Parallel two inverter generators of different brands?

[Ductard]

I started to look into paralleling inverter generators so that I can do things like run the AC on my toy hauler.

One of the first things you come across is that most (if not all) of the parallel kits say you have to use IDENTICAL generators.

But then you come across stuff like this guy paralleling a honda 2,000 and two 1,000's.

In the comments, there are people talking about paralleling things as different as a honda with a battery powered inverter....

What I'm trying to do is hook up a 2,000W honda with a 2,000W yamaha.

I have a parallel kit that says it can be used to hook up 2 hondas or 2 yamahas, so I know the plugs will fit.

Why risk it? Well, because I have a honda and a friend who will be sharing the hauler with me has a yamaha, so for $0 additional investment, I *could* be all set.


Hoping somebody has some insight. I can already imagine stuff like "what if the two phases aren't able to perfectly match up"? But hoping someone has something a little more definitive than that.

[xxaarraa]

Note to self: Do not pit next to Ductard.

[Ductard]

Note to self: Do not pit next to Ductard.

Good segue into my "can I connect two 2kg fire extinguishers instead of just buying a 4kg fire extinguisher" thread.

[Ductard]

I started to look into paralleling inverter generators so that I can do things like run the AC on my toy hauler.

One of the first things you come across is that most (if not all) of the parallel kits say you have to use IDENTICAL generators.

But then you come across stuff like this guy paralleling a honda 2,000 and two 1,000's.

In the comments, there are people talking about paralleling things as different as a honda with a battery powered inverter....

What I'm trying to do is hook up a 2,000W honda with a 2,000W yamaha.

I have a parallel kit that says it can be used to hook up 2 hondas or 2 yamahas, so I know the plugs will fit.

Why risk it? Well, because I have a honda and a friend who will be sharing the hauler with me has a yamaha, so for $0 additional investment, I *could* be all set.


Hoping somebody has some insight. I can already imagine stuff like "what if the two phases aren't able to perfectly match up"? But hoping someone has something a little more definitive than that.

For anyone interested, here are a couple of threads on the topic.

I can't say I've seen anything definitive, but here's the one post that gives me the most reason to opt not to try it out...although I have a hard time believing the hondas run 8 extra volts until heavily loaded...I thought the inverters were supposed to produce very "clean" power (assuming that "clean" would mean both waveform and voltage)

Posted: 10/27/14 11:54pm

Link | Quote | Print | Notify Moderator

---

Based on posts that I've read, the Yamaha generators have a more standard 120 volt output as compared to the Hondas that tend to run about 128 volts until heavily loaded. This means that if the generators did sync ok, the Honda would carry all of the load until it was close to overloading. Only then would the Yamaha pick up part of the load. The output voltages are incompatible, and they would not make a good combination. I've not read of anybody actually trying it. Theory is nice, but even if the risk seems small, most or all of us are too scared to take the chance of burning out an expensive generator.

RV.Net Open Roads Forum: Tech Issues: Parallel inverter/generator hypothesis...
https://www.rv.net/forum/index.cfm/f...g/1/page/2.cfm

[stoinkythepig]

From what I've heard, the Honda will sync with anything and is really rugged. I say go for it. Just be sure to start the Yamaha first. The difference in voltage is utterly irrelevant.

[dannyjm]

From what I've heard, the Honda will sync with anything and is really rugged. I say go for it. Just be sure to start the Yamaha first. The difference in voltage is utterly irrelevant.

the two generators will not be in phase unless there is some kind of sync so they would be as likely to cancel each other as add if you connect the outputs. the difference is in power (watts) not voltage so you might want to get advice from someone not quite as stoinky.

[Ductard]

the two generators will not be in phase unless there is some kind of sync so they would be as likely to cancel each other as add if you connect the outputs. the difference is in power (watts) not voltage so you might want to get advice from someone not quite as stoinky.

Both generators have an auto-sync function. They are designed to run in parallel with another (per the instructions, identical) generator. If there's one thing I have seen enough examples of online it is that running two different wattage Hondas is ok (ie an eu1000i and an eu3000i)

I understand the difference in voltage, current, and power, and I think the point someone made on the other thread is that given an equal resistance (because they are running to the same circuit) the higher voltage generator will take the full load. I vaguely remember the idea of shunt resistors from my physics class...which if I apply fuzzy recollections of ohms law...I would guess that would not be true, but the load will be taken proportionally based on the voltage difference, but that is vague, fuzzy logic.

[Woodsy]

Voltage has almost nothing to do with load distribution between generators in parallel because in parallel both generators will match voltage when you synch. It all has to do with there frequency response and speed droop characteristics. IE: if one generator slows down upon aplication of load the other generator doesn't the generator with the higher frequency will pick up more load allowing the other generator to recover.

see this link for more
https://en.wikipedia.org/wiki/Droop_speed_control

[jasnmar]

I agree. I've done a number of parallel generator designs, but don't know enough about the design of the inverter electronics to be educated. For a motor style generator droop control is incredibly important (and the goal is to stay away from droop it at all possible).

Inverter electronics are a completely different animal.

[Ductard]

I agree. I've done a number of parallel generator designs, but don't know enough about the design of the inverter electronics to be educated. For a motor style generator droop control is incredibly important (and the goal is to stay away from droop it at all possible).

Inverter electronics are a completely different animal.

Yeah, voltage droop has no effect on engine speed, because an inverter generator creates AC, converts it it DC, and then back to AC. That's why they are so expensive (and smaller, quieter and more efficient) the motor does not have to spin at a constant rate to maintain a constant current frequency, hence "eco throttle" and all this auto synching stuff that most of them have. The sine wave is already computer controlled.

[Garandman]

I've wondered the same myself, though I have two Hondas. Works slick.

[Ductard]

I've wondered the same myself, though I have two Hondas. Works slick.

We are not alone in wondering....unfortunately my internet research has only turned up some naysayers and a bunch of "in theory it should work" seem like everyone has too much sense or too little testicular fortitude to put $2k worth of generators on the line to prove out the theory.

[carsick]

seem like everyone has too much sense or too little testicular fortitude to put $2k worth of generators on the line to prove out the theory.

I'll do it! Bring them to round 4, we've got for or five sets of warmers that need to be ready at the same time. I'm not scared.

[jasnmar]

I hear carsick has a fire extinguisher ready, just in case.

[carsick]

One in the truck and trailer.

[stoinkythepig]

the two generators will not be in phase unless there is some kind of sync so they would be as likely to cancel each other as add if you connect the outputs. the difference is in power (watts) not voltage so you might want to get advice from someone not quite as stoinky.

Except they will be in phase. Those Hondas are specifically built to sync up and once in phase, they, like any other generator, are hard to get out of phase. Only one of the generators needs to be able to phase sync, the other is just the master clock.

If there's any concern, the OP could simply put a 3 amp fuse on the sync cable, connect them with no load and fire up the Honda after the Yamaha. The fuse will protect both. If it does not blow, you know they are in sync.

[xxaarraa]

Looking to buy generator enough for warmers.
Has to be in great condition. I don't care if it is loud or ugly. Functional is a must

And your ambulance has 2 batteries and 2 alternators lol. Win.

I started to look into paralleling inverter generators so that I can do things like run the AC on my toy hauler.

OK, Tsorface and Ductard need to get together, parallel the ambulance with Ductard's Honda. You'll make enough power to light up the whole East Coast, and have some spare power to sell to Canada.

BAM. I solved it. Next.