alternators and regulators

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legaltender

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Can anyone help me through the tangle of conflicting advice on upgrading charging systems?
I have a domestic bank of 540 amps (Delphi sealed lead acid) run 2 fridges using about 8-9 amps plus a lap top and spend long periods at anchor in Turkey and Greece.
I never let the batteries drop below 70% charged. My alternator is rated at 60 amps, and I spend an inordinate time running the engine to keep the charge level up.
I am minded to fit a larger alternator and a 3 or 4 step regulator. BUT I understand that once the batteries are above 70% charged, a high output alternator will not charge the batteries any faster than a standard one. SEcondly, fast charging sealed lead acid batteries is not good practice as it causes the water to evaporate and you can't replace the lost water. Thirdly, even if you charge faster and so save fuel and running hours, high output alternators use more horse power from the engine, hence more fuel; and finally, you need to fit serpentine belts, new pulleys etc with increased loading on the water pump bearings.

I intend to fit 200 watts of solar panels on my bimini and expect that will go some way to providing the power needed.

What is the solution so far as alternator and regulator are concerned? How big an alternator do I need and which is the best regulator. I had a Stirling Pro B fitted, but disconnected it after it caused a brand new Prestolite 90 amp alternator to fail. My engine is a Volvo MD 22 50 Horse.

Many thanks guys
 
nigelmercier said:
I have the same engine, slightly larger batteries (Lifeline 630Ah) a 100A Balmar alternator with a Balmar MaxCharge. Even with all this, I rarely manage to fully recharge with the engine alone. My solution is a good shore power charger, run by a Kipor generator if on anchor.
Click to expand...

If I was an anchor much of the time I would also use a small efficient diesel genny backed up with wind and solar.

Fitting a larger alternator is not the answer when at anchor for long periods but would be if motoring / motor sailing for long periods.

I did have the view that fitting a massive alternator and in effect using the main engine as a generator was an option, but due to the mechanical fitting problems and lack of space, plus possible reliability issues, I've now changed my mind. At least with a genny on board, you have a back up if the engine charging system fails.

The energy has to come from somewhere so its choosing the most efficient, reliable and affordable system, and also not putting all your eggs in one basket.
Ian
 
legaltender said:
What is the solution so far as alternator and regulator are concerned? How big an alternator do I need and which is the best regulator. I had a Stirling Pro B fitted, but disconnected it after it caused a brand new Prestolite 90 amp alternator to fail. My engine is a Volvo MD 22 50 Horse.
Click to expand...

Firstly, I can't see how a Sterling regulator could cause a Prestolite alternator to fail. Prestolite alternators are robust and reliable units (I have a 90A Prestolite on my boat).

You don't need additional belts for a 90-100A alternator (12v), larger than that and you'll need different belts.

Solar panels will certainly help, especially in your location.

For optimum charging, you'll need to have around 14.8v at the batteries (or possibly a little less, depending on your ambient temperature). This means you really need some sort of "smart" regulator. I use an Adverc. Delphi maintenance free batteries won't suffer at that voltage - I use similar batteries and they typically seem to last 8 years.

You certainly need some sort of decent battery monitor, a LinkLite or similar would do.

If you only discharge by 30%, you'll find the charging current won't be huge, and your 60A alternator might deliver all the batteries can accept. You need to check the charging current at 14.8v (temperature adjusted) and see whether it's anywhere near 60A, if so then a larger alternator might be worthwhile.
 
legaltender said:
What is the solution so far as alternator and regulator are concerned? How big an alternator do I need and which is the best regulator. I had a Stirling Pro B fitted, but disconnected it after it caused a brand new Prestolite 90 amp alternator to fail. My engine is a Volvo MD 22 50 Horse.
Many thanks guys
Click to expand...

A 100amp alternator will need about 3hp from the engine so engine bhp is not an issue. Driving the alternator fast enough to achieve max output can be if it is not geared up enough. Because so little power is required, having to run the engine way above idle speed is wasteful of fuel not to mention the noise.

In fact it is better to get a much higher output alternator than you need and run it at a lower speed. EG http://www.sp-shop.co.uk/Sterling-Power-Hi-Perfomance-12v-140A-Alternator-PN-AL12140.html

This 140amp alternator produces 100amps at 2000rpm - say 1000 engine rpm, but max output needs over 2500 engine rpm. So you can keep the engine rpm down most of the time and still have reserve charging capacity if you need it by increasing the revs (and the batteries can take it).
 
