Generator/Inverter with Battery & Solar

Submitted: Thursday, Dec 05, 2013 at 14:09

ThreadID: 105380 Views:3750 Replies:9 FollowUps:26

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DarkTorana

Hi guys,
Really hoping someone knows or could point me in the right direction, but it is a bit of a rare case i have, so i guess we'll just wait and see!

So without further ado;

I have a 150A/h AGM Battery that is running a LED light system and a few other bits and bobs (Phone chargers and the like) and it gets it's juice from a 120w Solar Panel. Everything's been running smooth and I did a lot of research to make sure that the system can run a few days without the sun if need be.

But now it's gotten to the stage where someone (could be the missus) has decided she wants to have some big power appliances. It seems the best way to run this would be with a 2Kva Generator/Inverter (I have checked all the wattages and PF ratings to confirm everything is well above what I'll need it to be). But then it got me thinking, if I have to go through all this effort to run her appliances, why not run my own?

So down the question, the appliances I want to run are 240v, but require very little current in the grand scheme, and should easily be able to run off the battery system that is already in place and if I don't have to run the generator it would make my life a lot easier. So instead of buying a generator/inverter AS WELL as another inverter for the less power hungry 240v devices, can I use the battery I already have?

Correct me if I’m wrong but from my understanding the Generator/Inverter produces power by:
Alternator produces 3 Phase --> Rectifier converts it to 12v --> Inverter converts to clean 240v (assuming pure sign wave)

Now knowing full well that it would void the warranty can I attach the battery to the other side of the rectifier? So;
Alternator produces 3 Phase --> Rectifier converts it to 12v --> Inverter converts to clean 240v (assuming pure sign wave)
12v Battery -----^

This way (theoretically) I can just use the inverter that is built into the generator inverter, and wouldn't need to go and buy ANOTHER inverter.

The main concern I have, and solution, is that when the generator is running it would try and push 12v INTO the battery through those same leads that would supply the inverter when the generator is off. But I figured worst case scenario I put a switch on those wires, best case, would it be as simple as a beefy Diode?

Sorry about the wall of text, I wanted to get enough information down to clearly explain what I was trying to do. I'm not expert in electricity (else I guess I would know the answer) but i'm not too clueless. So please don't be concerned with using the correct thickness wire, or the amount of amps that would be required etc, as I have a good idea of that already!

Thank you for any advice, assistance or answers you can provide!

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Reply By: Andrew D. - Thursday, Dec 05, 2013 at 14:43

Thursday, Dec 05, 2013 at 14:43

OP: "Correct me if I’m wrong but from my understanding the Generator/Inverter produces power by: Alternator produces 3 Phase --> Rectifier converts it to 12v --> Inverter converts to clean 240v (assuming pure sign wave)"

Above is totally incorrect assuming a Yamaha/Honda type inverter generator.

OP: "Now knowing full well that it would void the warranty can I attach the battery to the other side of the rectifier? So; Alternator produces 3 Phase --> Rectifier converts it to 12v --> Inverter converts to clean 240v (assuming pure sign wave) 12v Battery -----^
Can't be done so doesn't matter.

OP: "but i'm not too clueless."
How much clueless?

Modern Yamaha/Honda inverter generators work nothing like you think they do.

AnswerID: 522601

Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 15:48

Thursday, Dec 05, 2013 at 15:48

"Above is totally incorrect assuming a Yamaha/Honda type inverter generator."
Could you explain how the Honda type work? As direct from the Honda website it says:
"First, the generator's alternator produces high voltage multiphase AC power. The AC power is then converted to DC. Finally the DC power is converted back to AC by the inverter. "

I could be missing something, but isn't that exactly what i linked above? Admittedly i said 3 phase not multiphase, but it's still DC to AC via the inverter.

"Can't be done so doesn't matter."
You say it can't be done, but it seems to be on the assumption that there is not a DC to AC power source inside the generator, which would explain why it can't be done, but the Honda website specifically states that there is a DC to AC inverter. Now if the DC power being produced is greater than 12v then fair enough!

