Run Whole House on Wimpy Generator?

[redpoint5]

Originally Posted by vteco

Well there's always the fourth alternative, starting with success and working towards success.

Not waveform, but definitely frequency readout is available through a Kill-A-Volt, and is important to things like refrigerators. Just sayin.

My plan is success from 1st attempt. I expect the validation to prompt me to just streamline the process with quick connectors.

My Fluke will do frequency too, so I'll keep tabs on it.

[cRiPpLe_rOoStEr]

Originally Posted by j-c-c

I'm toying with the complexities of using my RV engine coolant to pre heat my RV's potable water tank while driving, allowing my shower point of use water heater to be downsized by having slightly above ambient water temp to heat.

I remember reading something about a Brazilian family who used a Peugeot Boxer motorhome with an exhaust-heated water tank. Nobody would take a shower with the vehicle running, so it had to be well insulated to retain the waste heat for a while.

[Piotrsko]

Frequency is important to most AC induction motors: freezers, fridges, fans, compressors. There's a lag angle built in for maximum efficiency. Transformer less powersupplies, maybe no effect. Being off frequency just causes power inefficiency, for fans/motors that just run faster or slower and get MUCH hotter. Some asynchronous motors rely on frequency to work. Could even crispy some electronics because they are shunting full voltage

Since most controllers use igbts for control, they also use pwm to change voltage through a LC time constant circuit. Generally called a chopper circuit back in the day. Guaranteed somewhere in the power band your EV has a 60 cycle output, dependent on pole count and rpm of the motor, even if it's DC.

[redpoint5]

Originally Posted by Piotrsko

Frequency is important to most AC induction motors: freezers, fridges, fans, compressors. There's a lag angle built in for maximum efficiency. Transformer less powersupplies, maybe no effect. Being off frequency just causes power inefficiency, for fans/motors that just run faster or slower and get MUCH hotter. Some asynchronous motors rely on frequency to work. Could even crispy some electronics because they are shunting full voltage

Since most controllers use igbts for control, they also use pwm to change voltage through a LC time constant circuit. Generally called a chopper circuit back in the day. Guaranteed somewhere in the power band your EV has a 60 cycle output, dependent on pole count and rpm of the motor, even if it's DC.

How does any of that matter if it's buffered by the 12v battery?

[Piotrsko]

Let me count the ways: 1st 12vdc must be run through two systems to make it 120 60cycle. One is a chopper that makes some sort of variable voltage. Transformers dont run on dc very well. Second is some sort of voltage increasing device. Transformer is more efficient that the equivalent capacitive voltage doubler and that would need many stages to get to 120, but the output is still DC and needs the chopper. Down side to the transformer is that they tend to be current limited OR they get really hot. Bigger size fixes the heat, but my whole house UPS weighs 150 lbs and is good for only 60 minutes of coordinated shutdown on the F250 dual #34 batteries, and it better be running when connected (assuming I got notice of imminent failure) whole house ups only runs the stuff that's annoying to restart, a radio, one small tv. and one 2000 sq ft rated pellet stove. Ok so you have a 100kwh 165 v battery. Tis good for one leg, you could use your motor controller for the other two, might piss off the controller not using the one leg, the 120 side might balance the 240 legs if the 240 legs balance. Remember 120 is average voltage, not peak to peak which is around 165. Now your controller is a variable frequency device otherwise you get one low speed from it unless you're like me and run series DC which is voltage dependent for speed, power is dependent on current, frequency is irrelevant.

Now all this mucking about is mostly efficient, but it's making heat in the battery and silicon control circuits which you're gonna have to cool. Not my pay grade, but it's a loss.

So you figure out the speed you need the throttle set for that gives you 60 hz, but it's gonna vary a bit depending on load unless you have a compensation feedback. My controller is run by a 486, but it's slow regulation so frequency varies between 50-70hz for a given fixed throttle request. Doesn't matter in the ranger its about 2mph different and remember, I am current regulated.

Now you're going to say, my battery is going through a regulated 120v 60cycle inverter. Doesn't work like that. Well yes, thats correct. My car inverter/controller is good for 300kw, indefinitely, yours is rated lower and will need potloads of relative cooling to run at max rating. Might be pack voltage to 165/120 I dunno, don't matter. It isnt a motor controller so it may not be part of the cooling system or controlled by the main car computer. If it isn't, needs control of the coolant cycle and control of the battery to avoid destruction of your drive pack. That gets it into the house on a 16 to 12 gauge extension cord or two. What no 8 gauge cord? Oh well that limits what you can run. Maybe even get to not fry your electronics

[vteco]

None of the following are opposition to your experiment, just explanation and suggestion for caution.

If battery voltage sags under an unanticipated load, inverters can get flakey. Available battery capacity in a used cell DIY system is often underestimated in practice. One frequent source of surging loads is refrigerator start.

Modern refrigerators can be quite sensitive to power parameters and are expensive to replace. Generally householders (like myself) do want refrigeration to continue in a power outage, since food can get ruined. Brief power outages are mere inconvenience. Extended ones are the ones I want a backup system to get through.

I use Kill-A-Volt as a frequency monitor, plugged into a wall circuit, during a power outtage when I'm on generated power. It once saved me a LOT of money when the generator's power regulator circuitry malfunctioned. Inverters can fail as well.

[vteco]

In a system, which is using a 110V generator, a charger, and an inverter which is supplying the 110V output:

If the system at any time is drawing more amperage from the battery than the generator/charger is supplying to it, the charge level of the battery will drop to compensate. Its output voltage will drop, likewise. A shortfall can carry on as long as the inverter can handle the voltage drop, but if it continues to drop eventually it will not be able to.

If the load reduces enough before that the battery will recharge at whatever rate of excess current is available through the charger.

There can be tip-over scenarios however where a sudden surge, doesn't work itself out (a motor starter circuit fails to get the motor up to speed). It isn't normal anticipated loads that are the problem for this kind of marginally sized system. It's the unanticipated ones.

[Logic]

Originally Posted by vteco

I have a 6 hp listeroid diesel one lung generator...objectionable to run in close quarters.

As these engines are fixed rpm; Quarter Wave and Helmholtz Resonators are an effective means of making them less objectionable.

They work on both the exhaust and the intake:

• NB that as there is no exhaust flow in a Quarter Wave Generator they stay cool enough to use an adjustable O-ring sealed piston in the pipe.
• Helmholtz Resonators are OEM in the intakes of a good number of cars.
• NB that more than one Resonator is practicle.
• Rounding the corners of the T-junction for a QWR will increase the effective frequency range.

But as there is a LOT of noise from the many cooling fins of an aircooled engine a Helmholtz designed enclosure seems best:

https://www.youtube.com/watch?v=4Y0Z_nGe1Vo&t=17s

Then there's always the old trick of exhausting 2 or 3 inches below the waterline on a boat.


(For ultimate efficiency: )

• You want a Tuned Length Exhaust that 'empties' into a Pressure Wave Termination Box (David Vizard), before any muffling.
• Similar for the intake, but also with properly designed Bell Mouths wherever there's a major change in tract volume like the filter box.
• There are calculators online for the tuned length and I've started various threads here on the other stuff mentioned.
• NB the surprising difference Bell Mouths make to intake efficiency once the throttle valve is close to fully open.

There's also all that 'wast' heat one could put to good use on a boat.