48v alternators

[IanD]

22 minutes ago, Antrepat said:

 

Let me check I understand.  It's possible to cap the engine effort by capping the field current, and hence reduce the risk of overtaxing a slightly puny engine (mine is 14hp)?

 

If your engine is 14hp flat out you've got no chance of driving big alternators like this anyway, look at the "bhp absorbed" and "torque" curves I posted...

[Antrepat]

1 minute ago, IanD said:

 

If your engine is 14hp flat out you've got no chance of driving big alternators like this anyway, look at the "bhp absorbed" and "torque" curves I posted...

 

Very much noted.  My engine actually appears to be some years older (early 80s) than the boat (early 90s) so I don't know if it was second hand when it went in.  In any case, it has problems (air getting in somewhere, coolant frothing in expansion tank, coolant loss, wild fluctuations in coolant level), which may be just gaskets but may be a cracked block.  If I replaced, different ball game, it seems.  Maybe I should have a word with Beta...

[IanD]

46 minutes ago, Antrepat said:

 

Very much noted.  My engine actually appears to be some years older (early 80s) than the boat (early 90s) so I don't know if it was second hand when it went in.  In any case, it has problems (air getting in somewhere, coolant frothing in expansion tank, coolant loss, wild fluctuations in coolant level), which may be just gaskets but may be a cracked block.  If I replaced, different ball game, it seems.  Maybe I should have a word with Beta...

 

The smallest engine that Beta fit big/dual high-current alternators on is the Beta 43, IIRC the smaller ones don't have crankshaft nose pulley attachments (splined shaft?) that can take the lateral load of the big/dual polyvee pulleys...

[Antrepat]

21 minutes ago, IanD said:

 

The smallest engine that Beta fit big/dual high-current alternators on is the Beta 43, IIRC the smaller ones don't have crankshaft nose pulley attachments (splined shaft?) that can take the lateral load of the big/dual polyvee pulleys...

 

Oh.  That's unfortunate, because a 180A alternator putting out, say, 58v, that's about 10kw (which I doubt would be practically achieved), and even if it were only 50% efficiency that would be, what, 26hp?  A 43hp engine would barely have to tick over, and I'm pretty sure I don't have room for one anyway

 

I'll see what Beta say.

[PeterF]

1 hour ago, Antrepat said:

Just saw this, which happens to be exactly the one I was just talking about.  I'm not sure that alternator is still made, but a similar setup with the Mahle is what I'm trying to explore.

I do not know if the Electrodyne GE100-48 is still made or not, I contacted them in 2019 and got the curve I posted above from them as it was not available on line.

[IanD]

23 minutes ago, Antrepat said:

 

Oh.  That's unfortunate, because a 180A alternator putting out, say, 58v, that's about 10kw (which I doubt would be practically achieved), and even if it were only 50% efficiency that would be, what, 26hp?  A 43hp engine would barely have to tick over, and I'm pretty sure I don't have room for one anyway

 

I'll see what Beta say.

You need to look at the engine (and alternator) torque/power curves -- you can't use the maximum engine power to run the alternator, because that means charging at peak power rpm (noise, wear...).

 

Most people with engines like the Beta charge at maybe 1200rpm when moored -- not lower because of torsional vibration problems, Beta forbid this -- at which point a Beta 43 can put out about half its maximum power (22bhp). And you need some power to drive the prop when cruising (e.g. about 4bhp at this rpm) which leaves 18bhp absolute maximum for the alternators. If these are 50% efficient (normal for automotive ones like the Iskra) this gives a maximum alternator output power limit for charging of 9bhp (less than 7kW), or about 20% of the maximum engine power...

 

Any narrowboat only ever uses a tiny fraction of the maximum engine power when cruising on a canal, measurements have shown that typically about 3kW/4bhp is required. Since propeller power goes up as the cube of rpm (actually, a bit faster), a Beta 43 propped to absorb 43bhp at 2800rpm (maximum power) will put 4bhp into the prop at about 1250rpm.

Edited October 14, 2022 by IanD

[Antrepat]

4 hours ago, PeterF said:

I do not know if the Electrodyne GE100-48 is still made or not, I contacted them in 2019 and got the curve I posted above from them as it was not available on line.

It's not in their online catalogue, at least.

