[Tfug] OT: Batteries

[johngalt1]

Without having more of an idea of the unit's purpose and 
price point, be prepared to discuss the philosophy of 
battery applications ad infinitum. Not sure how non-specific 
talk will be of any use.

Having said that, if there is a proprietary battery for 
which there are spares readily available, this could be 
could tolerated. For example, my Holux GPS receiver uses a 
rechargeable battery that was originally intended for some 
other device. (a cell phone or something like that...



----- Original Message ----- 
From: "Bexley Hall" <bexley401 at yahoo.com>
To: "Tucson Free Unix Group" <tfug at tfug.org>
Sent: Wednesday, November 25, 2009 1:05 PM
Subject: [Tfug] OT: Batteries


> Hi,
>
> I'm trying to come to grips with two very different
> approaches to battery selection for a device I am
> designing (there are actually three but the second
> is *effectively* the same as the third).
>
> 1. Customer replaceable (!) off-the-shelf batteries.
> This limits the design to battery form factors,
> chemistries and capacities that are "readily available"
> (i.e., buy replacements at Target, etc.).  Note that
> a separate issue is rechargability (as that complicates
> design, adds to cost, reliability impact, etc.).  With
> COTS batteries, recharging is just a *convenience* issue.
>
> 2. Proprietary battery.  This affords greater flexibility
> in form factor, choice of chemistries, battery capacity,
> etc.  It, however, *requires* the battery to be 
> rechargeable
> (or have a VERY long life -- years!) as replacement would
> be inconvenient (and possibly expensive since that means
> stocking a supply of replacement batteries and allowing
> people to purchase them -- adds overhead to each such 
> sale).
>
> 3. Proprietary battery *sealed* within the device!  (i.e.,
> option 2 might be something like a cell phone approach in
> which the battery *is* proprietary but the user *could*
> remove/replace it if he was able to get a replacement 
> part).
> This places even more demands on the battery (from the
> user's perspective) as replacing it would be a "factory
> service" operation.
>
> However, it offers some benefits that can be real wins:
> - device can be made far more weather resistant (I've 
> known
>  of two cell phones "destroyed" because they "fell" into
>  a toilet -- I have no idea *how* but...  :> )
> - cost of manufacturing goes down as you simplify the
>  design of the case
> - cost of *tooling* goes down (since the case has fewer
>  pieces, molds become simpler and fewer)
> - no need to stock batteries or battery covers as
>  replacement parts
>
> Price point seems to play a big part in my initial
> thinking on this.  E.g., a $20 device with a battery
> that will last a year you can think of the battery
> *and* device as "disposable" (in today's market).
>
> OTOH, how happy would you be about discarding your
> laptop/netbook after a year?  (and those aren't
> actually terribly expensive!)
>
> Comments?
> --don
>
>
>
>
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