Electric Engines

[Wanderer Vagabond]

3 hours ago, stegra said:

It's not the electric motor that can be switched off, it's the diesel generator. Assuming an appropriately sized battery bank and generator, the generator will only need to run periodically to charge the batteries. If properly sized, it can do this close to its peak efficiency. It's a bit like a compressor with its holding tank, if that makes it easier to relate to.

As well as this, the batteries can be cheaply charged overnight on surplus national grid generation that can't be 'switched off' and solar can contribute in good light. A decent sized battery bank with 'normal' cruising may need very little generator use, especially on obstacle-free stretches with little flow.

I've no interest in trying to convert anyone to the cause. I think the chugging of the engines sounds really nice. But from the first planning of my boat I decided that I wasn't going to be tied to 'heritage' and so try to look at each aspect from its merits as they relate to me. I'm the type that likes to plough his own furrow and it may be that I'm trying to churn up tarmac but if that's the case, it'll be a lesson for next time.

You rather confused me with the bit about,"....very little power is required to maintain momentum....." since at least one horse power (0.7 Kw) was always necessary.

The bit about recharging cheaply overnight is where the electric boat would fail me, since as a liveaboard, as I have no access to mains electric unless I pay to go into a marina. With mains access (or a really long extension lead ) the whole dynamic would change.

[Robbo]

7 minutes ago, Wanderer Vagabond said:

You rather confused me with the bit about,"....very little power is required to maintain momentum....." since at least one horse power (0.7 Kw) was always necessary.

The bit about recharging cheaply overnight is where the electric boat would fail me, since as a liveaboard, as I have no access to mains electric unless I pay to go into a marina. With mains access (or a really long extension lead ) the whole dynamic would change.

It takes very little power to move a boat under 4 knots (Speed over water).  Most boat engines are really overpowered for the majority of the time.   A Diesel engine is at its most efficient when it's ran at around 75% load, so running a generator too charge batteries you can run the genny at its most efficient level.  However apart from lithium batteries where it doesn't hurt them, charging above 80% SoC is slow so doing this bit over solar, grid or when the genny can be used for other means.

i believe that it's more efficient running a diesel genny/battery/electric boat than Diesel engine alone, however I don't believe you will ever get the purchase costs back over a standard engine. So if you want an electric boat it's not because it may be more efficient, it's because it brings other benefits and that could be just that it's just quiet.

[peterboat]

9 hours ago, cuthound said:

Don't forget that making an electric car uses far more energy, particularly in electric motor and battery manufacturers.  Both use less far common metals than iron ore and aluminium. 

I think electric cars will be a footnote in the history of cars. The future will be cars powered by hydrogen fuel cells  (but they have been telling us that these are close to economic production for the last 45 years or so) 

 

9 hours ago, Robbo said:

Isn't an Hydrogen fuel cell car an electric car!

I think when people/government realise that Nuclear Power has to be an option and ramped up to replace oil based fuel in the near future then the hydrogen fuel cell will be more common.

 

9 hours ago, cuthound said:

True, but a fuel cell can make electricity from a wide range of portable fuels, (lpg, petrol, diesel etc) so is not dependent upon being plugged into the mains for recharging,  and thus has a large range.

Another option for an electric car is to use an aluminium/air battery. These have a wide range  (200-300 miles) and are 95% recyclable, but dissolve their plates in the discharge process, so only viable if using standard batteries designed for rapid replacement, and a network of battery replacement centre will need to be developed.

 

9 hours ago, Robbo said:

I'm not disagreeing that hydrogen is the "future" fuel as I believe it will be.  It's just that the electric car will be here to stay for along time, but the source of that (direct) fuel may change to whatever the best mobile storage medium may be whether that be Hydrogen, super capacitors or batteries.   However I do believe the source of the electric will have to be mainly nuclear (hopefully fusion) based.

It will be electric cars with smaller battery packs and induction from the roads, hydrogen is power hungry to make, and from what I have read induction has been laid over a 10 mile length of road and has worked so why carry explosive fuels and large battery packs?

