External alternator regulator

[blackrose]

I assume these devices shorten the alternator life as they're making it work harder?

 

I'm thinking of getting the Sterling alternator to battery charger which does the same thing but with these you don't have to bypass the alternator's own regulator and do any complicated wiring. http://www.yachtbits.com/sterling_power/st...ry_chargers.php

 

One other question. I have twin alternators but I only want to run the alternator to battery charger from my domestic alternator (because the starter battery is connected to a voltage sensituve relay which tops up the bow thruster batteries & the instructions for the VSR say that you shouldn't use an external regulator). But if I fit one of these things to my domestic alternator could it affect the starter alternator in any way? I can't see how it would but I thought I'd check.

Edited September 20, 2006 by blackrose

[ChrisPy]

One other question. I have twin alternators but I only want to run the alternator to battery charger from my domestic alternator (because the starter battery is connected to a voltage sensituve relay which tops up the bow thruster batteries & the instructions for the VSR say that you shouldn't use an external regulator). But if I fit one of these things to my domestic alternator could it affect the starter alternator in any way? I can't see how it would but I thought I'd check.

I suppose it all depends if you are using both alternators to input to a common load (eg charge splitting diode).

In my case there is no connection between the two systems. I will use the standard LB starter battery and alternator, but a Sterling regulator on the domestic alternator and batteries.

PS : my thruster is powered from the starter battery with double welding cable running from the battery to the bow (and a naughty negative return through the hull), it should give me 3 minutes at 600A before it begins to die, which is enough to get off the mooring against the wind.

Edited September 20, 2006 by chris polley

[bottle]

Have a look here Smart gauge, you may not need an external regulator, if you have a newish alternator

[GUMPY]

I assume these devices shorten the alternator life as they're making it work harder?

 

I'm thinking of getting the Sterling alternator to battery charger which does the same thing but with these you don't have to bypass the alternator's own regulator and do any complicated wiring. http://www.yachtbits.com/sterling_power/st...ry_chargers.php

 

 

Check the charge voltage, if its 14.4 or there abouts you would be wasting your money.

If I understand their mode of operation correctly the newer Stering is just a charger that uses the alternator as its power supply so it must produce less energy into the battery than the alternator produces.

 

For some interesting reading fromm UKRW have a look here:

 

http://tinyurl.com/p2jy8

 

J

Edited September 20, 2006 by idleness

[blackrose]

Thanks for your advice. My voltmeter in the boat is pretty basic but I think I'm getting over 14v.

 

Can I stick a multimeter on the battery terminals while the engine is running - is that safe?

 

Going off topic for a minute, I 've had a look at the SmartGuage website and he seems to hate split charge diodes. I have a BEP voltage sensitive relay which splits the charge between my starter battery/bow thruster batteries. http://www.power-store.com/view-item.asp?itemid=1140&id=196&

 

If these things are so bad why have I never had a problem with either start or BT battery charging?

Edited September 20, 2006 by blackrose

[DHutch]

Can I stick a multimeter on the battery terminals while the engine is running - is that safe?

Yes, there nothing wrong with placing a multimeter, set on 50VDC or simular, accross the termials of the battery while the enignes runing.

- Just take care you dont get snaged in the fan belt, and dont have the meter in current mesuring mode!

 

 

 

Daniel

[GUMPY]

 

Going off topic for a minute, I 've had a look at the SmartGuage website and he seems to hate split charge diodes. I have a BEP voltage sensitive relay which splits the charge between my starter battery/bow thruster batteries. http://www.power-store.com/view-item.asp?itemid=1140&id=196&

 

If these things are so bad why have I never had a problem with either start or BT battery charging?

 

Because its a relay not a diode......

Relays are fine, if it was a diode your batteries would be at 0.6v lower than the charge voltage and hence not fully charged

 

J

[Noah]

I fitted Adverc's version of alternator controller because I got a good deal at the time:

 

http://www.adverc.com

 

It was a bit of a pain to fit as it involved modifying the existing regulator on the Lucas alternator. However, I have definately noticed an improvement in available battery capacity and I don't have to run the engine for as long to get the same state of charge. The charging voltage at my batteries (providing they are not extremely flat!) cycles between 14.2V and about 14.8V (dependant on ambient temperature). However, due to the characteristics of MY alternator, this improved charging will only commence if the engine is running above tickover.

 

I've had no problems after two years although I was concerned that anything that make an alternator work harder would probably increase its working tempeature so I try to ensure that it has an adequate supply of cooling air. Take note if you're engine is cocooned in insulation!

 

I try to keep things reasonably simple on my boat and I sometimes find the highly technical stuff a bit dull these days (despite being a former electronics engineer!) but there is loads on this topic at:

 

http://www.tb-training.co.uk/index.htm

 

http://www.smartgauge.co.uk/controllers.html

[John Orentas]

Because its a relay not a diode......

