The connector is only $6 when ripped off a cheap plug in charger.  Far
less than the time and effort to make your own, I'd think.  You might
want to beef it up with a velcro strap, cover, or some other mechanism
to hold it in place beyond the connector's friction.

http://www.shopacc.com/details.php?pID=3Dcanon-nb-5l-sd850-sd870-sd950-batt=
ery-charger

$6 including shipping from various stores on amazon.com:
http://www.amazon.com/gp/offer-listing/B000LCD9P0/ref=3Ddp_olp_new?ie=3DUTF=
8&condition=3Dnew

The chargers are junk, but you're not buying it for the internals,
just the fixture and springs which should work well.

-Adam

On Mon, Apr 20, 2009 at 1:38 PM, Philip Pemberton <piclist@philpem.me.uk> w=
rote:
> Hi guys,
> =A0 I'm currently thinking about building up a couple of portable (think =
pocket
> sized) test instruments, powered by Li-ion digital camera batteries. At t=
he
> very least I'll probably be building a capacitance and ESR meter, and pos=
sibly
> a power meter (three wires, measuring voltage, current and power -- for
> power-consumption measurement). All of these are going to be based on a
> standard platform -- one PCB with the PIC, power management and communica=
tions
> (RS232 or USB) on it, and another with the "device specific" hardware (the
> ESR, current, etc. measurement gear). Pretty simple, and it means I can s=
teal
> parts from one unit to fix the other, if that becomes necessary.
>
> =A0 I've got a pretty good idea how the power system is going to be struc=
tured.
> I'll be using a standard charge controller (Microchip MCP73812 or Maxim
> MAX1811, preference to the Microchip part due to cost, but I've got a ton=
 of
> MAX1811s in my junk box) and a switch-mode controller to boost the 4.2V f=
rom
> the battery to around 5V and a voltage reference to provide an accurate
> reference standard.
>
> =A0 The catch is, I need to build some form of connector for the batteries
> ("major high-street store" copies of the Canon NB-5L). Admittedly I could
> solder directly to the contacts, but that opens a big can of worms -- the
> battery casing is plastic, and even if the battery pack has a protection
> circuit built in (which it should), I'd still rather not solder directly =
to
> the pack.
>
> =A0 The standard battery clip for these is a set of three springs, inside=
 a
> moulding that's part of the plastic body of the camera. So even if I coul=
d get
> my hands on a broken Canon camera (and it'd have to be a fairly recent on=
e --
> Ixus series, 950IS, 82IS or something like that) I'd have to do a lot of
> hacking to make it fit my pocket case. On top of that, a casing for one of
> these cameras costs rather a lot of money... Canon UK won't sell them, an=
d the
> only local repair place I could find wanted about =A335 for the whole cas=
ing,
> and wasn't willing to split it ("what would we do with half a casing?").
>
> =A0 The only other thing I can think of would be to cut down some plastic=
 sheet
> (or FR4), and use crimp pins for (say) a Molex KK connector, suitably
> modified. The problem with this is that plastic welds (e.g. those made wi=
th
> Pro-Weld) on polystyrene (it's all the local hobby shop stocks) don't ten=
d to
> hold particularly well -- usually the clip works fine until the plastic s=
plits.
>
> =A0 Does anyone have any ideas how I could build up a clip for one of the=
se
> batteries?
>
> =A0 For reference, we're basically talking about a 32x45x8mm plastic box,=
 with
> three contacts, each 2x4mm, positioned on one of the 32mm sides, about 3.=
5mm
> from the right side, 2.75mm from the top side, about 1mm from the bottom,=
 and
> spaced about 1.2mm from each other. The contact pads are recessed about 1=
mm
> into the casing.
>
> =A0 Finally, there are two polarisation cutouts on the contact side, one =
on the
> bottom left, and one on the bottom right. They are both 5.5mm from the to=
p of
> the 8mm-high side, the left one is 2.5x3.5x43mm in size, and the right one
> 2.5x1.5x43mm in size. Both are positioned on the corners of the casing, s=
o the
> bottom-left or bottom-right corner of the cutout is on an edge. I'm not
> worried about these, because of their small size, and because the contact=
 pads
> are on one side -- even if the battery was inserted the wrong way, the
> spring-pins will only be making contact with plastic.
>
> Thanks,
> --
> Phil.
> piclist@philpem.me.uk
> http://www.philpem.me.uk/
>
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>

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