1-2-Both-Off

[jac]

I would fit isolating switches. Omitted from the diagram for clarity.

Post a diagram showing how you would do it.

Sorry Vic - not a criticism of your diagram per se - i think it would work as drawn.

My criticism was of the basic approach - 1 2 both off are an outdated approach that may have made sense when an engine start battery and a domestic battery were basically the same size and type and when manual start was a valid option for the engine but make no sense given the growth in demand on domestic electrics and larger engines that can't really be started manually. They run the massive risk that someone will leave them switched to both when using domestic bank and being unable to start the engine or in this situation leave it switched to charge the wrong set of batteries and again ending up with a flat.

Modern solutions remove that risk by automating the charging and making it v hard to discharge the engine start.

Personally i would have 2 banks - with isolators and another isolator to enable the domestic bank to start the engine in an emergency. Then keep it simple. Another smallish battery ( 100 Ah ish) in the bow for windlass and bow-thruster if required - charged by B2B charger. Then for charging - dual output mains charger for when shore power attached. I have also had good experience with a sterling A to B charger for when using the alternator to charge. Finally Solar via an appropriate controller wired to the domestic bank but would probably not bother with a dual output solar controller and charging to the engine start battery unless I was in the habit of leaving the boat for months at a time. If that ever become an issue a very small (5W?) Panel would probably provide enough to cover the self discharge of the engine start battery without introducing the complexity of split charge solutions into something that will almost always be charging the domestic bank anyway.

This still leaves the small risk that the engine start could be flattened by someone operating the emergency parallel isolator. That can be mitigated by having one with a removable switch and the switch is removed ( securely attached of course) then a simple visual check to ensure engine and domestic are on and the switch is removed from the parallel should suffice. It is one of those risks that is outweighed by the ability to switch to an alternative battery to start the engine in seconds rather than have to dig out jump leads etc.

 

[Tranona]

My biggest worry as systems get more complicated is the risk of switching off batterys from alternator while engine running .... as more switches and combinations are added ... the easier it is to have a brain-fart moment !!

IMHO of course ....

That simply won't be a problem. All the isolator does is isolate the individual battery from its circuits, the other(s) are still connected to the alternator through the splitter/VSR and will still be taking charge from the alternator.

It really is idiot proof unlike the old systems where you have to remember which battery is in use and you can flatten both batteries leaving no power for starting. What could be more simple than a battery for each function that is independent of the others and charged automatically from each charging source (alternator, mains, solar if you have it). It is the complexity of modern (and bigger boat) systems that require simplicity to operate well.

People get used to working round the shortcomings of what they have but if confronted with new systems quickly recognise the benefits. My latest car has automatic lights and wipers plus a digital speedo. Can't remember the last time I touched the switches (except to turn off the wipers when going through the car wash) or looked at the speedo dial. The biggest adjustment I have to make is when I drive my wife's old car.

 

[geem]

Sorry Vic - not a criticism of your diagram per se - i think it would work as drawn.

My criticism was of the basic approach - 1 2 both off are an outdated approach that may have made sense when an engine start battery and a domestic battery were basically the same size and type and when manual start was a valid option for the engine but make no sense given the growth in demand on domestic electrics and larger engines that can't really be started manually. They run the massive risk that someone will leave them switched to both when using domestic bank and being unable to start the engine or in this situation leave it switched to charge the wrong set of batteries and again ending up with a flat.

Modern solutions remove that risk by automating the charging and making it v hard to discharge the engine start.

Personally i would have 2 banks - with isolators and another isolator to enable the domestic bank to start the engine in an emergency. Then keep it simple. Another smallish battery ( 100 Ah ish) in the bow for windlass and bow-thruster if required - charged by B2B charger. Then for charging - dual output mains charger for when shore power attached. I have also had good experience with a sterling A to B charger for when using the alternator to charge. Finally Solar via an appropriate controller wired to the domestic bank but would probably not bother with a dual output solar controller and charging to the engine start battery unless I was in the habit of leaving the boat for months at a time. If that ever become an issue a very small (5W?) Panel would probably provide enough to cover the self discharge of the engine start battery without introducing the complexity of split charge solutions into something that will almost always be charging the domestic bank anyway.

