dc or ac generator ?

[coventrylad]

Could I please ask the members on here who are far better clued up on electrickery which would be the best option. A diesel driven 5kw 240 volt generator wired to my stirling pro combi, or a diesel driven 24 volt 180amp alternator wired to my battery bank. I am sure I have heard some where that it would be better to generate dc, rather than ac through my stirling pro combi only for it to change it to dc. I hope you all can follow the above (I am talking about a seperate diesel engine, Not the main propulsion engine )

[Robbo]

I would go for AC as then you'll be able to run AC items that use more watts than your combi can supply, and you won't need a over powered AC generator as your combi would be able to assist the generator if AC demands exceed the genny.

 

I guess thou it depends on which system you have more high powered items and how much your AC watts your combi can supply.

[Tony Brooks]

Could I please ask the members on here who are far better clued up on electrickery which would be the best option. A diesel driven 5kw 240 volt generator wired to my stirling pro combi, or a diesel driven 24 volt 180amp alternator wired to my battery bank. I am sure I have heard some where that it would be better to generate dc, rather than ac through my stirling pro combi only for it to change it to dc. I hope you all can follow the above (I am talking about a seperate diesel engine, Not the main propulsion engine )

 

 

Because your combi almost certainly "messes about" with the charging voltages it is likley to get more into your battery in a given period of time than a straight forward DC generator unless the DC unit is also fitted with a fancy charge regulator. The Combi is also likley to have an equalisation setting that will help deal with sulphation to a degree if used appropriately.

[OldGoat]

Because your combi almost certainly "messes about" with the charging voltages it is likley to get more into your battery in a given period of time than a straight forward DC generator unless the DC unit is also fitted with a fancy charge regulator. The Combi is also likley to have an equalisation setting that will help deal with sulphation to a degree if used appropriately.

 

 

A 24V generator will or at least should produce a regulated 24V supply, ehihc is not awhole lot of good for charging batteries because a fixed voltage (12 or 24) is too low to put much - if any - charge into a battery.

 

A battery charger - certainly one fit for your task - delivers a voltage from about 25.6 to 30V depending on the "state of charge" of the batteries in question - as part of that, it controls the current (amps) to a reasonable level. A generator wouldn't do that. a very high current is not good for batteries!

 

Quite apart from that rigmarole above, a 240v AC generator is more useful all round for normal domestic items should you go cruising.

[Guest]

A 240V ac genny is more versatile. If using through an existing multistage charger, ensure the genny you buy has enough power available.

[jckm2000]

A 24v dc genny should output 28.8v, mine, a German ex military unit is adjustable up to 30.2v. I don't like having petrol onboard and wouldn't be without my diesel DC.

Edited January 9, 2013 by jckm2000

[bottle]

Nor does the OP as he is deciding between 24v dc or a 240v ac generator, both diesel.

 

To OP go for the 240v ac, for all the reasons given by others above.

Edited January 10, 2013 by bottle

[coventrylad]

Hello every one I would like to thank you all for the input. 240 it is then.But which one ! I have a fair bit of space in the engine room, enough for one of them silenced kipors of about 6kw, but have mixed feelings about there life span. An old old Lister Petter though I love them dearly are just too noisy. The budget is max £1500, the pramac look good but just out of my price range.Any thoughts pleaes ? I am loath to go for anything chinse built.so about 5 kw but quiet ! thank you all again

[magnetman]

Hello every one I would like to thank you all for the input. 240 it is then.But which one ! I have a fair bit of space in the engine room, enough for one of them silenced kipors of about 6kw, but have mixed feelings about there life span. An old old Lister Petter though I love them dearly are just too noisy. The budget is max £1500, the pramac look good but just out of my price range.Any thoughts pleaes ? I am loath to go for anything chinse built.so about 5 kw but quiet ! thank you all again

 

if you have space a Kubota 'lowboy' would be a nice unit - you should get a sh one for 1500. or a Lister LPW powered unit as they are water cooled and can be boxed in

 

i'd prefer secondhand durable to low quality new gear.

[Robbo]

Hello every one I would like to thank you all for the input. 240 it is then.But which one ! I have a fair bit of space in the engine room, enough for one of them silenced kipors of about 6kw, but have mixed feelings about there life span. An old old Lister Petter though I love them dearly are just too noisy. The budget is max £1500, the pramac look good but just out of my price range.Any thoughts pleaes ? I am loath to go for anything chinse built.so about 5 kw but quiet ! thank you all again

 

You don't need to go as high kw as you may think, find out what your continuous AC load will be when using the genny. Gennys should be ran at around 75%

 

Your combi may will supplement and reduce charging depending on AC load - read the power post that's pinned in the equipment area (its a link to a Victron book). I'm guessing you won't need anything like 5-6kw but more like 3-4kw

[coventrylad]

You don't need to go as high kw as you may think, find out what your continuous AC load will be when using the genny. Gennys should be ran at around 75%

 

Your combi may will supplement and reduce charging depending on AC load - read the power post that's pinned in the equipment area (its a link to a Victron book). I'm guessing you won't need anything like 5-6kw but more like 3-4kw

Hi Robbo thank you for your input.The boat is not yet finnished,so i am unable to do a power audit even if I knew how too ! All the lights are led from bedazzled, but we are going for a domestic 240volt aa rated fridge, and a 240 tv, plus a small zanussi washing machine. my sterling pro combi s 2500w (24 volt.) is conected to 6 110 amp 12 volt batteries connected in series parralel to give 24 volts, my the lister engine is 12 volt starter and alternator, but with a 140amp 24 volt lecce neville alternater to charge the 24 volt battery bank. I have seen a Honda EU26I wich I like the look of 2600 watt , I am not sure if it would cope, I have emailed Sterling for there thoughts but as of yet no reply. Yes its petrol but I have a for wont of a better word a box on my tug deck which could house it, but is it big enough do you think ?

