Registered: Jul 2000
Location: Plant City, FL
Posts: 385

My two biggest concerns with the Prism were the display quality and the non-replaceable lithium battery. My display concerns went away as soon as I started using it, but that battery thing really bothered me. One of the things that I love about the Visor is that I can throw my keyboard and a pack of AAA batteries in my bag and be set for a couple full days of continuous use. Very handy for my occasional trips to Sweden.

The Prism, even if Handspring's 6 hour continuous use number is accurate, isn't going to survive a transatlantic flight (not to mention the domestic connections, bus rides, etc. at either end). And since you can't just pop the battery off and replace it with a fully charged unit like you can with a cell phone, I decided I needed a creative solution.

Fortunately I found one (and in the world of Windows CE of all places!). The Build a Battery Extender web page describes how to build a battery pack that uses ordinary alkaline batteries to power (or recharge) a Casio or iPaq PDA. The good news is that I just built one and it works great for the Prism too!

You'll need a hotsync connector (which I've seen folks selling here on VisorCentral) and less than $10 worth of parts from your local RadioShack. The instructions on the web site are very good. The only thing you should do differently when building one of these is leave out the diode (the Prism's internal charging circuit can easily handle the full 7 volts you'll get from a fresh set of alkaline batteries). When wiring to the hotsync connector connect the positive wire to pin 7 and the negative wire to pin 4. The only other change I made to the design was to put a connector on the other end of the cable so that I can plug in different types of battery packs depending on my needs (I'll carry a AA pack all the time for emergency charging and I'll carry a C or D cell pack when traveling).

Now that I know I can run my Prism anywhere in the world for as long as I want off easily obtainable batteries, I think it is here to stay

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Sep 1999
Location: Midland, Texas
Posts: 231

Mr. Kessler to the rescue again!

Thanks!

I had seen similar contraption for the Palm V, and I was about to go buy a cable and begin "experimenting." Thanks for saving me the trouble. (This issue of short battery life was/is a big concern for me as well.)

How fast does a battery recharge the Prism? Does the battery provide enough amps to recharge AND use the Prism at the same time?

Thanks again,

tyler

Registered: Jul 2000
Location: Plant City, FL
Posts: 385

The battery pack with fresh batteries should recharge the Prism just as quickly as the cradle. As the battery pack voltage drops, I'd expect the charging time to increase but I really can't predict how much.

The good news is that you can use the Prism and charge the battery at the same time (just as you can with the cradle) so charging time really isn't much of an issue

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Jul 2000
Location: Plant City, FL
Posts: 385

quote:

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Originally posted by dkessler
The only thing you should do differently when building one of these is leave out the diode (the Prism's internal charging circuit can easily handle the full 7 volts you'll get from a fresh set of alkaline batteries).

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Sep 1999
Location: Texan in Calgary for a while
Posts: 1361

Hopefully Tech Center Labs will make an emergency recharger for the Prism. They're looking into it, but no final word yet.

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James Hromadka
Old Friend

Registered: Dec 1999
Location: Connecticut USA
Posts: 2682

quote:

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Originally posted by dkessler
...I can throw my keyboard... ...for my occasional trips to Sweden.

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Sweden??? You have CF software to write!!! Sweden can wait! (just kidding, of course)

The next hardware hack we need is a Stowaway cable that will accomodate not only syncing but this battery pack adapter as well. That would be a truly mobile soultion, don't you think?

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God bless America, my home sweet home...

Registered: Aug 2000
Location: Indy
Posts: 38

Kessler's sharing his wonderful work again...thanks a million!
My question: could you use a 9 volt battery (w/ a diode) instead of AA, C or D?
Seems to me you'd get more out of your battery and have a heckuva lot less bulk to mess with.

'Course, I'm an electro-newbie, so I may be way off base... just trying to "think compact," as it were.
What do you think?

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<br><img src="http://brian.covert.net/pix/sitepix/sig.jpg" border="0">

Registered: Jun 2000
Location: Pembroke,MA
Posts: 307

Kessler.. you are da man! another cool thing to have, that should already have been marketed....

Be very careful at the airport xray machine though.. Unless the operator is a VC'er, you may get taken into the back room for some questioning

Registered: Jul 2000
Location: Plant City, FL
Posts: 385

quote:

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Originally posted by brijoco
My question: could you use a 9 volt battery (w/ a diode) instead of AA, C or D?

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Jul 2000
Location: Plant City, FL
Posts: 385

quote:

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Originally posted by MarkEagle
Sweden??? You have CF software to write!!! Sweden can wait! (just kidding, of course)

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Don't panic! I may be crazy enough to plug an untested battery booster into my brand new Prism but that doesn't mean I'm crazy enough to travel to Sweden in the winter

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Sep 1999
Location: Midland, Texas
Posts: 231

How about a solar recharger?

Following James' link to Tech Center Labs I ran across a comment by a fellow who used a solar battery charger to recharge his Palm V. Here's a link to a list of solar chargers from Edmunds Scientific: http://www.edmundscientific.com/Pro...s.cfm?catid=125 . The web page does not list any specifics on the performance of the solar panel other than to say that it will recharge two NiCad D cells in 48 hrs. That sounds a little slow, but it might work in a pinch.

