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Old 04-02-2011, 09:23   #1
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DC Main Wiring Mystery

As part of understanding the onboard systems on our new boat, I've been attempting to untangle the DC main wiring. Easier said than done! I've had a suspicion that the wiring is not correct based on voltage and amp readings across the house vs. main battery banks. I'm part way through the wiring and think I've found a couple of suspicious items. I would appreciate your taking a look at the wiring diagram and letting me know your thoughts.

To begin with the DC circuit includes a "West Marine Battery Combiner". The combiner appears to be not working, as no LED activity on the unit. The other suspicious item is the previous owner left the 1,2,Both battery switch in "Both". More likely, the way the boat is wired, the house + starter batteries are in parallel and he never had a problem.

To start, here's how I think the boat is currently wired. The yellow highlighted circuits are questionable. I'll review and revise the diagram this weekend; however, I pretty confident the wiring between starter and house batteries is properly represented.




In comparing this to Nigel Calder's "Boat Owner's Mechanical and Electrical Manual", it appears that I have both the "Relay" circuit, using the Cole Hersee SPST Solenoid joining the house and starter AND "Electronic Relay" circuit, using the West Marine Battery Combiner across the banks. I suspect the previous owner was having problems with the Cole Hersee solenoid and not charging the starter battery. Currently, with the "Engine Start" switch open, I measure 5.4v coming from the Cole Hersee solenoid to the "Engine Start" switch. If this isn't working, he probably added the "West Marine Battery Combiner" into the mix.

Here's what I think I need to do - would appreciate comments and suggestions.

1. Remove the West Marine Battery Combiner.
2. Remove the lead from 1,2,Both switch to Terminal Block, labeled "A".
3. Test, verify the Cole Hersee solenoid is working properly.
4. Verify Cole Hersee solenoid is tripped by oil pressure switch and not something else.

With that, I have the alternator charging direct to the house bank. If the engine is running (oil pressure builds, closes oil pressure switch), the Cole Hersee solenoid closes, allowing charge to starter battery. When starting, the Cole Hersee solenoid is open, so the starter battery runs direct to the starter motor (regardless of 1,2,Both switch position). In addition, the starter battery is never in the DC main circuit, powering boat lights, etc.

With that, I'm not sure about the Inverter/Charger. WIth the above changes, the inverter is only running off the starter batter (bad) and the house is never being charged. I think I then need to move Starter and the Starter Battery leads from the "Terminal Block" to the "2" position on the 1,2,Both switch. Then when on shore power, leave the swith on "Both" This completes the charge circuit to both banks. I'm still not happy with the inverter running from the starting battery, but don't expect to be running many 110v appliances. I guess this would be no worse than I have today. Here's how this might look with the above changes:



Much easier to understand! A final though, the Heart 10 Inverter/Charger claims to have an echo charge for a 2nd bank. I don't know why it isn't being used. Should I use this and does this change the analysis? Should the inverter be wired into the house? To do so, this introduces a wiring problem with the length of heavy wire from the inverter to the house bank (starter batter and inverter are in stbd lazerette and house batteries are in center of boat).

I'm going to review the wiring on the boat tomorrow and update the diagrams (if necessary). As part of this, I also plan on understanding the reamining circuits. I need to make sure the battery management circuits are right and I understand how they work. I look forward to your comments.

Thanks much,
Don
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Old 04-02-2011, 09:41   #2
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Cpt Don,

In reviewing your diagram the engine start switch is shown normally open, if this is the case then:
1. how does the Alt charge the Start bank or
2. how does the inverter charger charge the House bank
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Old 04-02-2011, 09:42   #3
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The 1, 2, both switch can be used as an emergency cross connect as it is wired now. Neither the Cole Hersee or combiner will be on when you're trying to start the engine. You can start using both batteries, or if you have a bad or dead engine battery, turn off its main switch and start from the house bank.

Yes combiner and Hersee switch redundant, one or the other.

The Heart on the start makes no sense to me. Not familiar with the Heart functions

John
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Old 04-02-2011, 09:42   #4
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Looking at that gave me a headache. It seems insane to me. The wiring of the solenoid and battery switch is very strange in both your drawings. Or I've misunderstood....