4 hours ago, IanD said:

You need to look at the engine (and alternator) torque/power curves -- you can't use the maximum engine power to run the alternator, because that means charging at peak power rpm (noise, wear...).

 

Most people with engines like the Beta charge at maybe 1200rpm when moored -- not lower because of torsional vibration problems, Beta forbid this -- at which point a Beta 43 can put out about half its maximum power (22bhp). And you need some power to drive the prop when cruising (e.g. about 4bhp at this rpm) which leaves 18bhp absolute maximum for the alternators. If these are 50% efficient (normal for automotive ones like the Iskra) this gives a maximum alternator output power limit for charging of 9bhp (less than 7kW), or about 20% of the maximum engine power...

 

Any narrowboat only ever uses a tiny fraction of the maximum engine power when cruising on a canal, measurements have shown that typically about 3kW/4bhp is required. Since propeller power goes up as the cube of rpm (actually, a bit faster), a Beta 43 propped to absorb 43bhp at 2800rpm (maximum power) will put 4bhp into the prop at about 1250rpm.

 

I'm not going to use the engine for propulsion at all.  That's the whole idea, to cruise electric and just use the engine for charging.  I can't afford £20k for a "marine generator", hence the DIY talk about modifying alternators and whatnot.

 

If I have to compromise to a lower power generator to have an engine that will fit in my boat, so be it!

Edited October 14, 2022 by Antrepat

[IanD]

1 hour ago, Antrepat said:

It's not in their online catalogue, at least.

 

I'm not going to use the engine for propulsion at all.  That's the whole idea, to cruise electric and just use the engine for charging.  I can't afford £20k for a "marine generator", hence the DIY talk about modifying alternators and whatnot.

 

If I have to compromise to a lower power generator to have an engine that will fit in my boat, so be it!

So a DIY series hybrid then?

 

Good luck 🙂

[IanD]

10 hours ago, IanD said:

So a DIY series hybrid then?

 

Good luck 🙂

Whether adding big alternators onto your existing engine or a new one, your biggest problem is going to be finding a way of taking out a lot of power (most/all of the engine power?) through belts, because engines simply aren't designed to do this.

 

The alternative would be to couple a PMAC motor directly to the crankshaft and use this as a generator via a 48V motor controller in regeneration mode, these can quite happily provide gundreds of amps -- actually this is your electric drive system in reverse, and will cost the same again, it's what the "Manel monster" you referred to is.

 

If you could figure out how to do clutches, you could put one between engine and motor and another one between motor and prop, which would allow diesel or electric propulsion or charging -- this is a parallel hybrid, means you only need one motor and controller.

 

Or put lots of solar panels on the roof and use these to provide most of your power in summer, and have a smaller cheaper generator (not built-in?) for charging -- but you still need the electric drive system and LFP batteries.

 

It looks like you're trying to build your own hybrid boat simply and very cheaply, and to be honest if it was that simple and cheap lots of people would have already done it... 😉

Edited October 15, 2022 by IanD

[Tony Brooks]

The OP says "That's the whole idea, to cruise electric and just use the engine for charging". That suggest to me that he could drive a large alternator from an adaptor bolted to the flywheel fixings. I am sure such an alternator will need gearing up so probably back to a wide flat belt or twin/triple V belts. So a series hybrid (I think).

[Martin Nicholas]

PM Generators or Fischer Panda perhaps?

 

[IanD]

3 hours ago, Martin Nicholas said:

PM Generators or Fischer Panda perhaps?

 

Too expensive according to the OP...

[IanD]

3 hours ago, Tony Brooks said:

The OP says "That's the whole idea, to cruise electric and just use the engine for charging". That suggest to me that he could drive a large alternator from an adaptor bolted to the flywheel fixings. I am sure such an alternator will need gearing up so probably back to a wide flat belt or twin/triple V belts. So a series hybrid (I think).

Indeed, but no way will V belts -- even multiple ones, which don't work well if they wear/stretch differently -- cope with the power/torque levels the OP is looking for. A single (wide) polyvee belt might still have issues, even with an idler pulley -- at these power levels toothed belts are more common because they can't slip and don't need a lot of tension.

