If you were to fit an alternator booster

[VicMallows]

So my contention is that it is not "a good alternative to traditional alternator boosters". Better to get the field wire connection modified.

I suspect that even Mr Sterling would agree with you as far as overall efficiency is concerned. The A to B converters are sold on the basis of ease of installation which is obviously something many people are willing to pay for.

 

[pvb]

OK - maybe I'm not succeeding either!

Yes its a clever piece of kit, but its inefficient. Booster regulators increase the voltage by feeding in more field current. With no field current control an A2B regulator has to work with the low voltage and use the maximum current all the time to achieve a higher voltage. Its only worth running an alternator up to 80% of battery charge after that the current falls away and at the point when the A2B regulator drops to float it may no longer need to suck the maximum current out of the regulator. Up to this point I maintain it does put "a continuous and unnecessary high load on the alternator".

If you have a 50 Amp 13.8v automotive alternator you will probably only get 40 amps from it - less when it is really hot. That's 13.8 x 40 = 552 watts. If you consider the A2B inverter/regulator to be only 85% efficient then the wattage available for charging the battery is 470 watts, so the current available for charging the batteries at 14.8 volts is 470/14.8 =31.7 amps. This is a 20% reduction in the available current to charge the batteries, so the alternator will have to run longer the get the same charge into the batteries.

So my contention is that it is not "a good alternative to traditional alternator boosters". Better to get the field wire connection modified.

There are so many misconceptions here that I can't hope to address them all. But, for starters, an A-to-B charger doesn't necessarily use maximum current from the alternator - it depends on how much the batteries can absorb. Batteries being charged at 14.8v place essentially the same load on an alternator regardless of whether the alternator has a "booster" or an A-to-B charger. The A-to-B charger will have some inherent losses (as does an ordinary diode splitter), but I haven't seen anyone publish the 85% efficiency figure you've quoted, and I wonder whether you've invented this; and I can't agree with your blanket dismissal of it as "inefficient". The fact remains that the A-to-B charger is an excellent alternative to traditional alternator boosters.

 

[Fr J Hackett]

Fair enough, and sorry if I offended. Was trying just to make a general point.

No offence taken I think the point is very valid too many people do not understand even the basics of their boats and engines, for some with very deep pockets it may be OK as long as they don't venture far but for many of us it is an integral part of the whole sailing experience and hopefully some of the comments and exchanges on here help people to get a greater depth of understanding and expertise.

 

[halcyon]

OK - maybe I'm not succeeding either!

Yes its a clever piece of kit, but its inefficient. Booster regulators increase the voltage by feeding in more field current. With no field current control an A2B regulator has to work with the low voltage and use the maximum current all the time to achieve a higher voltage. Its only worth running an alternator up to 80% of battery charge after that the current falls away and at the point when the A2B regulator drops to float it may no longer need to suck the maximum current out of the regulator. Up to this point I maintain it does put "a continuous and unnecessary high load on the alternator".

If you have a 50 Amp 13.8v automotive alternator you will probably only get 40 amps from it - less when it is really hot. That's 13.8 x 40 = 552 watts. If you consider the A2B inverter/regulator to be only 85% efficient then the wattage available for charging the battery is 470 watts, so the current available for charging the batteries at 14.8 volts is 470/14.8 =31.7 amps. This is a 20% reduction in the available current to charge the batteries, so the alternator will have to run longer the get the same charge into the batteries.

So my contention is that it is not "a good alternative to traditional alternator boosters". Better to get the field wire connection modified.

Just a quick comment, alternators can achieve a very high voltage without control, the control is done by cutting the feed to the rotor, thereby cutting output current, thus charge to battery and battery voltage. As the battery level and voltage increase the no output gaps get longer, thus the charge current you see reduces. To increase output voltage, you maintain the feed or earth to the rotor, by-passing the internal regulator, as the output voltage increases you reduce amperage. Alternators in the past were rated in watts at 14 volt DC into a resistive load, not just as a amperage.

