1,2 Both Switch - When on Both do the 2 batteries even out on charge?

[lw395]

I am just about to fit a 1-2-both switch on my Dufour.

It currently only has one battery bank that takes two batteries that are used for both starting and domestic as it was originally designed.

Double

So I'm adding a small 45ah starter in an adjacent well as an emergency start back up only with a dual sensing vsr.

I intend to use the (200ah) main bank to start and run the domestics as I do now but have the safety net of a separate starter battery ONLY as an emergency back up

So I will normally only ever switch the switch to 1 and go.

The alternator and 30w solar power will go straight to the main bank.

This means that I should have a back up starter battery that has a very easy life which I can check once or twice a season when I check for topping up etc.

Please feel free to play the Devils advocate...

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That sounds like you have thought about what you want and will understand what you have.
Personally I think VSR's need to be used with caution. I'd prefer a solid state solution.

 

[sailorman]

OK, so you use a single switch in the negative to isolate everything when you leave the boat.

Not everything, some items need a permanent feed.
Could i get the comfy chair out

 

[lpdsn]

Please feel free to play the Devils advocate...

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If you arrange the two existing domestic batteries as a single bank they'll have an easier life than if you try to use them as individual batteries controlled by a 1-2-both switch. Ah figures are based on a certain current. If you take a higher current out you'll get less capacity, but sharing that capacity between two or more batteries mitigates higher load currents.

A dedicated starter battery is a good idea (and by that I mean a high CCA designed-as-such starter battery) but there's no need to keep it as an emergency reserve. Use it as the normal starter battery.

Once you've got a system with dissimilar batteries, domestic bank and starter, each of a design and configuration optimised for their purpose, there is no logic that supports the fitting of a 1-2-Both switch.

 

[lpdsn]

Not everything, some items need a permanent feed.

I'm not convinced of that one. For example, my VHF is permanently powered up (subject to a chart table switch) because that's the way the boat was built. The only logic for it is keeping RF noise away from the other circuits. These days with decent ferrites on the VHF power supply I don't think it is necessary any more.

PS: there is of course a need to keep AIS transcievers powered up whilst the boat is left in the marina. If people don't do that I can't point to the cluster of targets on the display and tell the crew we're only x miles away from our destination.

 

[doug748]

"Please feel free to play the Devils advocate..."


Well not really, but after a wrestle with my memory I have just recalled how my set up works. I have something v similar to what you propose. But:

- I can start the engine on either battery or both. This will then charge either one or both.

- The house battery is on a separate isolation switch to services. The start battery is not wired to power the boat, it can't without jump leads.

- The house battery is charged additionally by a windgen with overcharge protection.

- The house battery is monitored by a Nasa BM1 and the start battery voltage can also be checked.

When I first had the boat it was more sophisticated.
In practice, with the revised system, all I do is charge the start battery now and again from the engine and keep an eye on things. It just sits there doing very little till the day I flatten the service battery totally.
The key attraction to an electrical num-nuts is that I can understand it and if it goes wrong it will be easy to deduce why.

 

[shaunksb]

A dedicated starter battery is a good idea (and by that I mean a high CCA designed-as-such starter battery) but there's no need to keep it as an emergency reserve. Use it as the normal starter battery.

My thinking is that if I were to use the starter all the time when it eventually fails i would have to team up a dead starter with a house bank. Using a switch I can isolate it. Plus as it would hardly ever be discharged it should always be there when I need it.

Also I wouldn't have chatter issues with a 200ah and 45ah bank?

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[PaulRainbow]

I am just about to fit a 1-2-both switch on my Dufour.

It currently only has one battery bank that takes two batteries that are used for both starting and domestic as it was originally designed.

Double

So I'm adding a small 45ah starter in an adjacent well as an emergency start back up only with a dual sensing vsr.

I intend to use the (200ah) main bank to start and run the domestics as I do now but have the safety net of a separate starter battery ONLY as an emergency back up

So I will normally only ever switch the switch to 1 and go.