"How much clueless?"
No need to take shots at me, all i'm going on is what i'm reading, via the manufacturer no less, if i'm misunderstanding then fair enough, that's why I am asking.

"Modern Yamaha/Honda inverter generators work nothing like you think they do."
Clearly if this is the case, i am misinterpreting the Honda website, which is quite possiable, could you explain what they mean by what i have copied above?

Thanks for your help :)

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Follow Up By: Member - Frank P (NSW) - Thursday, Dec 05, 2013 at 16:16

Thursday, Dec 05, 2013 at 16:16

DarkTorana,

"As direct from the Honda website it says:
"First, the generator's alternator produces high voltage multiphase AC power. The AC power is then converted to DC. Finally the DC power is converted back to AC by the inverter. "

I think you may have answered your own question, via the Honda website.

From my reading of that quote the DC that goes into the Honda's inverter is high voltage, not 12V. Therefore, even if you could access it, the DC entry point in the Honda inverter is not suitable for the 12V you want to apply.

Cheers

FrankP

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Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 16:34

Thursday, Dec 05, 2013 at 16:34

Hi Frank,

Thanks for that, I just assumed it would be 12v, which is where my understanding failed I guess.

Still I thought that there could be something altogether different that I was missing that even if the rectifier was producing 12V (give or take) it would still mean I wouldn't be able to do that idea.

I guess i'll just have to find out what voltage that rectifier produces and we can put this whole thing to rest!

Thanks for the insight,

DT

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Follow Up By: Member - Frank P (NSW) - Thursday, Dec 05, 2013 at 17:12

Thursday, Dec 05, 2013 at 17:12

If you could find a Honda EU20i service manual, or a link to one, you might find the info there ....

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Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 17:30

Thursday, Dec 05, 2013 at 17:30

Ahh, now that's a good idea. I'll give that a go and if I find anything i'll post it here, on the off chance that one day someone else is wondering lol.

Thanks for your help

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Reply By: Herbal - Thursday, Dec 05, 2013 at 14:48

Thursday, Dec 05, 2013 at 14:48

I am confused...

What you want to do...Is instead of the petrol engine in the genny supplying power to the inverter built into the genny, you want to connect the battery so that the battery supplies power to the inverter that is built into the genny?

But, you want both the petrol engine AND your battery to supply power to the inverter built into the genny, at the same time ?

Is that correct?

AnswerID: 522602

Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 15:52

Thursday, Dec 05, 2013 at 15:52

Sorry, I clearly didn't explain that too well, apologies for that.

I want to be able to use the generator to run the inverter when their are big loads (I'll go and turn the generator on for that).

But when there are light loads (as a bad example think charging a laptop from it's proper 240v charger (Yes i realise i could just step up 12v to 19v for that purpose, it's just an example)), i would like the inverter to just pull power straight from the battery i already have.

I definetly do NOT want it to pull power from both at the same time, though with a proper regulator i guess a case could be made to go from the rectifier to regulator to battery to inverter. But that's a different story than what i am asking here.

I hope that makes it clearer what i'm asking, but if not please don't hesitate to ask for clarification.

Thanks alot for taking the time to help.

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Follow Up By: Herbal - Thursday, Dec 05, 2013 at 16:20

Thursday, Dec 05, 2013 at 16:20

OK...I think I understand.

At the risk of sounding rude ( I don't mean to), I think you are trying to make a silk purse out of a pigs ear...

The bottom line is...you cannot get out more than you put in.

Some will differ, but it is generally agreed that 20% capacity is a safe maximum usage for lead/acid batteries. An AGM is a lead acid battery. You have 150AH, so 30 AH is a nice safe figure to work on. That is what you can take out of your AGM before having to recharge.

Your question seems to me to be whether or not you can use the inbuilt inverter of your genny as a stand alone inverter... I don't like to answer a question with a question, however, why would you want to?

