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battery switch

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redsnapper386

Regular Contributor
guy's what is the correct way to use a battery switch.example,my switch is a 1,2,and all.i usually alternate between 1and 2.now ,is it adviseable to run on all,all the time to keep both battery's charged.doe's this overwork the alternator which is a 61 amp.what would be the function of the all feature.thanks for your input.1987 350 alpha-1,thunderbolt-4 ignition.:confused:
 
This type of switch can be referred to as an MBSS.... (main battery selector switch).
You can do as you wish...... as there are several ways to skin this cat!
However, this seems to work well for many:

Typically, #1 will be your Reserve "Cranking Battery".
This should be a dedicated cranking/starting type battery.... not Deep Cycle.
We can start on #1, warm engine, charge while doing so..... and then switch to Bank #2.

Bank #2 is commonly referred to as the "House Bank".
This bank can be multiples of Deep Cycle batteries.... best if NOT cranking type batteries.
6 volt Golf Cart batteries (pairs cabled in series) work well here. Amp Hours is what we're after here!

Most will run on Bank #2 when on the hook, docked, etc., keeping #1 in Reserve.

Engine alternator charging occurs to which ever battery the MBSS is set to..... #1 or #2.
Some will charge with the MBSS set to ALL/BOTH....... although I don't care to charge unlike battery banks this way.
Additionally, setting to ALL/BOTH leaves us open to forgetting that we have combined banks. Not a good scenario, when ultimately we want to keep #1 in reserve! :mad:
Your call on that!

A Blueseas ACR (automatic charge relay) can be added also.

Your 2 Bank O/B charger leads can connect directly to the rear of this MBSS, terminals #1 and #2, making this a direct and permanent connection.
Schematically, this is the same as a direct battery connection, but avoids small terminal corrosion, and the "Rat's Nest" at our batteries!

If you have a bilge pump float switch, this connection can be made directly to the larger bank terminal, #2, keeping this as "un-interruptible" power.
MBSS "Off", and this float switch circuit remains powered.

Here's an example:



If you want a more sophisticated system, Blueseas offers some great battery management switching products.
 
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Ditto the above. I would add that it all depends on your boating. If you are away from the dock for anything more than a day trip or go far away from land it would be advisable to bring your battery charging system into the 21st century with the ACR and all. If you are just putting around and are within sight of land/other boaters and are out for only hours at a time you can get away with just your rudimentary charging system. You can always wave down a tow.
The more sophisticated system is for keeping the battery banks charged so that there is no chance of running them all flat and stranding you out at sea.
I have chosen to do away with the battery switch. I have my system set up to automatically charge both banks along with an emergency parallel capability. I monitor system health with an ampmeter and a voltmeter. Start battery is a Deka G27 AGM Marine Master, house bank is two G31 Deka AGMs. I use a Yandina 150 charge controller as well as a Balmar/Xantrex alternator regulator.

I must also add that it is possible to blow up your alternator if you have a switch that is not a field disconnect type. If the engine is running and you operate the switch, the built up charge may blow out the diode pack. It is important to know which kind you have. For good practice, just don't move the switch with the engine running.
 
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redsnapper386 said:
thanks rick,great stuff. i have been in the dark for awile on this subject.
Click to expand...
Well, now once your new system is installed, or changed around, you'll be in the light!
images


o2batsea, most all MBSS's today are "Make-before-Break" contacts.
I think we'd be hard pressed to find an MBSS that did not offer this.... even an older one!
If so, then switching between banks (engine running) is a non-issue.
However, switching through or to "OFF" (engine running) would be a real NO NO, as per what you suggest! That is where the risk is!

So Mr. Red Snapper, take note on that!
Switching from # 1 to ALL to #2 is OK ....... just DO NOT accidentally switch to OFF.
This is also a good reason to locate your MBSS out of reach of passengers and/or small kids! :)
(just not in the engine bay...... but that is another story! )

You'll do just fine, managing manually, if you follow a few basic rules.
Keeping #1 in reserve is the more important one! :)

.
 
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Somewhat off topic, but one of my favorite MBSS's.... believe it or not...., is the old Cole Hersee unit.
Hey...... Don't laugh! :D
These look to be "Old School", but surprisingly, they offer some of the largest and heaviest spring loaded contacts, over that of the modern day MBSS.... (unless we get into Bluesea stuff)
Plus, the rear cover comes off, and the contacts are serviceable (sealed via O-ring, btw).

IMO, this is the good stuff! :) I deliberately purchase these when I can find them. They're also what I use on my own boat!

images


Even this later version offers the same contact style... and w/ removeable rear.

images


All of the later ones are heat or chemically welded together.
(I've broken some of these apart to make a comparison...... Perko rates worst on my list! Small contacts..... not much spring pressure.)

.
 
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