Tip from an EE: What you have there is a wiring diagram of a sort. To understand the function one can redraw it as a schematic. Basically draw the positive mains horizontally across the top of the figure, the common across the bottom, and the various loads vertically between the mains and the common.
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Old 04-02-2011, 09:49   #5
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Quote:
Originally Posted by daddle View Post
Looking at that gave me a headache. It seems insane to me. The wiring of the solenoid and battery switch is very strange in both your drawings. Or I've misunderstood....

Tip from an EE: What you have there is a wiring diagram of a sort. To understand the function one can redraw it as a schematic. Basically draw the positive mains horizontally across the top of the figure, the common across the bottom, and the various loads vertically between the mains and the common.
I wish the people I worked for bought equipment from the company you have equipment from. Most of the schematics I look at I have to redraw to make any sense out of.

John
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Old 04-02-2011, 09:59   #6
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Capt. Don,

Very nice diagrams. Can you let us know what you are using to produce them?
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Old 04-02-2011, 10:11   #7
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To Start I believe I would wire the Start Battery to Bat switch 1, the house bank to Bat Switch 2, the Start feed for the starter would come off the Batt Switch common post. and the House feeds would also come off the Batt Switch Common post. As I understand the battery combiner it allows a bank of batteries to be charged and when they are at full capacity it then allows the charging current to charge the second bank. From the Schematic it seems the selonoid is there to bypass the oil pressure cut off switch during starting? However it seems to be in the wrong location.
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Old 04-02-2011, 10:17   #8
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ENGINE START switch is surely drawn in the wrong place, yes?

The KEY switches the regulator?

What function does SOLENOID serve? Closes with engine oil pressure because the combiner is broken, or vice versa?

Batteries, alternator, oil pressure circuit, regulator circuit and windlass need fuses.
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Old 04-02-2011, 10:23   #9
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Originally Posted by St. Elsewhere View Post
Capt. Don,

Very nice diagrams. Can you let us know what you are using to produce them?

+1 I'm also curious about this, having just started the same process to understand my old boat.
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Old 04-02-2011, 10:38   #10
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Your schematic:
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Old 04-02-2011, 10:46   #11
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Originally Posted by CDunc View Post
Cpt Don,
In reviewing your diagram the engine start switch is shown normally open, if this is the case then:
1. how does the Alt charge the Start bank or
2. how does the inverter charger charge the House bank
This is based on the current wiring. I left it in based on the following logic. To start using only engine, close "Engine Start", set 1,2,Both to "Both" or "2". When engine is running, Cole Hersee closes and alternater charges both House + Starter. If we leave the "Engine Start" open, we are starting from the House. Aside from the inverter, I like the idea of isolating the starter battery.
I could also move the inverter to the other side of the "Engine Start" switch.

Quote:
Originally Posted by daddle View Post
Tip from an EE: What you have there is a wiring diagram of a sort. To understand the function one can redraw it as a schematic. Basically draw the positive mains horizontally across the top of the figure, the common across the bottom, and the various loads vertically between the mains and the common.
Thanks - good suggestion. As my diagram evolves, I will revise.
Quote:
Originally Posted by cal40john View Post
The 1, 2, both switch can be used as an emergency cross connect as it is wired now. Neither the Cole Hersee or combiner will be on when you're trying to start the engine. You can start using both batteries, or if you have a bad or dead engine battery, turn off its main switch and start from the house bank.
John
Agreed. In both diagrams, this is accomplished by putting the 1,2, Both switch on "Both" and openning the "Engine Start" switch.
Quote:
Originally Posted by daddle View Post
Looking at that gave me a headache. It seems insane to me. The wiring of the solenoid and battery switch is very strange in both your drawings. Or I've misunderstood....
It gives me a headache too. The wiring is insane, especially with both the "West Marine Battery Combiner" and the "Cole Hersee" circuits and the lead labeeled "A" from the 1,2,Both to the Terminal Block. The 2nd diagram is work in progress and may not be 100% correct at this time.
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Originally Posted by St. Elsewhere View Post
Capt. Don,
Very nice diagrams. Can you let us know what you are using to produce them?
Diagram is prepared using Visio 2007. Earlier posts had other Visio diagrams, which I borrowed the idea from. Much thanks to "R. Laporte, Knottybouyz III Electrical System for the basis of this diagram.

Quote:
Originally Posted by daddle View Post
ENGINE START switch is surely drawn in the wrong place, yes?

