What size/type of relay for charging system and where to buy it

oldfatgit said:
If anybody has managed to read my rather turgid post, one final question; where does one buy a good quality VSR? I have used the Google thing but cannot decide.
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I had a BEP VSR which was about 60 quid and still working when I sold the boat. They are also available from motorhome suppliers for about half that and appear identical although they do not have the 'marine' tag. I personally wouldn't skimp on such a cheap item.
 
ghostlymoron said:
Yes I agree with pvb and nigel, the power taken to start the engine is very small (high current but short duration) assuming the engine doesn't require prolonged cranking.
I don't agree that most boats have advanced regulator controllers. It may be true of new boats (but I suspect it isn't) but I have yet to sail on one. The reason is that most boats alternator/regulator cope perfectly well with the power demands on them, even though the system was originally designed for automobiles. It's only when owners overload their boats with electric hungry gadgets that they need to squeeze the last joule of power from their system that the simple system isn't adequate.
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I think you've overlooked the difference between marine and automotive uses. On the road all the power requirements are supplied by the alternator and the battery only used for starting and therefore very quickly charged back up to its pre starting state. There is no requirement to charge the battery above the 80% or so of its actual capacity when its only needed for starting.

On sailing vessels, where power is required for long periods without any engine driven charging, its both logical and sensible to ensure the batteries are as fully charged as possible. Hence the need for intelligent multi stage regulators. What's the point of buying 100ah batteries if, due to a poor charging system their useable capacity is less than 40ah (80% less the 40% minimum discharge level = 40% ie 40ah). This is one of the main reasons for owners power problems. Adding larger or additional batteries is probably not necessary if the existing one(s) were properly charged and they'd last longer to boot.
 
ianj99 said:
I think you've overlooked the difference between marine and automotive uses. On the road all the power requirements are supplied by the alternator and the battery only used for starting and therefore very quickly charged back up to its pre starting state. There is no requirement to charge the battery above the 80% or so of its actual capacity when its only needed for starting.

On sailing vessels, where power is required for long periods without any engine driven charging, its both logical and sensible to ensure the batteries are as fully charged as possible. Hence the need for intelligent multi stage regulators. What's the point of buying 100ah batteries if, due to a poor charging system their useable capacity is less than 40ah (80% less the 40% minimum discharge level = 40% ie 40ah). This is one of the main reasons for owners power problems. Adding larger or additional batteries is probably not necessary if the existing one(s) were properly charged and they'd last longer to boot.
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So why don't most people fit them?
 
ghostlymoron said:
So why don't most people fit them?
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Probably because they don't understand why they should. I'd put money on most of the threads on this forum about battery problems are fundamentally due to poor charging systems and lack of thought on just how those big new batteries are actually going to be charged up again.
Adverc, another digital regulator manufacturer supply their alternators and regulators to ambulance builders so that the auxilliary batteries are both charged as close to 100% as possible, charge up faster, and the available charging current when the vehicle is sat idling is higher.

Motorhome owners suffer from exactly the same power shortages as yacht owners and they too benefit from an advanced regulator so the van battery doesn't require hours of driving to charge it back up after an overnight stop.
 
I agree that having more battery capacity makes no sense if you've got no means of charging it and that having a smart regulator is probably 'a good thing' but the fact remains that I and many other sailors don't need one provided we don't run a colour telly and refrigerator.
 
This discussion has been very useful for those of us less informed.

Can anyone recommend a alternator regulator and charging system,
I have engine start battery and a domestic pair. All 12v.
I am hoping to eek out the best of my batteries, and give them a longer life...
Is there a one or two box system that does all, without spending a thousand pounds.

Cheers
Rob
 
Robg71 said:
Can anyone recommend a alternator regulator and charging system,
I have engine start battery and a domestic pair. All 12v.
I am hoping to eek out the best of my batteries, and give them a longer life...
Is there a one or two box system that does all, without spending a thousand pounds.
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If cost is a consideration, for under £100 you could have a Sterling Pro Reg B alternator regulator, which would boost the charging voltage and achieve higher charging efficiency. But before spending the money, measure what charge voltage you're already getting at the batteries from your standard alternator. If it's 14.2-14.4v, you won't see much improvement with an add-on regulator.
 
pvb said:
If cost is a consideration, for under £100 you could have a Sterling Pro Reg B alternator regulator, which would boost the charging voltage and achieve higher charging efficiency. But before spending the money, measure what charge voltage you're already getting at the batteries from your standard alternator. If it's 14.2-14.4v, you won't see much improvement with an add-on regulator.
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I think i can manage a fiver more :)
I dont mind spending enough to do the job, (which hopefully wont be any where near a thousand.

I thought these regulators had far superior charging profiles, rather than just a different or higher volatge rail...
I will check my alternator though...

Cheers
Rob
 
Robg71 said:
I think i can manage a fiver more :)
I dont mind spending enough to do the job, (which hopefully wont be any where near a thousand.

