# Battery charging



## Bazbro (May 9, 2005)

Has anyone considered this:-

Rather than buy and run a generator, why not leave the engine ticking over for half an hour or so (when wild camping, of course!). Fuel used will be marginally more than a large generator, but you're saving on the initial cost of the genny.

Alternatively, add an extra fanbelt to a dedicated, high-output alternator to solely charge leisure batteries, or even drive a 240volt "generator" when on tick-over?

Any thoughts on this?

Barry


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## 88966 (May 11, 2005)

Hi Barry,
All the techniques you mentioned are used in the cruising sailing boat world, which is where I spent a lot of my life (before tugging and now having seen the light).
They are of course coupled with things like solar panels and small wind generators. One type which I don't think would go down well in the MH world is the towed propellor driven generator! (It's a bit like the old ships log).
I think is important to have a good sized leisure battery(s) capacity. Then if you move reasonably frequently (even if to return to the same spot) and have a good sized solar panel it is unlikely you will need any of the others.
See you soon,
BillD


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## DABurleigh (May 9, 2005)

Barry,

The issue is really a balance between the time the engine is ticking over and the charge being put into your leisure batteries.

With a bog standard set up, I would be concerned that the amout of ticking over my diesel engine would be required to do to get a sufficient charge would not be good for the engine, as well as make anyone in earshot irate (I appreciate you indicated wildcamping). The received wisdom seems to be that prolonged tickover with no/minimal load is not good for diesel vehicles.

However, with suitable steps being taken over battery management, invariable entailing getting direct access to the alternator, yes, what you propose, in combination with a moderately cheap and small inverter, would suit many MUCH more than a dedicated genny.

See:

http://www.sterling-power.com/htm/ar12vd.htm
http://www.adverc.co.uk/technical/technical-boat.asp

And message numbers 49048, 49118, 49113, 49589 in the motorhome email list.

Dave


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## Bazbro (May 9, 2005)

Thanks for those replies, Bill and Dave. Very helpful and encouraging.

Barry


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## Anonymous (Nov 10, 2000)

Well, over several years I've spent a fortune on a Honda generator, 40 amp switch-mode charger, 2 big leisure batteries and an 150 watt inverter. Overall I'd say the results are disppointing.

I'd say it's definately worthwhile having a seperate power source, but we wild camp throughout the ski season... However, if I was starting from scratch again, I probably wouldn't bother with the genny and spend 100 quid on a Stirling charge controller instead.

Chris


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## nukeadmin (Oct 10, 2003)

has anyone used or knows anything about Victron intelligent charger/inverters ?

www.victronenergy.com


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## brenbo (May 1, 2005)

Very interested to hear that Billd is an ex yachtie, I thought I was the only one who has finally swallowed the anchor.
I too was a sailor for many years, but decided to change to a MH, (Much to HWMBO's delight), mainly because I got fed up with strong winds/bad weather, and also the very expensive marina charges. At least you can use a MH in any weather!! You can also stay relatively clean and dry!!


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## Yorky (May 10, 2005)

Hello B & S
If you are going to relie on the engine to give the charge then you need to fit a really high output alternator, a bit costly to start with but you would'nt have to drive far or run the engine long to achieve the objective. 
Regards. Eddie


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## Anonymous (Nov 10, 2000)

Batteries and battery charging can be a bit of a minefield, but I'll do my best to keep things simple here. This is a very good, but somewhat lengthy, guide... http://www.victronenergy.com/BookRVA/ElectricityonBoard.pdf written by somebody with many years experience.

I've been thinking about electrics lately, and one of the things I considered was alternator charging.

I saw the following advantages...

1) Use existing engine, no extra weight and little extra cost.
2) It is a remote electric start genny!
3) Ostensibly can charge very fast.

There is a limit to how fast you can charge a battery, and the bottom line is you should spend at LEAST 5 hours fully charging a leisure battery, regardless of the size of the battery! Furthermore, that charge rate is only possible with a very flashy charger (temperature compensated, multi stage to be precise :? )

So, there's not much point in a really powerful alternator cause you'll just destroy the plates inside your leisure battery. Battery charging has to be carefully regulated by time, charge level and temperature.