 

The "Manel monster alternator" the OP posted could connect directly to the crankshaft, working range was 1300-2400rpm IIRC. And there are even bigger ones at even higher prices, which I suspect is the real problem -- what the OP wants can't be done for the money he wants to spend... 😞

Edited October 15, 2022 by IanD

[Antrepat]

On 14/10/2022 at 23:12, IanD said:

So a DIY series hybrid then?

 

I like crazy projects.  If it's not feasible, it's not feasible, but I'm not yet convinced it isn't.

[IanD]

30 minutes ago, Antrepat said:

 

I like crazy projects.  If it's not feasible, it's not feasible, but I'm not yet convinced it isn't.

It's feasible, but probably not for the money you want to spend... 😉

[Antrepat]

On 15/10/2022 at 10:04, IanD said:

Or put lots of solar panels on the roof and use these to provide most of your power in summer, and have a smaller cheaper generator (not built-in?) for charging -- but you still need the electric drive system and LFP batteries.

 

It looks like you're trying to build your own hybrid boat simply and very cheaply, and to be honest if it was that simple and cheap lots of people would have already done it... 😉

I know it's not going to be easy, nor did I expect it to be - if it were, people wouldn't be forking out £40k+ to firms to do it for them.  £57k for an electric conversion reported in one of the magazines a while ago, if I recall, and they only had LAs (goodness knows why given the weight and the limited DOD) and eschewed solar on their 60ft boat because "it wouldn't contribute anything significant".  Hmm, so my two cheap Chinese panels gave me 350W on a beautiful sunny West Yorkshire autumn day today, and I could fit four on at a push, so maybe 6 on a 60ft boat with plenty of room to spare, that's over a kilowatt in October.  I wouldn't call that "not significant" but I'm sure it was worth every penny of that £57k to lug about a ton of batteries from which you can never draw half the charge whilst basking in the kilowatts of uncaptured sunshine.  Perhaps I'm being unfair but I read that article and wondered about some of the professional advice people are buying.

 

I enjoy a challenge, particularly when it might allow me to save £0000s on professional services and will mean I know my own system inside out.  At least I can have fun learning and working out whether it is feasible, anyway.

 

Regarding solar, I could probably come up with over 800W with four panels on a great day, which is also not insignificant in my opinion.  My possibly-wrong-and perhaps-a-bit-potty reckoning, based on the guess that a mk. 1 horse (746W) can move a lightly-laden 72ft narrow boat at about 2mph (thus allowing me to estimate the drag coefficient), is that about 2.2kw of thrust is needed is needed for 3mph in a narrow boat - quite possibly an overestimate - so with 55% propellor efficiency and 90% electrical efficiency (former from advice on here, latter quoted for real motor drive products), that's 4.5kw of electrical power.  If someone has some data to show this is indeed a significant under- or overestimate, I'm all ears.  I'd especially like to hear from someone who has an electric boat and knows how many kw they draw at 3mph.

 

On 15/10/2022 at 10:04, IanD said:

Whether adding big alternators onto your existing engine or a new one, your biggest problem is going to be finding a way of taking out a lot of power (most/all of the engine power?) through belts, because engines simply aren't designed to do this.

 

The alternative would be to couple a PMAC motor directly to the crankshaft and use this as a generator via a 48V motor controller in regeneration mode, these can quite happily provide gundreds of amps -- actually this is your electric drive system in reverse, and will cost the same again, it's what the "Manel monster" you referred to is

Yes, I am understanding the on-the-side belt solution is a problem.  The Sincro DC generator is indeed in-line - I read the docs the other day.  It's about 60cm in addition to the length of the engine, and of course it has to go at the bottom which, if the engine were aligned with the propellor shaft like at present, there wouldn't be room for with a drive motor as well.  Of course, it doesn't need to be aligned with the propellor shaft at all, so I wonder if it could go sideways, with a redesigned engine bay.

 

Edited October 16, 2022 by Antrepat
Typo

[Antrepat]

19 minutes ago, IanD said:

It's feasible, but probably not for the money you want to spend... 😉

Well, it all depends on the generator:

 

Maybe £5k for LFP (EVE cells from Fogstar)

£2k for control equipment (BSS etc.)

£3.5k for drive motor, controller, etc. (specific quotation, adjusted for inflation)

£0 for solar - already have another two panels and the electrics are already set up.

£1k for wiring, switches, relays, breakers, etc.

£? for the generator rig

 

[Antrepat]

On 15/10/2022 at 10:22, Martin Nicholas said:

PM Generators or Fischer Panda perhaps?