There are very few things that "need" sine wave. Most things will run on modified wave inverters. To use your laptop example, it does NOT need a sine wave (pure sine wave). It will run perfectly fine on any old modified wave inverter...just make sure you have the laptops battery installed ;)

As others have said, inverters are quite cheap these days. Unless you need a "pure" sine wave for some specific purpose, a modified wave inverter will run just about everything you have.

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Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 16:40

Thursday, Dec 05, 2013 at 16:40

Hi Herbal,

I didn't take it as rude so no worries there!

I guess alot of things don't require pure signwave, but there's no denying it's superior, unless of course i'm mistaken about that too lol.

At the end of the day, if we ignore the effort it will take to make it happen, why bother taking two inverters? I know I can take two inverters and do the job, and i appreciate that you are trying to offer me alternative options that may be easier, but I'm more after the knowledge of IF it is possible and less of other ways of doing it.

Why shell out for another inverter, and more equipment when I potentially have everything I already need?

Thanks mate,
DT

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Follow Up By: Herbal - Thursday, Dec 05, 2013 at 17:07

Thursday, Dec 05, 2013 at 17:07

No worries mate...

I do understand now, where you are coming from.

Can it be done?...Maybe! with the right modifications and money...

As you say, it would void the warranty...So, the genny will cost say $600 to $1200 depending on brand, quality, size etc... A "pure" sine wave inverter of say 300watt will set you back under $100 or a modified wave inverter at 300watt will be $40 or $50...

So you are thinking of how to chop & slash a $1000 piece of kit, to save $50...

If twas me...I would shell out the dollars and get another inverter :)

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Follow Up By: Ross M - Thursday, Dec 05, 2013 at 18:50

Thursday, Dec 05, 2013 at 18:50

Herbal
It all depends on the switchmode power supply you connect to the inverter.
There are some power supplies which will run on crap mod square wave but run hotter, and there are others which definitely DO NOT RUN on the crappy one at all. Some will not start to switch/oscillate and if it is a type which just holds ON then it burns out shortly afterwards.
I have two laptops, Both will run on Sine but only one will run on the mod Sq.
So it all depends on what the item is.

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Reply By: Racey - Thursday, Dec 05, 2013 at 14:55

Thursday, Dec 05, 2013 at 14:55

Hi Dark Torana, The inverter in the generator is not really accessible for what you are proposing. They are usually encapsulated within a heatsink. I guess the solution really depends on what you deem to be big power appliances. Small sinewave inverters are not very expensive. In my own situation, I have 2 x 120 watt panels feeding 3 x 105ah agm batteries, with a generator to supply microwave etc, plus a battery charger to top up the batteries on dull days. When I do run the generator I make sure all the small items like phone chargers and camera batteries etc are also plugged in to ensure they are kept charged. In addition I also have a 300 watt sinewave inverter to run the entertainment and the small items when there is lots of sunshine.

Cheers

Racey

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Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 15:55

Thursday, Dec 05, 2013 at 15:55

Hi Racey,

That's more or less what I was looking at doing, and although the smaller inverters are not THAT expensive, it was just something i was trying to get out of doing, invest that same money into buying an additional solar panel or another battery...

Truth be told based on the responses i am getting it will most likely be the scenario i go ahead with, but it would still be cool to find out if somone has a reason it can't be done.

Honestly the only issues i can think of is power going through the rectifier back to the alternator, but i'm pretty sure rectifiers are made with diodes, so i doubt that's going to happen!

Thanks for posting a reply, i appreciate the time mate.

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Reply By: Allan B (Member, SunCoast) - Thursday, Dec 05, 2013 at 14:57

Thursday, Dec 05, 2013 at 14:57

Hi DT,

Correcting you "if you are wrong"......
The alternator does produce 3 phase AC but it is then rectified to supply the inbuilt inverter to produce 240v sine wave. This rectified 3 phase is usually at a voltage somewhat above 12v and is not available for supplying external loads.
Some alternators do have a dedicated 12vdc output available as well as the 240vac but it is not regulated and intended for extra-low voltage lighting and you would be well advised to not use it for battery charging for fear of harming your battery.

