[NANOG] Re: Small Capacity UPS

[Brandon Butterworth via NANOG <nanog () lists nanog org>]

On 06/04/2025 19:55:20, "Mike Hammett via NANOG" <nanog () lists nanog org> 
wrote:
> Most normal UPSes get terribly inefficient at lower load ratings.

You don't say how long you want to run for. Assuming the mention
of extendable batteries means you are looking for several hours or
more we've not found any small ones. Generally extendable batteries
start with 1kVA or greater units.

Due to the lack of suitable devices some UK providers have resorted
to -

https://www.ispreview.co.uk/index.php/2025/03/broadband-isps-vodafone-bt-kcom-and-zen-internet-prep-new-uk-battery-backup.html

but it relies on feeding the devices DC.

Our FWA sites are around 50W and are in cabinets so large batteries
and feeding things DC is easy. We tend to power everything with
POE so all that is needed is a switch with DC in (we've used Netonix
but there are others such as Mikrotik).

For sites where we want a packaged system delivering AC we've
used lightly loaded Eaton 5PX range with extra batteries and
just accepted the efficiency, which has not been terrible.

There are plenty of consumer portable battery units that offer
a lot more battery capacity than UPS generally have. Some operate
as UPS and provide AC or DC out. If you feed your devices DC then
there is no inverter low load inefficiency.

For example you could run all day on just a battery expansion pack
(there are larger ones)
https://bluettipower.co.uk/products/b80-expansion-battery
which can be charged off an AC adaptor and not need the main unit.

brandon

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