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Whilst looking around for an alternator upgrade I noticed that you can get water cooled alternators as fitted to Mercedes and Renault. As my engine compartment gets quite hot and I have a copious supply of cold/raw water I wondered if this might be an option. They seem to be about 190A and would be quite easy to plumb in. Maybe they are less likely to overheat on high load? Anyone tried using one?

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7 minutes ago, Mike Adams said:

Whilst looking around for an alternator upgrade I noticed that you can get water cooled alternators as fitted to Mercedes and Renault. As my engine compartment gets quite hot and I have a copious supply of cold/raw water I wondered if this might be an option. They seem to be about 190A and would be quite easy to plumb in. Maybe they are less likely to overheat on high load? Anyone tried using one?

I think those are controlled electronically by the cars ECU so might not work. I've been out of the motor trade for some years now so not certain.

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1 minute ago, Mike Adams said:

Good point - I will do a bit more investigating on the control circuit

 

External alternator controllers are available from several sources, Balmar are one of the best known, Wakespeed are new but maybe better. You need an alternator configured for this, some can be bought this way, some can be converted. What engine is this for?

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58 minutes ago, Mike Adams said:

Whilst looking around for an alternator upgrade I noticed that you can get water cooled alternators as fitted to Mercedes and Renault. As my engine compartment gets quite hot and I have a copious supply of cold/raw water I wondered if this might be an option. They seem to be about 190A and would be quite easy to plumb in. Maybe they are less likely to overheat on high load? Anyone tried using one?

As one who seems to regularly replace alternators I would agree regards the problem of how hot it gets in the engine compartment, I think that is what does for them. On the other hand would your drive belt cope with a 190A alternator? On mine I have a 70A alternator fitted for the engine battery where there should be a 50A one and every time I start up the belt squeals until it settles down. I've tried tightening the belt but to get enough tension to stop the squealing it trashes the bearing in the water pump (on the same belt). Not sure what the effect of trying a 190A alternator would be.

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A 12V 190A alternator will need a polyvee belt drive not a normal V-pulley, which means a new crankshaft pulley. Also might cause problems with the load on this depending how it's attached to the engine, early Betas had this problem.

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It's an Isuzu engine. I have an extra polyvee pulley for the crankshaft that fits on the crankshaft pulley. The main problem is mounting the alternator to the engine. It will need a substantial steel bracket mounted to the engine engine feet and other strong points along the crankcase in order to take the load. I don't expect to get 190A but say 80A would be good. I can only get about 50A max from the current 90A alternator. It will have to be an additional alternator, the single v belt is not up to this sort of load.

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This might fit the bill.

RENAULT ESPACE MK4 1.9 2.2 DCi DIESEL 2002-2010 NEW WATER COOLED 155A ALTERNATOR. As far as I can see L is the lamp connection and DF is a digital output from the alternator in PWM format to tell the ECU of the car the level of output.

123590719_alt4.jpg.9a1be3f57f6bd22f88f7a567a4ac4901.jpg2011360892_alt5.jpg.f1606e1065966a180473f297806264cb.jpg

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1 hour ago, Mike Adams said:

It's an Isuzu engine. I have an extra polyvee pulley for the crankshaft that fits on the crankshaft pulley. The main problem is mounting the alternator to the engine. It will need a substantial steel bracket mounted to the engine engine feet and other strong points along the crankcase in order to take the load. I don't expect to get 190A but say 80A would be good. I can only get about 50A max from the current 90A alternator. It will have to be an additional alternator, the single v belt is not up to this sort of load.

What's the charging voltage at the end of a day's cruise at about 1200 RPM. If its 14.2V+ then the battery bank may be better charged first thing in the morning that you think and if so a 90 amp alternator won't make much difference.

 

If it 14V or less then you may have a blown diode so have lost a phase.

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2 minutes ago, Tony Brooks said:

What's the charging voltage at the end of a day's cruise at about 1200 RPM. If its 14.2V+ then the battery bank may be better charged first thing in the morning that you think and if so a 90 amp alternator won't make much difference.

The problem is I am only working on a narrow speed range for the engine. It is fine (14.4ish)when cruising the Thames with 1100 engine rpm giving 8kph but on a narrow canal or working through locks all day I am only working between 750rpm (tick over) and 900rpm. The current alternator doesn't cut in until about 800rpm. The 50A is cold in the morning at 1100rpm. You can't do much with the current alternator such as making the pulley smaller or increasing the crankshaft pulley size because the primary belt will foul on the engine. So I need to fit a second alternator with a second larger pulley(which I now have) with a ratio of 3:1 as opposed to the current 1:1.75 ratio.

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1 hour ago, Mike Adams said:

The problem is I am only working on a narrow speed range for the engine. It is fine (14.4ish)when cruising the Thames with 1100 engine rpm giving 8kph but on a narrow canal or working through locks all day I am only working between 750rpm (tick over) and 900rpm. The current alternator doesn't cut in until about 800rpm. The 50A is cold in the morning at 1100rpm. You can't do much with the current alternator such as making the pulley smaller or increasing the crankshaft pulley size because the primary belt will foul on the engine. So I need to fit a second alternator with a second larger pulley(which I now have) with a ratio of 3:1 as opposed to the current 1:1.75 ratio.

So if you rev it out of gear at say 1500 rpm first thing in the morning do you get closer to the 90 amps.

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4 hours ago, Mike Adams said:

It's an Isuzu engine. I have an extra polyvee pulley for the crankshaft that fits on the crankshaft pulley. The main problem is mounting the alternator to the engine. It will need a substantial steel bracket mounted to the engine engine feet and other strong points along the crankcase in order to take the load. I don't expect to get 190A but say 80A would be good. I can only get about 50A max from the current 90A alternator. It will have to be an additional alternator, the single v belt is not up to this sort of load.