The best way for your needs would be a quality inverter-type alternator supplying both your 240vac loads and a multi-stage charger for the battery. Good quality "pure-sine wave" inverters are not expensive.

Cheers
Allan

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Follow Up By: Allan B (Member, SunCoast) - Thursday, Dec 05, 2013 at 15:59

Thursday, Dec 05, 2013 at 15:59

.
"Good quality "pure-sine wave" inverters are not expensive."

Don't know why I said that. It has nothing to do with the subject.

Cheers
Allan

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Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 15:59

Thursday, Dec 05, 2013 at 15:59

Hi Allan,

I think i've explained my situation poorly, i don't want to charge the battery from the 12vdc output of the Generator, i want to wire a battery into the generator/inverter, so that when the generator is off the inverter can still use the power from the battery.

A different way of looking at it would be this question:
"Can I take the inverter out of a Generator/Inverter and connect it straight to a battery to produce power?"

Thanks for taking the time to help Allan.

Cheers,
DT

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Follow Up By: Allan B (Member, SunCoast) - Thursday, Dec 05, 2013 at 16:24

Thursday, Dec 05, 2013 at 16:24

Actually, I do realise why I said " Good quality pure-sine wave inverters are not expensive." I'm doing several things at once here and getting confused.

What I had omitted was to say that I consider your scheme to utilise the inbuilt alternator inverter to be fed from the battery as being impractical and in any case of no significant economy because "Good quality pure-sine wave inverters are not expensive".

If you wish to produce 240vac from your battery then use a standalone inverter. If you wish to charge your battery from the gennie, do so via a multi-stage battery charger. Adapting the gennie to save on the cost of an inverter is not an option, even if you were skilled in electricity.

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Allan

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Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 16:45

Thursday, Dec 05, 2013 at 16:45

Ha! No worries Allan, no doubt theres plenty of people like myself after help so again, thanks for taking the time to help us!

"Adapting the gennie to save on the cost of an inverter is not an option, even if you were skilled in electricity."
Can you explain why though?

I appreciate that you think it's not worth doing, and that's fine, but why is it not doable? The closest reason anyone has given as a possibility is that the rectifier is producing greater than 12v, thus more than what a car battery can store, but that person didn't know, they were just putting it as a possibility.
Puting aside you don't think it's worth it, and that getting a second inverter is not that expensive, do you know why it is not doable, or is it more you think it's just more complex than it is worth?

Thanks for your help,

DT

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Follow Up By: Allan B (Member, SunCoast) - Thursday, Dec 05, 2013 at 18:46

Thursday, Dec 05, 2013 at 18:46

DT, I'll try to explain the thinking behind my answers although you may not find it definitive. I have not had reason to "go inside" a portable inverter type generator but my engineering knowledge and experience leads me to conclusions that may be considered reasonable.

I do not know the typical voltage input to the inverter section. It is a proprietary matter and would I'm sure, vary with manufacturers and with models. However, I would bet that it is not 12 volt but considerably more for the following reasons.
1. The considerations of winding the coils of the stator dictate the optimum gauge of winding wire. Too thick (low voltage) is more difficult to form into coils, too thin is fragile. So the wire gauge and number of turns is likely to be such that the voltage would be of the order between 70 and 150 volts.
2. The considerations of semiconductor devices are such that it is better to avoid low voltage, high current components. This applies to both the rectification and the switching transistors. Again, voltages in the range of 70 to 150 volts are optimal.
3. The inverted DC has to be 'transformed' to the output of 240v and it is more convenient to keep the primary/secondary ratio closer to unity than to have a high ratio. To explain why would need you to have a good electrical theory grounding.

Therefore I would make a reasonable assumption that the output from the gennie stator (input to the rectification) is somewhere between 50 and 150 volts. Thus the rectified DC to the inverter section will be of a similar order.

Now I may be quite wrong about this. The gennie's inverter may accept an input in the order of 12 volt. Indeed, the fact that most of these machines provide an accessible 12vdc auxilliary output gives me cause to wonder. Few users would need it so why bother with the cost and complication unless the 12vdc was coincidentally available? So maybe they do generate at a nominal 12 volts. I dunno.

