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Battery revamp is worth doing

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hpcboy Page Icon Posted 2020-10-15 6:59 AM
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Several days ago I replaced the old cells in my Jornada 720's standard battery packs. The official data says it's 1,500 mAh, but I read elsewhere that those Sony cells (US18650S) are actually about 1,300 mAh only. Anyhow, after revamping the battery, I kept using it every day with several programs running at the same time (writing notes and journals, playing audiobooks, opening resco explorer, playing PocketSlay, syncing and copying files on the cradle without AC etc.) until the power dried up after 16 hours 25 minutes.



This is the very first charging of the new cells (Sanyo, 3400 mAh, less than USD$5 each). I suppose repeating the complete charge-discharge cycles a couple of time can push the battery life even further.

I would say the most worth doing hardware mod on these old buddies is recelling the pack. It's rather simple and quick. It would be safe enough as long as you don't use soldering and sharp knives on the cells themselves (with a pair of reasonably steady hands and well-focused eyes of course).

The whole operations for both my Sigmarion III and Jornada 720 are documented here:
https://solochampion.blogspot.com/2020/10/book-of-sigmarion-iii-chap...
https://solochampion.blogspot.com/2020/10/book-of-jornada-chapter-2-...

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hpc12 Page Icon Posted 2020-10-15 11:32 AM
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This is a great guide & very much appreciated.

I would like to attempt this to my Casio A-11 NH-10A pack.

It would also be great to do for a MobilePro 900 & 780.


The Cassiopeia normally takes AAs, could you recommend how to get started on a project like this?

How do you find which lithium batteries are a good fit for the battery you are recelling?

Did you find a Jornada Datasheet?
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hpcboy Page Icon Posted 2020-10-15 11:55 AM
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I am not sure about Casio A-11 NH-10A. The machine was so old. If it uses some proprietary battery than recelling may be a challenge.

If the Cassiopeia just takes regular AAs, there seems to be nothing to mod here?

Recelling Mobilepro's battery packs should be pretty straightforward. I assume they are also using the commonplace 18650 cells.

Some tips for buying rechargeable battery cells (here I assume those Lithium Ion cells):
1. Always buy from renowned sellers. You may pay a bit more, but it's always a good guarantee.
2. Beware of the overstated capacity. As far as I know, even the large brands (Panasonic, Sony, Sanyo, Nitecore, etc.) are making cells capped at around 3,400 to 3,600 mAh. Do not be tempted to get those boosting 4xxx mAh. I'm not sure whether they even really exist.
3. Just as 2 implies, always buy cells made by good brands. Sanyo (like the ones shown in my blog post) is often recommened.
4. Stay away from dubious brands, such as "Ultrafire", which are infamous of having so many fakes all over the place. Super cheap, but you may get half the stated capacity at best, and poorly made explosives at worst.
5. Don't buy cells which are overly (and suspiciously) cheap. My impression is on average a 18650 sells for around USD$4-6.
6. Some cells are manufactured with a small protection board built on top of the positive terminal, making these cells longer than those found in the battery packs. Don't buy these cells because they just won't fit in the original battery pack casing. In general the charging circuits should already have certain builtin protection mechanisms.
7. I am no expert here. So refer to the professional guide https://www.hpcfactor.com/support/cesd/h/0054.asp
8. One more tip: Just like any not so simple hardware mods, if possible, try on less precious devices and see how far you can go and learn from that.

Edited by hpcboy 2020-10-15 12:04 PM
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hpcboy Page Icon Posted 2020-10-15 12:01 PM
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Though HP didn't seem to be specific about the actual capacity of the (standard) battery pack for Jornada, the specs listed on most HPC-related websites would say 1,500 mAh. But I found several online sellers selling exactly this cell stating that cell is of lower capacity.
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Mjolnir Page Icon Posted 2020-10-15 12:03 PM
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Nice work, also enjoyed your blog.
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CE Geek Page Icon Posted 2020-10-15 1:14 PM
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The standard-sized Jornada battery packs' capacity varied over time. I have one rated at 1.3Ah, another at 1.5Ah, and yet another at 1.96Ah.
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Rich Hawley Page Icon Posted 2020-10-15 1:15 PM
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It is aggravating as crap when you order new cells only to find out they are either junky low capacity, or used old laptop batteries that gave been resleeved in shrink wrap.

Back when I started rebuilding my battery packs they were premium prices too! Luckily with the increase of "vaping" here in the states, 18650s have become commonplace.

On the average…the typical great 18650 will be in the 2400mAh range…and usually you can verify this before getting into your rebuild by externally charging it and then under load, time the discharge. Who wants to go to the effort of a complete rebuild using crappy batteries?

An easier and most often true practice is simply to weigh the cell. A good one should weigh between 40-50 grams. Though I did get a cell one time that had weight added internally to fool the buyer.

Avoid cells with built in overcharging circuitry if you can. These normally have a cutoff value of 92% capacity. So while they work fine, 8% of ten hours work time means you are losing 48 minutes. Better to let your HPC contol and stop the charging. Also a few of these batteries are actually longer in length as they use an external tiny round circuit board on the end that adds length. Okay for an e-cigarette or lion celled flashlight… but not so when space inside the HPC battery pack is at a premium.

I have one MP900 that I modded that uses 18650s that slide in from the end of the cell. When the pack is in the unit, the cells are held in place with a removeable cap on the end. The advantage is I never plug in that MP900 and have a 4 battery 18650 charger to keep the cells hot. Swap in 2 while charging 2. Kind of like my 9 AAA battery MP880 battery I posted here on HPCFactor years ago.