Suggest you check how the extra polyvee pulley is mounted, there's a lot of sideways force on it with the belt tension needed for a big alternator. If it's just bolted on top of the existing pulley you might have the same problem the early Betas did, sometimes leading to damage needing a new crankshaft. If it's got a proper splined fitting intended for power takeoff like the newer Betas you should be OK. Maybe somebody with experience of doing this on an Isuzu knows more, but would be worth checking before going ahead.

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8 hours ago, IanD said:

Suggest you check how the extra polyvee pulley is mounted, there's a lot of sideways force on it with the belt tension needed for a big alternator. If it's just bolted on top of the existing pulley you might have the same problem the early Betas did, sometimes leading to damage needing a new crankshaft. If it's got a proper splined fitting intended for power takeoff like the newer Betas you should be OK. Maybe somebody with experience of doing this on an Isuzu knows more, but would be worth checking before going ahead.

Thanks - I was aware of this potential issue. The extra pulley was used by the original marinisers (HMI). I don't know of any problems but that doesn't mean there aren't any. Hopefully the crankshaft end is a bit more substantial than the Beta one. The any better solution I can think of is to fit a large pulley onto the flywheel itself between the flywheel and drive to the hydraulic pump and  carve away part of the bellhousing. Otherwise I could fit another hydraulic motor directly driving the alternator but that would be a lot of work.

I might try fitting a larger diameter machine in place of the standard alternator which logic tells me is likely to function at a lower speed.

Thanks for the help

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A couple of off the wall suggestions that might be less work than fabricating brackets etc. The problem seems not to be alternator output as such but the output at cruising speed so how about:

1. Fitting a "smaller" propeller.

 

As it now seem you have a hydraulic drive:

2. Fitting a smaller capacity pump or a larger capacity motor, either of which will give give you a greater reduction ratio. If you are using  a swash plate plump or motor then there is an outside chance the swash plate angle might be adjustable and that would have a similar effect.

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Well that's a new one on me, I haven't seen a piped one before. Mike is absolutely correct about the L and DFM terminals and the machine will be happy to work with DFM unconnected.

11 minutes ago, Tony Brooks said:

A couple of off the wall suggestions that might be less work than fabricating brackets etc. The problem seems not to be alternator output as such but the output at cruising speed so how about:

1. Fitting a "smaller" propeller.

 

As it now seem you have a hydraulic drive:

2. Fitting a smaller capacity pump or a larger capacity motor, either of which will give give you a greater reduction ratio. If you are using  a swash plate plump or motor then there is an outside chance the swash plate angle might be adjustable and that would have a similar effect.

Or even a hydraulic motor on the front of the alternator?

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Thanks for the numerous suggestions. I have machined/fitted the large polyvee pulley to the crankshaft and made up a large steel plate to fix to the side of the engine crankcase and modified the engine mounting to accommodate the new plate. So I now have a drive method and something solid to fix the 2nd alternator to. Now I just need an alternator and drive belt. I think the ratio will be about 4:1 so should give a decent output at tickover.

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2 hours ago, Mike Adams said:

Thanks for the numerous suggestions. I have machined/fitted the large polyvee pulley to the crankshaft and made up a large steel plate to fix to the side of the engine crankcase and modified the engine mounting to accommodate the new plate. So I now have a drive method and something solid to fix the 2nd alternator to. Now I just need an alternator and drive belt. I think the ratio will be about 4:1 so should give a decent output at tickover.

Plenty of high output alternators available, the marine-targeted ones like Balmar tend to be expensive compared to car/truck ones.

 

Just beware that if you get a big alternator and use a big step-up ratio like 4:1 it will indeed generate a lot of current at tickover, which means a heavy torque load on the engine, which many engines don't like either because it pulls the revs down too low or because of internal low-rev crank/flywheel torsional resonances -- IIRC Beta say not to run the engine under heavy charging load below 1200rpm, probably for this reason. They typically use 2.8:1 pulleys (180mm/65mm) for high-output alternators with polyvee drives...

Edited by IanD
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The other thing to watch is belt wrap.  At 4:1 unless the alternator and the crank pulleys are very well separated there will not be much wrap on the small pulley. That leads to overloading, belt squeal and rubber dust everywhere at lower speeds.  You cannot easily  go for a belt wider than the engine pulley so you may need an idler to get proper wrap.  Any idler does not need to be grooved though an 11tpi  die head chaser cuts passable J size belt grooves, I am told.

 

There are a number of websites with the details to work out the power capacity of a given poly V belt width and wrap.  IIRC the Continental one has the formulas and tables.  The Gates one may also be useful.  Most belt drives gear things down, not up, so watch the examples carefully to get things the right way round for your set up.

Finally, make sure your set up matches one of the standard belt lengths.  Much easier to buy replacements than some of the automotive special sized ones.

 

N

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1 hour ago, BEngo said:

The other thing to watch is belt wrap.  At 4:1 unless the alternator and the crank pulleys are very well separated there will not be much wrap on the small pulley. That leads to overloading, belt squeal and rubber dust everywhere at lower speeds.  You cannot easily  go for a belt wider than the engine pulley so you may need an idler to get proper wrap.  Any idler does not need to be grooved though an 11tpi  die head chaser cuts passable J size belt grooves, I am told.

 

There are a number of websites with the details to work out the power capacity of a given poly V belt width and wrap.  IIRC the Continental one has the formulas and tables.  The Gates one may also be useful.  Most belt drives gear things down, not up, so watch the examples carefully to get things the right way round for your set up.

Finally, make sure your set up matches one of the standard belt lengths.  Much easier to buy replacements than some of the automotive special sized ones.

 

N

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