs were to match that one, and I used 8, they would need to be about 450mAh each.
However, most of the AAs and AAAs in the catalogue are rated at around 1500mAh.
I'm guessing we don't want too much capacity. Anyone got any suggestions as to what would be ideal?
Currently, the total capacity of the battery is 3500mAh, so if the AAs were to match that one, and I used 8, they would need to be about 450mAh each.
However, most of the AAs and AAAs in the catalogue are rated at around 1500mAh.
I'm guessing we don't want too much capacity. Anyone got any suggestions as to what would be ideal?
Quadraman
Well-known member
I don't know how many cells are in your battery, but 12000 mAH sounds too high to me. I don't think I've ever heard of any laptop battery that delivers that much power. Are you sure you're looking at the correct type of cell for your machine? Does the place you are getting them from have a website so we can check it out? If your laptop spends most of it's time plugged in like most do, then recharge time shouldn't be an issue.
steve30
Well-known member
Well, there are 8 cells, and if the cells were 1500mAh which are listed in the catalogue, the total would be 12000mAh.
Smaller cells are avaliable.
Supplier is http://www.rapidonline.com
Smaller cells are avaliable.
Supplier is http://www.rapidonline.com
steve30
Well-known member
I was looking at the ones on this page because they have tags on:
http://www.rapidonline.com/Electrical-Power/Batteries/Nickel-Hydride/Nickel-metal-hydride-batteries-(industrial-sizes)/77632/kw/183870#techspec
http://www.rapidonline.com/Electrical-Power/Batteries/Nickel-Hydride/Nickel-metal-hydride-batteries-(industrial-sizes)/77632/kw/183870#techspec
tomlee59
Well-known member
Your math is not quite right. A mAh is not energy, so you don't just multiply the number of cells by the mAh rating. It is the product of current (milliamperes) and time (hours). If I have two cells in parallel, then I get double the current, and thus double the mAh. If the two cells are in series, the mAh rating does not change because the current does not change; the current is simply delivered at twice the voltage.
The original pack consists of 3500mAh or 4000mAh cells. So, using 1500mAh cells in a purely series combination would give you just 1500mAh, and hence shorter, not longer, runtime.
Anonymous Freak
Well-known member
In some notebook computer batteries, there are more cells than needed to generate the Voltage the computer needs. So, for example, if you had a computer that needed 9.6 Volts, you could achieve this with either 8 standard 1.2 V batteries, or with 16 1.2 V batteries (two 9.6 V packs in parallel.)
Putting batteries in series increases their Voltage, but does not increase the mAh rating of the pack. Putting batteries in parallel keeps the Voltage the same, but does increase the mAh rating. So if you were to create a double-cell pack, you double the mAh rating. That is how many PC laptops make 'extended life' batteries, they just double, triple, or quadruple the internal number of cells, keeping the Voltage the same, but increasing the mAh rating. (I had a Sony whose 'standard' battery fit totally internally, but the 'double' size pack stuck out the bottom, acting like a rear stand.) Apple has never had battery packs that could reasonably stick out of the computer, so it hasn't been possible to make these double-size battery packs for Apple systems. (Although it might be possible to rig up such a system for the original iBook.....)
Putting batteries in series increases their Voltage, but does not increase the mAh rating of the pack. Putting batteries in parallel keeps the Voltage the same, but does increase the mAh rating. So if you were to create a double-cell pack, you double the mAh rating. That is how many PC laptops make 'extended life' batteries, they just double, triple, or quadruple the internal number of cells, keeping the Voltage the same, but increasing the mAh rating. (I had a Sony whose 'standard' battery fit totally internally, but the 'double' size pack stuck out the bottom, acting like a rear stand.) Apple has never had battery packs that could reasonably stick out of the computer, so it hasn't been possible to make these double-size battery packs for Apple systems. (Although it might be possible to rig up such a system for the original iBook.....)
register
Well-known member
Sorry for replying late. For cell replacements check specifications thoroghly to meet the needs of your application. Years ago I played with this without lasting success. A lot of cells you get for RC applications have a nice capacity, allow high discharge current peaks, but do _not_ like high charge current. So you would need some current limiter to prevent the quick charge your PowerBook would l perform usually. Cells for standard applications might have a higher capacity but would be worn off by higher discharging current. I was not succesful with any of both because I did not take care of the specific needs of a given cell type. (After the first charging cycle the machine worked well, but after a few cycles the reworked battery pack reached end of life.)
A set of cells flattens a lot of money and time to rework the battery pack. So do this only when you have appropriate instructions and material, probably in combination with an improved charger circuitry. Otherwise it might be a waste of time and money. You better invest into some new (probably overpriced but hopefully) professionally made battery pack still available.
A set of cells flattens a lot of money and time to rework the battery pack. So do this only when you have appropriate instructions and material, probably in combination with an improved charger circuitry. Otherwise it might be a waste of time and money. You better invest into some new (probably overpriced but hopefully) professionally made battery pack still available.
