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Built-in Generators


Aprilia

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Looking to switch to the canals in the near future when we find 'the' boat.

Have noticed that some have generators on board ( not suitcase units) like Fisher Panda etc.

What is the logic/rationale behind these extra pieces of kit.

If you have the engine & an inverter to generate power for the boat appliances & to charge batteries, what is the major advantage of the seperate generator ?

Is it purely not to put hours on the drive train?

Thanks

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16 minutes ago, Aprilia said:

Looking to switch to the canals in the near future when we find 'the' boat.

Have noticed that some have generators on board ( not suitcase units) like Fisher Panda etc.

What is the logic/rationale behind these extra pieces of kit.

If you have the engine & an inverter to generate power for the boat appliances & to charge batteries, what is the major advantage of the seperate generator ?

Is it purely not to put hours on the drive train?

Thanks

Inverters pure and simple will destroy batteries if you try to use one to power a charger. Think about it battery > 12V > inverter > 240V > charger > 14V >battery. That is two voltage conversions plus inefficiency of battery charging so you end up flattening the batteries.

 

Off boat generators are all too often petrol and that is dangerous stuff, it kills or injures people every year. Also the cheap ones are noisy and even more so if you managed to find a diesel one. Very antisocial.

 

Built in generators are usually quieter and are diesel powered which is safer. They also allow you to run far more electrical equipment without worrying about your batteries.

 

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29 minutes ago, Aprilia said:

 

If you have the engine & an inverter to generate power for the boat appliances & to charge batteries, what is the major advantage of the seperate generator ?

Is it purely not to put hours on the drive train?

That, and a significantly higher power output, if you want to run high power 240V appliances. 

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33 minutes ago, Aprilia said:

Looking to switch to the canals in the near future when we find 'the' boat.

Have noticed that some have generators on board ( not suitcase units) like Fisher Panda etc.

What is the logic/rationale behind these extra pieces of kit.

If you have the engine & an inverter to generate power for the boat appliances & to charge batteries, what is the major advantage of the seperate generator ?

Is it purely not to put hours on the drive train?

Thanks

Take a look at Travelpower. I will only now buy boats with one fitted. Brilliant piece of kit that does all the hard work whilst normal cruising and allows all engine 12 volt alternater charging to go into the domestic bank at the same time.

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1 hour ago, Aprilia said:

Looking to switch to the canals in the near future when we find 'the' boat.

Have noticed that some have generators on board ( not suitcase units) like Fisher Panda etc.

What is the logic/rationale behind these extra pieces of kit.

If you have the engine & an inverter to generate power for the boat appliances & to charge batteries, what is the major advantage of the seperate generator ?

Is it purely not to put hours on the drive train?

Thanks

A separate generator can gave  a 230V output  which can then allow mains appliances such a a cooker or hob or immersion heater to be used  while also charging batteries as if connected to shore power .

Running the propulsion engine at idle simply to charge batteries may do it no good at all and is probably inefficient of fuel. Built in generators can be reasonably quiet from outside the boat but are never silent and certainly create noise/vibration inside the boat unless perhaps its a very large boat.

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A generator will use less fuel per hour than main engine, it will also produce more electricity, but this is irrelevant when the batteries are limiting the charge current, often they are running under a fair load for the engine size unlike a 40 HP engine producing a few tens of watts this reduces bore glazing. If done properly they produce hot water like the main engine, something a suitcase generator cannot do.  Having a Travel power unit on the main engine is a good alternative. though.

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40 minutes ago, MartynG said:

A separate generator can gave  a 230V output  which can then allow mains appliances such a a cooker or hob or immersion heater to be used  while also charging batteries as if connected to shore power .

Running the propulsion engine at idle simply to charge batteries may do it no good at all and is probably inefficient of fuel. Built in generators can be reasonably quiet from outside the boat but are never silent and certainly create noise/vibration inside the boat unless perhaps its a very large boat.

 

Except you should not run on idle to recharge our batteries. Run out of gear with the speed set and then adjusted to always provide the maximum charging current shown on the ammeter. That way you will always load the engine as much as charging will allow.

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The answers are all above - however that's not helpful inasmuch as you didn't say how much electrical power you are thinking of needing.

 

If you are using as much electric power as someone  land based house  would use - electric cooker, washing machine, appliances (microwave, toaster etc) then a generator might be best.

A generator would take up a fair amount of space and cost £4K -£5K to install.

If cooking by gas and no large appliances then a decent sized battery bank (say 5-6 12V batteries), a second alternator to charge them and a 2Kw inverter would suffice.

