Using a Battery Change over switch - Lesson please

[Roach1948]

You know the sort. 1+2+BOTH+OFF variety.

Well is it OK to change from 1 to 2 to both whilst the engine is running so long as you dont go via OFF?

I always thought this was the case until I contacted BETA about a recent charging problem and they were adamant that I should ONLY switch over to any setting when the engine is turned off. Bit confused here - have I been doing it wrong?

 

[tazzle]

If the switch is make before break, I'd have thought it OK - why not?

 

[Salty John]

Yes, if the switch is make-before-break you can switch between battery banks (not via off), if not you can't.

 

[Roach1948]

Sorry for being thick here, but can you explain the "make-before-break" bit?

 

[Gunfleet]

It means it doesn't have a moment when your alternator is connected to nothing, which can be catastrophic. It's the reason you can't go via off. SOme people hate these switches, reckoning they're accidfent prone. Some (like me) wonder what's the problem. Just don't ask inexperienced crew to switch over the batteries.

 

[MoodySabre]

I switch mine over with the engine running - how else could you charge the domestic battery which is never used for starting the engine.

Make-before-break means that the switch makes contact with the next setting before breaking with the previous. If the BOTH setting is between ONE and TWO then this will be OK.

I never leave mine on BOTH as any problem with one battery will drain down the other battery to equalise them.

 

[Roach1948]

Well this is what I thought, so I do have a make-then-break switch and I have been doing it right and haven't been damaging anything.

As for charging the BETA guy told me to switch to BOTH just before starting the engine and then switch back to the service battery after switching the engine off. Obviously he was one of these people that does not like these switches.

 

[Billjratt]

fit diodes, then the charging becomes foolproof and the switch is only used to select which battery will be discharged and when. Then think of a smart controller to really give your batteries a treat. It will force the charge rate up and use less engine time to fully charge the batteries. The diodes also stop the batteries all being dragged to the lowest common denominator (most knackered battery) as happens when switched to "both"

 

[webcraft]

We have a BETA and always start in 1 then switch to 2 - no problems. I have also accidentally switched off the ignition with the engine running on at least three occasions with no damage to the alternator - although I wouldn't recommend it!

- Nick

 

[morgandlm]

I do exactly the same as Webcraft, namely, start the engine with the switch at 1, switch to both when the engine is running and switch to 2 when sailing, to power VHF and instruments. I also have a Sterling controller to boost the charge rate. This system works fine for me although I know would be improved by fitting isolating diodes to "protect" the starter battery.

I have also switched off with the engine running - and the alternator diodes survived.
Morgan

 

[Roach1948]

I have to admit I have done the same too! Easily done..... I have now put a blob of red paint on the STOP button as I have had occasion when a crew member needed to stop the engine in an emergency and the black button simply looks like another warning light or alarm speaker. I printed a big label next to it too saying "PRESS to STOP"

 

[alldownwind]

[ QUOTE ]
fit diodes, then the charging becomes foolproof and the switch is only used to select which battery will be discharged and when. Then think of a smart controller to really give your batteries a treat. It will force the charge rate up and use less engine time to fully charge the batteries. The diodes also stop the batteries all being dragged to the lowest common denominator (most knackered battery) as happens when switched to "both"

[/ QUOTE ]
Just to add to this good advice, it's best to definitely fit a smart controller if you are charging through a diode splitter - this is because of the voltage drop incurred going through the splitter. There are alternative and more expensive splitters e.g. made by Driftgate which incur only a very small drop.

 

[SvenglishTommy]

[ QUOTE ]
As for charging the BETA guy told me to switch to BOTH just before starting the engine and then switch back to the service battery after switching the engine off. Obviously he was one of these people that does not like these switches.

[/ QUOTE ]
He wasn't one of those people who doesn't like the switches. He was one of those people who understands how electricity works and uses common sense.

 

[pappaecho]

I have a Beta 35 hp and run it on "ALL" having started on "ALL"
This charges 400 amps of both engine and domestic banks.
Backup is the Rutland 913, with charge controller, which stops revolving, so I know the system is charging. As soon as the engine is off we go to "2" for the domestic bank. No alternator problems

 

[cliff]

[ QUOTE ]
[ QUOTE ]
As for charging the BETA guy told me to switch to BOTH just before starting the engine and then switch back to the service battery after switching the engine off. Obviously he was one of these people that does not like these switches.

[/ QUOTE ]
He wasn't one of those people who doesn't like the switches. He was one of those people who understands how electricity works and uses common sense.

[/ QUOTE ]Does electricity work differently in Sweden than in the rest of the world?

Pos 1 - Engine start, domestic batteries isolated
Pos both - after engine running, charging all batteries.
Pos 2 - Domestic bank, engine start isolated, for use when sailing or when engine off.

Instruments (and eberspacher) connected to bank 2 so they do not reset due to low voltage on starting the engine provided pos 1 is used for engine start. Starting the engine in pos both or pos 2 can, and frequently does, drop the system voltage below 10.5v and cause instruments etc to switch off or reset.

As others have said a "make before break" switch is a good idea to prevent the possibility of accidently running the alternator on open circuit.
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[dulcibella]

I start my Beta 35 on 1 (the engine start battery!), switch to both when it is running (not necessary as I have a splitter diode - it's just habit), then to 2 (house batteries) when I stop the engine.

 

[SvenglishTommy]

No, electricity works exactly the same way in Sweden as everywhere else. Although for some reason the Swedes dont seem to see the need to check polarity or earth AC.

The thing, is why on earth do you start on pos 1? Start on both, run engine on both, isolate one when engine is off.

Why make life more complicated by using just the battery you have labeled the start battery, when you can have more power by using both, and dont have to remember to turn the switch while the engine is running? It is a completely pointless exercise that must have been conceived by people who dont really know how electricity works, and feel that because one battery is called the "start" battery that it, and only it, must be used for starting exclusively.

 

[cliff]

Simple - "start" batteries are high cca and are designed to deliver high current for short periods (for starting) whereas deep cycle (leisure?) batteries are designed to deliver low current for extended periods (deep discharge) - using deep cycle batteries for starting purposes is not conducive to long battery life, in a similar vein, deep cycling a "start" battery is a sure-fire way to kill it.
--------------------

"Artificial intelligence is no match for natural stupidity"
sailroom <span style="color:red">The place to auction your previously loved boatie bits</span>

 

[SvenglishTommy]

Maybe, if you use real traction batteries, but I bet in most boats the house bank is capable of kicking out way more than the start battery. I know that my, quite small, 160AH house bank can dish out more than twice the CCA of my start battery.

If you actually do the maths you will see that all that there is no point.

 

[tobble]

I find it hard to believe that a small fraction of a second of running an alenator open circuit, i.e. while one is changing a non "make before break" switch, is enough to damadge the altenator. I'm willing to be proven wrong, if anyone has witnissed this... Incidentally, my engine is only connected to the engine battery, and my wind turbine goes via a two- bank charger to both domestic and engine batteries, so I have no switch at all...