 

I do wish these firms would just publish a price list rather than get you to ask - it's just a way of getting you talking to a salesman.  I've asked FP anyway and got quoted £15,600 for their AGT-48v generator.  I haven't asked PM yet but is it likely to be much different?

[Antrepat]

On 15/10/2022 at 13:59, IanD said:

Indeed, but no way will V belts -- even multiple ones, which don't work well if they wear/stretch differently -- cope with the power/torque levels the OP is looking for. A single (wide) polyvee belt might still have issues, even with an idler pulley -- at these power levels toothed belts are more common because they can't slip and don't need a lot of tension.

 

The "Manel monster alternator" the OP posted could connect directly to the crankshaft, working range was 1300-2400rpm IIRC. And there are even bigger ones at even higher prices, which I suspect is the real problem -- what the OP wants can't be done for the money he wants to spend... 😞

The Sincro one is currently €1,488.40 - heavily discounted, I notice, which is curious.  Thanks to the Natural Party of Government, that's pretty much the same in £ now, but I'd happily pay that for a solid piece of equipment.  The issues are: cost of an engine of the appropriate power to attach it to (14hp is nowhere near enough), space to accommodate engine and generator, with a drive motor in the same bay, and control of the rig given the stringent requirements of LFP charge termination.  The Wakespeed WS500 is designed to control alternators, and this is not an alternator, at least, not in the conventional sense, and you can't just shut off the power when the termination point is reached, unless a relay signal to an engine auto start/stop makes for a sufficiently graceful shutdown (I doubt it).

[dmr]

31 minutes ago, Antrepat said:

I know it's not going to be easy, nor did I expect it to be - if it were, people wouldn't be forking out £40k+ to firms to do it for them.  £57k for an electric conversion reported in one of the magazines a while ago, if I recall, and they only had LAs (goodness knows why given the weight and the limited DOD) and eschewed solar on their 60ft boat because "it wouldn't contribute anything significant".  Hmm, so my two cheap Chinese panels gave me 350W on a beautiful sunny West Yorkshire autumn day today, and I could fit four on at a push, so maybe 6 on a 60ft boat with plenty of room to spare, that's over a kilowatt in October.  I wouldn't call that "not significant" but I'm sure it was worth every penny of that £57k to lug about a ton of batteries from which you can never draw half the charge whilst basking in the kilowatts of uncaptured sunshine.  Perhaps I'm being unfair but I read that article and wondered about some of the professional advice people are buying.

 

I enjoy a challenge, particularly when it might allow me to save £0000s on professional services and will mean I know my own system inside out.  At least I can have fun learning and working out whether it is feasible, anyway.

 

Regarding solar, I could probably come up with over 800W with four panels on a great day, which is also not insignificant in my opinion.  My possibly-wrong-and perhaps-a-bit-potty reckoning, based on the guess that a mk. 1 horse (746W) can move a lightly-laden 72ft narrow boat at about 2mph (thus allowing me to estimate the drag coefficient), is that about 2.2kw of thrust is needed is needed for 3mph in a narrow boat - quite possibly an overestimate - so with 55% propellor efficiency and 90% electrical efficiency (former from advice on here, latter quoted for real motor drive products), that's 4.5kw of electrical power.  If someone has some data to show this is indeed a significant under- or overestimate, I'm all ears.  I'd especially like to hear from someone who has an electric boat and knows how many kw they draw at 3mph.

 

Yes, I am understanding the on-the-side belt solution is a problem.  The Sincro DC generator is indeed in-line - I read the docs the other day.  It's about 60cm in addition to the length of the engine, and of course it has to go at the bottom which, if the engine were aligned with the propellor shaft like at present, there wouldn't be room for with a drive motor as well.  Of course, it doesn't need to be aligned with the propellor shaft at all, so I wonder if it could go sideways, with a redesigned engine bay.

 

 

Have a look at this:

 

https://nb-firecrest.co.uk/tag/power-curve/

 

It looks quite genuine, whilst some other figures available on the www are from over optimistic salesmen, or people so committed to electric propulsion that they have rose painted spectacles. 😀

[Antrepat]

On 15/10/2022 at 10:17, Tony Brooks said:

The OP says "That's the whole idea, to cruise electric and just use the engine for charging". That suggest to me that he could drive a large alternator from an adaptor bolted to the flywheel fixings. I am sure such an alternator will need gearing up so probably back to a wide flat belt or twin/triple V belts. So a series hybrid (I think).