This still leaves the small risk that the engine start could be flattened by someone operating the emergency parallel isolator. That can be mitigated by having one with a removable switch and the switch is removed ( securely attached of course) then a simple visual check to ensure engine and domestic are on and the switch is removed from the parallel should suffice. It is one of those risks that is outweighed by the ability to switch to an alternative battery to start the engine in seconds rather than have to dig out jump leads etc.

Sorry Vic - not a criticism of your diagram per se - i think it would work as drawn.

My criticism was of the basic approach - 1 2 both off are an outdated approach that may have made sense when an engine start battery and a domestic battery were basically the same size and type and when manual start was a valid option for the engine but make no sense given the growth in demand on domestic electrics and larger engines that can't really be started manually. They run the massive risk that someone will leave them switched to both when using domestic bank and being unable to start the engine or in this situation leave it switched to charge the wrong set of batteries and again ending up with a flat.

Modern solutions remove that risk by automating the charging and making it v hard to discharge the engine start.

Personally i would have 2 banks - with isolators and another isolator to enable the domestic bank to start the engine in an emergency. Then keep it simple. Another smallish battery ( 100 Ah ish) in the bow for windlass and bow-thruster if required - charged by B2B charger. Then for charging - dual output mains charger for when shore power attached. I have also had good experience with a sterling A to B charger for when using the alternator to charge. Finally Solar via an appropriate controller wired to the domestic bank but would probably not bother with a dual output solar controller and charging to the engine start battery unless I was in the habit of leaving the boat for months at a time. If that ever become an issue a very small (5W?) Panel would probably provide enough to cover the self discharge of the engine start battery without introducing the complexity of split charge solutions into something that will almost always be charging the domestic bank anyway.

This still leaves the small risk that the engine start could be flattened by someone operating the emergency parallel isolator. That can be mitigated by having one with a removable switch and the switch is removed ( securely attached of course) then a simple visual check to ensure engine and domestic are on and the switch is removed from the parallel should suffice. It is one of those risks that is outweighed by the ability to switch to an alternative battery to start the engine in seconds rather than have to dig out jump leads etc.

We have each batteries voltage displayed on the switch panel in the saloon using large illuminated led voltmeters. It soon becomes obvious when a battery is linked to another for me as the voltage would stay the same.
I am not a fan of VSRs as they don't consider battery charge of the joined batteries and simply bang amps in to an average battery voltage whether the battery needs it or not. They don't improve the charge profile any better than a 1,2,both switch. They simply provide a level of automation. In my mind things have moved on and you can now have a proper 3 stage charging profile using a B2B for your domestic battery bank, charging off the engine battery whilst motoring. Not cheap but far better.
There are so many ways to configure stuff these days and so much good kit about, the choices are endless

 

[oldmanofthehills]

All very well but none of the above are affordable and installable by Tom.

They are ideal as built in from new or installed by a budding electrical engineer with time on their hands and some cash - even I only tick two of those boxes.

A £5 isolator at the house battery is cheap and easy to fit in line - or just use separate halfords battery charger for the engine battery and jobs a good un

 

[Refueler]

All very well but none of the above are affordable and installable by Tom.

They are ideal as built in from new or installed by a budding electrical engineer with time on their hands and some cash - even I only tick two of those boxes.

A £5 isolator at the house battery is cheap and easy to fit in line - or just use separate halfords battery charger for the engine battery and jobs a good un

The Charge splitter is a very simple affair ... charge leads in ... two sets of leads out ... one for each battery. Its fit and forget.

He can then leave his present setup alone and when he wants to charge batt's - the 10 quid splitter will look after it.

2 Way Split Charge Relay Charging Module - 6, 12 & 24 Volts

Or a couple of these plugged into mains on boat and clipped one to each battery : >

Designed to maintain RV batterys during storage ...

 

[Tranona]

The Charge splitter is a very simple affair ... charge leads in ... two sets of leads out ... one for each battery. Its fit and forget.

He can then leave his present setup alone and when he wants to charge batt's - the 10 quid splitter will look after it.

2 Way Split Charge Relay Charging Module - 6, 12 & 24 Volts

Or a couple of these plugged into mains on boat and clipped one to each battery : >

Designed to maintain RV batterys during storage ...

Not quite as simple as it looks with that cheap device. the OP has a very big house battery bank and a big engine start battery (140Ah from memory to start an 80hp Perkins) and no doubt his battery charger is sized accordingly. So he may well find a 10A maximum (20A if mounted on a heat sink) rather limiting!

