Portable Generator Sizing

[Simon D]

I want to buy a small petrol generator for a number of tasks, one of which would be battery charging on my NB, which has a bank of four 110ah batteries.

 

It has a Sterling battery management system, so I guess I would attach the genny to the shore power inlet and let it get on with it, but minimising other power load while I do so.

 

Is there a minimum size generator to make this work? I would like to buy this 1kw machine which is the right size for the other tasks I need and is pure sine wave. and I will not be using it on the NB That often so I don't want to spend a lot of money for a NB specific one.

 

http://www.ukcampsite.co.uk/articles/view.asp?id=691

 

Any thoughts or comments appreciated.

 

Thanks

 

Simon

[Mike Tee]

You don't say what other equipment the genny would be powering. For example, you'd have to do some searching to find a vacuum cleaner (most run in excess of 1200w.), microwaves are around 850w. which would be at the top end of the one featured, forget irons, don't know about hair driers.. TV's Xbox, computers would be fine.

[smileypete]

Depends on what charger you want to use with it.

 

Clarke have a pretty poor reputation BTW, Kipor seem to be better.

 

cheers, Pete.

~smpt~

[Simon D]

You don't say what other equipment the genny would be powering. For example, you'd have to do some searching to find a vacuum cleaner (most run in excess of 1200w.), microwaves are around 850w. which would be at the top end of the one featured, forget irons, don't know about hair driers.. TV's Xbox, computers would be fine.

 

Nothing else, only battery charging - the boat does not have much that uses power, and has a 1.6kw inverter anyway. I just want something to recharge the batteries to keep the lights and fridge going for the few days a year (probably less than 5) when I am stationary and away from shore power.

 

The question is specifically about sizing a generator against a Sterling battery management system. If the generator can only deliver a limited amount of power will the charging system adapt to this and charge - albeit much slower - or will it get confused and cut out?

 

Simon

Edited November 22, 2013 by Simon D

[Mike Tee]

Cut out the middle man and ask the expert

 

http://www.sterling-power.com/contact.php

[Richard10002]

Nothing else, only battery charging - the boat does not have much that uses power, and has a 1.6kw inverter anyway. I just want something to recharge the batteries to keep the lights and fridge going for the few days a year (probably less than 5) when I am stationary and away from shore power.

 

The question is specifically about sizing a generator against a Sterling battery management system. If the generator can only deliver a limited amount of power will the charging system adapt to this and charge - albeit much slower - or will it get confused and cut out?

 

Simon

Which Sterling Battery Management System is it? Model and number? I'm assuming it is a charger with the facility to alter the Bulk/Absorbtion/Float voltages?

 

If your 240V charger is different to the above, Make, Model & Number?

 

How many Amps does it charge at maximum?

[bottle]

You don't say what other equipment the genny would be powering. For example, you'd have to do some searching to find a vacuum cleaner (most run in excess of 1200w.), microwaves are around 850w. which would be at the top end of the one featured, forget irons, don't know about hair driers.. TV's Xbox, computers would be fine.

 

That would be a very small microwave then.

 

A microwave sold as a 850 watt would actually need about twice that to run it. (1700 watt)

[Simon D]

Which Sterling Battery Management System is it? Model and number? I'm assuming it is a charger with the facility to alter the Bulk/Absorbtion/Float voltages?

 

If your 240V charger is different to the above, Make, Model & Number?

 

How many Amps does it charge at maximum?

 

This is the problem, I am not sure.

 

I need to buy a generator for next Wednesday for a non-boat related task - but I am 100 miles from my boat and all the manuals etc are on board, and I am not planning to go there for a few weeks, hence the questions. It would be nice to get one that works in the boat as well

 

Having done a bit more digging on the websites I now realise I have a Victron Multiplus inverter charger C12/1600/70, which charges up to 70Amps (the Sterling bit of kit is the alternator to battery charger - sorry to confuse you).

 

The Victron website does not specify the AC input power, but the Stirling website specifies 900 watts for a 60 amp charger, so it seems (to me, a non electrician) that a 1kw generator should be pretty close to doing the business for 70 amps. Or am I missing something?

 

Simon

 

 

 

.

[bottle]

There are those that can advise on that but I will just mention, when buying your generator check its 'continuous output'

 

Most generators are sold as say 1Kw (1,000 watts) but that is there peak power and that can only be used for seconds.

[smileypete]

Some Victrons you can dial down the input power, otherwise I cannot see a 900W Clarke genny powering an 70A charger.

 

If you're on a tite budget try googling for the 'petepower' website, lots of good advice and some decent seconhand gennies.

 

cheers, Pete.

~smpt~

[nb Innisfree]

Victron 120 requires 10 amp @240v input to give 12v@120amp battery charge, 70 amp charge will need about 1.25 kw input so if you want to use your Victron to it's full charging capacity a 2kva charger is necessary. Personally I would go for a Honda or Kipor 2kva inverter genny which give 1.6kva rated output, enough for your needs but with a bit in reserve.

[by'eck]

Victron 120 requires 10 amp @240v input to give 12v@120amp battery charge, 70 amp charge will need about 1.25 kw input so if you want to use your Victron to it's full charging capacity a 2kva charger is necessary. Personally I would go for a Honda or Kipor 2kva inverter genny which give 1.6kva rated output, enough for your needs but with a bit in reserve.

 

Agreed, a 1kW invertor/generator will not power your Victron with 70 amp charger. I would go for the Kipor IG2600 or for twice the price the lower power Honda EU20i - both are inverter/generators.

[bottle]

Victron combis come with the charger output set at 75% of maximum.

 

So if you or someone else has not gone into the settings and changed them (laptop and software required) then your combi (charger) is only giving out 52.2 amps.