As others have said more nuclear power is needed along with wind solar tide ect so that fossil fuel is preserved for more important uses and thats not boats or planes either

[mross]

A diesel engine may be more efficient at 75% load but you pay for fuel consumption!  A diesel running at 40% will cost less to run than when it is running at 75%.  This is what people forget.

[Robbo]

1 minute ago, mross said:

A diesel engine may be more efficient at 75% load but you pay for fuel consumption!  A diesel running at 40% will cost less to run than when it is running at 75%.  This is what people forget.

You well get better fuel consumption at 75% load for what ever the engine is geared to do.   If this is to charge batteries then you'll get a higher kw per litre of fuel.  If you ran at 40% load then it will take longer and use more fuel.

[cuthound]

9 minutes ago, mross said:

A diesel engine may be more efficient at 75% load but you pay for fuel consumption!  A diesel running at 40% will cost less to run than when it is running at 75%.  This is what people forget.

Very true. When I was working running projects to  install standby generators was my bread & butter. Part of the acceptance testing was to prove fuel consumption was as described by the manufacturer.

So with the engine running at a constant 1500 rpm (50 Hz), the generator would be loaded from 0% to 110% of rated load in 10% steps. Typically it would consume 50% more fuel at full load than off load. 

[IanD]

2 hours ago, Robbo said:

It takes very little power to move a boat under 4 knots (Speed over water).  Most boat engines are really overpowered for the majority of the time.   A Diesel engine is at its most efficient when it's ran at around 75% load, so running a generator too charge batteries you can run the genny at its most efficient level.  However apart from lithium batteries where it doesn't hurt them, charging above 80% SoC is slow so doing this bit over solar, grid or when the genny can be used for other means.

i believe that it's more efficient running a diesel genny/battery/electric boat than Diesel engine alone, however I don't believe you will ever get the purchase costs back over a standard engine. So if you want an electric boat it's not because it may be more efficient, it's because it brings other benefits and that could be just that it's just quiet.

A generator typically has about 25% efficiency from 30%-100% load, according to the Victron report. An electric motor will be about 90%, charging and discharging batteries loses about 20%, so let's say this gives 20% overall efficiency for a serial hybrid using a genset.

I worked out the efficiency for a modern diesel (Beta 43) from the consumption curves, this was 34% at full revs/power (43bhp/2800rpm) falling to 20% at half revs (4bhp/1400rpm) which would be typical cruising.

So it's difficult to see how a genset hybrid could be more efficient than a diesel in a narrowboat.

[Detling]

No one seems to have remembered that the time you really do need loads of power is in reverse, when the idiot coming the other way doesn't want to wait around while you go through the bridge. Stopping 15 tons of boat in anger uses a hell of a lot of power although only for 30 seconds or so with a big diesel.  On towpaths there aren't any sockets to plug into overnight. So just like rows of terraced houses, where you can't trail leads over the pavement and you rarely park outside your house, but somewhere in the vicinity. I understand that some 40% of the UK population live in hi-rise flats or terraced houses so have no car charging options.   Fuel cells or changeable batteries are their only options at present.

[Robbo]

9 minutes ago, IanD said:

A generator typically has about 25% efficiency from 30%-100% load, according to the Victron report. An electric motor will be about 90%, charging and discharging batteries loses about 20%, so let's say this gives 20% overall efficiency for a serial hybrid using a genset.

I worked out the efficiency for a modern diesel (Beta 43) from the consumption curves, this was 34% at full revs/power (43bhp/2800rpm) falling to 20% at half revs (4bhp/1400rpm) which would be typical cruising.

So it's difficult to see how a genset hybrid could be more efficient than a diesel in a narrowboat.

As you said at low revs the engine for propulsion is quite inefficient where the diesel/electric is roughly the same at this speed.  However, when it comes to locks or swing bridges the propulsion engine is still idling at 0% efficency and this can add up quite significantly on some journeys.   However as I said above, you wouldn't get a electric system for that reason.

