Anyone here who's measured a Generac generator waveform?

[Brad Johnson]

Quick revisit for a fuel consumption update.

Exercise run today. Uneventful, as always. Open fuel valve, give the float bowl a few seconds to fill, hit Start. Caught on the first spin. Full hour under constant 3000w load, two space heaters and two 16" pedestal fans. Guesstimating fuel use at about three pints.

Brad

[Brad Johnson]

Another quick revisit because I finally did a run-to-empty session. It was mostly to use up the two year old fuel in the onboard tank, but also to see how close my full-tank runtime guesstimates were. With a 300 watt load I got just over of 13 hours before it started sputtering. I tried to give it a 3000 watt load with a couple of space heaters but it was warm enough they kept tripping off on overheat even with fans providing additional airflow. Our max average load will be somewhere just shy of 1000w if we're not running the A/C, maybe 750-ish if I take time to kill a bunch of vampire loads, so I figure a solid 9-10 hours runtime. Reduce by 30-35% if we need A/C to keep anything from overheating.

Fuel stagnation is my main concern. After each regular exercise run I refill the onboard tank from one of the storage cans, empty what's left into the truck, and refill the can with fresh fuel. I have four cans I rotate through so stored fuel is never older than eight or nine months, a year at most. Unfortunately, the generator only uses a couple pints per session so onboard fuel gets ever older over time. There's just not enough fresh fuel being added to keep up. An extended runtime session for tank draining is no biggie, but it's unnecessary runtime hours. Plus, it's just loud enough that I'm concerned an all-day session, or two long sessions over two days, will annoy the neighbors. A simple tank drain would solve the problem. I'm surprised it's not a factory provision since extended storage prep is a common thing.

I've kept it on a battery maintainer and so far no problems, starts right up with no hesitation or indications of a weak battery. Even so, I'll replace it at three years as a preventive maintenance item.

Brad

[JTHunter]

Brad - a relative has a Generac 7500E portable that was bought in the summer of 2016.  It has a battery starter as well as a pull cord - which has never been used.  They use the blue "marine formula" Sta-Bil and they test run it for 10-15 minutes 2-3 times a year.  It has only been used 2-3 times in those 7 years and they changed the oil for only the second time a couple of months ago.  The battery for the starter has never been changed and it is still working fine.

[Brad Johnson]

Quick revisit because I discovered Champion now has a tri-fuel 9000W inverter model.

https://www.championpowerequipment.com/product/201176-9000w-electric-start-tri-fuel-inverter-with-co-shield/

Output is significantly hobbled on natural gas, but still plenty to keep us in lights, fridges, coffee, and entertainment should power fail. Also has both 14-30 and 14-50 outlets, so plenty flexible for panel hookup. Wish it'd been available three years ago.

Brad

[Brad Johnson]

Had an electrician doing work at the house yesterday so took the opportunity for testing using his clamp on ammeter.

Findings:

1) A general "we're home with lights on and watching TV" load is right at the 1kW I estimated. Generator RPM hovers in the lower end of the ECO Mode <--> Full RPM range. It will kick up momentarily when a fridge or freezer comes on.

2) In "conservation" mode with minimum lighting and all the vampire loads gone, it tends to stay at the low primary Eco Mode RPM. Again, kicks up momentarily when fridge/freezer cycles.

3) The generator's output is clean enough that none of our electronics complained, not even the UPSs which tend to be picky beasts.

4) Sans the oven, dryer, or A/C, we can run anything in the house in any combination with no problem even in the worst-case scenario of concurrent coffee pot, microwave, and air fryer use. It was definitely pushing it hard, though.

5) I will indeed run one 2-ton A/C just fine, though it struggles momentarily at start even with Eco Mode disabled and generator running at full RPM. To keep things relatively safe we'll need to be at minimum power use when the A/C kicks on. Once running, we can pretty much live normally so long as we don't use any other high-draw device.

6) Just over four hours runtime with a constant 1kW load and at least an hour at 3-5kw required approximately two gallons of fuel. That confirms my estimate of 10-12 hours per tank using a Conservation Mode runtime strategy.

Brad