Anelok: battery holder, quality issues

Werner Almesberger werner at
Mon May 19 09:00:47 EDT 2014

Felix wrote:
> What about not putting a battery door and just service the battery and the
> micro-sd card opening half of the case?

That's always an option. A small compartment that opens with the
rest of the case staying closed would be tidier and also protect
the circuit better.

In any case, the rapid degradation of the battery holders and the
way the case is closed are largely separate issues, and whatever
is done for closing the case will implicitly support the battery
in addition to whatever the actual holder does.

> Also switching from the clip holder
> to slot in holder (I though you tested) would do the device more durable.

You mean like the ones at 11 o'clock or the ones at 2 o'clock in

I've tried these and they produce an enormous downward force that
makes is very difficult to extract the battery if you don't have
360 degrees access to combine pushing and pulling when trying to
get it out. Forget fingernails but think of this as the sort of
tool you'd need:

That force also quite reliably detaches the retainer from the PCB
in the case of SMT. Through-hole can be made to at least stay in
place, but having those contacts poke up (in our case that would
be some 2.04 mm on the back side of the PCB) then screws up the
mechanical stacking.

You rarely see stand-alone coin cell holders in small commercial
products and everyone seems to have a custom design that is
integrated with the case. That would of course give us all the
flexibility we want.

The problem with this: I don't have the means to make such a
thing (it seems the usual formula is steel or bronze with nickel
and/or gold on top) and my attempts to mimick that with materials
at my disposal weren't overly successful.

Alas, it seems that bare contacts suitable for a compact design
aren't sold on the market, and scavenging a holder for just the
contacts would have numerous issues, too, the biggest one being
that they never have quite a form that would be nice to use.

Of my holders collection, the only ones that are halfway friendly
are ...

- the ones at 1 o'clock:

  They're larger than the MPD LP2032SM and need considerably more
  force for removal, though.

- and the ones at 6 and 5 o'clock. Alas, these are extremely
  large and have a rather cheapish feel to them.

I'd like to see if a custom design can be made, but that will need
considerably more resources than available for now.

- Werner

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