"Mike Scott"  wrote in message
news:qed32j$n0f$1@dont-email.me...
> On 18/06/2019 09:34, Mick Manning wrote:
>> On 18 Jun 2019, Lew Pitcher said the following...
>>   LP> Outside of the smarts, and the DC-AC converter, they seem to be
>> capable
>>   LP> of acting as a UPS for a Raspberry PI. Just plug the Pi into the
>> battery
>>   LP> pack's DC output port, and the wall wart into the battery pack's
>> charger
>>   LP> input port.
>>
>> What a GREAT idea. Thanks. :-)
>
> On the down side, I've heard it said that some won't supply power while
> they're charging themselves. I have no idea if that's true or not, but it
> has rather put me off the idea :-{ Can anyone confirm/refute this?


I've got an Anker 79AN7925 13,000 mAhr battery. I'd occasionally wondered
about using it as a UPS for my Pi, but I've just tested it and it does what
you feared: the output power is turned off whenever the battery is receiving
power from a mains source. Grrr.

I wonder if there are any batteries which maintain output power when input
power is connected and turned on?

It would be a useful backup in case of power cuts. I use my Pi for logging
data from a weather station and for recording TV programmes (using TVheadend
and DVB-T or DVB-S adaptors) so some resilience would be useful. Mind you,
when recording from satellite (DVB-S) I'd still need to find a way to
provide 12V for the dish LNB, and from terrestrial aerial (DVB-T) I'd need
to provide mains to the distribution amplifier in the loft. Maybe I just
need a UPS for the whole house ;-)

I have used my 12V-to-240V inverter that I keep in the car, to supply
emergency power at work to essentials like routers and telephone VOIP
switchboards during a lengthy power cut (JCB through high-voltage cable -
nasty), so they could continue to make/receive phone calls, even if they
couldn't use desktop PCs. I earned a few brownie points for coming up with
that solution ;-)  They left the engine of the company van ticking over (to
avoid flattening its battery) and had an extension mains cable snaking from
the van in through the door to the office - probably contravening loads of
health and safety rules, but what the hell.

--- SoupGate-Win32 v1.05