 

[Refueler]

Not quite as simple as it looks with that cheap device. the OP has a very big house battery bank and a big engine start battery (140Ah from memory to start an 80hp Perkins) and no doubt his battery charger is sized accordingly. So he may well find a 10A maximum (20A if mounted on a heat sink) rather limiting!

Did I say fit to alternator ??

It sits well between charger and batterys .... think you and P need to go back and read posts fully.

Knock it all you like guys ..... it works.

 

[VicS]

Did I say fit to alternator ??

It sits well between charger and batterys .... think you and P need to go back and read posts fully.

Knock it all you like guys ..... it works.

No
We are concerned with charging a large engine start battery and a very large house battery bank in parallel from a battery charger which presumably will have an appropriately high output current

Tranona's point was that the Kemo gadget probably does not have a high enough current rating for this application.

Nobody is knocking it or doubting that it works for the use you have for it

 

[Tranona]

Did I say fit to alternator ??

It sits well between charger and batterys .... think you and P need to go back and read posts fully.

Knock it all you like guys ..... it works.

No, but neither did I. You clearly have not read what I wrote, as in fact I specifically commented on his MAINS charger (and never mentioned the alternator), which I guess is 30 or 40A and if the 140Ah start battery is well down it will take all of that and fry that little gizmo.

If you have heavy duty gear you need to buy and fit things designed for that. I know you always go on about going to RV and caravan shops but that is really not a good idea when you have a boat with the type of system the OP has (or indeed even more modest boats like mine). Such shops sell exactly the same type of gear as marine IF the requirements are the same. That gizmo is cheap because it is for a lighter duty application than is normal in a decent size boat. Of course you can use such equipment on smaller boats if they fit within the simpler systems. It would work on mine (mounted on a heat sink) as I only have 15A charger, but if I wanted to charge more than one battery I would have fitted a 3 output charger which is incrementally around £20 more than a single - not much more than an inadequate separate splitter such as you are suggesting.

 

[Refueler]

AND ... it was an example ... if you guys care to check instead of jumping on the usual knock it band wagon ... there are various levels of units capable of covering MORE than what you are on about ...

A little googling of such split charge units will open up a world that will amaze you .... instead of just opening the wallet and getting fleeced ...

You will of course continue your jousting ... fine ... go ahead ... I'm away to sort out the purchase of a replacement genny ... much more important ...

 

[Refueler]

No
We are concerned with charging a large engine start battery and a very large house battery bank in parallel from a battery charger which presumably will have an appropriately high output current

Tranona's point was that the Kemo gadget probably does not have a high enough current rating for this application.

Nobody is knocking it or doubting that it works for the use you have for it

In fact I should have mentioned in the post - that it was an example of the units ... with then ranging in low to extreme high power ... I don't in fact disagree that the unit I used as example is not suited to high power rating ... but I quickly looked for an example ... next time to keep everyone happy - I shall link to the high power .... but for now - I'm not interested to do it ... no disrespect to you VicS ....

 

[Tranona]

AND ... it was an example ... if you guys care to check instead of jumping on the usual knock it band wagon ... there are various levels of units capable of covering MORE than what you are on about ...

A little googling of such split charge units will open up a world that will amaze you .... instead of just opening the wallet and getting fleeced ...

You will of course continue your jousting ... fine ... go ahead ... I'm away to sort out the purchase of a replacement genny ... much more important ...

You specifically said that unit would do the job for him - and it won't. You did NOT say it is an example. The same site has higher spec split charge systems that could handle the current BUT they are nearly 5 times the price of the one you suggested. so you can see why I was surprised that you thought a £10 gizmo would do the job.

Nobody is getting "fleeced". If you are buying a proper multistage charger that can be programmed to the exact charging profile of the batteries (which is what you need on a boat like the OPs), then the difference in cost between a single and a 3 output is minimal.

Assuming the OP does not want to buy a new charger then as suggested a small freestanding charger at lower cost than a split charger is a good alternative for occasional charging the start battery.

 

[PaulRainbow]

PBO

Practical Bodge Owners ??

 

[vyv_cox]

I have read all the arguments for replacing a 1-2-both-off switch many times but personally feel absolutely no reason to do so. Partly for space reasons, there is very little room to add much electrically, but mainly, having owned this boat for almost 30 years I am perfectly happy with my use of the existing arrangement.

