Author Topic: I’m toying with the idea of a car engine + generator for power backup  (Read 23089 times)

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Offline David Hess

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #150 on: December 14, 2021, 06:53:02 am »
The idea of using a hybrid car is pretty good, however you will most likely have to build your own inverter.

Many hybrid vehicles have a built in inverter to provide AC power, and some are quite powerful.  The 2021 Ford F150 hybrid is 7.2 kilowatts.
« Last Edit: December 14, 2021, 07:01:24 am by David Hess »
 

Offline JesterTopic starter

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #151 on: December 14, 2021, 02:18:58 pm »


Many hybrid vehicles have a built in inverter to provide AC power, and some are quite powerful.  The 2021 Ford F150 hybrid is 7.2 kilowatts.

Those 7.2kW inverters are going to be a hot commodity in the wrecking yards I wonder what the input voltage is?

Probably 120V out better yet if 120/240V, 7.2kW goes a long way when you have no power. A good inverter would simplify the engine control requirements.

Just looked it up, indeed 240V

https://news.pickuptrucks.com/2020/06/5-fun-facts-about-the-2021-f-150s-onboard-generator.html

$750 option, I would not skip that option. What a great idea.
« Last Edit: December 14, 2021, 02:33:44 pm by Jester »
 

Online langwadt

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #152 on: December 14, 2021, 02:38:09 pm »


Many hybrid vehicles have a built in inverter to provide AC power, and some are quite powerful.  The 2021 Ford F150 hybrid is 7.2 kilowatts.

Those 7.2kW inverters are going to be a hot commodity in the wrecking yards I wonder what the input voltage is?


I believe the battery  is ~400V

 

Offline james_s

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #153 on: December 15, 2021, 04:35:20 am »
I expect it will be tightly enough integrated into the other systems in the truck that it will be quite an undertaking to get it working on its own, but I'm sure somebody will try once the trucks have been around for a while.
 

Offline NiHaoMike

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #154 on: December 15, 2021, 01:28:38 pm »
while you can't easily buy an off the shelf inverter for the correct input voltage.
https://www.aliexpress.com/item/4001209712872.html
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Offline AaronD

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #155 on: December 15, 2021, 03:02:07 pm »
while you can't easily buy an off the shelf inverter for the correct input voltage.
https://www.aliexpress.com/item/4001209712872.html

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Offline james_s

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #156 on: December 15, 2021, 04:20:03 pm »
I have a similar board and it does work, but keep in mind it needs a regulated input voltage in order to get a regulated output voltage, at least mine does.
 

Offline JesterTopic starter

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #157 on: December 15, 2021, 08:29:00 pm »
I have a similar board and it does work, but keep in mind it needs a regulated input voltage in order to get a regulated output voltage, at least mine does.

The link provided does not specify the "correct" input voltage whatever that is?

Do these output 120V or 240V?
How are they with loads such as a motor starting?
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?
 

Online langwadt

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #158 on: December 15, 2021, 09:58:19 pm »
I have a similar board and it does work, but keep in mind it needs a regulated input voltage in order to get a regulated output voltage, at least mine does.

The link provided does not specify the "correct" input voltage whatever that is?

Do these output 120V or 240V?
How are they with loads such as a motor starting?
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?

looks like it based on these:

https://www.amazon.com/Inverter-EGS002-EG8010-IR2110-Driver/dp/B01E8X64CC
https://www.lz2gl.com/data/power-inverter-3kw/eg8010_datasheet_en.pdf


 

Offline james_s

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #159 on: December 15, 2021, 10:32:28 pm »
The link provided does not specify the "correct" input voltage whatever that is?

Do these output 120V or 240V?
How are they with loads such as a motor starting?
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?

The one I have requires about 400VDC on the input to get 240V out. I don't remember off hand if it will work from a lower input voltage to produce 120V. I'm only familiar with inverters up to about 2kW but maybe someone who has worked with solar systems will be more knowledgeable about larger ones. I'm forgetting what the context is though, most inverters are designed to accept a battery voltage, some multiple of 12V, others like these bare boards are the output section and are designed to run from a ~400VDC regulated bus.
 