I thought these regulators had far superior charging profiles, rather than just a different or higher volatge rail...
I will check my alternator though...
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Add-on "smart" regulators only increase the alternator voltage, they can't decrease it below the level set by the alternator's internal regulator. Therefore they can't achieve an ideal charging profile with a float voltage. But if the standard alternator voltage is too low, or if there are voltage losses due to diodes or thin cabling, an add-on regulator can help.

If you want to spend a bit more, consider a Sterling Alternator to Battery Charger. This can achieve a float voltage, doesn't require any modifications to the alternator, and has an unboosted isolated output to the engine start battery (so it effectively replaces a diode splitter arrangement).
 
So it will charge my main engine battery's, then switch to domestics....
All in one package, and put more juice in my battery's at the same time, as being kinder to them...

If so, then that sounds like just what i am after....
Cheers
Rob
 
Robg71 said:
So it will charge my main engine battery's, then switch to domestics....
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No, it has 2 isolated outputs, both of which work immediately and simultaneously. One output, for the starter battery, is unboosted and goes through a diode to ensure the start battery is isolated. The second output is boosted, using a fairly intelligent cycle including a float voltage. You can see typical expected voltage/current graphs in the installation manual ( http://www.sterling-power.com/image...or-to-Battery Chargers and Remote Control.pdf ).

I don't have one of these, and have no experience of it, but it's certainly something I'd consider if I needed an improvement to my charging regime.
 
Thanks very much.
At the moment i have two engines, each with its own alternator, each charging one bank. One engine, one domestic, but i would like to know my batteries are charged as efficiently and as full as possible. It may make the difference to another day at anchor or two....
So many thanks for the tips.

Hope i haven't hi jacked somebody's thread
Regards
Rob
 
Hi folks (OP, here)

Many thanks for a superb response. I would love to go the Sterling Alternator to Battery Charger route but I decided to start with something simpler and cheaper and sort all my other problems out first. I am eliminating all the power-hungry electronics on the boat... autopilots were the first to go in favor of Monitor+Tiller pilot because they were both (I had a backup) destroyed both times by the lightning... very expensive!

Thus I have bought a Cyrix-i 12/24V-120A Intelligent Combiner from Energy Solutions (at http://www.es-store.co.uk/victron-cyrix-battery-combinersisolators/SCR-CYRIX-120-I-12-24.html ) for £38.86 including VAT, free postage in the UK. I was persuaded by this thread that the Cyrix was better than the BEP. Incidentally, my local chandler (who I'd prefer to patronize) wanted £72.45 for a single-sensing BEP, while a double-sensing BEP (still in original packaging) went for £32 plus £3 postage on eBay yesterday.

Buying online from Energy Solutions was easy, instant and good value. I fear for the physical chandlers as online stores get better and better. A physical chandler merely offering the same high prices online won't be enough.

Again thanks to all for sharing so much experience and common sense. Very encouraging.

Kind regards

Gerry
 
The Cyrix looks a good choice although it hasn't got the indicator lights that tell you what it's doing like the BEP unit. This is a feature that I like but I suppose is not absolutely necessary. I don't like the idea of combining batteries in an emergency if the starter battery has packed up, I would prefer to have it set up so that you could use the 'house' battery on it's own. I'm not an authority on electrics but it would seem to me that if you combine a 10.1 volt battery with a 12.7 volt battery, you'll only get 11.4 volts which may not be enough to spin the engine fast enough.
 
ghostlymoron said:
I don't like the idea of combining batteries in an emergency if the starter battery has packed up, I would prefer to have it set up so that you could use the 'house' battery on it's own. I'm not an authority on electrics but it would seem to me that if you combine a 10.1 volt battery with a 12.7 volt battery, you'll only get 11.4 volts which may not be enough to spin the engine fast enough.
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I agree, and don't think it's a good idea at all. If you look at the little diagram I included in post #32, you'll see the emergency switch is wired in such a way that the starter battery switch can be turned off first, ensuring that the house battery voltage doesn't get dragged down by a flat starter battery. A simple way to ensure this happens is to use those switches with red removable handles, and only have 2 handles for the 3 switches - then the start battery switch has to be turned off to remove the handle to use on the emergency switch.
 
What a pleasant thread this is - everyone keeps agreeing with me. And outside the sun is shining, maybe I'll go and buy that 29 footer I'm looking at - there's just about enough time to get it up-graded by Easter. Sorry if anyone thinks this post should have been sent to the Lounge.:)
 
I realise this is an old thread, but I have read all the comments with interest and have pretty much decided to fit a VSR (Merlin VSR140) per the circuit on an earlier post. One of the reasons I had for fitting one is because I thought that it would enable some of the capacity of the engine battery to be used for domestic when the engine battery is fully charged. Am I correct in this thinking or is a VSR purely to ensure that the engine battery always has power?
 
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