Generators - What Wattage?

[Castletine]

I've seen a lot of ads. recently for inexpensive petrol driven generators - does anyone have bad experience of them and what are the spares availability like?

I'd like to buy one that will not only quickly and efficiently re-charge my batteries, but also run a TV and Laptop. What sort of Wattage output would be neccesary? can anyone explain?

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[Happy1]

I bought the whisper quiet Honda Eu10i, it is 1,000watts and runs Computer, lighting, toaster!, kettle (travel type), TV, and also has a 12v DC output so will charge batteries. Lovely piece of engineering and a snip at the right price.

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[tony_brighton]

I've been considering one of these - but rather than use the DC output would look to take its AC connection to the shore-power socket and through the onboard battery charger. Anyone used one of these generators in this fashion?

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[andyball]

know a few people use them this way...the 12V output isn't that powerful as I recall, so it's a quicker way to recharge.

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[HenryB]

Tony - I've an old Honda generator which, in most respects is very good, but it won't charge batteries via its AC output. I've tried 3 different chargers without success. I guess that it's something to do with the wave form of the AC.
Suggest that you get a practical demonstration before buying the generator.



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[MainlySteam]

Tony, I have never used one of the small Honda generators into the shore power connection myself, but I do know that it is done and have considered doing so myself. However, many countries (and I understand this is so in the UK) electrical codes require that where the distribution includes an earth, as it will on your yacht, that the earth and neutral be bonded at the point of supply but nowhere else. So when your shore power is connected, the earth and neutral are bonded on shore as part of the national distribution system, but are not connected together on the boat.

You must not be able to connect two ac sources at the same time to the distribution on your boat (it is catastrophic) so when you plug the generator into your shore connection the generator, to meet codes, must have its neutral and earth connected AT the generator. I have been told, but have not checked myself that the Hondas (along with others) may not meet this criteria - maybe someone knows the answer to this.

When you refer to having an onboard charger, if this is integrated with an invertor as they often are, then the invertor is also an ac power source which when there is no shore power connected, should be set up so that its neutral is connected to earth, but its neutral is then disconnected when shore power is connected (this is often done automatically in the invertor, or alternatively automatically at a switch for switching between invertor and shore power). In a production boat such as yours, as long as the factory installation has not been tampered with this should all be correct.

When a generator is installed on board, the neutral and earth must be connected together at the generator and no where else on the boat ie if the generator is connected, then the neutral earth bond at the invertor must be broken by the generator/invertor/shore power switch. However, if you plug the generator into the shore power connection it effectively substitutes for the shore power, then everything should be fine, as long as the generator has its neutral and earth bonded together at the generator.

All of these things do not necessarily apply when you operate the generator with an electrical appliance powered directly off it eg Happy's toaster.

If you wish to do it, I would suggest getting some first hand advice from an experienced marine electrician to ensure that all electrical requirements are met. As I say, I know the generators are used plugged into the shore power connection, it may generally be safe but there again it may not be and 230v kills. In the end I decided against it, in my case mainly because of the risk of using a portable petrol fueled device on board which has no intrinsic protection against refuelling fire risk, etc and the need in a diesel powered yacht to carry even more petrol on board than is required by the tender outboard motor.

John

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[tony_brighton]

Thanks guys - lots of useful points. Doesn't sound as straight forward as I'd hoped!

My battery charger is a sterling 40Amp switchmode charger without inverter capability. Think I'll have to have a chat with both sterling and Honda at the boat show!

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[surekandoo]

Had exactly the same dilemma. After looking at solar panels, shore power, wind gennies, and hanging my nose of the £543 honda 650w 4 stoke suitcase I spotted a bargain....

Northern Tool are selling a Chinese Mfr 650w portable genny for £99.99 + you have to buy £20's worth of something else from their catalogue (i bought a socket set) Genny & socket set arrived next day. 50:1 mixture in tank and started 1st pull.
Runs a small flymo (as a test) on AC and produces 8 amps x 12v DC from a separate socket. Not the lightest & quietest on the market but at that price!! Charges batteries OK.

Try www.NorthernToolUK.com or phone 0800 169 2266

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[surekandoo]

Sorry - forgot to state that prices don't include VAT

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[LadyInBed]

Tony, I use my generator plugged into my shore power socket when I want to run the cabin or immersion heaters or mains battery charger.
The 'Polarity Check' light comes on whichever way I plug the (Continental) plug into the gene, but that is to be expected as gene o/p is from a centre tap neutral and the gene frame is not connected to the boat 'Ground'.
If you get a Generator, go for a 1000W model, it won't struggle (voltage sag) so much when you load it (heater + kettle) [sad] or power washer! Mine is 800W.
Have a look-see next time we meet.


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[Happy1]

Re Honda EU10i, I have done some research for you guys, hope it helps /forums/images/icons/wink.gif Well made and will last for years if looked after.

