48v alternators

[Antrepat]

13 minutes ago, BEngo said:

The big problem with all friction àbelt drives is slip.  Toothed belts eliminate this so that is why they get used for camshaft.

If you want to use a toothed belt drive then some serious engineering is needed.

Start with the belt manufacturers websites where you will find all the data you need and the formulas to  plug the data into.  The outcome is a possible belt size.  That then needs to be compared with the impact on the driving unit.

 

As Tony says you need to see what the belt radial load on the drive and the alternator is.  The pull in the belt is just  arithmetic:  Belt force x beltspeed = Power.     Then work out the max belt force from the  engine power curve  and an estimate of the pulley ratio and sizes.  Then go back to the belt calls.  Rinse and repeat until it is all coherent

 

Then pick a suitable  and commercially. available belt and some pulleys. Go big rather than small. 

 

Or just suck it and see.  Be prepared to spend a lot of time and money, in case you are not lucky.. 

 

N

 

Well, I don't want to use a toothed belt drive particularly.  I just wondered if it would reduce the tension required, but if it's a lot more complicated to fit then I think you're suggesting it's not worthwhile.

 

Understood that a large radial load is going to need a large belt.  Balmar information for their large 48v alternators suggests they recommend wide multi-v belts, maximising the surface for friction I suppose.  My concern was more about the impact on the engine of a much larger belt-driven load - that is, one where the main power of the engine is not being delivered axially.

 

[BEngo]

16 minutes ago, Antrepat said:

Anyway, to get it to align with 1.5kw at 3mph, the baseline for that horse is about 2.4mph, so maybe it's the mk. 2 horse instead; or maybe it just shows how little I know about horses.

Remember that Jimmy À Watt wanted his steam engine customers to feel they were getting good value from his machine, so his definition of One Horsepower was very generous.  Not many horses can produce 746 W for any length of  time.  For horse to machine calculations it is best to say one horse is 300-500 W max  and remember it needs feeding and watering regularly.

 

N

[IanD]

Measurements on hybrid boats on real canals show about 3kW typical power consumption when cruising, see the Ortomarine report for example. When passing moored boats this drops to about 1kW -- and is of course zero when sitting stationary in a lock.

 

So if during an 8 hour day you spend 4h cruising and 2h each passing moored boats and in locks, that comes to 14kWh per day. If you can cover most of the roof with solar panels you can fit about 2kWp in, this would be expected to yield about 7kWh/day on average in summer. If your generator can charge at 140A (7kW -- the limit for a 48/10000 Victron combo) this needs to run for an hour per day -- this is all just for propulsion and ignores domestic energy use.

 

In winter the solar will give at most 2kWh/day so the generator has to run for longer.

Edited October 16, 2022 by IanD

[Antrepat]

Just now, BEngo said:

Remember that Jimmy À Watt wanted his steam engine customers to feel they were getting good value from his machine, so his definition of One Horsepower was very generous.  Not many horses can produce 746 W for any length of  time.  For horse to machine calculations it is best to say one horse is 300-500 W max  and remember it needs feeding and watering regularly.

 

N

OK, OK, 1.9mph at 400W, then!

 

Mph	m/s	Force (N)	Power (W)	hp
0.0	0.00	0	0	0.0
0.5	0.22	33	7	0.0
1.0	0.45	130	58	0.1
1.5	0.67	294	197	0.3
2.0	0.89	522	467	0.6
2.5	1.12	815	911	1.2
3.0	1.34	1174	1575	2.1
3.5	1.56	1598	2500	3.4
4.0	1.79	2087	3732	5.0
4.5	2.01	2642	5314	7.1
5.0	2.24	3261	7290	9.8

 

 

[IanD]

17 minutes ago, Antrepat said:

 

Well, I don't want to use a toothed belt drive particularly.  I just wondered if it would reduce the tension required, but if it's a lot more complicated to fit then I think you're suggesting it's not worthwhile.

 

Understood that a large radial load is going to need a large belt.  Balmar information for their large 48v alternators suggests they recommend wide multi-v belts, maximising the surface for friction I suppose.  My concern was more about the impact on the engine of a much larger belt-driven load - that is, one where the main power of the engine is not being delivered axially.

