You can save yourself some wire length by creating a jumper to the #2 position of the 1/2/B from the starter side of the ON/OFF..
House Bank - 2 separate or 1 parallel
- Thread starter scherzoja
- Start date
Bold: Nope, no, don't. That is NOT what I recommend, nor does Maine Sail. It's the way the boats came from the factory.
The improvement is noted in the links Maine Sail and I have been providing for the past ten or more years.
Move the AO to the house bank.
Please.
Maine,
Thank you for the tip on the cable length savings. I'll go read up on the Smart gauge.
Thanks again for your help.
Thank you for the tip on the cable length savings. I'll go read up on the Smart gauge.
Thanks again for your help.
Yes. From the link in Reply #6 on page one:
Option 2 courtesy of Maine Sail
PLEASE NOTE for Option 2: The wire from the 2 post of the 1-2-B switch is shown going to the starter; it can also just as easily be run to the lower post of the on/off switch, which is just the other end of the same wire. The switches are usually closer to each other, resulting in less wiring.
I didn't say to move the AO from the house bank.
I suggested that OP move the STARTER to the C post. (as per MS's diagram
Why would you run a wire from the "2" terminal of the master switch directly to the starter instead of the starter battery? There is no power at the starter. I would hook the No. 2 buss to the "2" terminal of the master switch since the point of having a master switch is to control which battery bank is being used. The 3 switch diagram that Main sail shows is actually the best setup even though it involves 3 separate switches rather than one as it allows you to run the separate banks at the same time without having to switch back to the house bank after you start the engine. Personally, I seldom use the #2 position for starting as it is too easy to forget to switch back to #1. Also, my alternator goes to the #C terminal so the house bank won't get charged unless it's on #1. I don't have an echo charger. My AC charger is hooked directly to the house bank. It's not a perfect world...
Some people want a "dedicated" direct wired start battery. By including the #2 position you retain all the redundancy of the 1/2/BOTH but gain a dedicated starting battery.
You can always direct wire a dedicated start battery with its own ON/OFF but it will get more complicated if you want to retain the ability to start off the house bank in an emergency and retain all the safety and isolation features the 1/BOTH/2/OFF can offer. This is why the 1/BOTH/2/OFF is such a good tool despite it often being so badly maligned.
The diagram below is one I favor when owners insist on a dedicated starting battery but also want to retain the flexibility of the 1/BOTH/2/OFF.
With this simple but very redundant system you retain all the isolation & redundancy of the 1/BOTH/2/OFF switch yet add a dedicated direct wired starting battery. Simply flip to #1 and ON and your ready to go. When you're done flip both switches to OFF. Label them carefully, Blue Sea sells the perfect labels...
Normal Operation:
#1 = ON (powers house loads)
ON/OFF = ON (powers engine only)
Start Bank Failure:
BOTH = ON (everything is now powered by the house bank)
ON/OFF = OFF (start battery is 100% isolated)
House Bank Failure:
#2 = ON (house bank isolated start bank powering everything)
ON/OFF = ON (start bank powers all)
If the start battery were to fail flip the ON/OFF to OFF and the 1/BOTH/2/OFF to BOTH and now the house bank is starting and providing house loads. Conversely you can still use the start bank to power house loads in an emergency with the 1/BOTH/2/OFF in position #2 and the start switch to ON.
This system is more complicated but ultimately considerably more flexible than some other systems where you must use the "combine" feature which is never a good choice when you have unknown bank issues..
My starter gets it's power from the C Post. I realize it leaves the system more vulnerable. The extra switch basically gives the same benefit as your separate 3 switch configuration.
While the 3 position main switch has an overlap, there doesn't appear to be any danger of blowing the alternator diodes when switching between banks. Just don't turn it to off with the engine running. For this reason I do like the idea of the AO going directly to the house bank along with the sensor wire.
While the 3 position main switch has an overlap, there doesn't appear to be any danger of blowing the alternator diodes when switching between banks. Just don't turn it to off with the engine running. For this reason I do like the idea of the AO going directly to the house bank along with the sensor wire.
