[NTLK] NewtonTalk Digest, Vol 38, Issue 28

[James Fraser]

Hello,

--- On Wed, 11/21/12, Gene Beaird <bgbeaird at sbcglobal.net> wrote:

> We have battery trays and battery packs for both, although I
> think the battery tray on my wife's Newt is broken. I'd prefer to use >something rechargeable, because throwing batteries out on something that's >used so little these days seems like such a waste.  

I agree; I used to buy standard AA batteries a lot, too.  Decent AA rechargeables are a comparatively recent innovation (anyone else remember the Millenium-brand rechargeable batteries from the late 80's?).

> Please explain 'Eneloops + battery tray combination'. 
> If it has been mentioned before, I don't get to read every
> digest that comes through these days.  Thank you.

Well, I'll give it a go. :)  John Heinrichs started us out with a link to Amazon: 

http://tinyurl.com/bfy46m2

Basically, the idea is that, rather than charging battery packs in the Newton itself, you spring for Eneloops and charge them separately in their own charger, then pop them into the battery tray.

(This method has the added advantage of allowing you to use regular AA batteries in case an power outlet isn't immediately available for your rechargeables, but a drugstore selling AAs is.) 

If you need AAAs for other doodads around the house (or, say, an OMP), the Amazon deal that John linked to is a pretty good one.  Personally, I went for a deal similar to this one:

http://tinyurl.com/awxz44p

...which offers eight AAs and two chargers for roughly the same price.  

If you're like me, you're always accidentally dropping, losing, or eating things (or, at least, ceaselessly fretting over the possibility of your doing so). Should that be the case, having two of any "something" you might have need of on hand is probably a good idea.

(Of course, you don't get the four AAAs with the latter deal, so only you know what would work best for you.)

There might also be another consideration when it comes to charging battery packs in the Newton itself:

>I have a nasty feeling this [a sharp popping sound, accompanied by a smell of something burning coming from the Newton] might be a failure similar to >that of two other MP2Ks I have seen which is a capacitor in the power >supply/charging circuit that has failed. The two Newts this happened to >were a total loss as the exploding cap had excavated a hole in the PCB. I  
>hope yours is not one of these.

http://marc.info/?l=newtontalk&m=122549663910141&w=2

Joel M. Sciamma then goes on to suggest a possible cause of this phenomenon in a subsequent post:

>I don't think it has anything particularly to do with rebuilt packs,  
>it's just that the heating and the high currents (that are normally  
>associated with charging batteries internally) stresses what are  
>getting to be elderly components. Failing tantalum electrolytic caps  
>that go high ESR experience a lot of internal heating, which can be  
>terminal. We could do tests of those caps with an ESR meter and swap  
>those out that look bad but it's easier just to avoid the problem.

http://marc.info/?l=newtontalk&m=122566195724631&w=2

(Bear in mind that the "elderly components" that Joel was talking about in 2008 are now four years older.)

So far, I'm only aware of the two examples Joel mentions above.  However, the fact that this phenomenon might be extremely rare would provide little consolation to me, at least, if a Newton I own happens to be the third victim.

There's also the (remote) possibility that the power source you plug the Newton into might supply an overvoltage to the Newton.  This is comparatively rare, but a NewtonTalker seems to have experienced a variation of this theme earlier in the year in the "Newton Repair Question" thread:

http://marc.info/?t=133582641700003&r=1&w=2

Granted, the culprit there seems to have been a "dirty" shipboard power source of some kind.  That is, if I understand correctly*, the Newton's native AC adapter is capable of dealing with -some- so-called "ripple" if the current from the power source exceeds the specified maximum.  However, like anything else, power adapters can fail.  In that particular case (aboard ship), a generator might be more prone than, say, a standard household outlet to presenting that sort of danger to your Newton.  

I can't really say for sure myself, so don't take all this too seriously as we're talking about possibilities (things that -might- happen) as opposed to probabilities (things that are -likely- to happen).  

I do know that I prefer to deal with rechargeable batteries like Eneloops if only because I don't have to worry about AC adapter cords being tugged on or tripped over and putting my Newton at risk for a fall.  Experience has taught me that when somebody tugs on or trips over a power cord, chances are excellent a device I care about will be on the other end of it. :(  YMMV.

Of course, one man's "healthy caution" is another man's "senseless paranoia," so you'll have to decide for yourself what measures you'd care to take to preserve your Newtons.  Being a dumb guy myself, when smart guys like Joel Sciamma suggest that "such-and-such *might* pose a problem," I tend to sit up and take notice.  Particularly when replacing a Newton with a halfway decent working unit at a non-silly price point seems to have devolved into a quest of epic proportions (or perhaps it just seems that way to me).

Anyway, I hope that at least some of this helps. 

(Aren't you sorry you asked?). :D


Best,

James Fraser

*Any of the for-real EEs on the list should not hesitate in the slightest to correct me if I'm goofing any of this explanation up.