Hi all.

I've used lithium ion cells in a few projects now, and they've served
me well. I'm contemplating trying to make my next project extremely
small (or, well packed at least, depending on your definition of
small), and I'm curious how others have handled the situation I'm in.

Basically the issue is that I'd like to have a removable battery, so
that it can be swapped out during operation if it becomes drained. The
case I'm using is a Hammond metal extrusion box (1455 series), so
there is no battery door, or option for a battery door. In the past
I've used 14500 cells, which have worked great. There's a company
called Bulgin that makes a panel mount AA battery holder (check it out
here: http://www.digikey.ca/product-detail/en/BX0011%2F1/708-1396-ND/198075=
4
) which works great. Unfortunately, it's a bit large. It takes up a
fair bit of internal volume, and for the box I want to use, it just
won't fit.

On my last project I used a small lithium polymer cell that worked
great. But they aren't really removable in any easy way. I chose a
pack that should provide the run time needed (so far it hasn't been a
problem) and added the option to run the device from an external USB
power source, such as an external battery pack.

One ideal solution would be to use one of the many cell phone, digital
camera or other electronic gadget packs. They seem to often require a
special form to hold them though.

So, how have you dealt with this? These are home projects, not
production items. Manufacturing a battery holder and fitting it into a
jam packed case seems unlikely from where I'm sitting, but I could be
missing something. I'm leaning towards the external battery pack idea
again, but I need to figure out how much my current draw is to see if
I can get the run time I want for the size of cell I think I can
squeeze in there.

I'm not necessarily looking for an outright solution, but getting
others' thoughts would be great!

Josh
--=20
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
=A0 =A0 =A0 =A0 -Douglas Adams

--=20
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.