Honda UK cost = http://www.seamarknunn.co.uk/catalog/items/item190.htm = £669 free delivery

Honda agent = <A target="_blank" HREF=http://www.honda-uk.com/handy_gens.htm>http://www.honda-uk.com/handy_gens.htm</A> = £645 inc VAT & delivery + free DC charging leads

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[William_H]

Hello Henry Couldn't resist commenting on your Honda failing to operate your battery charger. Theoretically the wave shape of the Honda should be perfect sine wave as it is generated by a rotating magnetic field. I would suggest that more likely the Honda is only delivery about 220 volts which gives a lower voltage output at 12 volts from the charger. The current into the batteries is a function of the voltage generated by the charger which is in excess of the battery voltage at the time. So you may find it will charge very flat batteries but not reasonably charged batteries. The very crude chargers use just a rectifier from the transformer output. This means that the voltage trying to force its way into the battery on each cycle starts low but at the peakof the cycle is a lot higher thyan you need. They tend to put some current into a fully charged battery and have a smooth onset of current with increasing charging (line) voltage. A sophisticated charger probably produces smooth DC which will not get any current into the battery until it exceeds the batttery voltage where there is a rapid onset of current increase with increase of voltage. If it is regulated DC out it probably does not have sufficient voltage into the regulator to produce your required output voltage. Note however this does not apply to the switcmode battery chargers without a large heavy transformer. especially if it's label rates it at 100 to 250 volts AC input. .
I suggest try a cheap crude charger , try you normal charger on flat batteries or when the batteries have a large load or try if you can adjusting the generator regulator to increase voltage.. Of course you can carefully measure the AC volts from the generator and compare with you actual shore power voltage. Please don't get electroplated.

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[MainlySteam]

If your reverse polarity light shows a fault either way, then ordinarily that would indicate voltage exists between both the neutral and the phase and the ground wire (and whatever else it is connected to on the boat eg the chassis of your charger, toaster, etc). That means that if you get between neutral and the boat's ac ground you will get shocked to a degree according to the voltage that exists between them.

Today I got hold of a typical small generator manual from Honda (EU10i) and from the wiring diagram it seems pretty clear that they (and I have also checked this applies to most small generators) have a floating neutral, so when you say that the generator's ground is not connected to the boat's ground, then you are probably incorrect if your generator is 3 wire (the EU10i is), as the generator will be grounded back to the boat's ground through the cable you plug into the shore power connection. I understand that it is typical for the polarity fault indicators to come on when you use a floating neutral generator plugged into the shore power connector.

While these things do not pose an immediate shock hazard, they do increase the likelihood of a hazard should there be any other fault in the boat's ac distribution. They may also affect the protection provided by devices such as breakers and ground fault circuit interupters (not sure what you call those in the UK - RCD's perhaps). Small portable generators are designed to run appliances, when you plug your boat into one you are effetively making your boat into an appliance inside of which you are now able to walk around. After looking into it a bit further today, I concede not exhaustively, it is not a situation I would be happy with on my own boat without a lot further investigation. These problems could likely be solved by bonding the neutral to the ground at the generator, but again, I do not think I would do so without an expert investigation of the generator (they obviously are not made to be connected up that way and one suspects they may see a ground to neutral connection as a fault) and probably any query to the manufacturer would result in a neutral stance.

In the case of an electrical fire on the boat, from whatever cause, while the portable generator was being used into the shore power connection, or, of course a fuel fire from a portable generator however it was being used, there would be a strong likelihood that your insurer would not respond to the loss.

A lot of people do it, and it seems without any significant record of accident, and in the end it is up to individual choice as long as it does not break any local regulations. It does however, not comply with any standards that I am aware of for vessel electrical systems, at least in as far as the ground/neutral bond at the generator is concerned.

Keep safe.

John

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[redhot]

I bought a 2.6Kva petrol generator from Makro for £235 inc. Vat. Which I thought was a bargain. Last time I was in there, they also had a smaller one that I think was about 1.5Kva for about £175 Inc Vat.
I already owned a 600W genny but this was not powerful enough as I have a 50AMP charger and that draws about 1000W.
The new genny will run my TV, Video, DVD, Freeview, Lighting, 50 Amp Charger, Stereo, Phone Chargers, and that's about all I have that is 240v on my boat.

Thanks
Mike.

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[IanBBA]

The 'cheap Chinese' generators you refer to are made by Alpha-Tiger and imported under several names including Tiger. Manufacturers website www.alpha-tiger.com.

I first came across these generators in the Gulf where the 650W model (beware the model number is 950!) retail at around £50-55!!! I bought one for my house out there as the electricity supply is a bit eratic. I was able to run the generator to the limit with ceiling fans, lights and TV. I would run for ~6-hours on 4l of fuel and ran faultlessly in ambient temperature of 40C+. That's the good bit.

Downside is that there is no chance of getting spare parts. The engine is a very simple 2-stroke and unlikely to give problems. Probably the most vulnerable part of the whole things is breakdown of the generator windings or rectifiers; both easily repairable but likely to cost more than the purchase cost! I think if you buy one, you have to accept that a major failure will render the unit scrap but hey, it costs so little and in the UK must have a 12-month warranty.

Some rebrand units have CE mark labelling. I think this is hightly unlikely to be genuine. The Chinese put CE marks on almost everything now as a matter of course. I have not seen any safety concerns with my generator.

My 'Tiger' is now in a packing case heading for the UK and my cockpit locker. Perfect for running the electric sander and charging the batteries. It is a little noisey; your neighbours in a quiet anchorage will curse like blazes!!

Ian.




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