[time-nuts] Oscilloquartz BVA has been sold. Thank you all who expressed an interest.

[Magnus Danielson]

Hi,

On 2020-09-27 09:02, Poul-Henning Kamp wrote:
> --------
> Bill Notfaded writes:
>
>> Are you saying if the load is small it'll still run out pretty quickly?
> Yes.
>
> The constant loss of the inverter-stage will be nothing compared
> to the full design load, but will totally swamp your light load.
>
> This is why UPS vendors only publish hold-up times for full load.
>
Which is why it is a good idea to run the load directly off the
batteries. In telecom, that is -48 VDC (check out the ETSI EN 300 132-2
spec) but there is also one for modern switch-mode supplies for more
IT-infrastructure which is feeding the 230 VAC side the DC it achieves
after rectifier (ETSI EN 300 132-3 spec), but that has not taken off as
far as I know. Both avoids the inverter part. Running straight of the
batteries for 24 VDC matches many of our devices. For instance, all the
atomic clocks and many OCXOs I have essentially run off 24 VDC, so that
will be my focus.

The voltage range for the -48 VDC is really -40 VDC to -60,5 VDC to
match the out of charge to charging voltages of normal lead-acid batteries.

Sure, the 24 V or 48 V may not fit the needs of applications, but you
can usually find DC/DC converters that can be decent enough loss-wise as
they do switched mode drop-regulation. Choosing wisely amongst those,
you can get better losses than a large supply which runs in a
non-optimal mode.

Cheers,
Magnus