The alternator and 30w solar power will go straight to the main bank.

This means that I should have a back up starter battery that has a very easy life which I can check once or twice a season when I check for topping up etc.

Please feel free to play the Devils advocate...

__________________________

Shaun tries hard, but could do better. 6/10



Makes no sense to fit all of the above and not use the new battery. Why not fit separate switches and use the new battery for engine starting all of the time ?

 

[lpdsn]

My thinking is that if I were to use the starter all the time when it eventually fails i would have to team up a dead starter with a house bank. Using a switch I can isolate it. Plus as it would hardly ever be discharged it should always be there when I need it.

Also I wouldn't have chatter issues with a 200ah and 45ah bank?

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There's no reason why your starter should die, what's taken out in starting the engine is quickly replaced. It's only if you have to try repeatedly to start the engine that you'll have any significant drain, but if you wire up individual switches you don't end up teaming up the dead starter with domestics, rather you switch the domestics into the starter circuit. That's what I have.

I don't use a VSR. If it can't cope with dissimilar banks then perhaps you need an alternative solution.

 

[PaulRainbow]

There's no reason why your starter should die, what's taken out in starting the engine is quickly replaced. It's only if you have to try repeatedly to start the engine that you'll have any significant drain, but if you wire up individual switches you don't end up teaming up the dead starter with domestics, rather you switch the domestics into the starter circuit. That's what I have.

I don't use a VSR. If it can't cope with dissimilar banks then perhaps you need an alternative solution.

A good VSR can cope with dissimilar banks.

 

[William_H]

I am just about to fit a 1-2-both switch on my Dufour.

It currently only has one battery bank that takes two batteries that are used for both starting and domestic as it was originally designed.

Double

So I'm adding a small 45ah starter in an adjacent well as an emergency start back up only with a dual sensing vsr.

I intend to use the (200ah) main bank to start and run the domestics as I do now but have the safety net of a separate starter battery ONLY as an emergency back up

So I will normally only ever switch the switch to 1 and go.

The alternator and 30w solar power will go straight to the main bank.

This means that I should have a back up starter battery that has a very easy life which I can check once or twice a season when I check for topping up etc.

Please feel free to play the Devils advocate...

__________________________

A separate emergency start battery might seem like a good idea but I fear you will not use it enough to really ensure that when you need it , it will do the job. As said use it all the time and be sure. olewill

 

[Tranona]

Please feel free to play the Devils advocate...

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why do you have to make it all so complicated. The norm now is two banks, one domestic, one engine start and a VSR to split the charge plus individual isolators for each bank. To make an easy and neat job of wiring a BEP Marine switch cluster is a good solution. Your start battery is near useless for domestic and should be used only for start. The alternator will recharge in minutes and then the VSR will direct all the charge to the domestic. Start battery will always be fully charged and will last for years with so little work to do.

Can't think of any new boat builder that uses those antiquated 1,2,both things.

 

[Bru]

Your start battery is near useless for domestic.

Not so, it's perfectly usable for domestics. Depending on type it probably won't withstand repeated deep discharge / recharge cycles as well as a deep cycle battery but that doesn't render it useless. Being able to switch over the essential "domestic" services to the starter battery in an emergency is a useful safety feature (as is being able to start the engine from the domestics - and there the reverse is true in that the ideal battery for domestic use won't tolerate routine cold cranking loads as well over a period of time. (There are battery types, e.g. many gel and AGM batteries that are perfectly happy doing both jobs)

The alternator will recharge in minutes and then the VSR will direct all the charge to the domestic.

Also not so, when the sense side of the VSR reached the preset voltage, the batteries will be paralleled until the voltage drops below the preset. Charging and (which most people forget) discharging will then happen across all the batteries as if they are one bank

Standard VSRs* rely on the fact that as soon as charging stops, the voltage will very rapidly fall to below the preset voltage thus separating the battery banks again with minimal discharge of the batteries

* More sophisticated, and correspondingly more expensive, devices are available but really only worth the expense on larger systems

 

[shaunksb]

The norm now is two banks, one domestic, one engine start and a VSR to split the charge plus individual isolators for each bank. To make an easy and neat job of wiring a BEP Marine switch cluster is a good solution. Your start battery is near useless for domestic and should be used only for start. The alternator will recharge in minutes and then the VSR will direct all the charge to the domestic.
.