Furthermore the engine of our Ducato based motorhome is MUCH noisier than our generator, and I understand that it's not good for diesels to be left idling for too long.

In summary, the disadvantages are...

1) You'd have to run the engine for at least 2.5 hours to 1/2 fill the battery
2) It may not be good for the engine (any comments on this?)
3) Alternator charging needs to be carefully regulated.

One more thing to be aware of is that you can't deduce very much AT ALL from the voltage of your battery. It depends on temperature, recent charging, current load, etc etc. It may look like you've put loads in when you turn your engine of and it says, say 12.6 V. But watch it and it'll drop fast. If you've been putting 20 Amps in for half an hour, then you've put AT MOST 10 Amp Hours into the battery. This is only 10% of the capacity of a 100Ah battery.

The only practical way to know what you have in your battery is to buy a 'current integrating' battery monitor. Sounds flashy, but it works a bit like a bouncer at a club, counting heads (bits of charge) on the way in and out. That way you can ask at any time how much is inside.

I could go on all day, moving into battery technologies, peak smoothing, wind and solar power, etc. The problem is I've got stuff to do today; I'm just too enthusiastic about this stuff I guess. The PDF guide above is well worth the read if you have time. 
I settled on a Victron inverter charger, after looking at Mastervolt, Struda, Prosine, Mobitronic and others. In answer to Dave's question, I know quite a lot about Victron, but since we're going to be selling them soon we don't want to appear to give biased advice.

(With regards to biased-advice, we're in a bit of a catch-22. We are full-timers who often come across a problem that needs solving. So, we go out and research everything that's available and make a decision about what to try. We buy it, try it and if it's good we find a supplier and sell it. If it's not good (like Grip Track) then we don't sell it. Of course that means we'll recommend everything we sell, and we pretty much sell everything we recommend! This makes giving advice feel a little awkward at times. We don't sell several brands of one product unless they are truly equal with varying merits. Some brands are, in our opinion, simply better than others in all respects)

Best wishes


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## Bazbro (May 9, 2005)

Thanks for that, Ben and Lizzie.

The mere fact that you've clearly explained your stance on what and why you stock your products is good enough (it might be worth reminding folks of this every now and then?) If you truly and honestly only stock stuff that you, as full-timers, can personally recommend, you should have a first-class business once the punters get to know and your reputation spreads!

I have to say that I was very impressed by the claims for the Sterling Power products. I haven't yet closely examined the Victron site (thanks for telling us about that) - do you have an opinion on Sterling?

And what about two alternators, one for one bank of batteries, and the other for a different bank of batteries? Is there any advantage there?

Thanks all of you for your replies. A lot for the rest of us to think about.

Barry


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## 89022 (May 12, 2005)

The guy that has written the Victron book about batteries etc is a dutchman,
managing director of victron energy.
Victron chargers and dc/ac convertors are widely used onboard megayachts.
The yachties among us will know the names like:
Huisman, Jongert, Contest etc etc.

The blue (victron) stuff is expensive but very good!!!!
(i've been working in the yacht electronics for about 15 years)

Leo


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## Anonymous (Nov 10, 2000)

Thanks for the support BarryandSue, we're trying hard and it's nice to be recognised. You asked about Stirling. I haven't seen or used their product. However these are the first people I investigated because I'd heard good things as well.

It was the technical specifications of the Victron that won me over, particularly their unique ability to ADD TO the incoming mains using the inverter... very clever stuff.

I know said dutchman, Mr Vader. He has bought technology from the computer Uninterruptable Power Supply market to his products, and certainly knows his stuff.

We're able to supply them direct from the Netherlands, at very competitive prices. However, not for a couple of weeks as we have to install and get to know our unit.


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## DABurleigh (May 9, 2005)

Ben & Lizzie,

I'm intrigued as to why the PowerAssist feature requires a "minimum shore current 2 A or generator capacity 2 kW required per MultiPlus." 
How does slightly inferior genny regulation compared with true mains lead to a four-fold increase in threshold for the mains source?

