Battery switches, advice please.

[biscuit]

I need to revise my battery switches. Boat (new to me) has 1 engine start battery & 2 service batteries.
It has identical separate single pole isolator switches for the engine, service batteries and earth.
The latter is awkwardly placed so that it is possible to knock it to the off position accidentally.
There is no provision for switching to either or both service batteries in the event of a failure of the engine battery, though it does have a VSR to help avoid this.
I propose to install a Blue Seas Rotary "make before break" dual circuit battery switch (it has provision for paralleling battery banks in emergency) which should solve some of these issues, but what should I do about the earth isolating switch, which seems redundant?

 

[Len Ingalls]

I need to revise my battery switches. Boat (new to me) has 1 engine start battery & 2 service batteries.
It has identical separate single pole isolator switches for the engine, service batteries and earth.
The latter is awkwardly placed so that it is possible to knock it to the off position accidentally.
There is no provision for switching to either or both service batteries in the event of a failure of the engine battery, though it does have a VSR to help avoid this.
I propose to install a Blue Seas Rotary "make before break" dual circuit battery switch (it has provision for paralleling battery banks in emergency) which should solve some of these issues, but what should I do about the earth isolating switch, which seems redundant?

Check this: https://www.dropbox.com/s/l7fuzp9c457dgf5/Battery Bank Wiring & Switching.pdf?dl=0


Some reading : http://forums.sailboatowners.com/index.php?threads/1-both-2-off-switches-thoughts-musings.137615/

 

[ghostlymoron]

I'd fit a blue Sea dual circuit plus www.bluesea.com/products/6011/m-Series_Mini_Dual_Circuit_Plus_Battery_Switch_-_Red
And incorporate your existing VSR. It's a quality switch and reasonably priced. Incorporates an emergency position for if your starter battery let's you down.

 

[PaulRainbow]

I propose to install a Blue Seas Rotary "make before break" dual circuit battery switch (it has provision for paralleling battery banks in emergency) which should solve some of these issues, but what should I do about the earth isolating switch, which seems redundant?

Excellent choice of switch. If you don't want to keep the Neg switch, take it out and bolt the cables together.

French boat by any chance ?

 

[pmagowan]

I fitter this BEP cluster which works well: http://www.defender.com/product3.jsp?path=-1|328|2289962|2289976&id=2156694

 

[jac]

I think you have 2 separate issues.

1) - what to do about the earth.
2) - How to parallel in an emergency.

Why not just bolt the cables together and remove the neg switch entirely as Paul Rainbow suggests.

Then - using the space freed up - fit another single pole battery switch that will parallel the batteries. If you fit one with a removable key and leave the key out ( but attached!!) then you will have a clear visual confirmation that the batteries are not paralleled. something like this https://www.mailspeedmarine.com/mailspeed-marine-battery-master-switch.html might work.

Whilst I rate the blue seas gear and use it myself I am nervous about a single switch turning everything on or off.

Should also say - be careful re paralleling to engine start if starter battery is dead. It will drag down the domestic bank and if that is small / low then it may mean you can't start it at all. Better to wire the installation so that you can isolate the engine start, join the starter circuit into the domestic bank and start that way

 

[PaulRainbow]

A second option occurs to me, although if it was me i'd still prefer the BlueSea switch.

You could take the cables off of the Neg switch and bolt them together, then fir two short cables from the existing Neg switch to the other two isolators to provide emergency starting. Paint the switch or label it accordingly. Wouldn't have to worry about knocking it off, it should normally be off anyway.

IMO, the BlueSea switch would be a much more elegant solution though.

 

[JumbleDuck]

I propose to install a Blue Seas Rotary "make before break" dual circuit battery switch (it has provision for paralleling battery banks in emergency) which should solve some of these issues,

I fitted one of these - a Blue Sea Dual Circuit Plus - last year and it works beautifully.

but what should I do about the earth isolating switch, which seems redundant?

Dump it. It serves no useful purpose and is just something else to go wrong.

 

[biscuit]

Thanks guys, some wise words and experience here again. And yes paulrainbow, you are almost right, boat is not quite "French", but like Hercule Poirot is actually Belgian, being an Etap.
I am going for the jumbleduck option, Blue Sea Dual circuit plus, but will think about using a switch to isolate any dud battery.

 

[JumbleDuck]

I am going for the jumbleduck option, Blue Sea Dual circuit plus, but will think about using a switch to isolate any dud battery.

My house bank is 2 x 60Ah (can't fit in bigger), each of which has a 250A circuit breaker, so I can disconnect either in about ten seconds if I ever need to.

 

[PaulRainbow]

The BlueSea switch keeps both circuits totally separate. If, for instance, the engine battery went flat you switch to "combine", start the engine and switch back to "on". No need to isolate the flat battery. You don't disconnect your car battery while you jump start the car.

If the battery has failed and will not hold a charge, it doesn't matter, the engine will run from the alternator. Same the other way around, with the domestic bank. If it's flat your stuff would run off of the alternator. In the event of a failed battery it might drag the good battery down, dependent upon why it's failed. In this case it's obviously wise to disconnect the dead battery. JD's circuit breakers is a neat solution, but if you don't have then you can disconnect the negative cable to the dead battery.

