Alternator advice please?

[NB Alnwick]

We are planning to remove our three way fridge that normally runs on gas and replace it with a modern electric fridge.

The only drawback is that our engine runs quite slowly and in most conditions rarely generates enough electricity to keep all our batteries fully topped up. We have a portable generator that we use to augment engine charging.

The alternator driven by the engine is a Lucas/C.A.V. AC5R 24V and my question is could we find a direct replacement for this alternator that would generate enough to charge the batteries at much lower RPM?

We already have the smallest practical diameter pulley on the alternator and an 18" pulley on the engine crankshaft/flywheel - so changing the gearing may not be an easy option.

[BEngo]

Low speed alternators exist.  They are not cheap!  It is also possible to rearrange the stator coils in a 9 diode alternator from star to delta ( or vice versa) so that it produces more at low speed but less at high speed.

 

@Sir Nibble is the expert on this.

 

N

Edited November 3, 2023 by BEngo
Not diodes, coils.

[ditchcrawler]

22 minutes ago, NB Alnwick said:

We are planning to remove our three way fridge that normally runs on gas and replace it with a modern electric fridge.

The only drawback is that our engine runs quite slowly and in most conditions rarely generates enough electricity to keep all our batteries fully topped up. We have a portable generator that we use to augment engine charging.

The alternator driven by the engine is a Lucas/C.A.V. AC5R 24V and my question is could we find a direct replacement for this alternator that would generate enough to charge the batteries at much lower RPM?

We already have the smallest practical diameter pulley on the alternator and an 18" pulley on the engine crankshaft/flywheel - so changing the gearing may not be an easy option.

What speed does your engine run at?

[IanD]

1 minute ago, ditchcrawler said:

What speed does your engine run at?

https://www.grahamoliver.com/alnwick/alnwick.htm#engine

 

140rpm tickover, 300rpm canal cruising, 600rpm maximum on tidal waterways.

Edited November 3, 2023 by IanD

[Mike Adams]

Why not run the alternator via a belt on the outside of the flywheel or I have seen an aluminium  washing machine pulley fixed to the front of the flywheel. Not trad but effective.

[ditchcrawler]

2 minutes ago, Mike Adams said:

Why not run the alternator via a belt on the outside of the flywheel or I have seen an aluminium  washing machine pulley fixed to the front of the flywheel. Not trad but effective.

I was going to suggest the flywheel option but I thought it wouldn't be any bigger than his 18" pulley already in use. The other option is an intermediate pulley to gear it up again

[MtB]

5 minutes ago, ditchcrawler said:

I was going to suggest the flywheel option but I thought it wouldn't be any bigger than his 18" pulley already in use. The other option is an intermediate pulley to gear it up again

 

Flywheel is 32" in diameter. 

 

Also, Taperlock pulleys go much bigger than 18". I had a 30" diam on on my K1. Worked a treat with an normal alternator

 

 

[ditchcrawler]

Just now, MtB said:

 

Flywheel is 32" in diameter. 

 

Also, Taperlock pulleys go much bigger than 18". I had a 30" diam on on my K1. Worked a treat with an normal alternator

 

 

In that case just wrap round the fly wheel. it will run without a grove

[MtB]

1 minute ago, ditchcrawler said:

In that case just wrap round the fly wheel. it will run without a grove

 

Prolly less work to swap the pulley size. Wrapping the flywheel means moving the alternator.

 

 

[alan_fincher]

I don't know the specs for variants of the AC5R, and in particular for 24 volt variants.

 

We have a 12 volt AC5R, and even if driven fast ours only outputs 60A max, so it could be that the 24V one you have only has a maximum output of 30A.

 

Very much higher output alternators exist, so you should be ale to find one that improves the situation - particularly as it should be easy in your case to avoid belt slip.

[NB Alnwick]

9 minutes ago, MtB said:

 

Prolly less work to swap the pulley size. Wrapping the flywheel means moving the alternator.

 

 

Yes - that is a possibility - and cheaper than changing a perfectly good alternator.

Can you suggest a source for the pulleys, please?

[magnetman]

Balmar do high power alternators but they are expensive. 

 

One problem with a larger pulley is the it all might get a bit noisy. 

[NB Alnwick]

34 minutes ago, alan_fincher said:

I don't know the specs for variants of the AC5R, and in particular for 24 volt variants.

 

We have a 12 volt AC5R, and even if driven fast ours only outputs 60A max, so it could be that the 24V one you have only has a maximum output of 30A.

 

Very much higher output alternators exist, so you should be ale to find one that improves the situation - particularly as it should be easy in your case to avoid belt slip.

 

The 24v version is rated at 55 Amps though I have rarely seen much higher than 30 on our ammeter.

The old AC5R model was a very robust and reliable alternator and I remember that we were fitting these to military vehicles in the 1970s when I was working in REME workshops.

[magnetman]

Leece Neville large frame alternators are good but would need modifications to the mounting. 

 

 

 

I don't use rotating electrics for power but have wondered at times if a permanent magnet alternator could be interesting. One could route the excess power to an immersion heater. 

 

 

[dmr]

19 minutes ago, NB Alnwick said:

 

The 24v version is rated at 55 Amps though I have rarely seen much higher than 30 on our ammeter.

The old AC5R model was a very robust and reliable alternator and I remember that we were fitting these to military vehicles in the 1970s when I was working in REME workshops.

 

Thats probably about right.

An external alternator controller like the Adverc will very likely increase the current quite a bit, but if it achieves too much it might lead to alternator overheating, especially at low speeds where there is less fan cooling.

Something like the new Wakespeed would be ideal as that controls temperature but its big money (£600). It might be worth it if you have any plans to move to Lithium one day.

 

 

[BEngo]

55 minutes ago, NB Alnwick said:

Yes - that is a possibility - and cheaper than changing a perfectly good alternator.

Can you suggest a source for the pulleys, please?

 

Erik, Bearing Boys, The Bearing Co.  All online.  Loads more if you Google "taperlock pulley".  I would be inclined to bimble along to a bearing stockist and have a chat with them, assuming they are not entirely staffed by spotty yoof with no product knowledge at all.

 

You will need to go for a pulley with a groove size that matches the alternator pulley groove.

 

 You will also need a stub shaft on the flywheel for the taperlock itself to grip.

 

What is the PCD of the model K flywheel bolts?   I have a 24 in diameter double V groove aluminium pulley  with 6 x 1/2 in dia. mounting holes on a 6 in PCD I would happily swap for beer coupons.

 

N

[Onewheeler]

My inclination would be to use an intermediate pulley if it can be mounted somewhere suitable.

[NB Alnwick]

3 hours ago, BEngo said:

What is the PCD of the model K flywheel bolts?   I have a 24 in diameter double V groove aluminium pulley  with 6 x 1/2 in dia. mounting holes on a 6 in PCD I would happily swap for beer coupons.

The boat is currently at Glascote Basin for its long overdue repaint - I will investigate the method of fixing the existing pulley when I next visit.

[BEngo]

7 hours ago, Onewheeler said:

My inclination would be to use an intermediate pulley if it can be mounted somewhere suitable.

If you mean a two- stage drive then in my experience it just introdufexmore problems than it solves.

 

If you mean an idler pulley to improve belt wrap then it can allow a smaller alternator pulley, particularly with a poly-V  belt.  The mechanics of mounting it are usually not easy.

 Flywheel rim belts are good, but often have really poor  belt wrap at the alternator,  limiting their benefit 

N