Otherwise a Honda EU10i genny in combination with a VictronEnergy C12/1200/50 Compact Phoenix Multiplus might be a very attractive & potent combination, albeit one costing over £1500 

However, I would still claim for the majority of cases in which:
a) one wants to consume a fair amount of juice from the from the domestic batteries, but:
b) the instantaneous ac power is NOT that big (eg 2kw aircon, 1.2kw hairdryer, mains microwave), and:
c) you are going to move on in 2/3 days or at least drive for an hour, say, then:

a Stirling digital regulator such as the AB12-90/ VA12-90 at £240 
http://www.sterling-power.com/htm/ab1290.htm
which is a very simple retrofit not entailing removal of the alternator, coupled with a cheap 300W modified-wave inverter from Maplins, is a powerful combination offering excellent value-for-money.

Dave


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## Anonymous (Nov 10, 2000)

Hi Dave

Thanks for the interesting question, I will find out why that discrepency exists. For the moment I will guess that it's something to do with the 'cleanliness' of the power and the relative difficulty of synchronising the sine waves :? 

I'll have a look at the Stirling link with interest, it would be nice to offer some decent British products too.

Best wishes

Ben


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## DABurleigh (May 9, 2005)

Ben,

Yes, that's what I initially thought, for indeed, as far as the Victron unit can deduce, I can't think of any other difference between the two inputs.

But then I would have thought that would have led to a lower MAXIMUM genny input than pure mains, not the reverse of a higher MINIMUM, as the Victron would have more trouble keeping its own output in phase with the input.

However, speaking as one who dropped out of a course specialising in electronic engineering to revert to much simpler physics, anything can happen with such dark arts.

It would be nice to know whether the EU10i's output is steady enough for Powerassist to work with it. Also, I assume, given its efficiency, that the Victron is capable of delivering a 50A charging current from an EU10i genny.

Dave


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## Bazbro (May 9, 2005)

Er, would an Ever-Ready PP9 help?

Sorry, chaps, I lost it there! What's really needed for dopes like me, is not so much a collection of electrical products available, but a choice of answers. For example, if I want to do such-and-such with my motorhome, I want someone to tell me that I will need "one of these" and "two of those" fitted, and sell me the whole set-up. Full stop.

The parts, including correct wiring, fuses, and full instructions, would get someone started, whereas at the moment, I believe a lot of people buy nothing because the alternative is to take a degree in electronics, or hand over their next six months wages to have someone else do it for them.

Many people are able to follow straightforward instructions, so could upgrade their basic system to something that is worthwhile, but they aren't able to make a sensible decision through sheer lack of knowledge. All they need is a businessman to offer a "package". So, Ben, "business opportunity" here! Perhaps offer two or three, basic, "upgrade" sytems for self-fit?

Me? I'm too frightened to do anything until you do! 8O

Barry


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## Anonymous (Nov 10, 2000)

DABurleigh, the good news is that the EU10i does have sufficient output to work with PowerAssist, and charge at nearly 50A

BarryandSue, thanks for the hint. We're working on putting together 2-3 packages to suit a variety of electrical needs. For example...

1) An EU10i with a suitable Victron for heavy hookup-free users

2) The smaller, cheaper Victron for those who use hookup a lot

3) Something I haven't thought of yet!

We'll get our Victron, suss it out and go from there. I DO have a degree in electical engineering, and Lizzie DOESN'T! Perhaps between us we can come up with something sensible *Meanwhile, we'd like to hear people's electrical needs*

By the way, Practical Motorhome are giving away a Victron this month!


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## 88724 (May 9, 2005)

*Victron system*

Reading between the lines with the victron it looks like all the power comes via the invertor, it takes the input current and charges the batteries with it and takes the power required for everything via the invertor, getting the phase in line between mains and then adding some from the invertor is not really feasable, sometimes it cvan be done with invertors but this is because the circuitry that sets the phase can be coupled and kept in phase with each other.

Sterling gear works the other way if the charger is supplying the batteries but you then switch on a hairdryer then the consumption of the charger is lowered until the hairdryer is switched off.

