Martin Gregorie wrote on 8/14/2017 7:29 PM:
> On Mon, 14 Aug 2017 23:44:30 +0100, John Aldridge wrote:
>
>> In article , gnuarm@gmail.com says...
>>>
>>> I've seen this discussed here many times and usually the devices
>>> mentioned don't do such a great job.  Here is one that may not be as
>>> small as you would like, but is going to work.
>>>
>>> https://www.newegg.com/Product/Product.aspx?item=N82E16842301444
>>>
>>> It has two USB ports and three 110VAC outlets.  The 110VAC outlets
>>> won't be as useful if you live where power is 220VAC, but even there
>>> many devices are universal input voltage.
>>
>> The 110V input voltage may be an issue, though!
>
> I see it claims 70 watts out and a little under 36 minutes run-time at
> that load, i.e. just 45 watt-hours capacity. From the quoted size I see
> that it might accommodate a motorcycle size accumulator, which are
> typically 7.5 watt-hours capacity for a 12v SLA. You can get 25 watt-
> hours from a similar-sized LiFePO4 cell, but they certainly aren't
> fitting those: they retail for $US 260, but they only want 40 bucks -
> unless they sell them without a battery fitted.

UPS typically use SLA, sealed lead acid, batteries, I suppose because of the
cost.  Notice it is very hard to get capacity info on most UPS units.  They
are happy to tell you how many amps or VA they will provide (less often
watts), but almost never a WHr rating.  

Regular Li batteries would be good enough and much smaller or more energy or
some of both.  But the cost would rise.  But then a replacement SLA is not
cheap either.  The one from APC is as much as the unit and a Power Sonic
battery is still $35!  They can last a long time though.  I've had one for
well over a decade and it's still keeping my devices running through a power
failure.  Usually my ISP goes out and I can see my modem not being able to
get to the rest of the world.  Lol!

I wrote them a note letting them know the lack of a 3 pin connector is a
problem for me and that they should consider making a unit specifically for
the rPi with an external 5 volt PS and physically smaller.  I don't expect
them to follow up on that though since their core competence is SLA
batteries and that would almost demand a Li battery.

--

Rick C

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