So if we have a 700 watt alternator this will give us 50 amp @ 14 volt, increasing voltage to 14.8 via DC -DC booster @ 92% efficiency, output current would fall to 43 amp.

It is a lot more complicated, as alternator output varies with type of load it is feeding, the DC-DC efficiency will vary with input-output voltage ans charge current, then the output charge profile of the pulsed alternator and the switchmode output can effect battery charge.

Brian

 

[sailorman]

Just a quick comment, alternators can achieve a very high voltage without control, the control is done by cutting the feed to the rotor, thereby cutting output current, thus charge to battery and battery voltage. As the battery level and voltage increase the no output gaps get longer, thus the charge current you see reduces. To increase output voltage, you maintain the feed or earth to the rotor, by-passing the internal regulator, as the output voltage increases you reduce amperage. Alternators in the past were rated in watts at 14 volt DC into a resistive load, not just as a amperage.

So if we have a 700 watt alternator this will give us 50 amp @ 14 volt, increasing voltage to 14.8 via DC -DC booster @ 92% efficiency, output current would fall to 43 amp.

It is a lot more complicated, as alternator output varies with type of load it is feeding, the DC-DC efficiency will vary with input-output voltage ans charge current, then the output charge profile of the pulsed alternator and the switchmode output can effect battery charge.

Brian

Thanks Brian
what would you fit

 

[halcyon]

Thanks Brian
what would you fit

The first question I always put to people for the last 20 odd years ... do you have a battery problem at the moment ?

Brian

 

[sailorman]

The first question I always put to people for the last 20 odd years ... do you have a battery problem at the moment ?

Brian

we had "fridge" issues. running the batteries down, had that re gassed, batteries duff after 4 yrs 10 months & not hepled by the fridge.
So we now have a fridge that works as it should, 3 new 125Ah deep cycle sealed batteries but are spending more nights away from mains power. we do have an aerogen 4 ( i think might be a 6).
Just musing really as what if anything to do.
we have a Nanni 37.5 hp it does have issuse with the single vee belt making dust & a pain to keep adjusted. To change to Poly V belts & pulleys is very expensive.

I had a Kestral booster when they first came out but fried alternators ( Lucas ACR) as no heat sensing in those far off days

 

[halcyon]

we had "fridge" issues. running the batteries down, had that re gassed, batteries duff after 4 yrs 10 months & not hepled by the fridge.
So we now have a fridge that works as it should, 3 new 125Ah deep cycle sealed batteries but are spending more nights away from mains power. we do have an aerogen 4 ( i think might be a 6).
Just musing really as what if anything to do.
we have a Nanni 37.5 hp it does have issuse with the single vee belt making dust & a pain to keep adjusted. To change to Poly V belts & pulleys is very expensive.

I had a Kestral booster when they first came out but fried alternators ( Lucas ACR) as no heat sensing in those far off days

The drive belt issue will not be improved by fitting a booster, in fact reducing charge may improve matters it is possible that the belt is slipping and giving bad charge.

The first job is what voltages are you charging at with the alternator, measured at alternator output terminal and also at battery terminal.

Do you have a voltmeter and ammeter to monitor ?

You need to find what your problem is, i.e. low voltage, letting the batteries fall to low before charging, slipping belt, to short a charge cycle, then the cure can be sorted.

Brian

 

[dutyhog]

I can strongly recommend retro-fitting a poly-V belt, whatever the expense or space to get it into. I changed to it years ago after having to re-tension every few weeks, and getting through at least one belt per season. Since then I've not even had to re-tension the new one. It doesn't create soot, slip or squeak, and more current goes to the batteries. 14.0/14.4 volts at the battery terminals gives a fairly full charge (Adverc managed). Gordon

 

[pvb]

A stop-gap measure is to buy the best v-belt you can find - Gates belts are very good.

