[Beowulf] Mobo battery life in constantly on systems?

[andrew holway]

Once you break the seal on a battery pack they start to degrade, react
with the air etc.

I seem to remember someone telling me about breaking the electrical
seal on a battery, once you start it, it reacts away to its self at a
low rate. Bit like a bottle of water, crack open the top and it will
evaporate over time. I think its the conductivity of the moisture in
the air maybe?


On 28/07/07, David Mathog <mathog at caltech.edu> wrote:
> The question: what is the expected motherboard battery lifetime in
> systems that are continuously on?
>
> Background:
>
> The question arises because it was necesary to cycle the power today
> on a couple of nodes by unplugging them and then plugging them
> back in again.  When one came back up the BIOS settings were gone.
> That wasn't evident until a keyboard and monitor were plugged in.
> Losing BIOS settings when power is removed is pretty much the
> classic symptom of a dead motherboard battery.
>
> These nodes are now about 5 years old, and that is about the average
> battery lifetime in PCs that are turned off every night.  However these
> nodes have been on 99.99% of that time, so presumably the drain on the
> battery should have been nil.  Shelf life for motherboard batteries is
> typically about 10 years. There is no info on how old the batteries were
> that went into these systems, but presumably Tyan goes through a lot of
> batteries and these were probably fresh when installed.
>
> So bottom line, is this just a freak event or would you expect the
> other motherboard batteries to also die soon?
>
> Thanks,
>
> David Mathog
> mathog at caltech.edu
> Manager, Sequence Analysis Facility, Biology Division, Caltech
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