Firstly, I NEVER use the 'both' position. My domestic bank of 3 x 110 Ah batteries is perfectly capable of starting a little 3-cylinder Yanmar, which it does nine times out of ten starts. My starter battery, a Red Flash 1100, is pretty much an emergency start fallback. I switch to '1' once or twice per week and run on it for 30 minutes or so, then switch back to '2'. This ensures that the starter battery is always ready for use, which it has been for nearly 10 years now. Solar panels charge both banks during the day, or charge the starter battery if the engine is running and charging the domestic bank.

A simple and fool-proof system.

 

[PaulRainbow]

I have read all the arguments for replacing a 1-2-both-off switch many times but personally feel absolutely no reason to do so. Partly for space reasons, there is very little room to add much electrically, but mainly, having owned this boat for almost 30 years I am perfectly happy with my use of the existing arrangement.

Firstly, I NEVER use the 'both' position. My domestic bank of 3 x 110 Ah batteries is perfectly capable of starting a little 3-cylinder Yanmar, which it does nine times out of ten starts. My starter battery, a Red Flash 1100, is pretty much an emergency start fallback. I switch to '1' once or twice per week and run on it for 30 minutes or so, then switch back to '2'. This ensures that the starter battery is always ready for use, which it has been for nearly 10 years now. Solar panels charge both banks during the day, or charge the starter battery if the engine is running and charging the domestic bank.

A simple and fool-proof system.

But not like the OPs ?

 

[vyv_cox]

But not like the OPs ?

No, his thruster battery is an additional complication.

 

[VicS]

I have read all the arguments for replacing a 1-2-both-off switch many times but personally feel absolutely no reason to do so. Partly for space reasons, there is very little room to add much electrically, but mainly, having owned this boat for almost 30 years I am perfectly happy with my use of the existing arrangement.

Firstly, I NEVER use the 'both' position. My domestic bank of 3 x 110 Ah batteries is perfectly capable of starting a little 3-cylinder Yanmar, which it does nine times out of ten starts. My starter battery, a Red Flash 1100, is pretty much an emergency start fallback. I switch to '1' once or twice per week and run on it for 30 minutes or so, then switch back to '2'. This ensures that the starter battery is always ready for use, which it has been for nearly 10 years now. Solar panels charge both banks during the day, or charge the starter battery if the engine is running and charging the domestic bank.

A simple and fool-proof system.

I'd add a couple of rules:

1. Only the skipper is allowed to operate the battery selector switch

2. Never switch to OFF while the engine is running. A change from one battery to the other must go via the BOTH position

 

[geem]

I'd add a couple of rules:

1. Only the skipper is allowed to operate the battery selector switch

2. Never switch to OFF while the engine is running. A change from one battery to the other must go via the BOTH position

My rules
1. Either of us can use the switch. We are both knowledgeable.
2. No need for a number 2. Read number 1.

 

[Refueler]

I unsubscribed from this thread because it became the usual anti 3 pos switch bullshit we see so often.

I only looked back now to see what crap was now posted ....

vyv_cox ... you may not agree with me ... but on this - I'm with you ....

For me - OP has tried to create a system using a 3 pos switch ... but seems to have missed out on what each position does on that switch - particularly on the OFF position.

The 'ex spurts' on here have as usual stuck the knife into me ... but in reality one of the simplest solutions for OP is to fit a charge splitter ... suitable units do not cost the earth ... just a matter of using a bit of Google.

Practical Bodge Owners .... I like that ... sort of harks back to the REAL idea for PBO ... instead of the Credit Card Boat owner solutions we now see !!

I will unsubscribe once I post this .... not interested in the bullshit that will reply ...

 

[PaulRainbow]

I unsubscribed from this thread because it became the usual anti 3 pos switch bullshit we see so often.

I only looked back now to see what crap was now posted ....

vyv_cox ... you may not agree with me ... but on this - I'm with you ....

For me - OP has tried to create a system using a 3 pos switch ... but seems to have missed out on what each position does on that switch - particularly on the OFF position.

The 'ex spurts' on here have as usual stuck the knife into me ... but in reality one of the simplest solutions for OP is to fit a charge splitter ... suitable units do not cost the earth ... just a matter of using a bit of Google.

Practical Bodge Owners .... I like that ... sort of harks back to the REAL idea for PBO ... instead of the Credit Card Boat owner solutions we now see !!

I will unsubscribe once I post this .... not interested in the bullshit that will reply ...

Awww you're just teasing us.......