 

Most boaters don't ever wear out their engines through use, thus running it to charge the batteries or to generate 240v power is not unreasonable. Indeed if you will be cruising a lot Beta marine make and sell a combined power generator / battery charger and propulsion unit (this latter can be electric / hydraulic / direct).

 

There aren't many narrowboats around with separate generators or hybrid drives or 240v alternators around, thus the question is a bit academic.

Hence people fit a large second alternator an larger battery bank and an inverter to meet their needs (in most cases - not quite their needs...)

 

 

 

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53 minutes ago, OldGoat said:

The answers are all above - however that's not helpful inasmuch as you didn't say how much electrical power you are thinking of needing.

 

If you are using as much electric power as someone  land based house  would use - electric cooker, washing machine, appliances (microwave, toaster etc) then a generator might be best.

A generator would take up a fair amount of space and cost £4K -£5K to install.

If cooking by gas and no large appliances then a decent sized battery bank (say 5-6 12V batteries), a second alternator to charge them and a 2Kw inverter would suffice.

 

Most boaters don't ever wear out their engines through use, thus running it to charge the batteries or to generate 240v power is not unreasonable. Indeed if you will be cruising a lot Beta marine make and sell a combined power generator / battery charger and propulsion unit (this latter can be electric / hydraulic / direct).

 

There aren't many narrowboats around with separate generators or hybrid drives or 240v alternators around, thus the question is a bit academic.

Hence people fit a large second alternator an larger battery bank and an inverter to meet their needs (in most cases - not quite their needs...)

 

 

 

Thanks for all the replies.

My main concern is for the little lady, she uses alot of washing machine time. I've already started the education on electricery and the limitations, but im sure we will need more than usual for a boat, at the start at least. Gas will be for cooking, the only real high electric will be the w/mach & microwave, but that for occasional use for cooking.

We will be going 2nd hand boat, not new, so I was looking to see what ones have generators already installed rather than installing an new unit.

I didn't appreciate that a similar situation could maybe be achieved via a larger battery bank & large inverter.

If this is the case, then it would widen the options somewhat as I could add batteries almost at will then.

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10 minutes ago, Aprilia said:

Thanks for all the replies.

My main concern is for the little lady, she uses alot of washing machine time. I've already started the education on electricery and the limitations, but im sure we will need more than usual for a boat, at the start at least. Gas will be for cooking, the only real high electric will be the w/mach & microwave, but that for occasional use for cooking.

 

Do you realise that if you set the machine to cold wash and use a thermostatic mixing vale on the water input most more modern engines with 100 amp plus alternator will cover the washing machine load as long as the engine is revving enough. Similar for the microwave as long as you  remember the power drawn is about twice the stated cooking power.

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9 minutes ago, Aprilia said:

Thanks for all the replies.

My main concern is for the little lady, she uses alot of washing machine time. I've already started the education on electricery and the limitations, but im sure we will need more than usual for a boat, at the start at least. Gas will be for cooking, the only real high electric will be the w/mach & microwave, but that for occasional use for cooking.

We will be going 2nd hand boat, not new, so I was looking to see what ones have generators already installed rather than installing an new unit.

I didn't appreciate that a similar situation could maybe be achieved via a larger battery bank & large inverter.

If this is the case, then it would widen the options somewhat as I could add batteries almost at will then.

 Choose a boat that is basically right for you, that fits the space that you need (including space for more batteries, washing machine and so on, but which has a good enough engine for you to fit a larger alternator if needs be.

I would seriously suggest that you limit your inverter capacity to 2 or 2.5Kw maximum as a larger unit will need heavier cabling and larger battery bank - and because if you have lots of A/C capacity you will use it - and it will take a lot longer to recharge the batteries (not logical but as a result of Sod's Law).

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16 hours ago, OldGoat said:

 Choose a boat that is basically right for you, that fits the space that you need (including space for more batteries, washing machine and so on, but which has a good enough engine for you to fit a larger alternator if needs be.

I would seriously suggest that you limit your inverter capacity to 2 or 2.5Kw maximum as a larger unit will need heavier cabling and larger battery bank - and because if you have lots of A/C capacity you will use it - and it will take a lot longer to recharge the batteries (not logical but as a result of Sod's Law).

It's not that difficult to build a higher-power system (~5kW) round a bigger (48V?) battery bank and inverter if the engine can support bigger alternators. I've been talking to Beta Marine about exactly such a system with two series 24V 100A alternators on a Beta 43 (with external 48V alternator controller to manage the load) to generate 5kW, a 48V 400Ah lead-carbon battery bank, and a Victron Multiplus II 48/5000. Plus a fair bit of solar (~1.5kW) + MPPT to keep it all topped up.

