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NiCad vs. NiMH

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phdarch
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Registered: Jan 2001
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I shoulda read this forum before buying NiCads for my Visor Deluxe. I did so on the advice of the Radio Shack guy, who said that the power capacity of the NiCads is slightly higher than NiMHs (confirmed on package). But now I see that the consensus is that the NiMHs are the better choice. Has anyone actually had bad results with the NiCads? Is there any reason for me to get NiMHs or should I stick with the NiCads? Thanks in advance.

phdarch is offline Old Post 01-12-2001 06:31 PM
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Winchell
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Cool

IMHO NiCads are a bad idea.
You see, your Visor warns you when it is time to change the batteries.
With NiCads, you'll get the warning about ten seconds too late to do anything about it. The little monsters have a very steep voltage drop curve. They will go dead and everything you had on your Visor will be gone.

Get NiMH.

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Winchell is offline Old Post 01-12-2001 07:21 PM
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phdarch
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NiCad vs. NiMH cont.

Oh yeah, one other factor in my purchase I forgot to mention is that the Handspring site expressly recommends against NiMH, saying their power output is too high and could damage the Visor...any comments on that?

phdarch is offline Old Post 01-12-2001 08:31 PM
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PDAENVY
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Re: NiCad vs. NiMH cont.

quote:
Originally posted by phdarch
Oh yeah, one other factor in my purchase I forgot to mention is that the Handspring site expressly recommends against NiMH, saying their power output is too high and could damage the Visor...any comments on that?


Can you post a link to that?
This battery FAQ page doesn't say anything about NiMH.

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PDAENVY is offline Old Post 01-12-2001 09:13 PM
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phdarch
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Sure--here is is:

http://handspring.modusmedia.nl/han...isorfaq.asp#q5a

I should have said "one Handspring site expressly recommends..." since this is a European site.

[Edited by phdarch on 01-12-2001 at 04:21 PM]

phdarch is offline Old Post 01-12-2001 09:17 PM
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iluvblue
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I had rechargeable Nicad before I bought my visor and it really suck since a full charge one last around 5 hours before I have to replace it. I recently purchased Nimh rechargeable pack from Extend for 35 bucks, a full charge one will last over 9 hours. I love it now since I can run a week before I need to charge compared to every 3 days. Of course, if you plug the Extend recharge in every day the you rarely need to look at the battery level. I only charged fully twice since I bought the pack to test how long the battery last. Now that I know, I will plug it in every night by my desk

iluvblue is offline Old Post 01-12-2001 09:36 PM
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MPM
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Exclamation I don't think so...

quote:
Originally posted by phdarch
I did so on the advice of the Radio Shack guy, who said that the power capacity of the NiCads is slightly higher than NiMHs (confirmed on package).


I haven't see the Radio Shack NiCd package you refer too, but this is likely marketing hype. Batteries are rarely rated by "power capactiy". Instead they are rated by "energy efficiency". Here NiCds rate at 150 Watt-hours per liter (Wh/l) and 50 Watt-hours per kilogram (Wh/kg). And NiMHs rate at 225 Wh/l and 70 Wh/kg. So NiMHs cram more energy (Wh) into the same volume (l) and also cram more energy into the same weight (kg). NiMHs are better than NiCds.

For Visor (and Palm) users what really matters is battery life. This is rated by milliamp-hours (mAhr). For that, current technology NiCds have a 250mAhr capacity, while NiMH have a 700mAhr capacity (I just bought some GE/Sanyo ones at Fry's that were rated this high. And only $3 each!) So NiMH have 2.8 times the capacity, thus 2.8 times the battery life, of NiCds.

quote:
Originally posted by phdarch
Oh yeah, one other factor in my purchase I forgot to mention is that the Handspring site expressly recommends against NiMH, saying their power output is too high and could damage the Visor...any comments on that?


I could not find this anywhere on Handspring's web site. All they say is to only use alkalines in the Visor.

It's BS anyway. The output voltage of NiCds is 1.2V nominal. The output voltage of NiMHs is 1.2V nominal. The same! And the current draw is whatever the Visor needs at the moment. The only time ANY battery, at the same voltage, will output too much power is if something fails in the Visor and it shorts out the battery. This usually results in heat and smoke, and of course, a dead Visor. But the failure was not caused by the batteries.

MPM is offline Old Post 01-12-2001 09:37 PM
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DBrown
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And if Handspring really only expected you to use alkalines, they wouldn't have included a method of changing the battery meter to expect NiCAD voltage levels.

I've got NiMh's in my platinum, running with the battery meter set to NiCad. They work fine.

Dave

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DBrown is offline Old Post 01-12-2001 09:51 PM
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phdarch
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Re: I don't think so...

quote:
Originally posted by MPM

I haven't see the Radio Shack NiCd package you refer too, but this is likely marketing hype. Batteries are rarely rated by "power capactiy". Instead they are rated by "energy efficiency". <snip>
For Visor (and Palm) users what really matters is battery life. This is rated by milliamp-hours (mAhr). For that, current technology NiCds have a 250mAhr capacity, while NiMH have a 700mAhr capacity


I was guilty of the same loose terminology as yourself. The package of NiCads I bought stated that the "power capacity" is 300mAhr and the equivalent NiMHs was 275 or something like that.

quote:
I could not find this anywhere on Handspring's web site. All they say is to only use alkalines in the Visor.