[Murflynn]

I believe there are hydrogen vehicle filling stations in the USA which are independent of any external power source.

If you have good solar power you can make hydrogen on site, which is what they do.  Probably works in Arizona but I'm not sure if it would work in Royal Wooton Bassett.

[ditchcrawler]

2 minutes ago, Robbo said:

As you said at low revs the engine for propulsion is quite inefficient where the diesel/electric is roughly the same at this speed.  However, when it comes to locks or swing bridges the propulsion engine is still idling at 0% efficency and this can add up quite significantly on some journeys.   However as I said above, you wouldn't get a electric system for that reason.

You soon learn to switch the engine off if you hire in France, They charge you by engine hours run at some silly rate, they say its for the diesel.

[Robbo]

4 minutes ago, ditchcrawler said:

You soon learn to switch the engine off if you hire in France, They charge you by engine hours run at some silly rate, they say its for the diesel.

Wouldn't it be easier just to turn the ignition off?

[Chewbacka]

11 minutes ago, Murflynn said:

I believe there are hydrogen vehicle filling stations in the USA which are independent of any external power source.

If you have good solar power you can make hydrogen on site, which is what they do.  Probably works in Arizona but I'm not sure if it would work in Royal Wooton Bassett.

But as there aren't many H2 powered cars they don't have to be able to make a lot.  If they were as busy as our local Sainsbury's petrol station I reckon they will need a fair size solar farm out the back. ............

[Wanderer Vagabond]

4 hours ago, Robbo said:

It takes very little power to move a boat under 4 knots (Speed over water).  Most boat engines are really overpowered for the majority of the time.   A Diesel engine is at its most efficient when it's ran at around 75% load, so running a generator too charge batteries you can run the genny at its most efficient level.  However apart from lithium batteries where it doesn't hurt them, charging above 80% SoC is slow so doing this bit over solar, grid or when the genny can be used for other means.

i believe that it's more efficient running a diesel genny/battery/electric boat than Diesel engine alone, however I don't believe you will ever get the purchase costs back over a standard engine. So if you want an electric boat it's not because it may be more efficient, it's because it brings other benefits and that could be just that it's just quiet.

I'm not really sure that having a quiet engine is such a benefit, I have been shouted at on a number of occasions by fishermen who didn't hear my Lister LPW4 coming (doesn't really explain why they didn't notice a 60' boat approaching, or notice the 'tide going out' on their fishing float), I suspect that with a virtually silent electric motor, being shouted at by fishermen would be an even more common occurrence. Perhaps after installing a silent engine, you'd then need to include sound effects (like a Bolinder for instance)

[ditchcrawler]

2 hours ago, Robbo said:

Wouldn't it be easier just to turn the ignition off?

Shhhh

[MtB]

On 13/03/2017 at 19:41, Robbo said:

Wouldn't it be easier just to turn the ignition off?

 

On a compression ignition diesel engine??

[Robbo]

3 hours ago, Mike the Boilerman said:

 

On a compression ignition diesel engine??

Yes, the hour meter needs power, but the engine doesn't. Ignition is the wrong word, but don't believe it's called anything else even on a diesel?

[mross]

A lot of diesels won't stop if you turn the "ignition" key off.

[WotEver]

42 minutes ago, mross said:

A lot of diesels won't stop if you turn the "ignition" key off.

I think that was the point

The hour counter would...

[Robbo]

11 hours ago, Wanderer Vagabond said:

I'm not really sure that having a quiet engine is such a benefit, I have been shouted at on a number of occasions by fishermen who didn't hear my Lister LPW4 coming (doesn't really explain why they didn't notice a 60' boat approaching, or notice the 'tide going out' on their fishing float), I suspect that with a virtually silent electric motor, being shouted at by fishermen would be an even more common occurrence. Perhaps after installing a silent engine, you'd then need to include sound effects (like a Bolinder for instance)

Look at ya watch and shout back quarter to two (or whatever the time may be) no matter what they shout.