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Alternator / Battery wiring question


chunkyj

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oh dear so are you going to tell them :)

You're really not very observant, are you? Matty did so 5 posts before you asked this question.

95 quid for a VSR you are avin a larf

If you have a SmartGauge then Smartbank interfaces with it intelligently for a lot less, I believe.

 

Tony

Nothing relating to VSR relays on Google. Who made up the abbreviation.sad.png

I just googled for "12V VSR" and got dozens of hits.

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It is not only about the current from the alternators it is also about the current available to flow between the two batteries when the relay makes and when using the domestic as an emergency start backup

 

that doesn't make sense to me, under the conditions that would require you to use the domestic batteries as starter batteries (in itself a bad idea if they are traction ones) the relay would be open circuit.

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He's probably put me on ignore like hes put everyone else that keeps correcting his electrical misinformation posts.

Ahh yes, quite likely.

 

that doesn't make sense to me, under the conditions that would require you to use the domestic batteries as starter batteries (in itself a bad idea if they are traction ones) the relay would be open circuit.

You're correct John except that it offers a feature whereby you can force it to close temporarily for just such an eventuality.

 

Guess I should edit to add 'just like Smartbank'

Edited by WotEver
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You're really not very observant, are you? Matty did so 5 posts before you asked this question.

 

If you have a SmartGauge then Smartbank interfaces with it intelligently for a lot less, I believe.

 

Tony

 

I just googled for "12V VSR" and got dozens of hits.

 

I did not need to be told I knew what it was, still not sure you did. But people who own boats don't always know all the acronyms. As for Matty who is he I see no post?

 

Re your google searh, your search was different to the natural search any non technical boater was likely to use, they would use the acronym VSR

 

that doesn't make sense to me, under the conditions that would require you to use the domestic batteries as starter batteries (in itself a bad idea if they are traction ones) the relay would be open circuit.

 

Try reading the spec

Edited by Graham.m
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As for Matty who is he I see no post?

Well now, you see, here's the problem.

 

If you continue to put everyone who corrects all your erroneous posts onto 'ignore' then you miss whole sections of a thread. Then you make yourself look stupid by asking a question that was answered half a dozen posts previously. Or by repeating something that's already been said.

 

But don't mind me, feel free to carry on. I'm sure that any observer can quickly determine who offers accurate information and who doesn't.

 

Tony

VSR comes up with it in the list of related searches

Yup, it does.

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I have posted these figures before. If you have a big, big engine that draws 350A to start and you crank it for ten seconds (count it off, that's a long start) Then the battery has expended ONE Ah. Prioritising the engine battery to full charge would be technically difficult and utterly purposeless as well as wasting hundreds of Ah that could have gone into the domestics. Connect both alternators to the domestics and relay across to the engine and forget it forever.

  • Greenie 1
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I have posted these figures before. If you have a big, big engine that draws 350A to start and you crank it for ten seconds (count it off, that's a long start) Then the battery has expended ONE Ah. Prioritising the engine battery to full charge would be technically difficult and utterly purposeless as well as wasting hundreds of Ah that could have gone into the domestics. Connect both alternators to the domestics and relay across to the engine and forget it forever.

 

 

Point of order M'lud...

 

The draw would need to be 360A for ten seconds, not 350A...

 

ninja.gif

 

 

But the principle you are illustrating stands. I'm just enjoying the opportunity for a bit of extreeme pedantry :)

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Ok guys, some good comments there, and some slightly of topic as well ;)

 

Just for a bit more clarification, I have a Princess 32 motorboat, it has 2 x GMC 6.2litre v8's with a 70A alternator on each engine

 

At present I am not happy with the battery setup, it has 3 x 110aH batteries all connected seperatly over 2 (1/2/both/off) rotary switchs.

What I am looking for is a solution so I can have 2 x 110aH batteries as my starter batteries and another bank of domestic batteries.

 

Now I have seen this http://sterling-power.com/products/volt-drop-alternator-splitting-system-pro-split-r?variant=882767643

but I don't know if there are any better options out there?

 

Hope this adds a bit of clarity to the proceedings?

 

:D

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At present I am not happy with the battery setup, it has 3 x 110aH batteries all connected seperatly over 2 (1/2/both/off) rotary switchs.

What I am looking for is a solution so I can have 2 x 110aH batteries as my starter batteries and another bank of domestic batteries.

Being pedantic, the batteries can't all be separate with that switch, two of them must be in a pair already.

 

Depending on the current rating of your switch you can have the batteries arranged as you desire without requiring any extra hardware, but it does require manual discipline.

 

Engine 1 has its alternator connected to bank 1 (call it the starter bank if you like).

Engine 2 has its alternator connected to the other (domestic) bank.

 

Once both engines are running switch the switch to 'both'. When the engines are stopped switch the switch to the domestic bank only.

 

Lastly, I doubt that you truly need two batteries to start the engines. Once one engine is running it will quickly start to replenish the small amount you've taken to start it.

 

Tony <-- not the one Snib was referring to

 

Edited for clarity.

Edited by WotEver
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Ok guys, some good comments there, and some slightly of topic as well ;)

 

Just for a bit more clarification, I have a Princess 32 motorboat, it has 2 x GMC 6.2litre v8's with a 70A alternator on each engine

 

At present I am not happy with the battery setup, it has 3 x 110aH batteries all connected seperatly over 2 (1/2/both/off) rotary switchs.

What I am looking for is a solution so I can have 2 x 110aH batteries as my starter batteries and another bank of domestic batteries.

 

Now I have seen this http://sterling-power.com/products/volt-drop-alternator-splitting-system-pro-split-r?variant=882767643

but I don't know if there are any better options out there?

 

Hope this adds a bit of clarity to the proceedings?

 

:D

What I'd do is to connect both the alternators to the domestic bank. Then from the domestic bank +ve have relays going to each of the engine battery +ves. These relays would ideally be operated by connecting the coil between the relevant alternator's D+ wire ( ie the one that goes to the warning light), and -ve.

 

So with the engine off the voltage on the D+ will be low and the relay open, domestic and engine batteries seperated. When the engine starts and the alternator warning light goes out it does so because the voltage on the D+ rises to system voltage and so the relay operates and connects the starter battery to the domestics and thus receives charge.

 

Personally I think this is a better and cheaper way of doing it than a VSR, and a common way, although I think with some types of alternator it can requir a bit of tweaking such as adding a resistor across the alternator warning light to compensate for the relay sapping excitation current.

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