GMC small Generator sets (for camping and emergency power)

You'll all be aware of those small Generators now available for as little as
$98 at Bunnings and at various other Hardware stores throughout WA etc

Marketed under several apparent brand names including "GMC" and "Diesel"
(yep !), GMC URL LINK they are a Chinese clone of an old Yamaha design (I've seen them
still available new, for about $795) Sometimes the decals list them as 750
watts and sometimes 850 watts. But it seems they are all the same in major
construction. Minor variations occur like For some the 12 volt battery
charging circuit connects with screw thread terminal posts, while other
models have a special 2 pin socket (a suitable plug and cable is supplied to
fit)

Recently a friend I know bought one even cheaper than that, (it was an ex-display model that needed some minor
fixing), and recently I bought one too (it's seeming ever more likely that my mains electricity supply will be cut off by "Western Power" due a a dispute with my meter reading which they refuse to resolve, even though, by my calculation, I'm actually $15 in credit, on my electric bill !). Perhaps other folks have also
bought one for camping or during power outages/storms etc ?

I's researching this model of small Generator on the wwweb, and came across a bunch of forum
postings from some 4wd and camper type folks ,sorry can't remember the url
exactly.

The general consenus is that these are fine and work well, almost on a par
with similar sized, name-brand Gensets costing more than $1,000. The produce mains voltage of aome 240 volts AC, and have a second circuit that provides low voltage DC to charge 12 volt car batteries.

WITH ONE PROVISO..........the low voltage ("car battery charging") circuit
is stated to be 14 volts and 8 amps maximum current, however some folks on that forum have
found this to be poorly regulated, ie somewhat approxiamate. (in some cases, a higher voltage, which therefore allowed an excessive current to flow)

The warning is basically DO NOT use the low voltage charging circuit to
charge small batteries eg Motorbike batts, and do not leave it to charge car
or deep-cycle batteries for longer than an hour or two at the most. (unless you keep a check on them, such as using some kind of voltage or current meter, and checking that the battery is not becoming over-heated)

If you want to charge batteries "properly" then plug a normal home car
battery charger into the mains voltage output, and this will provide a more
regulated charge, Note that small home chargers only put out 2 or 3 amps,
larger models 4 to 6 amps, so many hours is required to totally re-charge a
totally flat battery...........so try not to let them go fully flat in the
first place, plus it's bad for their longterm lifespan.

Using the GMC Generator's inbuilt 14 volt system for Charging car batteries which are fairly flat, for short periods of time is
not a worry. So if you are stranded at your campsite with a flat car
battery, then it'd be fine to use the built in charging circuit and in half
an hour or an hour your car battery should be replenished enough to start
the car again

I checked the voltage output of mine, and although my test-meter is old and
not 100 % accurate, it seemed to be plenty alright, both on the "14 volt"
circuit and on the mains voltage circuit

The instructions with the small gensets indicate that you cannot use the 14
volt charger output and the mains output at the same time, as the low
voltage circuit breaker will trip.

Now this seems to be wrong, certainly if you are running only light mains
voltage loads, well within the generator's capability, you'll probably be
able to use both outputs at the same time. I have done some brief tests on
my genset and this is also the case as detailed by posters on that forum I
read yesterday

If you have one of these small gensets or are thinking of buying one,
remember that they WILL NOT run large current draw appliances like fridge,
freezer, wash machine, kettle Microwave ovens etc. (remember that a
so-called "600 watt" power microwave oven takes nearly 1200 watts input
mains power to achive it's rated output of 600 watts of radiowave power)
These little generators WILL run an angle-grinder (which with a
metal-cutting disc could be useful if you need to cut your way through a
high security door or a locked gate, to evacuate an area say or cut an
injured person from a crashed car........A metal-cutting disc will do in mere seconds what would take ages
with a hand-hacksaw) They will also run most hand powertools that you might
need around your campsite or when doing emergency house repairs after a
storm say. However do not expect them to run an electric chainsaw, and
definitely NOT even a small home arc-welder (that would require a generator
of about 6 times the size ! )

A warning comes with them re running sensitive electronic equipemnt like
computers but I think they just print that for legal reasons as most
electronic things nowadays have a power supply designed to smooth out power
irregularities.

The GMC branded ones as sold through Bunnings state a 30 day, no quibble,
money back guarantee. Now assuming that. at least *some* (even just very
few) customers return them as such, then I'm guessing there must be a
stockpile of returned units (certainly not looking like new anymore, perhaps
missing their carton etc), perhaps sold off cheaply on an as is where is
basis ?????????

cheerio