 

Toothed belts (like used to drive camshafts or superchargers) aren't really any harder to use than polyvee, pulleys and bells are more expensive but they don't need so much tension so sideload is smaller -- however this will be big anyway at these power levels.

 

However diesel engines are only designed for a small fraction of full power to be taken off like this (not axial), trying to absorb much more than this is likely to cause problems.

 

9 minutes ago, Antrepat said:

OK, OK, 1.9mph at 400W, then!

 

 

Mph	m/s	Force (N)	Power (W)	hp
0.0	0.00	0	0	0.0
0.5	0.22	33	7	0.0
1.0	0.45	130	58	0.1
1.5	0.67	294	197	0.3
2.0	0.89	522	467	0.6
2.5	1.12	815	911	1.2
3.0	1.34	1174	1575	2.1
3.5	1.56	1598	2500	3.4
4.0	1.79	2087	3732	5.0
4.5	2.01	2642	5314	7.1
5.0	2.24	3261	7290	9.8

 

 

 

Theoretical calculations bear little relation to actual measurements on typical (narrow, shallow) canals, they're usually far too optimistic. Suggest you read the Ortomarine report, there's a lot of useful information in there.

Edited October 16, 2022 by IanD

[Antrepat]

8 minutes ago, IanD said:

Measurements on hybrid boats on real canals show about 3kW typical power consumption when cruising, see the Ortomarine report for example. When passing moored boats this drops to about 1kW -- and is of course zero when sitting stationary in a lock.

 

So if during an 8 hour day you spend 4h cruising and 2h each passing moored boats and in locks, that comes to 14kWh per day. If you can cover most of the roof with solar panels you can fit about 2kWp in, this would be expected to yield about 7kWh/day on average in summer. If your generator can charge at 140A (7kW -- the limit for a 48/10000 Victon combo) this needs to run for an hour per day -- this is all just for propulsion and ignores domestic energy use.

 

In winter the solar will give at most 2kWh/day so the generator has to run for longer.

Sadly my solar capacity isn't likely to top 1kw very often, but still, this is encouraging.

[IanD]

https://www.ortomarine.co.uk/ortomarines-electric-narrowboat-performance-trials-event-final-report/

[BEngo]

21 minutes ago, Antrepat said:

My concern was more about the impact on the engine of a much larger belt-driven load - that is, one where the main power of the engine is not being delivered axially.

You can be crafty here.  If the belt driven device is above the flywheel the vertical force from the flywheel mass can be helpful.  It reduces the load on one side of the belt  but increases it on the other sides and you can arrange things so there is no or little  extra load on the flywheel bea.rings. You do have to arrange things so it is helping you, not hindering🥴

 

Belt drives  is not difficult, but you do need to do proper engineering.  Nor is chains, but they're In need of even more engineering.

 

N

[springy]

Comparison with a horse is misleading, its 500w (or however much it can provide) is being put into the solid ground of the towpath and transferred through the towline, More realistic would be to compare an appropriate number of humans (500w worth) with oars attempting to row the boat, a couple of humans with long shafts punting would probably be more effective even in the soft bed of the canal. I remember some years ago being amazed at how quickly a horse drawn boat accelerates out of a lock compared with a motor boat.

 

springy

[nicknorman]

4 minutes ago, springy said:

Comparison with a horse is misleading, its 500w (or however much it can provide) is being put into the solid ground of the towpath and transferred through the towline, More realistic would be to compare an appropriate number of humans (500w worth) with oars attempting to row the boat, a couple of humans with long shafts punting would probably be more effective even in the soft bed of the canal. I remember some years ago being amazed at how quickly a horse drawn boat accelerates out of a lock compared with a motor boat.

 

springy

More to the point, an actual horse can produce up to 15hp. One hp is the average output of a horse over a whole day. A human can produce 1hp for a short while.

[Antrepat]

44 minutes ago, IanD said:

Theoretical calculations bear little relation to actual measurements on typical (narrow, shallow) canals, they're usually far too optimistic. Suggest you read the Ortomarine report, there's a lot of useful information in there.

Agreed.  Mine, however, appear to be pessimistic, if 3kw (electrical) at 3mph is at all accurate.  I'll have a look at the report tomorrow.

