1-2-Off vs 1-2-Off-Both switches

[Bob666]

Hi!

I don't like the "Both" setting of the 4 position switches, so I found a BlueSea e-Series Selector 3 Position Battery Switch with AFD with settings 1-2-Off only.

When parallel coupling ("both"/"all" setting of 4 Position Switch)
A. 1 dead battery + 1 healthy AGM
B. 1 healthy Gel + 1 healthy AGM
C. 1 bad Gel + 1 healthy AGM
etc

What happens really? I got a house bank of four GELs of same brand, model and batch that are working fine. What would happen to them, or the other battery, if introducing them to any of the above scenarios?

1. Parallel coupling as in A, B or C for 1 second.
2. Parallel coupling as in A, B or C for 1 hour.

Secondary, if I go for the 3 position switch, I would have a voltage drop of 2.2 V from second bank if cranking at 90 A. Enough to crank engine if battery fully charged? It's an open acid battery so assume >12.7 V.

I have no means of testing as the boat is on the hard and I don't want to crank the engine.

Cheers

[john61ct]

Not a big issue, unless the problem on the dead side is a catastrophic fault, short etc.

There are auto combiners based on sensing charge voltage. Many have a self-jump momentary switch, and some have decent protective circuitry.

[john61ct]

Also with different chemistries you may not be charging them at the same voltage.

Xantrex Echo Charge steps higher down to 14.4, also limits to 15 A

[skipmac]

Hi Bob,

Your concern about combining a good with a bad battery with a Both position is quite valid. Bad of course can be a battery that is dead or dying and cannot hold a charge or just a battery that is very discharged but still good or could even be a battery with a shorted cell.

Paralleling a good, charged battery in some of these could just discharge the good battery or, if the second battery is shorted, result in a serious problem; overheating and even possibly a fire.

However, occasionally having two batteries that are partially discharged to parallel can give you that little extra you need to start the engine or whatever.

I would get the 1-2-both switch but just be very conservative about when I used the Both position.

[Badsanta]

To eliminate confusion for myself and crew, I replaced the 1-2-both-off switch with separate on-off switch. One for house and one for start. I can combine, but it uses a removable key. Alternator charge to house bank with smart charger to charge start battery. Works well and I don't have to think about it.

[Cadence]

In my humble opinion "both" is good and intended for one thing which is getting enough cranking power in an emergency. Good to have for that reason.

[Bob666]

Ok. I got young kids though.

Sent from my SGP511 using Cruisers Sailing Forum mobile app

[sklitzky]

Very much in the learning phase. Will both batteries charge if set in all positions? 1, 2, Both, Off?

[skipmac]

Originally Posted by Bob666

Ok. I got young kids though.

Sent from my SGP511 using Cruisers Sailing Forum mobile app

How tall are they? You can mount the switch higher than they can reach.

Or get a switch with a key lock built in and hide the key in the nav table.

[skipmac]

Originally Posted by sklitzky

Very much in the learning phase. Will both batteries charge if set in all positions? 1, 2, Both, Off?

If you connect the charging source (alternator, solar, wind, etc) to one battery bank that is connected to 1, you have a second bank connected to 2 then at Both all the batteries will be connected together, either for output or charging.

A better, more foolproof solution, wire all charging sources to the house batteries. Then install an automatic combiner like an Echocharge or Yandina Combiner between the house and starting battery. Then anytime the house batteries are being charged the combiner will also connect the start battery and it will be charged. The benefit, when you stop charging (turn off the engine, sun goes down and solar stops, etc) the combiner automatically disconnects the start battery from the system so you don't accidentally keep it connected to the house and kill it running the lights or stereo or whatever.

[Stu Jackson]

Originally Posted by sklitzky

Very much in the learning phase. Will both batteries charge if set in all positions? 1, 2, Both, Off?

Electrical Systems 101 Electrical Systems 101

[Cadence]

Originally Posted by Stu Jackson

Electrical Systems 101 Electrical Systems 101

Stu, it is excellent advise. Reading post after post a lack of basic DC fundamentals seems to be prevalent. I hope anyone with a boat takes the advise. It isn't brain surgery just a good evenings read.

[Sunsetrider]

What about on-off-both? With a Blue Sea ACR and a smart 2-lead charger? That is what I went with when I re-wired my battery setup and I have been very happy with it. Turn the switch to On and fuggedaboudit!

[skipmac]

Originally Posted by Sunsetrider

What about on-off-both? With a Blue Sea ACR and a smart 2-lead charger? That is what I went with when I re-wired my battery setup and I have been very happy with it. Turn the switch to On and fuggedaboudit!

If this is the switch I'm thinking about there's one major downside. It only allows paralleling two battery banks, not 1 or 2 or Both. So if bank 1 is totally dead or worse, shorted, you parallel 2 with the one using the Both option and you kill bank 2 as well.

I much prefer the option to choose 1 or 2 or both or all off.

[Stu Jackson]

Originally Posted by Sunsetrider

What about on-off-both? With a Blue Sea ACR and a smart 2-lead charger? That is what I went with when I re-wired my battery setup and I have been very happy with it. Turn the switch to On and fuggedaboudit!

Except when one bank dies: this is one of the threads on my previous link to Electrical 101

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowner...ght=darn%20agm

Besides, your ACR should do both banks, so no need for a 2 lead charger.

But if it works for you, so be it. But you may be missing something in your understanding of how the system should work.

Also, many folks are plugged in and start with full banks, while most electrical discussions do (and should) work just the other way: I'm on the hook with a partially depleted house bank from using it last night.