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charging when battery isolated

Boaty McBoaty
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Boaty McBoaty Engager

Boaty McBoaty

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Hi there. 

 

Am I right to assume that when on shore supply an inverter/charger will charge the batteries even when the batteries are isolated? 

 

Our canal has been bone dry for months so Boaty is sitting on the bottom and engine skin tanks are out of the water so I haven't been running engine.  When on board I have only turned on the leisure batteries and been using generator via my shore supply to charge batteries.  I am assuming that even though I have kept the starter battery isolated it should still be charged from the inverter/charger?  Thanks.

 

 

 

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Alan de Enfield Veteran II

Alan de Enfield

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1 minute ago, Boaty McBoaty said:

Hi there. 

 

Am I right to assume that when on shore supply an inverter/charger will charge the batteries even when the batteries are isolated? 

 

Our canal has been bone dry for months so Boaty is sitting on the bottom and engine skin tanks are out of the water so I haven't been running engine.  When on board I have only turned on the leisure batteries and been using generator via my shore supply to charge batteries.  I am assuming that even though I have kept the starter battery isolated it should still be charged from the inverter/charger?  Thanks.

 

 

 

 

Normally - YES.

 

But every boat is wired up differently - is your battery charger wired in via the isolator switches or directly onto the battery terminals ?

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nicknorman Veteran II

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Posted
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13 minutes ago, Boaty McBoaty said:

Hi there. 

 

Am I right to assume that when on shore supply an inverter/charger will charge the batteries even when the batteries are isolated? 

 

Our canal has been bone dry for months so Boaty is sitting on the bottom and engine skin tanks are out of the water so I haven't been running engine.  When on board I have only turned on the leisure batteries and been using generator via my shore supply to charge batteries.  I am assuming that even though I have kept the starter battery isolated it should still be charged from the inverter/charger?  Thanks.

 


Depends on the inverter charger and how it is wired. Many inverter chargers have a secondary charging output for the starter battery. Which may or may not have been connected. The BSS allows the charger connection to bypass the battery isolator. But it may or may not have been wired up that way.

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Tracy D'arth Veteran II

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Posted
Posted
23 minutes ago, Boaty McBoaty said:

Hi there. 

 

Am I right to assume that when on shore supply an inverter/charger will charge the batteries even when the batteries are isolated? 

 

Our canal has been bone dry for months so Boaty is sitting on the bottom and engine skin tanks are out of the water so I haven't been running engine.  When on board I have only turned on the leisure batteries and been using generator via my shore supply to charge batteries.  I am assuming that even though I have kept the starter battery isolated it should still be charged from the inverter/charger?  Thanks.

 

 

 

If it is wired correctly and your BSS examiner was happy,    no.

The clue is in the word "isolated"

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nicknorman Veteran II

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1 minute ago, Tracy D'arth said:

If it is wired correctly and your BSS examiner was happy,    no.

The clue is in the word "isolated"

Incorrect. The BSS allows a battery charger to bypass the isolator provided the wire is fused. Why not have a look at the actual documentation instead of guessing?

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ditchcrawler Veteran II

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Posted
Posted
26 minutes ago, Boaty McBoaty said:

Hi there. 

 

Am I right to assume that when on shore supply an inverter/charger will charge the batteries even when the batteries are isolated? 

 

Our canal has been bone dry for months so Boaty is sitting on the bottom and engine skin tanks are out of the water so I haven't been running engine.  When on board I have only turned on the leisure batteries and been using generator via my shore supply to charge batteries.  I am assuming that even though I have kept the starter battery isolated it should still be charged from the inverter/charger?  Thanks.

 

 

 

As you will have realised, it is impossible to say without looking at your system. A volt meter on the batteries while the genny/charger are working will tell you.

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Tracy D'arth Veteran II

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Posted
Posted (edited)
27 minutes ago, nicknorman said:

Incorrect. The BSS allows a battery charger to bypass the isolator provided the wire is fused. Why not have a look at the actual documentation instead of guessing?

Its not a battery charger but an inverter charger therefore it should be isolated. Why don't you learn some manners instead of being shirty?

Edited by Tracy D'arth
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nicknorman Veteran II

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Posted
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2 minutes ago, Tracy D'arth said:

Its not a battery charger but an inverter charger therefor it should be isolated. Why don't you learn some manners instead of being shirty?

You are incorrect. It is functioning as a charger. Thousands of boats have Combi inverter chargers connected both to the domestic batteries and the starter batteries, bypassing the isolator switches. Including ours. And of course it is installed in accordance with the manufacturer’s installation manual. Thankfully you aren’t a BSS examiner.