So much for my technical reasoning. My practical reasoning, based on much experience, is that it may well be a cute idea to have the gennie's inverter perform double duty but it is not worth the hassle and possible dire consequences when standalone inverters are reasonably small and low-cost. I gave up weirdo arrangements as I emerged from adolescence. LOL

If you do manage to make this idea work, please do not publish it. I shudder at the thought of innocents delving inside their gennies wielding a soldering iron.

Cheers
Allan

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Reply By: Ross M - Thursday, Dec 05, 2013 at 15:10

Thursday, Dec 05, 2013 at 15:10

Not sure why the focus is on the phases as it doesn't matter if it is more. A car alternator is usually/just happens to be 3 phase, cos that is the way it is wound.

A Generator/inverter can have as many phases as the designer makes it with.
It just creates the power in it's alternator section to feed an inverter which makes 240vac.

To run items on 240vac you just have to start the engine and plug it in. No real need to create losses by pumping up a battery and then using a stand alone inverter to make 240vac. A stand alone inverter is handy though.

If you are going to charge the battery from the generators output, then that is a new game with it's own special requirements. Most generators have around 8amp 12v dc output plug but it is useless for charging a battery as it will take days of running to even make it hapen.

You don't won't have access to the energy from the generators alt section before it goes to it's own inverter and it may run at a far higher voltage than you imagine it does. So, tapping the alt in the generator is out of the question I think.

AnswerID: 522607

Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 16:04

Thursday, Dec 05, 2013 at 16:04

Hi Ross,

Sorry about the talk of multiphase, i'm not too concerned with that so much, i was just making sure i understood how they work correctly.

The part I am interested in is after the rectifier but before the inverter. If I have read you correctly, you're saying the voltage that the rectifier produces could be quite high, as in, much higher than 12v?

This was my main concern, if the inverter is getting higher voltage from the rectifier than 12v then clearly my idea wouldn't work!

For clarification, i'll copy the question i posted to another member that might better explain what I am trying to do:
"Can I take the inverter out of a Generator/Inverter and connect it straight to a battery to produce power?"

Cheers for taking the time to help me out Ross.

DT

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Follow Up By: Allan B (Member, SunCoast) - Thursday, Dec 05, 2013 at 16:08

Thursday, Dec 05, 2013 at 16:08

Ross, The OP made reference to "3 phase" so I rode with it for clarity rather than introducing "multi-phase". I don't think there is any "focus" on the phases.

Cheers
Allan

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Reply By: Member - Frank P (NSW) - Thursday, Dec 05, 2013 at 16:29

Thursday, Dec 05, 2013 at 16:29

DarkTorana,

I think it is established now that, sadly, you can't do what you want to do :-), so you'll have to buy an inverter. You mentioned a certain someone :-) wants to power some power-hungry 240V appliances, so you'll no doubt be thinking of a pretty solid inverter.

Let me warn you of an inconvenience we have had to work around. Our hybrid CT is fitted with a Xantrex 1800 watt inverter, which will run some pretty heavy duty stuff.

Odd thing is, it doesn't wake up if you plug a really light light load in, such as a camera battery charger or phone. If you trick it into waking up, it goes back to sleep, presumably due to the light load. (A laptop is ok).

So for very light 240V loads like the camera and phone chargers we have had to buy another small inverter to add the the crap we carry around. No big deal, but if you shop carefully you might do better.

Cheers

FrankP

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AnswerID: 522611

Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 16:53

Thursday, Dec 05, 2013 at 16:53

Hi Frank,
Unfortunetly for me, it hasn't been established that it can't be done. People have given me other good options, and they have said it isn't worth doing. But except for where it was suggested that the rectifier might produce more than 12v, nobody has given me a reason as to why it can't be done.

I should have asked a different question, as i feel i've given too much information and people have misunderstood what i am actually asking, so the better question would have been:
"Can I take the inverter out of a Generator/Inverter and connect it straight to a battery to produce power?"