Offline Berni

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #160 on: December 16, 2021, 06:27:15 am »
That is actually a pretty neat module. Not sure i would trust using it at anywhere near its max power rating since i had chinese crap blow up well before the max ratings. When such a high power inverter blows up, it can be pretty spectacular with a bang, smoke, sparks, fire etc.

By the looks of it this is basically a really big open loop D Class audio amplifier. That in itself is just a pair of buck switchmode converters with an agile output voltage. So this setup will not be able to boost voltage, So the DC input determines the largest peak to peak AC signal it can make (minus some headroom for losses). So for making 220V AC it should need about >340V DC of input.

The encouraging thing is that is does have an adjustment pot to tune the output voltage, but it is not closed loop, so even if you do tweak it to make the right output voltage, it will still ride up and down with any variations in input voltage. But i suppose it wouldn't be too hard to add some circuitry to make it actually sense the input voltage.

I suppose the only thing that determines the max output power is the power transistors and output choke. So the same PWM driver module could be used to build a bigger model for say 10kW. Also since you are from the US you will need a way to get split phase in order to run a house. So you either need an inverter capable of that, or use a large transformer to provide the center tap for the 'neutral'. For EU houses its easier since even tho there is often 3 phase, we typically don't need it to actually be 3 phase in residential houses, so all 3 phases could simply be powered from 1 phase.
 

Offline james_s

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #161 on: December 16, 2021, 07:58:47 am »
When I power my house from my generator I just tie the inputs together so both bus bars are fed from the same source. All of my 240V loads are much too large to run from my generator so this doesn't cause any problems. Obviously if you need to power 240V loads from the generator then this will matter.
 

Offline BradC

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #162 on: December 16, 2021, 10:49:00 am »
By the looks of it this is basically a really big open loop D Class audio amplifier. That in itself is just a pair of buck switchmode converters with an agile output voltage. So this setup will not be able to boost voltage, So the DC input determines the largest peak to peak AC signal it can make (minus some headroom for losses). So for making 220V AC it should need about >340V DC of input.

The 8010 is actually an ASIC that drives a H-bridge. It does closed loop voltage regulation within reason and it's pretty good at working with perverse load waveforms. The rest is just a big H-bridge and output filter.
 

Online langwadt

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #163 on: December 16, 2021, 04:16:24 pm »
That is actually a pretty neat module. Not sure i would trust using it at anywhere near its max power rating since i had chinese crap blow up well before the max ratings. When such a high power inverter blows up, it can be pretty spectacular with a bang, smoke, sparks, fire etc.

By the looks of it this is basically a really big open loop D Class audio amplifier. That in itself is just a pair of buck switchmode converters with an agile output voltage. So this setup will not be able to boost voltage, So the DC input determines the largest peak to peak AC signal it can make (minus some headroom for losses). So for making 220V AC it should need about >340V DC of input.

The encouraging thing is that is does have an adjustment pot to tune the output voltage, but it is not closed loop, so even if you do tweak it to make the right output voltage, it will still ride up and down with any variations in input voltage. But i suppose it wouldn't be too hard to add some circuitry to make it actually sense the input voltage.

if you need to boost the voltage like in a 12V inverter, that could be handled by the boost converter at the front

I suppose the only thing that determines the max output power is the power transistors and output choke. So the same PWM driver module could be used to build a bigger model for say 10kW. Also since you are from the US you will need a way to get split phase in order to run a house. So you either need an inverter capable of that, or use a large transformer to provide the center tap for the 'neutral'. For EU houses its easier since even tho there is often 3 phase, we typically don't need it to actually be 3 phase in residential houses, so all 3 phases could simply be powered from 1 phase.

for higher powerlevels you might need to beef up the gate drivers
 

Offline NiHaoMike

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #164 on: December 17, 2021, 04:33:08 am »
3kW is smaller than I would like.  Any links to an affordable, reliable inverter in the >7kW range?
Use multiple boards? There's not many single >3kW residential loads that are essential to run on backup power. It's also not that difficult to mod the boards to do V/Hz scaling to allow turning down the power of motor loads. (For that matter, VFDs would be a good choice to run motor loads from HVDC.)