I know, my previous Jeanneau had this but I'm a bit concerned about the disparity between the 45ah and 200ah (or maybe 230ah if they will fit) banks. Would a vsr give as much to a depleted house bank compared with wiring the alternator directly to it?

Also if my vsr were to fail I have an effective manual override with a switch.

When we did a season around the Hebrides in the Jeanneau my (newish) house bank died and I had to keep the engine on if I wanted instruments on the way back.

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[Bru]

if my vsr were to fail I have an effective manual override with a switch.

The BEP cluster mentioned has an emergency cross link switch (a manual over-ride in other words)

 

[VicS]

The BEP cluster mentioned has an emergency cross link switch (a manual over-ride in other words)

The trouble with the BEP clusters is that the emergency coss link switch parallels the batteries. This means that a dead battery cannot be left switched out of circuit while all systems run off the good battery.

http://www.bepmarine.com/~/media/inRiver/322225-13490.pdf

http://www.bepmarine.com/~/media/inRiver/327549-18219.pdf

They would be better they they were reconfigured and connected so that they parallel the engine circuit with the domestic dis board. This would allow a dead battery to be left isolated.

 

[Bru]

The trouble with the BEP clusters is that the emergency coss link switch parallels the batteries. This means that a dead battery cannot be left switched out of circuit while all systems run off the good battery.

http://www.bepmarine.com/~/media/inRiver/322225-13490.pdf

http://www.bepmarine.com/~/media/inRiver/327549-18219.pdf

They would be better they they were reconfigured and connected so that they parallel the engine circuit with the domestic dis board. This would allow a dead battery to be left isolated.

I agree entirely which is why I rewired one to just that configuration

(It's easy, the individual units of the cluster are just standard BEP isolators and a VSR so it's just a matter of changing the connections over)

 

[shaunksb]

I agree entirely which is why I rewired one to just that configuration

(It's easy, the individual units of the cluster are just standard BEP isolators and a VSR so it's just a matter of changing the connections over)

OK, that's the effect I want but you are losing me now on the detail

Would this do any more than the simple 1 2,both switch I originally suggested?

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[Bru]

OK, that's the effect I want but you are losing me now on the detail

Would this do any more than the simple 1 2,both switch I originally suggested?

Yes, you wouldn't have to fiddle around with a 1-2-both switch!

You simply turn on the Engine and Domestic isolators and leave it alone

The VSR will prioritise Engine battery charging then automatically bring in the Domestics (usually after a few minutes), you don't have to remember to switch over

Further, there's no danger of leaving the setup on "Both" and flattening all your batteries

The Link switch is just left off and only used if you have a flat battery. (Whether it's worth changing the way the cluster is wired is debatable)

 

[shaunksb]

Shaun tries hard, but could do better. 6/10



Makes no sense to fit all of the above and not use the new battery. Why not fit separate switches and use the new battery for engine starting all of the time ?

Paul Rainbow. An independent thinker but fails to back up his opinions with reasoned evidence. 3/10 see me after class.

I'm trying to be be able to isolate either bank should they fail. My thinking is that adding a switch in the way I describe gives me something "extra" to the standard way boat builders do it now. (Which has let me down once)

But I am, as Noddy says, all ears...

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[shaunksb]

Yes, you wouldn't have to fiddle around with a 1-2-both switch!

You simply turn on the Engine and Domestic isolators and leave it alone

<snip>

The Link switch is just left off and only used if you have a flat battery. (Whether it's worth changing the way the cluster is wired is debatable)

But with what I'm proposing I wouldn't be fiddling with the switch either. I would only use it in an emergency and then it would give me the easy option to isolate or link the banks.

I realise I am probably missing something...

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