Forget the generator, forget what the load is, forget secondary inverters or pure vs modified sine wave, does the inverter in an generator inverter take 12v after the rectifier.

I guess, for obvious reasons, nobody has ever tried, which is why getting an answer is a bit hard. I might just have to get generator inverter and check the voltage that is output from the rectifier!

Ahh that's really interesting about the load required to wake it up, and something i never considered. But the lights and chargers will all run off of the battery system so hopefully that won't be a concern for me :)

Thanks Frank,
DT

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Follow Up By: Brian 01 - Thursday, Dec 05, 2013 at 21:07

Thursday, Dec 05, 2013 at 21:07

Many good quality inverters such as your Xantrex have the ability to go to sleep if they detect no load.
This gives them a much better low output efficiency figure and saves your battery.
Unfortunately a light load sometimes fails to wake it up.
This is easily overcome by plugging in a small globe (15w is ample) or similar when you want to use very low drain appliances. No need for a separate inverter.

With regard to inverter generators such as Honda etc, the actual generator section outputs multiphase high voltage AC for the next inverter section plus an extra low voltage single phase AC for the 12 volt outlet. This single phase AC is rectified to DC and fed to the 12v outlet.
The multiphase AC is rectified to an even higher voltage DC (41.4% higher to be pedantic, and can be in the vicinity of 400 - 500 volts) and then fed to the inverter stage which electronically inverts it to a very pure sine wave AC with the output voltage stabilised to the required tolerances of the supply (in our case 220 - 250v).
There is no possibility to interconnect another feed to the input of the inverter either safely or effectively.

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Reply By: Dennis Ellery - Thursday, Dec 05, 2013 at 16:56

Thursday, Dec 05, 2013 at 16:56

Hi Dark Torana
Since the units aren’t designed for the purpose you intend, then the only way to know for sure is to give it a go. That is if you have the ability to locate the DC input side and can get a qualified electrician to connect it up. Next get the missus to stand by with a fire extinguisher and then stand back and flick the switch. Assuming either it or yourself doesn’t disintegrate in a cloud of smoke – then get the sparky to check the output for voltage, frequency, regulation %. Then run it under full load for a minimum of half an hour, again performing all the above checks again. If you and the inverter survive this experiment, it will be a fair bet that you could have achieved the same result by purchasing an inverter designed for the job in the first place.

AnswerID: 522613

Follow Up By: DarkTorana - Thursday, Dec 05, 2013 at 17:44

Thursday, Dec 05, 2013 at 17:44

Yeah seem's your right. I have no issues with testing the voltage on the rectifier, having seen inside one it's clear the wiring isn't exactly complex (then again how complex could it have been), please note i said wiring not components lol.

"That is if you have the ability to locate the DC input side and can get a qualified electrician to connect it up."
Assuming the rectifier IS putting out 12v, i'm pretty sure I won't need an electrician to hook up 12v to two wires lol. Having spent dozens of hours inside computer power supplies, I'm still significantly more scared of them than 12v to 12v.

"output for voltage, frequency, regulation %"
This could definetly be a learning point for me, but with the assumption that the inverter does indeed need 12v, why would the voltage or frequency of the 240v output change based on where the 12v is coming from? Since DC doesn't have a frequency I would have thought the inverter will produce the same clean 240v regardless of the source of the 12v, assuming there is enough amps for it of course.

"Then run it under full load for a minimum of half an hour"
The battery wouldn't be capable of running it at full power, in fact i only want the inverter to take about 1/5th of max load of the inverter, so i'll skip this test!

"it will be a fair bet that you could have achieved the same result by purchasing an inverter designed for the job in the first place."
Not if the job was to take one inverter ;)

Thanks for the input mate,
DT

FollowupID: 803706

Follow Up By: Brian 01 - Thursday, Dec 05, 2013 at 21:14

Thursday, Dec 05, 2013 at 21:14

Please don't even think about doing this.
You are dealing with both AC and DC voltages far in excess of your household AC supply, and it can be fatal.
No electrician worth his salt would even contemplate such madness.