All Sterling gear is rated accurately ie if it says its a 1000w continous, even at 40 degrees it will run a 1000w appliance constantly 24/7

Just as an example the Victron 3000w Combi (Multi) on the surface you would expect that it is a 3000w Invertor however on checking their specification carefully you will see that it is rated at 3000 w only at 25 degrees and only 2000w at 40 degrees, check the small print here

http://www.victronenergy.com/DatasheetsPDF/SinusInverterChargers/GBPhoenixMulti.pdf

If however you buy a Sterling unit it is always rated at the 40 Degree point so will always even in warm climates, still runs at its rated output 24/7

Compare a Sterling 1500w to the Victron 2500w unit and see which is better ? surprising isnt it?

Note also that Sterling are always better priced too even more so when you take the above into account.

BTW having researched this I can tell you, I use Sterling its the best equipment you can buy Pound for pound.

BTW Victron are not the only rating "cheats" all the manufacturers except Sterling Over rate their products.

Barry, Tell me what you want from a system and I will let you know what you need. all the Sterling stuff comes with clear easy instructions.

George


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## Anonymous (Nov 10, 2000)

I'm interested in this bit...

"it looks like all the power comes via the invertor, it takes the input current and charges the batteries with it and takes the power required for everything via the invertor, getting the phase in line between mains and then adding some from the invertor is not really feasable, sometimes it cvan be done with invertors but this is because the circuitry that sets the phase can be coupled and kept in phase with each other."

It doesn't make a lot of sense to me, but perhaps I'm underqualified? I can't see how you can take 2200W from a 1000W generator through a 1200W (at 25 degrees C) Victron if all the power comes through the inverter?

The Victron uses technology from UPS systems to add to the incoming power (see earlier in thread). I understand that Victron is the only company with this technology at present, that's why I chose them. Furthermore, I was impressed with the peak power rating of their inverters, important for starting inductive loads (e.g. electric motors)

I take the point about continuous power rating, and it should be up to the buyer to be discerning here. 25 degrees is a reasonably typical temperature for most people. It's a balance between underselling your product, and overstating the specification. The key is disclosure, as long as the specs are clear on this matter.

I'm sure Sterling do some great stuff, and once we've had a chance to evaluate some we may start selling this brand too. After all, we'd all rather sell and buy British :wink:


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## 88966 (May 11, 2005)

Hi Barry and Sue,
I am going to stick my neck out for you and try and give you a cost effective and simple solution.
Let me tell you first that I have something like 40 years experience in boats, caravans and MH. Generally the requirements are fairly similar and the solutions also are similar.
I have carried generators around (I have a Honda Eu1.0 which is a good piece of kit and supplies a good steady voltage from its inverter) and I have rarely used them for myself but have helped others out occasionally. They are like insurance, it's nice to have one and hope you don't need it.
The solution that has worked for me is to have decent battery capacity (about 2x100Ah) and a good sized solar panel. The battery takes the buffering of varying daily usage and will last several days of 'normal' usage. The solar panel will work to some extent even on dullish days and again the battery acts as the buffer.
Keep your battery topped up with water and keep an eye on the voltage if you are in doubt about the charge (the best time is first thing in the morning before the sun gets to work).
If you feel your battery is losing it go for a drive for an hour or two. In extremis go to a site and hook-up for a day.
I practice what I preach and in 2 or 3 months away at Xmas time I rarely go on a site and then it is usually because we don't feel comfotable wild camping where we are.
If you have TV or computer and require 240v get an inverter (300w cheapie does it for me).
I would not recommend an inbuilt generator unless you need aircon. or high levels of heating (winter skiing) or must have a microwave. It is an expensive and heavy piece of kit.
It doesn't do a lot of harm to leave a diesel engine ticking over for an hour or two, especially if you give it a burst of revs now and then. The problem referred to is glazing and will happen if left ticking over for many hours. We are driving basically commercial vehicle engines which in their other lives run for hundreds of thousands of miles and have you noticed bus, lorry and van drivers carefully stopping their engines!
I am not saying that all these other expensive chargers (which require the engine to run) are not good pieces of kit but I think mine is a simpler and cost effective solution which I know works.
BillD.