 

[Bru]

Nope, don't like it. Won't recommend it either

Battery isolators should be dedicated seperate isolators for each bank

I've seen boiling batteries and with the combined switch you can't isolate the failed bank and run on the good bank

That could put you in a hairy situation with no power despite having a perfectly good battery bank available

When fumes are billowing out of the battery compartment and you're smack in the path of an oil tanker, it is not the time to be getting the spanners out to swap battery leads around

The BEP block is good and if space won't permit I build the same setup with separate switches - an isolator for each bank, a keyed isolator across the service side of the battery isolators for emergency cross-linking and if required a VSR

That allows for all systems to be run off either battery bank or both

 

[PaulRainbow]

Nope, don't like it. Won't recommend it either

Battery isolators should be dedicated seperate isolators for each bank

I've seen boiling batteries and with the combined switch you can't isolate the failed bank and run on the good bank

That could put you in a hairy situation with no power despite having a perfectly good battery bank available

When fumes are billowing out of the battery compartment and you're smack in the path of an oil tanker, it is not the time to be getting the spanners out to swap battery leads around

The BEP block is good and if space won't permit I build the same setup with separate switches - an isolator for each bank, a keyed isolator across the service side of the battery isolators for emergency cross-linking and if required a VSR

That allows for all systems to be run off either battery bank or both

You're not following BEP fitting instructions then, because they defeat what you're saying. I can see the sense in your method though. But, with JD's circuit breakers between the battery and the isolater the same can be achieved with the BlueSea switch. Pop the breaker for the faulty bank and switch to combine.

 

[Bru]

You're not following BEP fitting instructions then, because they defeat what you're saying.

They do and I don't

(The BEP wiring diagram has the emergency cross link wired to the battery side of the isolators. I wire it to the service side for the reasons stated earlier)

I can see the sense in your method though. But, with JD's circuit breakers between the battery and the isolater the same can be achieved with the BlueSea switch. Pop the breaker for the faulty bank and switch to combine.

The circuit breakers thus being used as the isolators with the switch being used as just a selector switch.

But I have an objection to using breakers as isolators - you can't remove the key or knob to prevent the circuit being turned back on. Call me an old school sparky but I had it drummed into me from the tender age of 16 that master isolators should be lockable or have a removable key (the BEP rotary isolators have a removable knob).

For what bog standard keyed isolators cost, I would always fit proper isolator switches to each battery bank.

 

[PaulRainbow]

They do and I don't

(The BEP wiring diagram has the emergency cross link wired to the battery side of the isolators. I wire it to the service side for the reasons stated earlier)




The circuit breakers thus being used as the isolators with the switch being used as just a selector switch.

But I have an objection to using breakers as isolators - you can't remove the key or knob to prevent the circuit being turned back on. Call me an old school sparky but I had it drummed into me from the tender age of 16 that master isolators should be lockable or have a removable key (the BEP rotary isolators have a removable knob).

For what bog standard keyed isolators cost, I would always fit proper isolator switches to each battery bank.

My boat has the original 1-2-both switch and i really hate those. To my mind they don't really give you twin banks/systems, they just give a spare battery for emergency use. It has to go. I've always liked the BlueSea switch but can see some merit in your method. Your way of wiring the switches certainly makes more sense. So, i've had a rethink and will order the BEP switches, thanks for the suggestion/advice.

That said, i'd suggest the OP might re-look at his situation. As he already has three switches perhaps the BEP ones make even more sense for him. He could replace the two red ones with BEP switches with red tops and replace the Neg isolator with one with a yellow top. There isn't much difference in price and it also solves the problem of redundant holes.

 

[ghostlymoron]

I too have a reservation about the wisdom of paralleling a good but low house battery with a dead starter battery. It is plain to me that under certain circumstances, you'll end up with insufficient volts to start your engine, particularly if it's a poor starter. I've expressed my opinion on this forum and been shouted down by people I respect. But I still have concerns.

I think you have 2 separate issues.





Should also say - be careful re paralleling to engine start if starter battery is dead. It will drag down the domestic bank and if that is small / low then it may mean you can't start it at all. Better to wire the installation so that you can isolate the engine start, join the starter circuit into the domestic bank and start that way

 

[JumbleDuck]

Nope, don't like it. Won't recommend it either

Battery isolators should be dedicated seperate isolators for each bank

I've seen boiling batteries and with the combined switch you can't isolate the failed bank and run on the good bank

I shared your concern. However, if either or both of my house batteries fail I can disconnect it at the flick of a switch and if the engine battery fails I can disconnect it with a spanner in a minute or so. The dual circuit + combine switch is easy and just about foolproof to use.

 

[JumbleDuck]

That said, i'd suggest the OP might re-look at his situation. As he already has three switches perhaps the BEP ones make even more sense for him. He could replace the two red ones with BEP switches with red tops and replace the Neg isolator with one with a yellow top. There isn't much difference in price and it also solves the problem of redundant holes.

I considered the BEP cluster myself, but it's bigger than the BlueSea and more complicated in operation. I'd have used it cheerfully, but the BlueSea suited me better.

 

[PaulRainbow]

I considered the BEP cluster myself, but it's bigger than the BlueSea and more complicated in operation. I'd have used it cheerfully, but the BlueSea suited me better.

It would be a little more work for me to fit the BEP switches, but i like the extra options they would give me. Unlike you i don't have the battery circuit breakers, so to get that functionality i'd have even more work and expense. My switches are right next to the batteries, under the saloon seating so there really isn't any point in fusing the cables. It's all wood in there and the longest cable isn't much more than a couple of feet.

 

[Chalker]

I agree with Bru and others, the BEP wiring is wrong.
The jumper switch to parallel the batteries should be on the load side of the individulal battery switches. That way you can isolate a battery or parallel them as required. The BEP wiring only allows you to parallel them. Simply reverse the battery/load connections to each switch.
If you have the cluster with a VSR built in I've no idea if this still works, I have the simpler 3 switch version