 

[Fr J Hackett]

A controller that gives a ramped start up is likely to reduce the dust and belt wear as this is where slippage usually starts assuming that everything is aligned. Twin belts and pulleys are also adviseable at anything much above or at 100 Amp alternators, but may be possible to retrofit to your existing set up at releatively small cost.

 

[temptress]

I'd be looking at Balmar for alternators and controllers. I've always had excellent service from these products.

+1 We have a Balmar alternator fantastic. I

 

[pvb]

A controller that gives a ramped start up is likely to reduce the dust and belt wear as this is where slippage usually starts assuming that everything is aligned.

Almost all of them have a slow start function, including Adverc/Sterling boosters.

 

[pvb]

+1 We have a Balmar alternator fantastic. I

They're re-branded Prestolite alternators. You can get effectively the same performance by buying the Prestolite at about a quarter of the cost.

 

[Bobc]

I had charging issues (I was only getting 12.9v to the batteries after the diode splitter had done its work, and could never get the house batteries properly charged). I fitted a Sterling AtoB in place of the diode splitter, and it completely transformed the charging. I've had it now for 2 years, not suffered any belt problems (or even any noticeable increase in wear or stretch), and go from 12.2v up to float in about 3 hours (whereas before I couldn't get this done in 6 hours).

JFDI.

 

[westernman]

A controller that gives a ramped start up is likely to reduce the dust and belt wear as this is where slippage usually starts assuming that everything is aligned. Twin belts and pulleys are also adviseable at anything much above or at 100 Amp alternators, but may be possible to retrofit to your existing set up at releatively small cost.

I have a single belt on at the moment despite having twin pulleys. Last time we changed we had three new belts in the spares - all of marginally different sizes despite being the same size on the box.

I have a 110A Balmar Alternator + Balmar intelligent controller. It will deliver 115A at little over tick over if the batteries are discharged a significant amount.

The belt does not slip, there is no sign of any black dust anywhere. The controller ensures that the ramp up is very gradual. It takes a couple minutes until it reaches maximum current.

115A is a lot of current for which you need big thick wires! Even then the wire from the alternator gets pretty hot.

 

[temptress]

They're re-branded Prestolite alternators. You can get effectively the same performance by buying the Prestolite at about a quarter of the cost.

I am not sure you are right here. I always thought Balmar designed and built their own equipment. They are a US company, http://www.balmar.net/ claim to hold the 'patents' for the internal workings of their alternators. I may be wrong. We fitted one having tried several alternatives before. We found them helpful and am more than happy with the outcome.

 

[claudio]

I have a single belt on at the moment despite having twin pulleys. Last time we changed we had three new belts in the spares - all of marginally different sizes despite being the same size on the box.

I run a Balmar alternator and regulator off my Perkins. This is also fitted with twin pulleys. Many belt suppliers can supply 'matched belts' if you ask, so no problems with one belt taking the load whilst the other slapping away.

 

[Fr J Hackett]

I have a single belt on at the moment despite having twin pulleys. Last time we changed we had three new belts in the spares - all of marginally different sizes despite being the same size on the box.

I have a 110A Balmar Alternator + Balmar intelligent controller. It will deliver 115A at little over tick over if the batteries are discharged a significant amount.

The belt does not slip, there is no sign of any black dust anywhere. The controller ensures that the ramp up is very gradual. It takes a couple minutes until it reaches maximum current.

115A is a lot of current for which you need big thick wires! Even then the wire from the alternator gets pretty hot.

Pretty much like my old installation which I had a Heart monitor incorporated the figures were very similar and like you I never bothered to go down the twin belt rout as there was no need. The previous installation had an Adverc which did produce some belt dust but nothing untoward.

 

[pvb]

I am not sure you are right here. I always thought Balmar designed and built their own equipment.

No, Prestolite manufacture the Balmar alternators. Here's just one example of a Prestolite product sheet which notes that it's an alternator marketed by Balmar - http://www.prestolite.co.uk/pgs_pro...l_id=312&item_series_id=97&refresh=1367043525