On Thu, 23 Nov 2017 09:44:23 +0000, Andy Burns wrote:

Johnny B Good wrote:

I might yet invest in another battery pack for my basement UPS after
all (a small 7AH one - I'm not made of money!).

I'm using four of the Powerline PL17-2 in a SU-2200, which at £80 for
the set isn't too bad, they've been in use for over two years and are at
89% capacity, I don't run the weekly self-test but it has run a couple
of times for power cuts.

Their NP7 equivalent is only a tenner ...

https://www.tayna.co.uk/PL7-12-Powerline-Mobility-Battery-P9076.html

Thanks for that info, Andy. I've bookmarked the site.

I noticed a standard delivery charge of £7.97 in that "More Information"
page which would nearly double the price on a single battery order.
However, since the standard delivery charge is only a penny more for the
PL75-12 battery, I'm assuming this delivery charge is per order based on
weight (a 70AH 12v battery will be approximately ten times heavier than a
7AH 12v one) so I'm guessing you only paid the same delivery charge on
that set of four PL17-12s (assuming you opted for standard delivery).

A delivery charge of just under 8 quid spread over 4 batteries is pretty
cheap as far as delivery charges go (even more so for a set of ten such
batteries) but I suspect I just might be able to cut a better deal with
my local Alarm Supplies company's proprietor who used to be in the same
computer club I used to frequent way back in the mid 80s. Mind you, iirc,
I paid 22 quid or so for a pair about 15 years back so maybe not but it's
still worth checking out.

Annoyingly, the "Technical Specification" not only fails to specify the
AH discharge rate, it also neglects to specify the maximum discharge
current ratings. The 7AH alarm batteries had an 80A rating which is
comfortably in excess of maximum demand on a 1500W/2KVA sine-wave
inverter UPS with a 48v battery pack.

I calculated the per AH cost of each battery. For those PL7s it was
£1.43, dropping to £1.33 for the PL12, then down to £1.23 for PL17 and
PL26 batteries before climbing up to a hefty £1.87 for the PL45. Clearly,
it pays to use paralleled banks if more than 33AH's worth of battery is
needed.

When I do finally get hold of an inverter genset to put me back in the
market for a set of UPS batteries, I think I just might go for the
PL12-12s as a compromise between capital investment cost and improved
autonomy. That extra 60% spend is likely to buy me a doubling or more of
autonomy thanks to Peukert's Law.

Even a cheap Aldi/Lidl 1.2KVA inverter genset should be enough, at a
pinch, to power a couple of PCs (the NAS box and my desktop PC), the VM
SH2 an 8 port Gbit switch, a TV set, the CH/HW pump and all the lights
(including a couple of fluorescents and the loft aerial distribution amp.
Basically, just "The Essentials"[1]. :-)

Obviously, a 2 or 3KVA inverter genset would be better but I think those
1KVA (continuous, 1.2KVA peak) Aldi/Lidl gensets at 150 quid or less
would make a nice start, even if I do have to take care not to light the
whole house up like Christmas tree in the cold depths of winter.

At a first guestimate, the IT kit looks like it'll be a total of 300
watt's worth, leaving some 700W. The CH/HW pump and the Potterton
controller and the 3 port zone valve (say 100W max) should leave some
600W or so of capacity for the lights and the living room TV set.

Including a 100W incandescent lamp in the bathroom, four 35W tungsten
halogen downlighters in the shower room, a "58W" 5ft tube in the office
and a "40W" 4ft quickstart fluorescent lamp in the basement (52 actual
watts), I estimate a maximum lighting load of just 400W, leaving in
excess of 200W to power the main TV set in the living room so it looks
like even a mere 1KVA inverter genset should be able to power the
essentials *and* light the whole house up like a Christmas tree to make
our neighbours envious.

BTW, I monitored the power used by the BackUPS500 after shutting the NAS
box down and disconnecting it to move it onto my workbench to disconnect
the now redundant 3TB HDD and update the N4F firmware. After some 12
hours or more, the initial battery recharging consumption of circa 12
watts eventually tailed right off to a mere 2.2 to 2.5 watts, averaging
some 2.3 watts versus the 2.7 watts I'd mentioned previously.

Disconnecting the 3TB Hitachi Cool-Spin drive ,rather surprisingly, only
saved a mere 3 watts at best. I had anticipated something like a 5 to 7
watt saving when taking the power consumption of the drive being
reflected onto the mains through the additional losses in the 145W PSU.

Now that I've completed the maintenance and testing of the NAS box on
the workbench, I've restored it to its rightful place and the overall
consumption (NAS box and UPS) is hovering just below the 50W mark which
represents a small but welcome reduction.

[1] Of course, if I'm looking to protect against outages much longer than
4 hours, I might need a 2 or 3 KVA rated genset to include the fridge and
freezer. The fridge looks doable on a lightly loaded 1.2KVA inverter
genset (a 60 or 70W compressor load afaicr when I last tested with a plug-
in energy monitor a year or two back, so maybe a surge load of 350W max).

If I *really* need to know what the startup surge is, I can repeat the
test with my trusty Metrawatt analogue wattmeter which, unlike those plug-
in energy monitors with their digital displays, can give an unambiguous
indication of a brief peak power surge (provided I remember to switch to
the 25A and 100v range combination - it's normally kept plugged in and
set to the 1A and 100v range combination (100W scale) to monitor IT kit
on the workbench).

If we ever do see an extended outage, with careful management, I might
even be able to keep the freezer going by leaving it un-powered for at
least 12 hours before selecting a time in the day when all the lights,
the CH, TV set and desktop PC are shut down before plugging it into the
handiest UPS protected socket and let the UPS handle the surge. The
SmartUPS2000 can cope with the massive degaussing surge of a 19 inch CRT
colour monitor which bodes well for this strategy to keep the freezer
contents safe (it's also another good reason to choose PL12s - they
should have a higher maximum current rating than the PL7s).

--
Johnny B Good