Lots of boats are already fitted with a 1/2/BOTH and if you want all the safety, isolation and redundancy, p[lus dedicated starting, then adding an ON/OFF is a good option.. Rewiring for three ON/OFFS is not always feasible or cost effective if the boat did not already come that way.
weinie, Sorry, BIG time
weinie, I'm sorry, you are absolutely right. I was COMPLETELY wrong. I apologize.
I didn't say to move the AO from the house bank.
I suggested that OP move the STARTER to the C post. (as per MS's diagram
weinie, I'm sorry, you are absolutely right. I was COMPLETELY wrong. I apologize.
If the AO goes to the house bank, you can turn the switch off with the engine running with no harm.
Wouldn't this setup run the starter continuously when #2 is selected?The diagram below is one I favor when owners insist on a dedicated starting battery but also want to retain the flexibility of the 1/BOTH/2/OFF.
With this simple but very redundant system you retain all the isolation & redundancy of the 1/BOTH/2/OFF switch yet add a dedicated direct wired starting battery. Simply flip to #1 and ON and your ready to go. When you're done flip both switches to OFF. Label them carefully, Blue Sea sells the perfect labels...
Normal Operation:
#1 = ON (powers house loads)
ON/OFF = ON (powers engine only)
Start Bank Failure:
BOTH = ON (everything is now powered by the house bank)
ON/OFF = OFF (start battery is 100% isolated)
House Bank Failure:
#2 = ON (house bank isolated start bank powering everything)
ON/OFF = ON (start bank powers all)
If the start battery were to fail flip the ON/OFF to OFF and the 1/BOTH/2/OFF to BOTH and now the house bank is starting and providing house loads. Conversely you can still use the start bank to power house loads in an emergency with the 1/BOTH/2/OFF in position #2 and the start switch to ON.
This system is more complicated but ultimately considerably more flexible than some other systems where you must use the "combine" feature which is never a good choice when you have unknown bank issues..
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Sorry , when both are selected, isn't power continuously applied to starter via #2.???????????
The only "device" being "powered" by the 1-2-B switch is the distribution panel. Otherwise, the 1-2-B switch simply selects which "source" i.e., battery bank, provides power to the DP or to the secondary switch. Follow the electrons based on reply #27.
I'm sorry, I thought in the "both" position both #1 and #2 were connected to the C terminal?The only "device" being "powered" by the 1-2-B switch is the distribution panel. Otherwise, the 1-2-B switch simply selects which "source" i.e., battery bank, provides power to the DP or to the secondary switch. Follow the electrons based on reply #27.
They are but the only reason to ever use BOTH or #2 is in the event of a bank failure.
Otherwise only #1 and ON/OFF are used. BOTH or #2 are only used in EMERGENCIES.....
BOTH could also be used for parallel charging but you are much better off to fit an ACR or Echo type charger so that #1 and ON/OFF are all that are ever used...
It is all in the text you quoted from post #27...
Brain fart, I was thinking start switch was starter solenoid, then nothing made sense in wiring diagrams.
On/Off is then the "Battery Disconnect Switch" for the Starting Battery, probably mounted near the battery. Nice to have when changing out battery, no sparks when disconnecting battery terminal.
Other than that, what are the odds that that battery will fail with a shorted cell, compared to the odds that one of the house batteries will fail in that mode, does it really buy you anything in terms of system reliability?
When would you know when to switch it, the first time the start battery fails to start engine?
Or only after switching to "Both" failed to start the engine.
Or is the "Start Battery" truly an "Emergency Start Battery" and is used only when House Bank will not start engine. and the switch becomes an "Emergency Battery Select" switch?
If used as Emergency Only, forget extra switch, just connect to terminal 2 and connect starter to C, select 1 for normal operation never select "Both" and test #2 once a month for proper operation.
This will give highest overall system reliability.
This is an oft repeated and common misunderstanding. EITHER bank is adequate to start the engine.
If one bank is determined to have failed for whatever reason, going to B is the very worst thing a skipper can do.
That's why they are separate to begin with in this design.
Stuff fails. Chances? Depends how how good you are at "not murdering" your batteries, by neglect, by avoiding under and over charging, checking water levels, equalizing when required...those sort of things clearly discussed here by Maine Sail and in the Ample Power Primer.