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## 88724 (May 9, 2005)

*Hmm*

Multiple invertors can be synchronised as the waveform is electronically controled so you can get 2 or more invertors in parallel (good ones Sterling Victron and some other major brands) This is what the Victron bumpf shows.

If you power everything via invertor it will cope with the extra demands, what appears to happen is that the unit measures the mains current being used, it has a manual preset so you set it to the available from shore power ampage (on a 6 amp hook up set it to 6 amps) if the unit see's that you are using 8 amps in a flash it changes to Invertor power (UPS style)

In practice the Sterling power sharing technology will do the same thing and cost you less.

Where have you got the figures 2200w from a 1000w genny Via 1200w invertor from? if those are true then He has managed to Add power too the mains input, rather than quickly replace with invertor as it appears, but I cant seem to find this amazing fact on their website. and the reference to switching between power sources seems to say that they dont actually Add power to mains rather it is replaced by the invertor.

BTW the peak from Sterling Invertors is better in most cases than the peak from an equivilent Victron (I say most because I cant be bothered with checking every one !)


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## DABurleigh (May 9, 2005)

George,

See:
http://www.victronenergy.com/TechnicalInfo/TechPDF/Achieving the impossible.pdf

for the PowerAssist function section 1.10, and example 2.4. This is what Ben & I were discussing earlier in this thread.

Dave


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## 88724 (May 9, 2005)

Hi DA

That example does not include the maths that were refered too, 2200 w from a 1000w genset and a 1200w invertor.

Looking at those examples non exceed the amount of power given by the 3000w invertor combi, look at all the examples not one shows a combined power in excess of the number of invertors ie with only one combi in the system the power is never over 3000w, with two the power never exceeds 6000w

Quote

"The Victron uses technology from UPS systems to add to the incoming power (see earlier in thread)"

Have looked earlier in the thread and see only assumptions based on Victron advertsing, but no-where in Victrons bumpf do I see an example that matchs or even comes close.

No ups (uninteruptable power supply) system adds to power to mains all just replace mains quickly in the event of power failure.

The main difference with the Victron system seems to be that if the shorepower is exceeded (set by you and assuming that you know what that ampage limit is) then then the Multi powers the devices instead, The advertising implies that it is adding power to the mains power. 

Keeping the waveforms of 2 different invertors matched is not impossible, both have waveforms generated electronically and these controllers can be joined, trying to match the wave forms of an invertor with that of a mains supply is another story altogethor, never mind the varying voltages. 

Also this could actually prove fatal say the power was out shore side and someone was working on the box, mains would then be supplied from the Victron however the most likely scenario is that the ~Victron would be attempting to supply everyone else in the loop and it would overload very quickly. It is against regs to connect a genny or invertor to your house without removing any link to the grid for this very reason.

The system I have built using Sterling gear does the following.

The charger can run on any shore supply in from 80v to 300v and the waveform can be at anything between 40hz and 400hz

under normal circumstances the Auto mains crossover will select the best power source ie shorepower first, Genny next and invertor last.

In a 4a shorepower situation I would leave the charger only running fro shorepower and power everything from the invertor, when nothing big was running the charger the 30A version would be charging the battery bank (10 X 110 ah set), if say the microwave is used then the usage would exceed the charging for a short while.

This seems to be what the Victron is doing, the only addition being the UPS switchover

George


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## Anonymous (Nov 10, 2000)

I'm not sure where this thread is going now. We have chosen a Victron after considering all the alternatives, based on conversations with many boat and motorhome fitters. Of course there are pros and cons of all makes and models. We were, however, looking from the standpoint of finding the best unit, and not necessarily the cheapest.

I got my information about UPS technology being used during a phone call with Mr Vader, the inventor of the Victron units. He used to own a large UPS company, which he has since sold.

The bottom line is that MultiPlus units can offer more power than can be supplied by the genny / hookup, and can continue to do so until the battery is exhausted.