Generally, +1 with pvb

I am minded to fit a larger alternator and a 3 or 4 step regulator. BUT I understand that once the batteries are above 70% charged, a high output alternator will not charge the batteries any faster than a standard one.
You're largely right. This is more of a regulator issue. With a standard car-type regulator, the alternator won't charge the batteries at all for the last 15 per cent or so. Incidentally, if you've always used a standard regulator, you may find that your customary 70% of full charge is actually more like 70% of 85%, or 64%.

SEcondly, fast charging sealed lead acid batteries is not good practice as it causes the water to evaporate and you can't replace the lost water.
As pvb said. Plus, most smart regulators have a facility for modifying output to suit different battery types.

Thirdly, even if you charge faster and so save fuel and running hours, high output alternators use more horse power from the engine, hence more fuel;
I'd have thought that the increase in fuel consumption on a 50hp engine was tiny. I'd be more worried about running it on (almost) zero load for extended periods.

and finally, you need to fit serpentine belts, new pulleys etc with increased loading on the water pump bearings.
Not essential, but highly recommended for hard-working alternators. Serpentine (polyvee) belts are brilliant compared to their neolithic predecessors. They will not increase loading on bearings compared to a V-belt doing the same job; however, a bigger alternator, however driven, will increase such loads.
 
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macd said:
Serpentine (polyvee) belts are brilliant compared to their neolithic predecessors. They will not increase loading on bearings compared to a V-belt doing the same job; however, a bigger alternator, however driven, will increase such loads.
Click to expand...

I would love to fit a Poly-Vee belt, but I would need two new pulleys for the engine, and one for the alternator. Volvo Penta have no info, so can you suggest a supplier?
 
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legaltender said:
....My alternator is rated at 60 amps, and I spend an inordinate time running the engine to keep the charge level up.....
Click to expand...
When charging deep cycle house bank batteries, the output current of the alternator determines the time it takes to charge the bank. Your size of bank could take a 135 alternator, so fit a 100 amp and change the belt every year..

A standard automotive alternator with its internal regulator is designed for charging a start battery that never gets highly discharged. This alternator regulator will not properly charge a deep cycle house bank, the battery capacity and life will be severely reduced. Marine alternators will be much more expensive and can be controlled by an external multi stage regulator. They also may have a “Hot Rated” output that will give a more realistic idea of their true performance when under continuous heavy load.

Boats about 15 years old may have an automotive alternator which charges at only 13.8 – 14 volts. Battery charging at these voltages will take much longer. If split diodes are used to charge both the starter and house batteries then the voltage drop lost across these diodes (0.7volts) means that the batteries only get a charging voltage of 13.1-13.3 volts. Batteries may never get anywhere near charged at these voltages! Boats with a more modern 14.2-14.6 volt alternator with a built-in regulator may have a battery sense wire that can be connected directly to the battery to allow the alternator to measure the actual battery voltage and so compensate for the split diodes and cable losses.

With sealed batteries always fit an external regulator which will drop the charge down to float mode at 13.2-13.8 volts to avoid gassing and overcharging. A good regulator will also delay the charge current for about a minute at start up until the engine oil is well distributed. A 100 amp alternator draws 4 HP which is a heavy load on an engine when starting with a weak battery.

It is often too easy for the alternator on a boat to get too hot if used for long periods. A good external regulator will also accept sensors to measure both the alternator and the battery temperatures and control the charge rate. An alternator could be providing 15 amps to the boat systems, another 25 amps to say a watermaker or an inverter, and then a heavily discharged bank may be demanding 50 or 60 amps. In this situation the batteries may not get charged and the alternator will burn out from continually trying to deliver its maximum output if not protected by a temperature sensor. Battery temperature will also rise with a heavy charge current so the charge voltage must be reduced as the temperature rises. At 25ºC batteries start to gas at 14.4v, at 40ºC they gas at 14v so the external regulator will reduce the charging voltage automatically to compensate for this. If batteries are fitted in an engine compartment it is very easy for them to get too hot and lose water. This is fatal for sealed batteries.

Balmar make some of the best kit - yes its expensive but it does what it says on the tin. Similar to the Prestolite I believe but they are hot rated for continuous heavy duty use, dual fans, high temperature diodes - engineered to do a better job.
 
nigelmercier said:
Thanks, but I'm not sure I want one that much :)
Click to expand...

Yes, it's scandalous.

The cheap alternative is to remove your pulleys and take them along to a good car scrappers. Almost every car there will have a polyvee (or more than one: they drive air-con, too). But some machining would be almost certainly be required.