Interesting if nothing else.

tyler

Registered: Feb 2000
Location:
Posts: 1571

Wrong Business

Dkessler:

I think you in the wrong business! You should be in the Visor hardware business not the software business. I can see some practical uses for a battery pack and a CF Module. I am sure that they would be best sellers if they were deleveloped as commercial products.

Registered: Jul 2000
Location: Plant City, FL
Posts: 385

quote:

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Originally posted by tyler
How about a solar recharger?

Following James' link to Tech Center Labs I ran across a comment by a fellow who used a solar battery charger to recharge his Palm V. Here's a link to a list of solar chargers from Edmunds Scientific:

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A solar recharger certainly is possible, however I doubt that any of the kits Edmunds Scientific offers would do the trick (though it's hard to say for sure without any technical specs). The Prism uses a constant current mechanism until the battery reaches 90% so panels designed to "trickle charge" ni-cads won't work. The solar panel would have to be able to produce at least 1A at 6V. By my calculations that means an array of about 12 4" x 2" crystalline cells. So you're looking at about an 8" x 12" panel. And of course you also need a source of direct sunlight (crystalline solar cells usually won't operate under indoor lighting).

It's an intriguing idea for people who might find themselves in remote sunny areas for extended periods of time, but I think most people would find it more convenient to just carry a few extra sets of batteries

__________________
<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Sep 1999
Location: Texan in Calgary for a while
Posts: 1361

Plus the fact that the Prism isn't easy to read in the outdoors anyway makes a solar charger less desireable.

__________________
James Hromadka
Old Friend

Registered: Sep 1999
Location: Midland, Texas
Posts: 231

quote:

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Originally posted by dkessler
By my calculations that means an array of about 12 4" x 2" crystalline cells. So you're looking at about an 8" x 12" panel. And of course you also need a source of direct sunlight (crystalline solar cells usually won't operate under indoor lighting).

It's an intriguing idea for people who might find themselves in remote sunny areas for extended periods of time, but I think most people would find it more convenient to just carry a few extra sets of batteries [/B]

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Details, details...

Still, in a serious pinch...

I am looking at a trip to Peru in about a year that would have me out in the bush for a few weeks in a tent with no power available. This is what was driving my thinking. (Because, of course, there is NO way I wouldn't have my Prism qwith me! )

tyler

Registered: Oct 1999
Location:
Posts: 48

quote:

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Originally posted by tyler
[QUOTE][i]I am looking at a trip to Peru in about a year that would have me out in the bush for a few weeks in a tent with no power available. This is what was driving my thinking. (Because, of course, there is NO way I wouldn't have my Prism qwith me! )

tyler

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Tyler -- WOW! I'm jealous. I spent about 10 months living in Peru's altiplano -- it's a great country and just beautiful scenery.

I've seen solar panels for running/charging laptops (don't remember the link right now). Would those work?

By the way, there are other advantages to having solar charging -- particularly environmental. (Okay, I'm biased -- I just joined the American Solar Energy Society and went on their Solar Tour -- pretty cool stuff out there!!)

Registered: Jul 2000
Location: Plant City, FL
Posts: 385

quote:

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Originally posted by reconnect
[QUOTE]By the way, there are other advantages to having solar charging -- particularly environmental.

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Not to mention the geek factor . Seriously, it's one of those things that would be very cool to do just to know that you could! I don't have time to search for suitable solar panels, but if anyone else finds a source, I'd love to hear about it. What you want to find is a panel that can put out 2 amps at between 4.75V and 6.2V. Happy hunting.

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<ul><li>Dave Kessler<br>President - Kopsis, Inc.</li></ul>

Registered: Mar 2000
Location: aurora, co, usa
Posts: 21

here's another possibility for recharging one's Visor Prism

I wonder if this hand-powered recharger could be modified to work on a Visor Prism


Here's the blurb from the website:
It happens to us all. We reach the end of our talk time before we're ready! And how do we recharge when we're far from a power source? With this innovative new hand-powered generator, you don't need any power source other than your hand! Just squeeze Aladdinpower(r) for a few minutes and your cell phone (or radio, GPS unit, or CD player) is fully recharged--anytime, anywhere! Requires DC power cord (the one you probably already have that plugs into your car's cigarette lighter socket). Just 5-1/4 long. Includes genuine leather carrying case with three compartments and belt loop. (4 oz)

http://shop.gorp.com/magellans/prod...9&sku=ET250


Alladdinpower Hand-Powered Generator with Case
ET250 $75.00

A little pricy but it's an option unless of course someone decides to manufacture and market the D Cell solution created by this thread's originator.

Registered: Jul 2000
Location: Oklahoma City Ok.
Posts: 42

I love this barrery extender idea and i was just going through my junk box and have all the parts but the hotsync connector anyone know where i can get one without ordering 50 or screwing up a $30.00 cradle?

Registered: Sep 1999
Location: Midland, Texas
Posts: 231

How about "screwing up" a $20 hotsync cable?

tyler