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ditchcrawler Veteran II

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1 hour ago, Boaty McBoaty said:

OK, so seems the general consensus is 'likely/probably' ................. next time on board I will look and see if I can see where the wires go etc and also put a volt meter on to experiment with isolators on/off etc.  Thanks everyone, much appreciated. 

 

Boaty  

 

 

Unless your charger has multiple outlets, Sterling do a charger with three, its unlikely its charging both domestic and starter batteries, what charger do you have. 

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Alan de Enfield Veteran II

Alan de Enfield

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42 minutes ago, ditchcrawler said:

Unless your charger has multiple outlets, Sterling do a charger with three, its unlikely its charging both domestic and starter batteries, what charger do you have. 

 

For example my Victron (50 amp) charger has a dedicated '4-amp trickle charger' for the starter battery and 2 separate outputs (total 50 amps) for 2x domestic banks. If only one of these outputs is connected then it gets the full 50 amps.

 

 

 

Screenshot (1597).png

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Boaty McBoaty Engager

Boaty McBoaty

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37 minutes ago, Alan de Enfield said:

 

For example my Victron (50 amp) charger has a dedicated '4-amp trickle charger' for the starter battery and 2 separate outputs (total 50 amps) for 2x domestic banks. If only one of these outputs is connected then it gets the full 50 amps.

 

 

 

Screenshot (1597).png

I think you might be on to something there........... mine suggests an additional loop is required to include the starter battery in the charging loop if I understand the diagram correctly............ so I need t follow the cables and see what Ido and don't have and like you said before I will experiment with a meter to see what is and isn't receiving any charge.  So if I have inadvertently neglected to charge the starter then will have to get a new one but should be a bit better informed thanks on how to look after that one.........

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nicknorman Veteran II

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Posted
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1 minute ago, Boaty McBoaty said:

I think you might be on to something there........... mine suggests an additional loop is required to include the starter battery in the charging loop if I understand the diagram correctly............ so I need t follow the cables and see what Ido and don't have and like you said before I will experiment with a meter to see what is and isn't receiving any charge.  So if I have inadvertently neglected to charge the starter then will have to get a new one but should be a bit better informed thanks on how to look after that one.........

Whilst not ideal for long life, if the starter battery has been isolated for say 6 months, it should still be fine for starting the engine. Self-discharge rate for a starter battery in good condition is quite low.

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Boaty McBoaty Engager

Boaty McBoaty

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3 minutes ago, nicknorman said:

That one doesn’t have a separate starter battery output, so the starter battery won’t be charged unless there is an additional VSR etc.

So that's what the 'Strombegrenzendes Spannungsempfindliche Relay' is on my schematic 😉 need to find an english booklet lol

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Tony Brooks Veteran II

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Posted
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5 minutes ago, Boaty McBoaty said:

So that's what the 'Strombegrenzendes Spannungsempfindliche Relay' is on my schematic 😉 need to find an english booklet lol

 

Google suggests it might be a voltage sensitive relay, but it also talks about current limiting so who knows. As your diagram says relay I would suggest that you post an image of the diagram so we can see where and how it is connected. If it is a single alternator boat it makes it being a VSR more likely. If so your charger should charge both banks, the engine bank via that relay.

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Tony Brooks Veteran II

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Posted
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My advice is not to wire as per the Sterling diagrams because you put the full alternator output plus more provided by a well charged start battery with lower domestic batteries make relay burn out more likely. There are other opinions, but in my view they are a result of lack of thought and marketing bullshine.

 

I would always connect the alternator output to the domestic bank and use the VSR to connect the start battery to the charge. Unless faulty start batteries are almost always more or less fully charged, even immediately after a start, so the current flowing through the relay is low and the domestic bank can't add anything more to it. The two banks will automatically apportion the available charge between themselves according to their relative states of charge.

 

Personally if your alternator is a 100 amp unit or less I would not buy a well known branded marine make, I would use an ordinary sub £59 140 amp bidirectional VSR from the likes of Cargo.

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blackrose Veteran II

blackrose

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Posted (edited)
2 hours ago, Alan de Enfield said:

 

For example my Victron (50 amp) charger has a dedicated '4-amp trickle charger' for the starter battery and 2 separate outputs (total 50 amps) for 2x domestic banks. If only one of these outputs is connected then it gets the full 50 amps.

 

 

 

Screenshot (1597).png

 

All chargers are different of course. On my 3 x output Sterling Pro-digital charger (not combi) if you are only charging one battery bank then the recommendation is to link all 3 outputs together. If you are charging 2 battery banks then 2 outputs should be linked and connected to the biggest battery bank. Your Victron charger is probably more sophisticated and takes care of that itself.

Edited by blackrose
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