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## 88724 (May 9, 2005)

*Value for money*

Well it seems to me that if they (Victron) are selling a 2000w invertor (when rated correctly) but claiming it to be a 3000w invertor there is something missing (ie the power you think you are buying!!)

Sterling Products cost far less and are very good quality.

I went to Sterling (spoke with the owner and designer) Charles Sterling, I asked about their 3000 w Pure sine wave invertor List price £1292.50 he asked what I wanted to power and then proceeded to sell me an 1800w Quasi Sine wave at a discount from the list of £364.25 it actually saved me £1000 in addition he guaranteed that it would run everything I wanted and offered to exchange for a Sine at no cost if it didnt power everything as He said it would, it as powered all the items and far more no problems.

I have rang several other companies with the same story and all have tried to make the sale on the sine wave even tho its not actually needed !

The advantages of the quasi are.

Cost

Lower power overhead just to run internal components, pure sine wave uses more ampage just to live !

The bottom line with the Sterling gear is it can do the same at a lower cost with no "flannel"

George

BTW my motorhome uses a mains fridge, TV 17 " Flatscreen, DVD , Playstation, low wattage "aircon" all mains powered and all can be used long term without hook up or running the genny.


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## DABurleigh (May 9, 2005)

It would be nice to confirm that with an EU10i genny delivering 1kW max continuous mains into a Victron Multiplus 12/1200/50 also capable of delivering 1kW max continuous mains, that the output is 2kW continuous.

I would have thought this was indeed the case, otherwise I see no reason to stipulate constraints on the mains input in order to invoke the Powerassist function, if all it is doing is running the charger to reduce the net load on the battery.

I'm not sure what other substantive points of debate there are in this thread. Both Victron and Stirling produce quality products.

Dave


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## Bazbro (May 9, 2005)

Thanks, all of you, for some fantastic replies and ideas.

What a tremendous thread this is becoming - there's more useable information here than I've seen in a long time.

Keep discussing this, folks. I can't be the only one who's totally enthralled by all the info!

Ben: Like a majority (?) my 'van has just one, pathetic 60ah leisure battery (bloody cheapskate Auto-Sleepers) that would probably last us two (maybe three) days of careful usage, and with a built-in battery charger. But when not on hook-up, I don't want to have to "be careful" with usage, so BillD's idea of 2x100ah batteries is appealing. I have 12v air-con and it would be nice to run this for an hour or so's relief; the telly/DVD; lights; pump; the usual requirements. If you could sort out a "basic upgrade" to the standard set-ups, that would be a tremendous help for many people, I'm sure. The sort of set-up the manufacturers ought to be doing (as an option, at least).

Thanks again, guys. Keep the information coming.

Barry


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## 88724 (May 9, 2005)

*Reasons*

Hi DA

the reason for setting the ampage control is that when the max avaiable from the shore power is exceeded it quickly swaps to the invertor, this leaves the shore power running the charger to add as much battery power as possible.

The ones shown achieving the impossible pdf at no point is any example showing more power than the invertor can supply. Why ? If it could do that the examples would show it.

At £1170 for the Multi alone the 1200w version (900w true rating) Sterling properly rated 1500w would cost around £900 the 3000w (2000w proper rating) Victron costs just under £2000 Sterling properly rated 3000w £1408 !

Running the usual kinds of air con is not really practicable via invertor, yes you can buy an invertor big enough it would be impractical (generally) to carry enough batteries, I have a 10 X 110 ah bank and this would not run full air con for any decent length of time away from hook-up. On mine I have a air cooler which only uses 60 watts on full and provides very cool air, this can be run for hours without a massive battery bank.

George


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## 88724 (May 9, 2005)

*Whilst on the subject of ratings*

The 900w generator is advertised as a 1kw on the van gear website ?

The honda EU 10i is a 1 KVA or 900w genny, The EU26i, 2.6kw genny is actually a 2400w generator not 2600w

Sorry, but if your extensive research and degree have not spotted the difference, why should we trust your Judgement on other potentially expensive additions, which won't do what they are advertised to do?.

Also you claim to try and extensively use your products before reccomending them, but you are reccomending Victron without even having tried one and putting togethor 2 or 3 packages ?