 

But apart from the problems of fitting all this (especially half a ton of batteries...) onto a existing boat (no problem on a new build) it's not cheap, all the above costs something like seven grand so you've got to really *want* your electric appliances and gadgets or have very deep pockets... ?

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Just remember at all times that you are on a boat and not a power station. Think as if you are camping, use the minimum of power, and water.

its great having a washing machine, big battery bank etc. but the more you have the longer it takes to put it all back.

 

Use the power when you are moving. If you are not cruising 5 to 6 hours a day you will have to spend a lot of time tied up and charging batteries and it gets to be a real bind for you and your neighbours.

Solar is a dead loss in winter.

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I run my WMC on cold-only programs, and I only run it when the engine is running, so the hit on the batteries is small and the recharge time correspondingly reduced.  If you are running the WMC a lot, be sure that you have a decent sized freshwater tank. 

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3 hours ago, Tracy D'arth said:

Just remember at all times that you are on a boat and not a power station. Think as if you are camping, use the minimum of power, and water.

its great having a washing machine, big battery bank etc. but the more you have the longer it takes to put it all back.

 

Use the power when you are moving. If you are not cruising 5 to 6 hours a day you will have to spend a lot of time tied up and charging batteries and it gets to be a real bind for you and your neighbours.

Solar is a dead loss in winter.

Even if you've used twice as much power running all those appliances, if you spend the money and do it properly and double the size of everything (alternators, battery bank, inverter, solar) it takes exactly the same time to put it all back... ?

Edited by IanD
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55 minutes ago, Tracy D'arth said:

Are you absolutely sure? Is it twice as much fuel too?  Will the neighbours appreciate that?

 

But there are only the same number of hours in a day.

Yes I'm sure, it's maths.

 

A bit more fuel because the engine is generating more power (but at higher efficiency so not double the fuel) but pretty much the same noise for the same time so no different as far as neighbours are concerned.

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2 hours ago, IanD said:

Even if you've used twice as much power running all those appliances, if you spend the money and do it properly and double the size of everything (alternators, battery bank, inverter, solar) it takes exactly the same time to put it all back... ?

 

Exactly, many moons ago I worked in a London International telephone exchange with 5 x 15050Ah batteries, which could be rechdrged from 0% within 24 hours.

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4 minutes ago, cuthound said:

 

Exactly, many moons ago I worked in a London International telephone exchange with 5 x 15050Ah batteries, which could be rechdrged from 0% within 24 hours.

Ah yes, but were they Lead Acid??

(I have some other type that came from a 'signalling source' and they're not Lead Acid (and I'm very glad - even though they weigh around a ton...)

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4 minutes ago, OldGoat said:

Ah yes, but were they Lead Acid??

(I have some other type that came from a 'signalling source' and they're not Lead Acid (and I'm very glad - even though they weigh around a ton...)

 

Yes lead acid plante cells. Each battery would happy take 6,000 amps in the bulk phase because of the thick plates. It is only the absorbtion phase, typically from 80-100% SoC that takes a long time.

Edited by cuthound
To unmangle the effects of autocorrect.
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52 minutes ago, cuthound said:

It is only the absorbtion phase, typically from 80-100% SoC that takes a long time.

But, as you and Ian correctly said, absorption takes the same amount of time whatever the size of the bank :)

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On 04/10/2020 at 15:34, MartynG said:

Built in generators can be reasonably quiet from outside the boat but are never silent and certainly create noise/vibration inside the boat unless perhaps its a very large boat.

 

Not if if it's a proper cocooned 1500rpm water cooled marine generator. No engine is silent of course but a balanced 3 cylinder generator which has been properly installed shouldn't create excessive vibration and will be pretty quiet. Mind you, you'll be about £6k out of pocket by the time you've finished.

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I dunno, loads of people on this forum say an engine room is a waste of space on a boat, whilst others are saying that two engines is a really good idea....a big engine with a little alternator and a little engine with a big alternator ?.

 

..................Dave

 

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10 hours ago, WotEver said:

But, as you and Ian correctly said, absorption takes the same amount of time whatever the size of the bank :)

 

Yes, perhaps better to say that providing the charging source is matched to the battery capacity, all lead acid batteries take the same time to charge for a given SoC.

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1 minute ago, cuthound said:

 

Yes, perhaps better to say that providing the charging source is matched to the battery capacity, all lead acid batteries take the same time to charge for a given SoC.

Yes, it fits in well with the second of my oft-repeated three step process of...

1. Do a power audit

2. Work out how you will replace that usage daily

3. Buy 3x or more the result in (1) of battery capacity. 

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