Relays are fine, if it was a diode your batteries would be at 0.6v lower than the charge voltage and hence not fully charged

 

J

 

 

Every time you pass an electrical current through a diode, as Idleness says you lose half a volt or so, the only way to get around this is to do what the add-on controllers do that is to pick up the reference voltage on the battery side of the diodes rather than from the alternator output, hence turning it into a 'machine sensed' system. In fact that missing 0.5 volts makes a massive difference to the charge rate almost enough to prevent charging altogether.

 

In practise it is much better to use a relay but it must be a big one or even use two heavy duty relays* as I have done with the coils wired in parallel that gives around 100 max capacity for those rare occasions when it may be required.

 

* Some alternators don't like to do this, but there is a simple way round it if anyone is interested.

[DaveR]

Ok, my knowledge of electrics consists of how to operate a light switch.

 

Question, instead of these sensors, relays etc. to make more power available, can the same effect be achieved just by adding another battery to the bank?

[Moley]

can the same effect be achieved just by adding another battery to the bank?

I think, if I've got the gist of Noah's second link, that what we are looking at is the percentage to which your batteries are being charged. Your 100A/h battery only likes to let you use 50% of its capacity. If you're only charging to 80% then that means you've only got 30% or 30A/h available to use.

 

So if you add another battery, that too is only going to be charged to 80%, but you've now got 60A/h available.

 

In a way, the answer to your question is Yes, but I think we're trying to get more than 80% charge into the batteries.

 

I think

[John Orentas]

Ok, my knowledge of electrics consists of how to operate a light switch.

 

Question, instead of these sensors, relays etc. to make more power available, can the same effect be achieved just by adding another battery to the bank?

 

 

It should always be borne in mind that batteries are purely for power 'storage' every bit of electrical power you take out of your batteries will have to be replaced from you alternator or some other source. Extra batteries will allow you perhaps to recharge more infrequently.

 

If you have a very large bank of batteries, say 6 or 8 this is the only real justification for a charge controller, the alternator can be made to function close to it's limits for long periods of time, but then you must start to pay attention to efficient cooling (a common problem on boats) and also beef up the wiring and other bits and pieces.

[Sir Nibble]

We have discussed a few times the need for sufficient current carrying capacity in split charge relays. It occurrs to me that there is no reason not to charge the domestic batteries directly and use a relay to pass the far smaller current needed by the engine start battery. Any comments?

[GUMPY]

We have discussed a few times the need for sufficient current carrying capacity in split charge relays. It occurrs to me that there is no reason not to charge the domestic batteries directly and use a relay to pass the far smaller current needed by the engine start battery. Any comments?

Its what I've done for years as its a couple less connections between the alternator and the battery.

Mind you if the domestic battery is very flat the relay will still have to pass a resoable ammount of curent as the starter battery will attempt to charge the domestic as it clicks in. This is of course unless you are using a VSR which will only switch when the first battery being charged reaches the switching voltage.

 

 

J

[John Orentas]

We have discussed a few times the need for sufficient current carrying capacity in split charge relays. It occurrs to me that there is no reason not to charge the domestic batteries directly and use a relay to pass the far smaller current needed by the engine start battery. Any comments?

 

 

Hi Snibble.

 

It wouldn't help much. The systems are usually wired so that the start battery is wired directly in order that if anything goes wrong you will at least be able to start the engine and drive away even with flat domestic batteries. In fact the greatest load that is put through the split charge relay is the very fact that you are connecting two banks of batteries together not the output from the alternator, there are many scenarios, the obvious one being that one bank is fully charged and the other bank could be as flat as a haddock.

 

With a badly designed circuit the problem may be compounded because the starter motor is at the same time trying to draw 150 amps. This is why it is important that the engine starting is completed before the battery banks are connected together, the most elegant and almost universal way to do this is to use the charge light output* from the alternator, you can normally guarantee that when that output goes off the starting procedure is over, but even then there can be difficulties as was identified on another thread.

 

This is also why those manual one-both-off switches are not a good idea, massive electrical loads can be put through wiring and components that were not expected to take it.

 

*Some people have problems understanding this output, it is not a strait-forward on/off signal, it instead changes state from +12 volts to 0 volts as charging begins, the light having a permanent +12 volts on it so the light goes out when charging starts. The split charge relay has a 0 volts permanently on it so you will conclude that the relay is energised when the light goes out and charging starts.

[GUMPY]

*Some people have problems understanding this output, it is not a strait-forward on/off signal, it instead changes state from +12 volts to 0 volts as charging begins, the light having a permanent +12 volts on it so the light goes out when charging starts. The split charge relay has a 0 volts permanently on it so you will conclude that the relay is energised when the light goes out and charging starts.

 

Dont think that is quite what you meant to say your voltages are the wrong way round!

 

The light has +12v on it from the IGN switch, this is fed to the alternator through the lamp.

This is what excites the alternator and make it start charging.

When the light is on, the lamp terminal on the back of the alternator is at 0v so if the +ve of your relay is connected here (as it should be) it will not be on.

As the alternator starts to charge this terminal rises to 12v and as there is now no PD across the lamp it goes out, however there is now 12v across the relay so it switches on.

 

 

J

[John Orentas]

Dont think that is quite what you meant to say your voltages are the wrong way round!