You say earlier that the buyer should be decerning ie dont trust that a 3000w invertor is 3000w invertor "read the small print", surely its better to tell the whole truth straight away and advise the buyer on the correct product. How will your punters feel when they buy the 3000w multi to run a washing machine rated at over 2000 watts and then find the invertor cuts out because it can only run at 2000w when it gets warm?

The following explains a bit about the difference between KVa and watts,

Real Power, measured in Watts (W). This is the power drawn by a resistive load, e.g. a heater element in a kettle, and has a power factor of 1. (unity power factor, cos F=1, 1.0pf or pf=1)

Reactive Power, measured in Volt Amperes reactive (VAr's). This is the power drawn by a reactive load (a load with a winding around a core), e.g. an electro-magnet, and has a power factor of 0. (zero power factor, cos F =0, 0pf or pf=0)

Apparent Power, measured in Volt Amperes (VA). Many loads have a combination of resistive and reactive elements. (in fact it is not possible to produce a purely inductive load, since the wire used to form the windings has a resistance). This combination of elements means that both real power (W) and reactive power (VAr) are drawn together.

The proportion of Real Power to Reactive Power is defined as the power factor. [Nearly all resistive load (e.g. Universal motor used in hand tools) then power factor 0.95 to 1.0, nearly all inductive load then power factor ~ 0.3]

The vast majority of single-phase loads have power factors approaching 1. Therefore, single-phase generator power ratings are taken at power factor =1, and are consequently in Watts (W) or kilo Watts (kW), where 1 kW = 1000 W.

Three-phase loads tend to have lower power factors, approaching 0.8, therefore, three phase generator power ratings are taken at power factor =0.8 and are in VA or kVA.

There is obviously a relationship between real power, reactive power, apparent power and power factor….

i) Apparent Power (VA) = Ö [(real power (W))2 + (reactive power (VAr))2]

And

ii) Power factor = Real Power (W) 
Apparent Power (VA)

Therefore…

Apparent Power (VA) x Power factor = Real power (W)
If the Power factor =1, then all the Power is real, and 
Apparent Power (VA) = Real Power (W)
(W = VA @ 1.0 pf)

For a single-phase generator, the rating should be at 1.0 pf, in which case
Watts = Volt Amperes.
But, for a three-phase generator the rating is at 0.8pf.

This is where confusion can arise!

Example.
A three-phase generator has a continuous rating of 5 kVA at 0.8 pf.

Now, at this rated load, the Real power (kW) will be …

Real Power (kW) = Apparent Power (kVA) x Power factor

Real Power = 5 x 0.8 = 4kW

This means that a generator producing 5kVA at 0.8pf is actually producing 4 kW of Real power, but it is also producing some reactive power.

From i)…
5000 VA = Ö [( 4000 W)2 + ( Reactive Power)2]
Reactive Power = 3000 VAr's

It is this combination of 4kW of real power and 3kVAr's of reactive power that has defined the limit for the generator rating.

If the same generator was loaded with a resistive load only, then it may be capable of more than 4kW, however, there is no formula that can be used to find this limit from the 0.8pf rating. It can only be found through testing of each machine.


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## 88724 (May 9, 2005)

*Adding power to the shore supply*

Hi all

In a seperate conversation I have just learnt that Xantrex make a grid tied invertor which matches the mains frequency for use if you are using net metering ie if you are producing solar power at home and your usage drops the excess is fed back into the mains.

So it appears that it is possible, it still strikes me as odd that no example shown by Victron shows more power being used than that which is capable of being supplied by the invertor alone.

George


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## 90473 (May 1, 2005)

Hi Barry,

I am one of the majority, with a basic leisure battery set up, you mentioned earlier. I have a genuine interest in trying to follow basic advice on improving my system but having followed this particular thread I am tempted to use the phrase, "Here we go again". :? 

It has all become rather pointless. Why is it that electricity brings out the worst in people ? I noted with interest your reference to "useful information" :? Are you sure you spelt useful correctly  

Anyway, seeing as how I was very interested in a reply to your original post, would you PM me, if you ever get an answer. Something that a bog standard, thicko like me could understand. This would help me evaluate any suggestions made when I go along and ask an 'expert' for the actual equipment.