36 minutes ago, BEngo said:

If the belt driven device is above the flywheel the vertical force from the flywheel mass can be helpful.  It reduces the load on one side of the belt  but increases it on the other sides and you can arrange things so there is no or little  extra load on the flywheel bea.rings.

Aha, aha, is this what @Tony Brooks was getting at?

[Antrepat]

13 minutes ago, springy said:

Comparison with a horse is misleading, its 500w (or however much it can provide) is being put into the solid ground of the towpath and transferred through the towline, More realistic would be to compare an appropriate number of humans (500w worth) with oars attempting to row the boat, a couple of humans with long shafts punting would probably be more effective even in the soft bed of the canal. I remember some years ago being amazed at how quickly a horse drawn boat accelerates out of a lock compared with a motor boat.

 

springy

 

I think the torque of a horse is probably different but surely it's about efficiency?  500 Joules per second of energy expended to apply force on a towline is exactly the same as 500 Joules per second to apply force with a propeller, but the efficiency of the horse in converting its fodder into the energy expended isn't going to be the same as the combined efficiency of an electro-mechanical drive.  Don't get me started on rowers, how inefficient must that be?

 

Can believe what you say about horse-drawn acceleration out of a lock.  Didn't they used to tie one end of a rope to a fixed point at the tail of the lock, then it went through a pulley (or something like that) on the boat, then to the horse so that the force was doubled?  Once the boat passed the fixed point, the rope was released and the main towline took over.

[dmr]

19 minutes ago, nicknorman said:

More to the point, an actual horse can produce up to 15hp. One hp is the average output of a horse over a whole day. A human can produce 1hp for a short while.

I read somewhere that the term HorsePower was coined by James Watt, and was a figure plucked out of the air for marketing purposes. The marketing dept. is not a new thing 😀. It was in his interest to give it a low value in order to make his steam engines look good in comparison.

[Antrepat]

23 minutes ago, dmr said:

I read somewhere that the term HorsePower was coined by James Watt, and was a figure plucked out of the air for marketing purposes.

Perhaps you read it above?

1 hour ago, BEngo said:

Remember that Jimmy À Watt wanted his steam engine customers to feel they were getting good value from his machine, so his definition of One Horsepower was very generous.

 

This is a widespread view and probably correct, which is why I adjusted my estimate to use 400W.  Anyway, it appears that my theoretical model (which does have a real basis) was being far too conservative as it predicted 5kw to get 3mph, not 3kw.  I will read the report that @IanD recommends.

1 hour ago, IanD said:

diesel engines are only designed for a small fraction of full power to be taken off like this (not axial), trying to absorb much more than this is likely to cause problems.

Yes, noted, hence the interest in what @BEngo (and I think @Tony Brooks) pointed out about hooking up to the flywheel end instead:

 

1 hour ago, BEngo said:

If the belt driven device is above the flywheel the vertical force from the flywheel mass can be helpful.  It reduces the load on one side of the belt  but increases it on the other sides and you can arrange things so there is no or little  extra load on the flywheel bea.rings.

 

If I could possibly fit an axially-mounted generator in, that would be the ideal solution.

[dmr]

3 minutes ago, Antrepat said:

Perhaps you read it above?

 

 

This is the result of speed reading this thread whilst doing several other things at the same time, including drinking cider 😀

[Antrepat]

2 minutes ago, dmr said:

This is the result of speed reading this thread whilst doing several other things at the same time, including drinking cider 😀

 

Very much appreciate everyone's advice.

[IanD]

On the cost of commercial/professional series hybrid installations, when asked the question about a year ago Finesse said "about £30000 more than a standard diesel" -- and given recent price rises I expect this would be closer to £35k today.

 

Note that this is for a "bleeding-edge" system with a custom high-power direct-drive motor/controller/BMS, massive LFP battery bank (35kWh), silenced 9kVA marine generator, 10kVA inverter -- but this cost isn't all for propulsion, adding similar "at home" 230Vac capability to a standard diesel (including big alternators/controller/inverter/batteries) would also add a big chunk to the "standard diesel" cost.