[Bob18]

Since you are using a domestic 230V fridge etc. there is no debate - get an AC generator.

Generally AC generators are less expensive than DC ones of equivalent power rating, and more readily available.

[OldGoat]

A 24v dc genny should output 28.8v, mine, a German ex military unit is adjustable up to 30.2v. I don't like having petrol onboard and wouldn't be without my diesel DC.

 

 

somewhat frustrated -

as is so usual with this type of bald "what do I do" posts , the OP didn't give "us" any parameters - he has now which makes (most) of the advice redundant as it's obvious to him now that 240V is the obvious answer!

 

Ho, hum, 'tis the way on all fora....

 

Anyway, I agree with you; if the 24V genny was designed for battery charging, then it would generate the appropriate voltage mix. However, I thought it prudent to base my assumptions on a fixed 24V output. Your's, IMO was designed to charge batteries?

 

Still, thyat debate is now over.

 

Just to throw another spanner in the works - and it hasn't (yet) been suggested. What about a travel power? There seem to be several folks on here who say that they are good. I had an excellent similar type on my boat (until it died with no reason) and it was quiet, took up no additional space and did the job.

Running at a low engine speed, say 1100rpm for my then loads it was magic.

 

As the OP has set a low budget figure, all he is likely to get is a 3,000 rpm unit. I have at home an ST1 gen set at that speed and it is incredibly noisy. Anything suitable at his price point is going to be bulky and waste spece in his engine room.

OTOH a TP will do the job and as it's a new build can be incorporated onto (into) the engine.

 

Such a good idea that I'll expect it to be ignored......

 

Pearls and sw....

 

Sniff.

[coventrylad]

somewhat frustrated -

as is so usual with this type of bald "what do I do" posts , the OP didn't give "us" any parameters - he has now which makes (most) of the advice redundant as it's obvious to him now that 240V is the obvious answer!

 

Ho, hum, 'tis the way on all fora....

 

Anyway, I agree with you; if the 24V genny was designed for battery charging, then it would generate the appropriate voltage mix. However, I thought it prudent to base my assumptions on a fixed 24V output. Your's, IMO was designed to charge batteries?

 

Still, thyat debate is now over.

 

Just to throw another spanner in the works - and it hasn't (yet) been suggested. What about a travel power? There seem to be several folks on here who say that they are good. I had an excellent similar type on my boat (until it died with no reason) and it was quiet, took up no additional space and did the job.

Running at a low engine speed, say 1100rpm for my then loads it was magic.

 

As the OP has set a low budget figure, all he is likely to get is a 3,000 rpm unit. I have at home an ST1 gen set at that speed and it is incredibly noisy. Anything suitable at his price point is going to be bulky and waste spece in his engine room.

OTOH a TP will do the job and as it's a new build can be incorporated onto (into) the engine.

 

Such a good idea that I'll expect it to be ignored......

 

Pearls and sw....

 

Sniff.

Are you drunk ?

[OldGoat]

Are you drunk ?

 

Sorry, No.

Occasionally I get ** off, because the initial problem is not described properly - wastes a lot of folks' time - but more importantly doesn't really give the OP much help.

I'm here to help, not engage in banter (not a comment on you).

So often I've seen a thread wander away from the original purpose - and thereby, I suspect the OP's original plea for help is missed.

[magnetman]

Sorry, No.

Occasionally I get ** off, because the initial problem is not described properly - wastes a lot of folks' time - but more importantly doesn't really give the OP much help.

I'm here to help, not engage in banter (not a comment on you).

So often I've seen a thread wander away from the original purpose - and thereby, I suspect the OP's original plea for help is missed.

 

did you read the original post?

[Robbo]

Hi Robbo thank you for your input.The boat is not yet finnished,so i am unable to do a power audit even if I knew how too ! All the lights are led from bedazzled, but we are going for a domestic 240volt aa rated fridge, and a 240 tv, plus a small zanussi washing machine. my sterling pro combi s 2500w (24 volt.) is conected to 6 110 amp 12 volt batteries connected in series parralel to give 24 volts, my the lister engine is 12 volt starter and alternator, but with a 140amp 24 volt lecce neville alternater to charge the 24 volt battery bank. I have seen a Honda EU26I wich I like the look of 2600 watt , I am not sure if it would cope, I have emailed Sterling for there thoughts but as of yet no reply. Yes its petrol but I have a for wont of a better word a box on my tug deck which could house it, but is it big enough do you think ?

 

This is the best time to do a power audit! It will show you how much power you will use and need to generate per charging cycle.

 

Ill point you to my blog post that has my thoughts and a few links around this area http://dbhalcyon.wordpress.com/2012/06/03/batteries-and-power-balance/