PS I don't have a clue about physics/electronics/electrical systems. I don't even have a degree


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## 88966 (May 11, 2005)

Hi Keng,
Can I refer you back this stream to my previous entry. I tried to reply in a down to earth way in non technical terms with a solution that I know will work.
I was trained as an electrical engineer so I can understand most of what is being said but as far as the basic question is concerned it mostly comes in the category of intellectual masturbation!
There are lots of ways of skinning this particular cat and it is not easy to give an answer that covers everyones requirements. If you have a more specific question try that.
BillD


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## 90473 (May 1, 2005)

should have mentioned that I followed your post to the letter. It was most unfortunate that it was on page two in amongst the 'other stuff'. Anyhow, it was very well put and as you say it is difficult to cater for everyone as there are so many variables.

I don't have massive demands on the electrical front as we prefer to stay on hook ups with an occasional overnight 'in the wild', but it is nice to improve one's basic knowledge of something that we take for granted.

To cut a long story short, I really wanted to ask about using a small, Honda, EX650 generator (my father and I bought this for doing some work at a remote location and it is 'as new'). Can it simply be connected to the mains inlet on the side of the van and used in the same way as if on site ? I'm nearly afraid to ask this but I don't think any of them are around at present so I won't get intellectually anaesthetised if I do :roll: 
Quite simply, (here goes :idea: ) do I need an inverter as a safeguard ? 

There won't be any great demand other than lighting and maybe TV. I have researched other info and the size/weight/power output/storage/noise etc won't be an issue as it will only be for an occasional 'wild night'. Basically, it's a case of can't see the point of buying a bigger leisure battery when I have this sitting in the garage.

Finally, I would genuinely appreciate your views and apologise for not making that clear in my previous post.


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## 88724 (May 9, 2005)

*Yes*

"Can it simply be connected to the mains inlet on the side of the van and used in the same way as if on site ?"

Yes you can,

Only one thing to be aware of, when starting the generator do not have any sensative electrical equipment switched on.

Best is to allow genny to settle after starting then connect or switch on apliances after.

Also this is a low wattage genny you woould not be able to run much in the way of mains equipment ie dont try running water heating and a 240v space heater at the same time.

George


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## 90473 (May 1, 2005)

Thanks for the info George. It is very much appreciated.

Cheers


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## Anonymous (Nov 10, 2000)

We are recommending Victron purely on the basis of research, and not practical experience. We are not yet selling Victron products, precisely because we have not tried them. When we do start selling them, we will do so at a discount so any price comparisons at this stage are meaningless.

We strive to be totally upfront and honest about everything. We joined Motorhome Facts before we started VanGear to be part of the community, and NOT to advertise our since-started venture.

We construct our own reviews and opinions, based on our experience. Information about generators given earlier in this thread, and more, can be found here: http://www.justgenerators.co.uk/pages/FAQ.htm

We are not happy with the hostile tone of this thread, and will not be posting back until we've tried our Victron and have some simple, helpful news to share.


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## Anonymous (Nov 10, 2000)

Keng

May I offer you a word of caution, Some of the older gennys (of which I think yours is one) are not suitable for direct coupling to the modern motorcaravan due to the electronic charging system, trust no one, ring the makers of your charging system, the name should be on the box of tricks.

A mistake could be very costly, and it's you who has to pay the bill.


Rdgs Ken


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## 88724 (May 9, 2005)

Hi Keng,

The reason is upon start up the genny can produce spikes, this is due to the fact that geeny heads need to be run at a set speed to set the frequency, obviously on start up things may be slightly erratic, with older transformer based chargers not much problem, it could potentially cause a problem with newer chargers.

Hence the words of caution above Start genny allow to settle then connect up or switch on appliances.

George

Previous to finding out the above I used to do it all wrong start the genny connected with all the loads I wanted tp run (including my charger) switched on, fortunately it never caused a problem, but you never know.


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## 90473 (May 1, 2005)

Thanks again guys, caution is my middle name.


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