Thinking about my existing engine, this would be the opposite end from the usual location of an alternator pulley.  The concerns people are expressing seem to be that a large alternator putting out 7kw or something will have issues with belt drive effectiveness and in any case, "normal" engines are not designed to have such large devices attached in this way and an in-line generator would be much better.  As it happens, the cost of one of those is comparable to the large alternators, but my issue with that idea is that I'm not sure I would have space to fit one in.

 

Thinking about the moment of force on the engine crankshaft bearings, the larger the alternator, the more tension is needed, and the more sideways force there is being applied on the shaft.  Indeed these engines are intended to be connected to something axially, and to deliver most of their power along that axis and not to something through a belt.  So, what is the advantage of a belt drive coming off the flywheel rather than off the other end?

 

Would a toothed belt significantly reduce the tension required, at the expense perhaps of being noisier and wearing out more often?

[Tony Brooks]

3 minutes ago, Antrepat said:

Would a toothed belt significantly reduce the tension required, at the expense perhaps of being noisier and wearing out more often?

 

I am not sure the sideways force discussed is just caused by ordinary belt tension. Remember one side of the belt is pulling the alternator round and at the sort of powers you are talking about the "pull" on the belt would be significant, so even a slack toothed belt would be trying to pull the crankshaft to one side.

[BEngo]

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

[Antrepat]

17 minutes ago, dmr said:

 

Have a look at this:

 

https://nb-firecrest.co.uk/tag/power-curve/

 

It looks quite genuine, whilst some other figures available on the www are from over optimistic salesmen, or people so committed to electric propulsion that they have rose painted spectacles. 😀

Now that you mention it, I've seen that before.  Avoiding salesmens' rose-tinting is definitely one of my objectives.

 

It looks like about 3kw on a canal and less on a river (as I'd have expected).  That is, of course, electrical input into the system, so that suggests my estimates are significantly more than practical reality: given 55% propellor fluid-mechanical efficiency and 90% electrical efficiency (perhaps optimistic but assume I've got good kit and really thick wires), you'd get about half that power as actual thrust.  Here are my estimates for raw thrust needed to achieve different speeds, based on the mk. 1 horse being able to pull a lightly-laden full-size narrow boat at 2mph:

 

Mph	m/s	Force (N)	Power (W)	hp
0.0	0.00	0	0	0.0
0.5	0.22	52	12	0.0
1.0	0.45	209	93	0.1
1.5	0.67	469	315	0.4
2.0	0.89	834	746	1.0
2.5	1.12	1303	1456	2.0
3.0	1.34	1877	2517	3.4
3.5	1.56	2554	3996	5.4
4.0	1.79	3336	5966	8.0
4.5	2.01	4222	8494	11.4
5.0	2.24	5213	11652	15.6

 

That means about 5kW electrical power to make 3mph, so clearly I'm being too conservative (if that chap's data are correct).

 

Sadly the Horseboating Society have so far ignored my request for the speed at which a good horse can actually pull a lightly-laden boat (they're probably dismissing me as a crank, and they're quite likely right), so I had to guess, and I dare say there are other factors I haven't included in the model.  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.

 

Mph	m/s	Force (N)	Power (W)	hp
0.0	0.00	0	0	0.0
0.5	0.22	30	7	0.0
1.0	0.45	121	54	0.1
1.5	0.67	271	182	0.2
2.0	0.89	483	432	0.6
2.5	1.12	754	843	1.1
3.0	1.34	1086	1456	2.0
3.5	1.56	1478	2313	3.1
4.0	1.79	1931	3452	4.6
4.5	2.01	2443	4916	6.6
5.0	2.24	3017	6743	9.0

 

This is very encouraging, as it implies a 400Ah battery, which is what I'd estimated I'd need, would deliver a lot more silent cruising than I thought.

[Antrepat]

On 15/10/2022 at 10:17, Tony Brooks said:

drive a large alternator from an adaptor bolted to the flywheel fixings.

 

36 minutes ago, Antrepat said:

what is the advantage of a belt drive coming off the flywheel rather than off the other end?

?