 

The light has +12v on it from the IGN switch, this is fed to the alternator through the lamp.

This is what excites the alternator and make it start charging.

When the light is on, the lamp terminal on the back of the alternator is at 0v so if the +ve of your relay is connected here (as it should be) it will not be on.

As the alternator starts to charge this terminal rises to 12v and as there is now no PD across the lamp it goes out, however there is now 12v across the relay so it switches on.

J

 

 

It does sound like one of my daft mistakes but I have read your 'correction' 9 or 10 times and I think we are saying the same thing (except I left out the complication of the IGN switch), I should have said the output changes from 0v to +12v as charging begins but the description is correct.

[GUMPY]

It does sound like one of my daft mistakes but I have read your 'correction' 9 or 10 times and I think we are saying the same thing (except I left out the complication of the IGN switch), I should have said the output changes from 0v to +12v as charging begins but the description is correct.

 

Exactly but it make a whole world of difference

[Denis R]

I'm having a Sterling 4-Stage alternator to battery charger installed at the moment. Both alternators will feed into the unit and the switching between starting battery and domestic batteries is handled by the unit internally. According to the Sterling literature it kicks off by giving the starting battery a boost before switching over to the domestic batteries and then at regular intervals stops what it's doing and goes back to the starting battery and gives that another shot. Their literature describes it properly! My rationale is that I can add the output of my 70 amp and 40 amp alternators to give more 'oomph' to the domestic batteries' charging.

The installer tells me that he's never had any come-back on these units before, but I'll keep you posted on how well it works....

[John Orentas]

Hi Denis.

 

Can I ask, how many batteries have you got.

[Denis R]

Five domestic and one starting I believe.

[blackrose]

I'm having a Sterling 4-Stage alternator to battery charger installed at the moment. Both alternators will feed into the unit and the switching between starting battery and domestic batteries is handled by the unit internally. According to the Sterling literature it kicks off by giving the starting battery a boost before switching over to the domestic batteries and then at regular intervals stops what it's doing and goes back to the starting battery and gives that another shot. Their literature describes it properly! My rationale is that I can add the output of my 70 amp and 40 amp alternators to give more 'oomph' to the domestic batteries' charging.

The installer tells me that he's never had any come-back on these units before, but I'll keep you posted on how well it works....

 

 

I thought part of the idea of these units was that unlike the Sterling alternator regulators they were simple to install and you could easily do it yourself. I assume you chose the 90amp model?

 

Are your alternators an old design? I was made aware by others on this thread that I probably didn't need one of these things because my alternators were modern and would be kicking out over 14v by themselves.

Edited September 22, 2006 by blackrose

[Denis R]

As far as I'm concerned it is easy to install - just that my boat's still under warranty so the builder's doing it and also I couldn't be bothered to do it myself anyway. My understanding of the theory of charging lead acid batteries is not complete and I've no intention of opening a debate on it, but from what I've read, the 4-stage charging method is superior to the basic charge profile from an alternator, even the modern ones fitted to my Beta 35. I'm going for it so I don't have to run the engine whilst I'm stationary any longer than I have to. The 4-stage charging certainly seems to work with the Victron inverter I've got installed, so I thought I'd replicate it on the engine charging circuit. Mine's the 160 amp model.

[John Orentas]

Five domestic and one starting I believe.

 

 

Hi Denis.

 

The maximum charge rate you could reasonably put into your 660 a/h battery bank is about 66 amps so your 70 amp alternator will comfortably take care of that on it's own. By making a connection between your two alternators as you propose you will be destroying the most important aspect of a twin alternator system, that of having two totally independent circuits.

 

Indeed worse than that no matter what others or even the manufacturers may say a fault on one part of the system is likely to take out both alternators, like you I have no wish to enter into any kind of further debate.

 

Edited for picky criticism.

Edited September 22, 2006 by John Orentas

[GUMPY]

Hi Denis.

 

The maximum charge rate you could reasonably put into your 660 a/h battery bank is about 66 amps so your 70 amp alternator will comfortably take care of that on it's own. By making a connection between your two alternators as you propose you will be destroying the most important aspect of a twin alternator system, that of having two totally independent circuits.

 

Indeed worse than that no matter what others or even the manufacturers may say a fault on one part of the system is likely to take out both alternators, like you I have no wish to enter into any kind of further debate.

 

I have to pick up on this as its misleading

There is no such thing as maximum charge rate, its all down to how long you want to keep your batteries.

You could charge at 400amps but the batteries wouldnt last long, a good compromise is between 25-35% of the battery capacity the 10% rule is utter B......

Yes if you charge at 10% your batteries will last a long time but think of this a 100Ah battery charging at 10amps from 50% charge will take 6-7 hours at 20 amps it will take 3-3.5hours yes I know that it will fractionally shorten battery life but in an ideal world batteries should be float charged and not charged and discharged.........

 

If you doubt my words look here

 

http://www.smartgauge.co.uk/chargesize.html

 

Yes I know its that site again but its one of the few that tell it as it is and dont perpetuate old wives tales.

 

J

Edited September 22, 2006 by idleness