You can also get a Prius inverter (about $100) and hack it, but it's far from a plug and play solution at this point.
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Offline Ed.Kloonk

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #165 on: February 09, 2022, 01:59:19 am »
I'll just leave this here.

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Offline Vtile

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #166 on: June 18, 2022, 06:00:24 pm »
Our power here is pretty reliable, that being said if it goes down during the winter, not so pleasant that happened a few years ago during a nasty ice storm, no power for about 2-3 days, I’m glad we had a conventional fireplace.

I had that experience during the 2007 North American Ice Storm.  I burned a month's worth of wood in one week to keep from freezing.  Since then I bought a backup generator, which I have used yearly since, and backup propane and kerosene heating.

Quote
My thought of the day is to pickup a used small engine from a wrecked econo-box car perhaps 1.5 litre and mate it to a suitable generator something about 20-30kW (will depend on what is available used and cheap). I will need some sort of gear box to increase speed to generator perhaps 2:1 or  2.5:1 would allow the engine to run at about  1500 rpm. Will need to make some sort of speed control to keep the generator at 3600 rpm as load changes.

For simplicity, I would consider using pulleys and belts instead of a geared transmission.

They are less common, but a 4-pole generator head would allow engine operation at 1800 RPM.  They are more common with backup diesel generators.

Another great idea 4 pole generator

The belt and pulleys suggestion is also a great idea, makes  things much simpler, need to figure out belt requirements, probably need one of those double or triple wide pulleys for 25 ish HP?

How much a typical timing belt stand tension. It might be enough and pulleys can be found on car graveyards.
 

Offline Milmat1

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #167 on: August 06, 2022, 02:16:15 pm »
A co-worker and I had discussed building a generator that would run from rollers that you would drive the front wheels onto (front-wheel drive cars). Then the vehicle's speed could be adjusted using the cruise control to maintain the generator's output. For emergency situations. We even began building the prototype. But we got distracted and never finished the project.
Anyway, it was a cool idea...
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Offline Ed.Kloonk

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #168 on: August 06, 2022, 11:26:00 pm »
A co-worker and I had discussed building a generator that would run from rollers that you would drive the front wheels onto (front-wheel drive cars). Then the vehicle's speed could be adjusted using the cruise control to maintain the generator's output. For emergency situations. We even began building the prototype. But we got distracted and never finished the project.
Anyway, it was a cool idea...

The trick is picking what ratios to use. Just comparing very rough numbers, a car would have at least an order of magnitude more power available than the generator needs. There should be a frequency meter visible so the operator can rev the engine to the correct speed. As for coupling the car, look at how dynos work. Take note how the car -must- be strapped down to avoid slip (wasted energy) and worse yet, slip off! (youtube videos if you want to see what happens).

Another problem is, generally, the weight of a contraption that receives such horse power from something like a car is the unit itself prolly should be at least as heavy as the car or perhaps even heavier and fixed down. Portability can be an issue.

Sounds like a fun project tho.  :-+ I hope you do end up making it.
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Offline james_s

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #169 on: August 07, 2022, 12:26:10 am »
That sounds like a very inefficient way to make a generator. You've got all those different coupling stages between the engine and the generator, surely it would be more efficient to just use a portable generator.
 

Offline Ed.Kloonk

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #170 on: August 07, 2022, 12:32:14 am »
That sounds like a very inefficient way to make a generator. You've got all those different coupling stages between the engine and the generator, surely it would be more efficient to just use a portable generator.

