VisorCentral.com - li-ion invasion, AAA retreat

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VisorCentral.com (http://discussion.visorcentral.com/vcforum/index.php)
- Visor General Chat (http://discussion.visorcentral.com/vcforum/forumdisplay.php?forumid=31)
-- li-ion invasion, AAA retreat (http://discussion.visorcentral.com/vcforum/showthread.php?threadid=25066)

Posted by ragamuffinn on 07-26-2002 12:56 PM:

Re: Non- removable bateries

quote:
Originally posted by tantousha
Yes but most users won't switch to rechargable batteries because Handspring warns against it and to the non-education average PDA user, Handspring is the omnipotent, unquestionable god of PDAs...

I agree--most users will not switch to NiMHs. However, I just have to reiterate that my point is not that I dislike li-ion as a power source. I have already indicated that there are sensible applications of li-ion (e.g., color, backlit screens; slim profile PDAs, etc.). However, the currently engineered implementations of li-ion are very anti-consumer and simply make little sense to me.

quote:
Originally posted by EJSHUMAK
That's the problem -- not what type of AAA you use -- If we have a built inbattery, there is gonna be a problem if the unit is kept for an extended period of time.

Precisely. For instance, let's look at the design of the Palm V and Vx. If you read the backstory on the development of these PDAs, you'd know that these units were actually glued shut because Hawkins really, really wanted a slimline PDA, which had no room for screws. Battery "replacement"? Try unit "replacement." The batteries in these devices weren't even replaced--an entirely different unit was shipped to the customer in the event of battery failure, and I gather this was done at cost to the customer if the warranty had expired.

Yes the Palm V and Vx are nice looking devices. And maybe it really wasn't possible to make them with serviceability. However, the battery issues were never really made clear to the customer then, and they are not made clear now at Handspring--at least not until you need to search for that info.

Posted by Madkins007 on 07-26-2002 03:57 PM:

The "Care and Feeding" of Li-Ion, NiMH, and similar batteries is an odd issue. No two sites or sources seem to agree on the best way to treat these, and this is a subject that has been raised on this and other forums a lot.

Most sources, especially battery manufacturers, seem to agree that Li-Ion and NiMH either should be, or are at least not badly hurt by, being kept as fully charged as possible.

Note- Li-Ion batteries are NOT affected by so called 'battery memory' or 'memory accumulation', the effect that made it necessary to discharge other kinds of rechargeables as low as possible before recharging. (Source: http://www.sanyo.co.jp/energy/english/f10.htm)

With a PDA or similar device, this is also the logical choice as we want to ensure that at any given moment, the device will last for as long as possible.

The flip side is that Li-Ion batteries do not like being charged for long periods or trickle-charged, so they should not be left in a charger that keeps trying to charge them for too long. ('too long' is rarely defined, but I would not charge them for more than about overnight.)

One of the best articles I have found on this subject is here: http://www.amazon.com/exec/obidos/t...4792096-2072854

To answer EJSHUMAK's question about storage:
"Li-ion batteries should be stored charged. If they're stored for over three months with a cell voltage of less than 2.5V, unrecoverable capacity loss will occur. Also, leakage and corrosion are more likely. Some Li-ion battery packs won't allow a recharge if individual cell voltages fall below 2.5V, because at this point cells will have chemically altered and recharging could be hazardous. It's best to store Li-ion batteries charged at between 70 and 90 per cent of full capacity.

All rechargeable batteries suffer from self-discharge when stored or not in use. Li-ion batteries self-discharge by three to five per cent in the first 30 days of storage, then settle down to one to two per cent per month. With intelligent batteries, the control circuits packaged with the battery can consume as much as three per cent of the charge per month. This means that a 90 per cent charged Li-ion intelligent battery can be stored for around 18 months before falling below the minimum charge limit. Shorting out, piercing, crushing, applying a reverse current or heating a Li-ion battery can lead to very high case temperatures or even battery explosion. (Source: http://www.corrosion-doctors.org/Se...li-ion-reac.htm)"

Handspring does not recommend rechargeables instead of Alkaline AAA's, but that is because of their concern that users will mess things up more than because of the performance of the batteries (if you read between the lines a little!) Using NiMH batteries and a re-conditioning charger, and swapping the batteries frequently worked great for me! (Of course, I used the old 'command dot dot 7' trick to reset the battery type!)

I WAS mistaken on one issue- I thought NiMH was about as environmentally harmful as alkaline and NiCad, but it is not!

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Posted by EJSHUMAK on 07-26-2002 09:13 PM:

Thanx 007

Thanks for the info -- that clears some things up for me and maybe prevents me from wasting my "spare" unit--

Posted by Digisane on 07-27-2002 05:09 AM:

Another weird instruction

I found another odd instruciton that contradicts any of your posts regarding recharging Li-ions batteries.

This is from the instructions book of my Kyocera cellphone, and it says to charge for 24 hrs in the first usage, then drain the battery before recharging again.

It's Li-ion.

Anyway, regarding the battery on my Pro, is it possible I keep it topped up by just leaving it on the cradle with the power on while recharging (even if it's 100% done)?

I noticed that the last time i did that by accident I left the Visor in the cradle for about an hour after at full charge the Visor is not heated at all, unlike when during normal charging. Since it states that Li-ions cannot be overcharged I think that the Visor simply isn't charged when it reached 100%.

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Posted by Madkins007 on 07-27-2002 06:37 PM:

Re: Another weird instruction

quote:
Originally posted by Digisane
I found another odd instruciton that contradicts any of your posts regarding recharging Li-ions batteries.

This is from the instructions book of my Kyocera cellphone, and it says to charge for 24 hrs in the first usage, then drain the battery before recharging again.

It's Li-ion.

Yeah- annoying, ain't it? If you do a Google search for "Li-Ion charging", you get over a thousand articles, mostly in other languages or about the charging circuitry necessary for this.

I tried to stick to sites that either make the batteries themselves, or are run by people that I generally find reliable- but even then you get a lot of contradictions.

It DOES suddenly occur to me that perhaps part of the problem is the actual charging circuitry! MAYBE some of the differences in advice have to do with the charger rather than the batteries only. After all, I DID find several different designs for the chargers in my searches.

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Do what you can, with what you have, where you are at!

Posted by terrysalmi on 07-27-2002 07:14 PM:

I used to have a Visor Deluxe. I thought it was a pain having to change my rechargeable batteries atleast twice a week, and making sure to get the dead ones back in the charger, etc. Otherwise, I loved how I could use my battery holster and keep a backup pair on my keychain.

I know use a Sony T615c. I love how it recharges itself everytime it is in the cradle (which is most of the time). If the battery dies after two years, so be it. That is why I purchased my Best Buy 3-year Service Plan - which covers battery replacement. That should allow me to get a new battery when mine dies, or replace it for the newer model at difference of cost. (I don't abuse the plan and use it just for upgrading...I actually wait until something is wrong w/ the device...)

As a side note, AAA battery holders in Palm's can downgrade too. I hear stories on the boards, usually with Palm III series, of how the batteries will not hold a charge anymore, and deplete within a day. There is no guarantee the AAA holder will last forever....

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