On Mon, 28 May 2018 22:07:10 +0100, Dave Liquorice wrote:

On Sat, 26 May 2018 02:34:31 GMT, Johnny B Good wrote:

The XYL returned from a quick shopping foray this afternoon with the
latest magazine showing next week's offers which included a "Golden
Oldie" first seen two years back. Said Golden Oldie (the PGI 1200 A1),
presumably being priced for nostalgic reasons, is on 'offer' at the
original 129 quid price (their version of "Rollback Pricing" I'm
guessing).

After Mr Plowmans post on laser levels and this one I'm glad that there
isn't a Lidl where I normally go... Aldi is OK but doesn't have the
range of wallet threatening "big boys toys" that Lidl does. B-)

Both produce the same total sound power of 95dBW but the B2 claims to
be 1.3dB quieter at the 1 metre SPL test distance (80.2dBA).

Hum those figures don't add up 95 dBW (aka 95 Lwa) is 87 dBA @ 1m or 70
dBA @ 7 m (7 m being the "industry standard distance" for gensets). I
think that's the same as the mower.

I see references to the 7m SPL dBA figure in generator youtube vids (or
as the Yanks call it "the 23 foot SPL reference distance"). I did query
those figures in my mind but since a class 2 SPL meter is only able to be
calibrated to within +/- 1.5dB accuracy anyway, it didn't seem to be a
significant enough discrepancy to get all hot and bothered about.


I have an open frame 2.2 kVA, non-invertor, diesel set, now that is fing
noisey, difficult to hold a conversation next to it noisey! However it
is electric start(*) and uses about a litre an hour. But at about 60p/l
less than petrol as it can use red diesel.

That's not only a useful saving, it's also less of a long term safe fuel
storage problem. The penalty for going for the affordable open frame
option being the horrendous noise pollution if you can't run it in its
own little brick outhouse to keep the noise level in check.


I've used a couple of Honda EU20is, linked, and they where really
quiet, audible but not overly so as reflected by the quoted 52dBA @ 7m
(89 Lwa).

If I've done my quick 'n' dirty calculations correctly, I reckon that
would equate to a 1 metre SPL of 66dBA. A significant reduction on the
80.2dBA quoted for the PGI 1200 B2 (which will be the no load eco
throttle idling condition - idling with eco-throttle disabled raises the
level another 10dB or so and loading it up with a 980W load will raise
that by yet another 6dB or so).

Those Honda suitcase inverter gensets are remarkably quiet but I can't
justify shelling out an extra 800 quid plus for one. Since it's not so
much for day trips out into the wilds and more a solution for a minimum
level of emergency home power come the next winter (or the ones after
that), I feel a more optimal solution is to build a little brick outhouse
behind the garage in which to both secure and operate it without creating
a noise nuisance for both myself and my immediate neighbours.

At least this way, if I do opt for a "cheap" 2 or 3 KVA inverter genset
at a later date, I can forego the quietness of a genuine Honda inverter
genset by making sure there's ample space for an even larger open frame
genset inside. Whatever the upgrade, one thing's for certain, it won't be
a conventional genset destined to go the way of the Dodo - only an
inverter type will do the job.


(*) In theory so that SWMBO'd should be able to start it. Probably never
happen as it's also rather heavy even though it's mounted on a 4 wheel
flatbed trolly. She'd never manage to pull start it far to complicated a
process. Release the compression, spin it up on the cord, drop in the
compression and hope it fires... I think your suposed to be able to set
the engine and compression release so that one pull does the complete
cycle and off it goes but if you get it wrong and pull into compression
it don't half jar your arm. B-)

Tell me about! It's bad enough pull starting a diddy 53.5cc single
cylinder four stroke when I'm as unfit as I am. :-( It's the reason for
my describing in detail my "Dry starting" routine.

Wishing this inverter genset had electric start got me to wondering
about add-on electric starter upgrade kits to replace the recoil starter
cord. I know some of the larger open frame generators can be upgraded to
electric start (retaining the pull starter cord) but they either need a
starter ring gear fitting or else they already had a starter ring to
begin with but were simply not fitted with the starter motor, solenoid
and battery to provide a cheaper option to their customer base.

Then it hit me! Inverter gensets already have the core part of a
permanent magnet brushless DC motor disguised as a multi-pole three phase
PM alternator. :-)

All it would need is a starter battery and a DC brushless motor
controller module add-on to neatly upgrade an inverter genset to electric
start. Better still, the electronics could all be integrated into the
micro-processor controlled inverter module itself, only requiring the
installation of a small starter battery (say a 7A SLA or its smaller
lightweight Li-ion equivalent).

TBH, this is such a "No Brainer" idea, I'm surprised none of the quality
names in suitcase inverter generator manufacturing aren't already using
this technique in their latest "Must Have" product lines to 'freshen up'
market demand. Perhaps they have and I just haven't noticed.

Anyhow, this got me to ruminating on the possibilities such a revamping
of the old "Dynastart"(tm) could provide. For starting purposes, you
wouldn't need to use the full 400 volt (200v for a 120v generator),
probably just a quarter of output voltage would suffice. However, using a
DC-DC converter to generate the full voltage from a 12 or 10.8 volt
starter battery would allow an even more frugal eco-throttle setting to
be used without fear of stalling the engine on pick up of a sudden
increase in load.

Then I thought, "Why stop there? Why not combine the function of an
inverter genset with that of a line interactive UPS?". It's quite thought
but with a lightweight Li-ion battery pack it need only be a few pounds
heavier than a pull start inverter genset since the battery would only
need to provide a few minutes of autonomy for the UPS function and from a
battery that demonstrates only a fraction of the Peukert effect that's
routinely relied upon to protect UPS SLAs from excessive DoD.

It's surprising what you can come up with when you let your mind wander
where it will. :-)

--
Johnny B Good