I know. It'd be fun to tease the neighbors with it though..
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Offline Berni

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #171 on: August 07, 2022, 09:30:24 am »
That sounds like a very inefficient way to make a generator. You've got all those different coupling stages between the engine and the generator, surely it would be more efficient to just use a portable generator.

Well it is not that bad of an idea really.

Sure you might use some more fuel to generate the same amount of power, but a car already has a powerful engine that you regularly maintain anyway, while you rarely need a backup generator.

There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

You also don't need to run it all the time. If you are this serious about power then you probably would also want to own a sizable battery bank to make it so you don't need to run the generator on any short few minute power outage and give you time to get the generator up during a long outage. This way you can run things from battery backup for light loads to keep fridges running and lights on. If you have a central heating system it it also plenty of power to run the furnace and pump hot water around.

That being said for a lot of cases people can get by using a little 2kW generator just fine. You just avoid turning on any large loads. Using a car makes more sense when you want like 20kW of backup power.
 

Offline AaronD

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #172 on: August 07, 2022, 11:56:28 am »
There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

The cruise controls that I've used aren't exactly "precision".  In terms of PID control (not the only way to make a control system, but very common), I wouldn't be surprised if they were purely proportional (throttle = gain x error), with low enough gain to guarantee that it doesn't oscillate ever.  That goes for both vacuum and electric ones.  The speed does droop with increasing load (non-zero throttle requires non-zero error), though it might manage to keep +/-10% at highway speed.

For comparison, the mechanical governors on small engines are almost always purely proportional (flyweights (or a paddle in the fan) control the throttle directly, while the speed control pulls on a spring), and some of them do have high enough gain to oscillate.
 

Offline james_s

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #173 on: August 07, 2022, 07:11:58 pm »
I think a cruise control is going to be precise enough for this application, there is quite a lot of mechanical inertia in such an arrangement and the governors on conventional portable generators aren't exactly precision devices. It's normal for the frequency to be around 64 Hz at light load and 56 Hz under load. For most things this doesn't really matter.
 

Offline brucehoult

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Re: I’m toying with the idea of a car engine + generator for power backup
« Reply #174 on: August 07, 2022, 08:44:26 pm »
There is no need to adjust the throttle because the the cruise control does the job on its own. It will keep the wheels turning at exactly the same speed no matter the load put on it, so the more load you put on the generator the more the throttle opens to keep it going. You also don't need to hit exactly 50/60 Hz, going +/- 10Hz is going to work just fine.

The cruise controls that I've used aren't exactly "precision".  In terms of PID control (not the only way to make a control system, but very common), I wouldn't be surprised if they were purely proportional (throttle = gain x error), with low enough gain to guarantee that it doesn't oscillate ever.  That goes for both vacuum and electric ones.  The speed does droop with increasing load (non-zero throttle requires non-zero error), though it might manage to keep +/-10% at highway speed.

The cruise control on my 2008 Subaru (Outback 2.5xt) droops a maximum of about 5 km/h from the set speed at the start of a steep hill, but if the hill continues at the same steepness long enough (a km maybe) then it does get back to zero error.

It's obviously deliberately tuned for smoothness/comfort rather than precision at all costs. When following another vehicle it maintains a very steady 2 seconds behind (that's the setting I use) with gradual speed changes, but it only does what can be adjusted with coasting or with acceleration in top gear (and torque converter locked up) unless the following distance changes quite a lot.  I've never actually measure it, but at a guess it starts actually braking when the following distance drops to about 1 second, or will change down if it drops maybe 4 seconds behind (it's quite a bit). Once speeds are again roughly matched it takes maybe 10-15 seconds to adjust the following distance back to 2 seconds.

I had an almost ten years newer Outback (2017) for the year I lived in California and the cruise control on that was probably a bit more proactive on making bigger adjustments, both in braking earlier if the following distance started to rapidly drop, and in accelerating harder to stay with the vehicle in front.

But the older 2008 model works very acceptably and a heck of a lot better than not having the system!
 


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