The pulleys themselves can be bought cheaply enough from specialist belt/pulley suppliers; but again the problem will usually be finding and aligning pulleys that fit your shafts.

HTD belts are another alternative, and can be set-up to be more tolerant of misalignment by specifying a slightly wider master pulley. HTDs can be used for transmissions, so are more than capable of driving the biggest alternator.

If I planned on keeping a boat long-term I would definitely go to the trouble. In fact I was in the process of doing so (it would have become an article in PBO) when my last engine died...:( The new one has a polyvee.
 
Thanks one and all; so far as the Sterling Pro B reg is concerned, I think the problem was that with such a large battery bank, the regulator was keeping the alternator at maximum output without ever reaching float level, so causing the alternator to burn up. Next time round I'll fit a temperature sensor.
I'm inclined to fit a higher power alternator which produces good output at low revs, eg a 100 amp Powermaax together with an Adverc or Balmar regulator. That way, hopefully, I can get away with retaining existing pulleys and belt, though I am told you can get kevlar belts. Here in Turkey at least you can usually find a restaurant with a jetty and shore power to bring the batteries up to full charge every so often.

Does anyone want to buy a Sterling Pro B regulator, little used and going cheap!
 
nigelmercier said:
I have the same engine, slightly larger batteries (Lifeline 630Ah) a 100A Balmar alternator with a Balmar MaxCharge. Even with all this, I rarely manage to fully recharge with the engine alone. My solution is a good shore power charger, run by a Kipor generator if on anchor.
Click to expand...

+1, Have been in the Med now 4 years and still use the standard alternator (80 amp) via a diode splitter augmented with a 4KVa genny driving a water maker and a 4 stage shore power charger and lots of 240v equipment, on a combined *500AH bank have recently added 80 watts of solar deployed at anchor and when the boat is laid up. - WHY?

Could n't find anyone who was getting value for money from the big alternator smart regulator set-up even if they motored everywhere and even then they seldom achieved more than *90% charge - I get *85% under the same conditions so what's all the fuss about?

Also belt wear and bearing loading if you keep the standard belt IS a BIG issue, these guys are always changing belts and water pump bearings - DAFT for 5%. I still have the original belt now 10 years (650hrs) old - when its worn out I will replace it. - yes its a sailboat we sail it.

AND these guys spend their lives monitoring batteries, there is more to life I promise; when my madly inaccurate over optimistic analogue voltmeter says 13.5V (by experiment testing with a digital meter I have found this is equivalent to a resting voltage of around 12) I press a button and charge the batteries. (I am interested in the battery not the voltmeter which goes off the scale when the bat is charged!) In reality this level of discharge is seldom reached as the need for water has already started the genny.

My last set of really cheap and nasty flooded cells lasted 8 years and were still testing as OK when I ditched them.

Others around me have all sorts of expensive gizmos and expensive batteries but don't seem to fare any better and they work through a lot more cash.

* Based on a theoretical value of what we think the capacity of the battery is based on resting voltage and what the manufacture said it was. However, in reality we never know the ACTUAL capacity without performing heavy discharge tests that could destroy the battery. In may respects these figures are meaningless.
 
200w of solar will deliver around 15 amps but only from about 10 am to about 5 in summer so you would be ok then.

The challenge of running a big engine lightly loaded for long periods to just charge the batteries is too risky. I'm with the suggestion of fitting a generator. In fact then you could do away with the solar and just drive your current shore power charger and the laptop off 220v
 
Cant seem to get any info, have tried.
Are the sterling alternators insulated return (-) or case return, I need insulated return. Proper marine engines.
 
legaltender said:
What is the solution so far as alternator and regulator are concerned? How big an alternator do I need and which is the best regulator. I had a Stirling Pro B fitted, but disconnected it after it caused a brand new Prestolite 90 amp alternator to fail. My engine is a Volvo MD 22 50 Horse.

Many thanks guys
Click to expand...

First find out what your problem is.

Check your charge voltage at the battery during recharging, at the same time check what the amperage levels are, this will indicate what your problem is with regard to recharge level. This could be low charge voltage, low amperage, high voltage rapid current drop could indicate batteries, but first find out what you are trying to cure.

Brian
 
ccscott49 said:
Thankyou, that's them out of the equation then, looks like a very expensive solution is required.
Click to expand...

Not necessarily, look at the Prestolite/LeeceNeville range, many are insulated return. They are excellent, inexpensive, robust alternators with a good output at low revs. Balmar alternators are made by Prestolite.
 
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