Successful recelling is very gratifying…
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hpcboy Page Icon Posted 2020-10-15 1:24 PM
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CE Geek - 2020-10-16 8:14 AM

The standard-sized Jornada battery packs' capacity varied over time. I have one rated at 1.3Ah, another at 1.5Ah, and yet another at 1.96Ah.


If I remember what I read correctly, 720's has lower capacity (1,300/1,500?) than 728's (1,800+.
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CE Geek Page Icon Posted 2020-10-15 1:43 PM
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I think the 1.3 was for the 680/690, the 1.5 for the 720, and the 1.96 for the 728. But they can be used interchangeably.
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hpcboy Page Icon Posted 2020-10-15 1:44 PM
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Rich Hawley - 2020-10-16 8:15 AM
On the average…the typical great 18650 will be in the 2400mAh range…

Is this still true of today? I've seen local shops are selling brands with 3400mAh cells like this one: https://www.nitecorestore.com/18650-batteries-s/2532.htm

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Rich Hawley - 2020-10-16 8:15 AM
Successful recelling is very gratifying…

Absolutely. And such prolonged battery life definitely underscores the strength of these archaic CE devices, putting all those trendy netbooks and umpcs out there to shame.
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CE Geek Page Icon Posted 2020-10-15 1:50 PM
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Especially on the Jornada, where the 1.96Ah standard pack already gives nine hours of use. Your recelled pack could keep it going over 16 hours without having to use that bulky extended pack that HP put out.
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hpcboy Page Icon Posted 2020-10-15 2:04 PM
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CE Geek - 2020-10-16 8:50 AM
Especially on the Jornada, where the 1.96Ah standard pack already gives nine hours of use. Your recelled pack could keep it going over 16 hours without having to use that bulky extended pack that HP put out.


That giant extended battery looks like a 6-cell pack, being advertised to last 3 times as long as the standard pack. I suspect those cells are not really high in mAh given such footprint.

Sure, 16+ hours of runtime is more than enough, given the small size. At least that means I just need to charge my machine after a few days of use, unlike all my "modern" devices which I must charge ritually at least once a day.

If need be, there is another old pack unused in my "junk" pile...

The caveat here is I have yet to use any networking CF/PC card which is the major battery killer for HPCs.


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hpc12 Page Icon Posted 2020-10-15 11:20 PM
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hpcboy - 2020-10-15 11:55 AM

I am not sure about Casio A-11 NH-10A. The machine was so old. If it uses some proprietary battery than recelling may be a challenge.

If the Cassiopeia just takes regular AAs, there seems to be nothing to mod here?

Recelling Mobilepro's battery packs should be pretty straightforward. I assume they are also using the commonplace 18650 cells.

Some tips for buying rechargeable battery cells (here I assume those Lithium Ion cells):
1. Always buy from renowned sellers. You may pay a bit more, but it's always a good guarantee.
2. Beware of the overstated capacity. As far as I know, even the large brands (Panasonic, Sony, Sanyo, Nitecore, etc.) are making cells capped at around 3,400 to 3,600 mAh. Do not be tempted to get those boosting 4xxx mAh. I'm not sure whether they even really exist.
3. Just as 2 implies, always buy cells made by good brands. Sanyo (like the ones shown in my blog post) is often recommened.
4. Stay away from dubious brands, such as "Ultrafire", which are infamous of having so many fakes all over the place. Super cheap, but you may get half the stated capacity at best, and poorly made explosives at worst.
5. Don't buy cells which are overly (and suspiciously) cheap. My impression is on average a 18650 sells for around USD$4-6.
6. Some cells are manufactured with a small protection board built on top of the positive terminal, making these cells longer than those found in the battery packs. Don't buy these cells because they just won't fit in the original battery pack casing. In general the charging circuits should already have certain builtin protection mechanisms.
7. I am no expert here. So refer to the professional guide https://www.hpcfactor.com/support/cesd/h/0054.asp
8. One more tip: Just like any not so simple hardware mods, if possible, try on less precious devices and see how far you can go and learn from that.


Thanks for this.

The Cassiopeia does indeed take AAs, however I have the aftermarket NH-10A which appears to take lithium cells. Have been through both your teardown and the official guide multiple times, but it "feels wrong" to cut into this battery pack. Never mind that it's been leaking acid.

Luckily, there are no shortage of electronics suppliers here, so I'm able to avoid eBAY. Perhaps I'll try and do this one on the leaking AA pack & spare A-11, and report back.

As for the MobilePro, that would be great. I assume that once you've replaced the batteries with your own, it's possible to plug in and charge as normal? Or, is it a requirement to take them out every time. That would be inconvenient.
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hpcboy Page Icon Posted 2020-10-16 1:03 AM
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Leaking is bad. I would take out the cells because the leaking cells can kill the circuit inside anytime.
To minimize cosmetic damage to the casing, start scoring on the connector side.
The mobilepro pack is just like any other regular battery pack. With the right cells in it will work just as normal, and better.
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Rich Hawley Page Icon Posted 2020-10-16 2:50 PM
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3400 mAh cells would be nice. However, I wonder how they determined that rating?

We all know that mAh is basically computed based on voltage, resistence, current, and time. Theoretically, these values would be consistent no matter what the load… that is until we bring Peukert's law into the equation.

You see, under higher loads, where you draw more current, then the mAh values change. They get worse with higher loads. Hence if you had a very very tiny current draw…you might be able to calculate the mAh rating to your favor… inflating it immensely.

Do this test again, but this time in near freezing temperatures and the numbers get even better.

Not false advertising…simply just controlled testing…
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