[Nut-upsuser] Bluetti as a UPS?

[Greg Troxel]

Bill Gee <bgee at campercaver.net> writes:

> I have been getting very frustrated by the short runtime of my main
> UPS.   It is an APC BR1500G.  I have a pair of 35ah batteries on it,
> but even so it runs for only 10 minutes.  The batteries are good
> (independent testing) and the load is only 350 watts.  I think the UPS
> runtime calibration just does not work.

Did the testing do a controlled discharge at 25A and measure the
capacity to 10.5V?

Change your shutdown to trigger at 22V, instead of remaining lifetime.
I suggest logging battery voltage and claimed remaining runtime, and
doing a test with a simulated failure, graphing that, and posting it for
comment.

> Recently I noticed that some models of Bluetti power bank, such as
> AC200L and Fridge, have a "UPS" feature.  They boast of switching time
> under 10ms in event of a power failure on the AC mains.  The energy
> capacity is around 2kwh which should run my load for three to four
> hours.  Expansion batteries can be added.  And the price is not much
> different from a brand new 1500 VA traditional UPS.

That's interesting.  The first thing I checked was the battery
technology.  Units like this used to have Lithium ion and that would
seem dangerous.  This says it is LiFePO4.  It claims listing to UL2743.

> Has anyone used one of these as a computer UPS?

not me :-)

> Is there a way to have NUT monitor it?

It looks like bluetooth/app, the modern disease.  I would suggest
contacting bluetti, exlaining NUT, and asking for protocol details.
I suspect if you asked a lot the manufacturers of UL listed LiFePO4
power banks, one of them might end up being reasonable.