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

[Mark Spencer]

Yes running being able to run at least some of my OCXO's from a DC battery system is my desired state of affairs for my home time lab.  It is nice to have two devices that have been running for a decade.  

Anyways thanks all for the comments about various ways to power my BVA and the trip down memory lane re large UPS systems, Telecom battery plants etc.  

It will be nice to have the BVA powered from the a DC battery system.   I will be curious to see how the BVA performs after being powered up for at least a year.  Currently after running for a month or so it seems to often outperform the other OCXO's  that have been running for a decade or so.   Between occasional power outages that exceed typical UPS run times and the need to change batteries on occasion in the consumer grade UPS systems I use in my home time lab, getting multi year un interrupted run times without using a DC battery system to power devices during AC power outages seems unlikely for me.



Mark Spencer
mark at alignedsolutions.com
604 762 4099

> On Sep 27, 2020, at 4:06 AM, Magnus Danielson <magnus at rubidium.se> wrote:
> 
> 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
> 
> 
> 
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