It's BS anyway. The output voltage of NiCds is 1.2V nominal. The output voltage of NiMHs is 1.2V nominal. The same! And the current draw is whatever the Visor needs at the moment. The only time ANY battery, at the same voltage, will output too much power is if something fails in the Visor and it shorts out the battery. This usually results in heat and smoke, and of course, a dead Visor. But the failure was not caused by the batteries.



That's exactly what I thought when I read it. See the link I posted above for the URL.

phdarch is offline Old Post 01-12-2001 10:02 PM
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phdarch
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quote:
Originally posted by DBrown
And if Handspring really only expected you to use alkalines, they wouldn't have included a method of changing the battery meter to expect NiCAD voltage levels.



Ping! It was this fact that made me think NiCads would be OK. And since I don't think Handspring acknowledges the .7 shortcut on their site, I wonder if their admonition against NiCads (based on the rapid power drain) is really valid, or if the .7 shortcut adjusts the warning to accommodate them.

phdarch is offline Old Post 01-12-2001 10:07 PM
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PDAENVY
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I followed the link. I think whoever wrote it had no idea what they were talking about, especially since the US site makes no mention of it.

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PDAENVY is offline Old Post 01-12-2001 10:09 PM
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MarkEagle
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quote:
Originally posted by DBrown
And if Handspring really only expected you to use alkalines, they wouldn't have included a method of changing the battery meter to expect NiCAD voltage levels.


They didn't... that's the PalmOS. Since the Visor is not a rechargeable device, naturally Handspring won't condone the use of rechargeables since it would add additional "support" issues to their tech support.

My VDx is 1 week shy of a year old and I've been using NiMH's since the second week I had it... never had any problems and have saved a ton of money on replacements. Back in December, I started using the FullCharge so now I don't even have to swap batteries anymore.

As for NiMH vs NiCad, NiMH's are superior. They're higher capacity and are better suited for high-drain applications. (they're the "standard" for digital camera's - devices that are very power hungry). NiCad's die quickly as their voltage level drops. NiMH's are a bit more forgiving. Plus, NiCad's suffer from the "memory" effect and really must be almost fully discharged before recharging. NiMH's can be safely recharged at any level as they don't suffer the same "memory" effects.

Bottom line, NiMH's are the way to go if you're going to use rechargeables. A little advice, though: invest in a good charger. The batteries can be negatively affected by an inferior charger. I use a Maha MH-C204F which is rated as one of the best NiMH chargers on the market.

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MarkEagle is offline Old Post 01-12-2001 11:22 PM
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phdarch
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quote:
Originally posted by MarkEagle
Plus, NiCad's suffer from the "memory" effect and really must be almost fully discharged before recharging. NiMH's can be safely recharged at any level as they don't suffer the same "memory" effects.


FWIW, the $12 Radio Shack charger I bought has a "discharge" button built in which fully discharges the NiCads before beginning to recharge them.

Thank you all for your help! Since I've got
'em, I think I will attempt to stick with the NiCads for awhile, swap 'em at 10% charge and not wait for the notice, and see what happens.

[Edited by phdarch on 01-12-2001 at 06:41 PM]

phdarch is offline Old Post 01-12-2001 11:39 PM
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CrayDrygu
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Registered: Oct 2000
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What about Energizer's e2?

I've got a set of Energizer's new "e2 Titanium" batteries in my Visor now...anybody else have experience with these? I have the backup module, so I'm not too concerned with losing data if they do the sudden voltage drop thing for some reason. I've had them for about two weeks and the battery meter hasn't dropped yet, but I never really paid attention to how long that takes.

CrayDrygu is offline Old Post 01-13-2001 08:41 AM
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thatch
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Finally! something I know about!

The main difference is that you are supposed to deep-cycle (run dry) Ni-Cds to keep them from developing a memory. On the other hand, NiMHs will lose a small portion of their capacity (somewhat like a memorty) if you do deep-cycle them. I've got a set of Enegizer Accu-Rechargables in my Visor, with another set for the charger. Mine were about $4.50 a set, wich has paid off. I no longer have to bring 5 different sets of batteries on trips-I just bring the charger.

One last thing--you can use BatteryInfo or BatteryMeterHack to change the type also (and BatteryMeter lets you change the values of it isn't warning you soon enough on NiCds.

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thatch is offline Old Post 01-13-2001 06:55 PM
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everything's a blur
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NiMH are so much better than NiCad...

quote:
Originally posted by phdarch
I was guilty of the same loose terminology as yourself. The package of NiCads I bought stated that the "power capacity" is 300mAhr and the equivalent NiMHs was 275 or something like that.


275 mAh on a NiMH AAA battery? I use Radio Shack NiMH AAA batteries and they are rated at 550 mAh each! I just got some Panasonics that are 650 mAh.