 

That is the beauty of the Victron it can be adjusted.

 

Sorry to muddy the waters but if you have a 440 amp hour battery bank that is about right size charger (see http://www.smartgauge.co.uk/chargesize.html).

 

So maybe those that have already advised could advise again as to whether a smaller generator will do.

 

 

Proviso: you must be sure as to how your Victron is set up.

[nb Innisfree]

When I installed our Victron Multiplus I tried a few gennies, despite various dip switch settings it wouldn't accept a Honda EU10i, or any other genny of around that size but it would accept larger ones especially a Honda EU20i and Kipor 2kva, both inverter gennies. The spec for our Multiplus states it needs a genny input minimum of 1kw. Some say a smaller one can be accepted using VE configure.

[Charlotte Burnett]

Innisfee - did you select the "allow low voltage input" button in the settings? It's referred to by some as the "Honda" button.

 

OP - do NOT by a Clarke inverter generator. They are crap. I've come across 4 people who have sent them back under warranty. I've not actually met anyone who is happy with theirs. Kipor have a good rep, as do Hyundai, Yamaha and, of course, Honda. I say this despite having been happy enough with other Clarke tools (I used to hammer a 3hp compressor from them for years before selling it.)

[Simon D]

Some Victrons you can dial down the input power, otherwise I cannot see a 900W Clarke genny powering an 70A charger.

 

If you're on a tite budget try googling for the 'petepower' website, lots of good advice and some decent seconhand gennies.

 

cheers, Pete.

~smpt~

 

Thanks for all the input, really useful.

 

I agree that a 2kva generator is probably the ideal size if I was continuous cruising or live-aboard, but I can't justify that cost for a few days a year which is how often I would use it. I am just trying to work out if a smaller generator (which is what I will have available - at half the price) would do the job to a certain extent to save me having to run the diesel.

 

I wonder if Pete has the answer. My Victron has a "power control" dial to regulate the current it draws from the shore supply or generator, so by winding this down it should be compatible with a smaller generator, just taking a bit longer to fully charge.

 

Comment above about Clarke generators noted above too - thanks.

 

Simon

[nb Innisfree]

I'm not aware of a 'low voltage button' I tried every variation of the dip switches, Multiplus wouldn't even react to anything smaller than 1kva, having said that one exception was an old Clarke 650, but it rejected it after about 30 secs.

[Richard10002]

Thanks for all the input, really useful.

 

I agree that a 2kva generator is probably the ideal size if I was continuous cruising or live-aboard, but I can't justify that cost for a few days a year which is how often I would use it. I am just trying to work out if a smaller generator (which is what I will have available - at half the price) would do the job to a certain extent to save me having to run the diesel.

 

I wonder if Pete has the answer. My Victron has a "power control" dial to regulate the current it draws from the shore supply or generator, so by winding this down it should be compatible with a smaller generator, just taking a bit longer to fully charge.

 

Comment above about Clarke generators noted above too - thanks.

 

Simon

Buy the Kipor IG1000 for about £350, only £50 more than the Clarke. Keep you fingers crossed that you can reduce the output of the Victron. If you can't, you could buy an older second hand charger to fit for use when you use the new genny. I have a 25A charger aswell as a Sterling Pro Combi S 2500W inverter/80A charger.

[nb Innisfree]

Victron output can definitely be reduced from its max right down to a few amps but I wouldn't chance any genny until I'd tried the same model.

[Mike Tee]

If you only need the genny on board for a few days a year, why go to the expense of buying a larger genny that will do the job properly. If the smaller one does what you want off the boat, buy that one and use the boat engine for the 'few days' required.

 

Spending on a Honda or Kippor cannot be justified for those few days, they are designed to be used on a daily basis.

[Simon D]

If you only need the genny on board for a few days a year, why go to the expense of buying a larger genny that will do the job properly. If the smaller one does what you want off the boat, buy that one and use the boat engine for the 'few days' required.

 

Spending on a Honda or Kippor cannot be justified for those few days, they are designed to be used on a daily basis.

 

Thanks Mike, and that is where I have finally got to.

 

I will buy the cheaper, smaller genny because that is all that I can justify in terms of cost against planned use on our smallholding down here in Salisbury, and I have to have it installed and running by next Wednesday.

 

However thanks to the advice on this site I have a good steer towards how to make it work on the boat as well if I need to. But if I can't make it work on the boat, then I will be running the diesel rather than splashing out on a bigger genny.

 

Simon

[Mike Tee]

Simon, just a thought - if its on a smallholding, it could be more efficient to go for one of the gennys in a frame rather than a suitcase type. They are normally cheaper and bigger, downside is they are noisier, but its easy to build a sound reduced box to tuck away somewhere.

[by'eck]

Simon, just a thought - if its on a smallholding, it could be more efficient to go for one of the gennys in a frame rather than a suitcase type. They are normally cheaper and bigger, downside is they are noisier, but its easy to build a sound reduced box to tuck away somewhere.

 

Unfortunately such are not likely to be inverter/generators and so highly likely to upset the Victron's charger which is well known to be unreasonably fussy about less than perfect AC sine wave feeds.

[smileypete]

If it is literally a few days say for fitout work, maybe consider hiring.

 

cheers, Pete.

~smpt~

[nb Innisfree]

 

Unfortunately such are not likely to be inverter/generators and so highly likely to upset the Victron's charger which is well known to be unreasonably fussy about less than perfect AC sine wave feeds.

Not so with our Multiplus, it was quite happy with a couple of cheap 3/3.5 kva frame gennies. Victrons will mimic whatever the incoming sine wave is, what they can't do is 'clean up' or improve a sinewave. Waveform check can be disabled if required