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Follow Up By: philw - Thursday, Dec 05, 2013 at 21:34

Thursday, Dec 05, 2013 at 21:34

Anyone remember when camping was a simple pleasure?

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Reply By: The Bantam - Saturday, Dec 07, 2013 at 00:05

Saturday, Dec 07, 2013 at 00:05

I know a lot has been posted above ...but I think a few things need clarifying.

Inverter generators work like this.
They use a multiphase alternator because it is more efficient......they use a inverter circuit because it enables them to run the motor where it is most efficient.

The main alternator of a modern inverter generator varies greatly in its frequency possibly no where near 50 Hz mains frequency ( actually much higher) and its voltage output varies also...The inverter circuit then takes what ever the motor and alternator can produce most efficienly...however it comes..and converts it into nice clean stable 230V 50 Hz AC.
The fact that the inverter may or may not convert to DC is of no relivence to the user....this DC if it exists in a particular design is not usable or accessable..OR of any real interest to the user...this DC voltage most certainly will not be 12 volts, it may in fact be 500 volts or more

The 12 volt output that some generators have is a completely different set of windings and is a very crude low capacity output and only capable of charging small batteries.....it is very much like the magneto charging circuit in a rider mower or small outboard......pissy and crude...of very little use for charging large batteries.....I wont go into the details of why, but there is more to it than just low output.

Now if you want to charge batteries efficiently and fast, the best option by far is a generator specificlly designed to charge car sized batteries.
Crystie engineering make such a machine and it is more or less a car alternator bolted to a motor....and it will output 50 odd amps at 12 volts.

Now...if you want to look at multiple sources of charge for your batteries.....there are a couple of DC to DC battery management systems that will do this very well.
they will take the output of solar pannels with Maximum power point tracking, the output of your car alternator AND the output of another charge source and maximise what is delivered to the battery, depending on what is available one, two or all 3 sources at once.

As for this whole 240V thing.......there are less and less good reasons to have 240V every day....a great many of our modern equipment is 12 volt native or can be obtained in a 12 volt version.

Almost without exception, it is more efficient to charge anything that has a battery direct from 12 volts rather than via a 240V inverter.

Just some thaughts.
cheers

AnswerID: 522685

Follow Up By: Allan B (Member, SunCoast) - Saturday, Dec 07, 2013 at 08:36

Saturday, Dec 07, 2013 at 08:36

.
Et non habetis DarkTorana, ad plenum. LOL

Cheers
Allan

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Follow Up By: Brian 01 - Saturday, Dec 07, 2013 at 10:12

Saturday, Dec 07, 2013 at 10:12

To the contrary Allan,
I would have thought that Se habet hoc in plena.
Or maybe Et respondendum est, quo indiget

FollowupID: 803833

Follow Up By: Allan B (Member, SunCoast) - Saturday, Dec 07, 2013 at 11:27

Saturday, Dec 07, 2013 at 11:27

Sane Brian.

Cheers
Allan

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FollowupID: 803840

Reply By: Member - Jefec (WA) - Saturday, Dec 07, 2013 at 11:27

Saturday, Dec 07, 2013 at 11:27

The Honda EU10i manual has a circuit diagram Aust type is U. You can see from the circuit that there are separate windings ignition,control, and 12V,via a rectifier, for battery charging. A 3-phase winding feeds the power block which in turn outputs 230V ac single phase. The physical size of the power block suggest that the conversions inside the block are at a high frequency (8-14khz being typical) to keep component size down. The dc rails inside probably vary in voltage and be 100 t0 400v - cannot find specific numbers.
Incidently almost all modern power supplies for laptops, phone chargers etc. are "switchmode" most of which do not tolerate non sinusoidal inputs.
If you want to run airconditioner use adequatelly sized generator, if a microwave or similar short time load use an appropriate size sine wave inverter and a small eg 1kVA generator for battery charging via a 20A multistage charger. Solar panels , 120W or larger,are OK for every thing except A/C units.

Jefec

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AnswerID: 522700