The real downfall of NiCad batteries is that they can (and do) lose their power even while they are inactive. They have a tendancy to have very inconsistent power output, whereas NiMH puts out a more consistent voltage. NiMH batteries also tend to last a lot longer than NiCads; a well treated set of NiMH batteries can be recharged between 700-1000 times.

I do not remember ever reading an official Handspring document stating that NiMH batteries are expressly discouraged, but I do remember reading against using Lithium Ion batteries. Lithium batteries are supposed to get hotter than other battery types, and for that reason are discouraged. I've never confirmed this though; I can neer find Lithium Ion AAA batteries.

For more battery theory as it relates to Palm devices, check out this old site:
http://www.pstec.de/ppp/ppppowpi.html
http://www.pstec.de/ppp/pppaccu.html

everything's a blur is offline Old Post 01-14-2001 06:23 AM
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DBrown
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Registered: Jan 2001
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Food for Battery Thought.

I own a Visor Platinum. I've had it a week.
My wife has a Visor 2meg model

Using the .6 shortcut I determined my new visor's production date is 11/8/00. That is the SAME date as shown using the UP/Clock/down easteregg.

Using the same shortcut my wife's date shows 1/25/00. But her easteregg date is 31-Aug-99.

Using the .7 shortcut, there are FOUR battery options on my platinum. They are: NiCad, Rechargeable Alkaline, NiMH, and Alkaline.

On my wife's basic there are three: NiCad, rechargeable alkaline, and Alkaline.

The OS version on my Platinum is "Palm OS software v. 3.5.2H1.." My wife's OS is "Palm OS Software v. 3.1h2". I mention this since an earlier post claimed the NiCad battery setting was a feature of the palm OS, and unrelated to Visor specifications and recommendations. The H in the OS number indicate a Handspring version. I find it very hard to believe they would accidently "leave in" an OS feature if it was detrimental to the function and use of their products.

My conclusion? Use any kind of battery you want, except maybe LIon. Although The basic Visor does't have a setting for NiMH batteries, I suspect that coincided with the earlier development date and less familiarity with all the battery options out there. IN fact, I'll bet that if AAA LIon rechargeables become readily available, then later versions of the OS will support them in battery meter settings.

I personally have used all four types in my wife's Visor. Alkalines clearly have a longer useful life. NiMH last longer than NiCad. Rechargeable alkalines "seem" to last as long as regular alkalines, but there may be a slight difference.

Dave

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DBrown is offline Old Post 01-14-2001 05:42 PM
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thatch
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Lightbulb

It is quite possible that something is all right to use, yet it is still 'unsupported.' I work in around tech support people who have a policy of not supporting AOL's AIM. It works fine in every case (they've never had a problem with it) but wish to reserve the right to ask you to uninstall it if your computer is acting the slightest bit funny. I would reluctantly say it's the same case with NiMHs. If your Visor isn't working, they can say "Oh, you're using non-standard batteries. That's different, then, now isn't it?" and void your warranty.

That's the way techs work. They only support what they have to. In fact, centralized computer maintence at a university here only supports Intel processors and only one size of hard drive, only sell one speed CD-ROM, one CD-RW...you get the picture. Saves them so much time you can't shake a stick at it. I know-it's a cliche. But it serves the purpose.


[Edited by thatch on 01-14-2001 at 01:15 PM]

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thatch is offline Old Post 01-14-2001 06:11 PM
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mattbehrens
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quote:
Originally posted by DBrown
And if Handspring really only expected you to use alkalines, they wouldn't have included a method of changing the battery meter to expect NiCAD voltage levels.


But they also included shortcut-dot-8 (flip backlight), and it don't work. :-)

FWIW, I use NiMH, and I have no trouble whatsoever, except that the voltage tends to drop when I have extended Liberty sessions (need to Afterburn for those)...

mattbehrens is offline Old Post 01-16-2001 09:17 PM
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Eug
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quote:
Originally posted by MarkEagle

As for NiMH vs NiCad, NiMH's are superior. They're higher capacity and are better suited for high-drain applications. (they're the "standard" for digital camera's - devices that are very power hungry). NiCad's die quickly as their voltage level drops. NiMH's are a bit more forgiving. Plus, NiCad's suffer from the "memory" effect and really must be almost fully discharged before recharging. NiMH's can be safely recharged at any level as they don't suffer the same "memory" effects.



Actually, it would seem the new standard for digital cameras is LiIon, since they do not discharge (much) if left for weeks, unlike NiMH. That is one issue with NiMH (and NiCad). Also, I'm not sure about the complete lack of "memory" effect. Some literature I've read said while the memory effect is vastly reduced vs. NiCad, it is still present. I noticed this with my NiMH phone battery, although I've also read that with better more-tweaked chargers specifically NiMH, this problem can be reduced to a minimum. Unfortunately, no LiIon rechargeable AAA batteries exist.

[Edited by Eug on 01-17-2001 at 09:41 PM]

Eug is offline Old Post 01-18-2001 02:38 AM
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