 

By doing all this yourself (with your own "free" labour) and using somewhat cheaper/lower-power/lower-quality/secondhand components there's no doubt that the cost could be considerably lower than this, but I think you'd have a job to come in at under £10k all-in -- unless you can use cheap secondhand gear like some on the forum did, and take the risk -- especially with LFP batteries -- that you don't quite know what you're getting...

 

 

[Martin Nicholas]

I forgot Polar Power. I think they use PM alternators.

[cuthound]

13 hours ago, Antrepat said:

 

Well, I don't want to use a toothed belt drive particularly.  I just wondered if it would reduce the tension required, but if it's a lot more complicated to fit then I think you're suggesting it's not worthwhile.

 

Understood that a large radial load is going to need a large belt.  Balmar information for their large 48v alternators suggests they recommend wide multi-v belts, maximising the surface for friction I suppose.  My concern was more about the impact on the engine of a much larger belt-driven load - that is, one where the main power of the engine is not being delivered axially.

 

 

Have you considered one or more chains to transmit the power?  They can transmit more power than belts (toothed flat or vee section) and are more durable.

[Antrepat]

2 hours ago, cuthound said:

 

Have you considered one or more chains to transmit the power?  They can transmit more power than belts (toothed flat or vee section) and are more durable.

Haven't.  Noise?

[Antrepat]

5 hours ago, IanD said:

On the cost of commercial/professional series hybrid installations, when asked the question about a year ago Finesse said "about £30000 more than a standard diesel" -- and given recent price rises I expect this would be closer to £35k today.

Exactly.

 

5 hours ago, IanD said:

Note that this is for a "bleeding-edge" system with a custom high-power direct-drive motor/controller/BMS, massive LFP battery bank (35kWh), silenced 9kVA marine generator, 10kVA inverter -- but this cost isn't all for propulsion, adding similar "at home" 230Vac capability to a standard diesel (including big alternators/controller/inverter/batteries) would also add a big chunk to the "standard diesel" cost.

No intention of going big on AC.  I haven't got anywhere even to put a microwave.

 

5 hours ago, IanD said:

By doing all this yourself (with your own "free" labour) and using somewhat cheaper/lower-power/lower-quality/secondhand components there's no doubt that the cost could be considerably lower than this, but I think you'd have a job to come in at under £10k all-in -- unless you can use cheap secondhand gear like some on the forum did, and take the risk -- especially with LFP batteries -- that you don't quite know what you're getting...

Did I actually mention a limit?  Obviously there is one, and it's nowhere near £30k, but no, I didn't expect any change out of 10.

[IanD]

13 minutes ago, Antrepat said:

Haven't.  Noise?

And lubrication, and tensioning...

[cuthound]

14 minutes ago, Antrepat said:

Haven't.  Noise?

 

Whilst chains have the potential to be noisier than belts, the difference would be drowned out by the noise of the diesel engine.

[IanD]

Just now, cuthound said:

 

Whilst chains have the potential to be noisier than belts, the difference would be drowned out by the noise of the diesel engine.

True, but there are several very good reasons why most drives at these power levels (e.g. superchargers, camshafts) use toothed belts nowadays instead of chains, being able to run without lubrication being one of them.

 

Chains come into their own at even higher power levels, but usually Morse chains not toothed ones like on a bike/motorbike...

[Antrepat]

I've had some response from Beta.  I told them I wanted a quote for a replacement for my existing engine (14hp) which would deliver more power and would be suitable to convert in the future from driving the propeller to driving only a large alternator for battery charging.  They've come back recommending a Greenline 20 engine (about £6k inc. VAT), with the caveat that it would need to spin at at least 2,200rpm to reach a sufficient point on the power curve to drive the alternator I indicated (that Mahle one).  So far they haven't said they foresee any drive belt etc. issues with hooking up a much (much) larger alternator, but I'm working on focussing their minds on the issue, asking specifically about whether it's a problem and whether mounting it off the flywheel would be better.

 

I've followed up with an observation that their 2/6 genset uses a really compact 2-cylinder engine and is rated for 6-7kw at 3000rpm.  They don't do a 48v generator, but I've asked whether they foresee any issue getting the same engine (Kubota BZ482) and attaching the Sincro E3 2-48/150 (150A, 2-pole, 48v, 3000rpm) rather than Beta's AC generator.