The KEY switches the regulator?

What function does SOLENOID serve? Closes with engine oil pressure because the combiner is broken, or vice versa?

Batteries, alternator, oil pressure circuit, regulator circuit and windlass need fuses.
Engine start switch possibly drawn in the wrong place. I added that as a way to show tripping the starter solenoid and powering the "Xantrex Digital Alternator Regulator". Yes, per their documentation, the brown wire is either the key or oil pressure switch. I'll verify the Xantrex's wiring.
Agreed on fuses - boat probably has them.
As I understand Nigel Calder's description of the "Relay" circuit, when the engine is running, the oil pressure builds, closing the "Oil Pressure" switch. This in turn, closes the "Cole Hersee" solenoid which completes the circuit between "Alternator" and "Starter Battery".
Quote:
Originally Posted by daddle View Post
Your schematic:
Thanks - I'll compare to what I have and revise the diagram.

Thanks for the feedback so far. It sounds like I should move the Inverter to the other side of the "Engine Start" switch or run wires to the house. I also may find that both the Cole Hersee solenoid and the West Marine Battery Combiner don't work (or one or other work) and need to replace. Should I consider replacing both with a new battery combiner, when wired correctly across the "1" and "2" of 1,2,Both switch? This would simplify things futher.
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Old 04-02-2011, 12:14   #12
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Cpt Don,

I would remove the Engine start switch and run the lead directly to the Battery switch. If you wire the combiner between the #1 and #2 post on the Battery switch when the first bank is full the second bank will begin charging. Typically Starting does not deplete a battery that much due to the short demand of Amps. I would wire the charge circuit to primarily charge the house bank then with the combiner when the house bank is full the start bank will begin charging. Also if you really need to you can directly charge the start bank via selecting it on the Batt switch. I would agree moving the Inverter Charger to the House bank due to its Larger amp hours. No fuse is neccissary on the Start feed, however fuses will be required on the house bank wiring.
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Old 04-02-2011, 12:25   #13
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Oh, also I almost forgot..The combiner.. if you open it up is usually three or more Diodes, Check the Diods with a Diod Tester the Diod Tester sends a small current through the Diode to Close the circuit usually around .6v, the Diod will only work one way so be sure to reverse the leads when testing to be sure you should get a reading one way and no reading the opposite way. When you find the bad Diode the you can save some money by replacing the offending Diode.
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Old 04-02-2011, 12:29   #14
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I would have exactly 3 things connected to the Start Battery:

1. The Engine
2. The #2 position of the battery switch
3: The Battery Combiner

There's a problem with the WM battery combiners. They combine the batteries if they detect a charging voltage. Might be the engine or solar or shore power. If the big batteries are on one side and a big load on the other, like your windlass, or the starter, the a situation can develop that overloads the combiner as it conducts the power for the heavy load. I would either find another way, or protect the combiner battery leads with a suitable breaker.
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Old 04-02-2011, 13:22   #15
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"The combiner.. if you open it up is usually three or more Diodes,"
No, you are thinking of an "isolator". The West Marine Combiner is not an isolator. (It is actually made by Yandina and also sold under that name.)

The WM/Y Combiner is a high power relay (75A and 150A versions, IIRC) with a voltage sense and a timeout to prevent chatter. When it is correctly hooked up it is dirt simple, reliable, and practical. I would disagree with daddle on there being a problem with overloads, because any "overload" here is operator (installer) error! You buy and use the one with the right power rating, and don't exceed that load through the combiner. Higher loads to the battery directly won't be seen through the combiner, so they won't matter.

The Combiner is connected to the starting battery with a "sense" lead (subject to length limits, you do need to read the instructions) as well as a power lead to the second battery bank, usually the house bank. When the voltage on the primary battery exceeds 13.8V, the relay closes and supplies power to BOTH BANKS. If the voltage drops below 13.8 (which is typically the low limit for an alternator) the relay opens again, separating the batteries. And there's about a 30-second time delay to prevent it from chattering if the voltage is going up and down from loads, etc.

This is not a perfect way to charge two batteries--but it works pretty well. It relies on the starting battery typically needing only a short charge to be topped up, and then the house batteries sucking up the alternator power as they need it.

Whether you add a 1/2 switch, control it manually, or use other controllers...all optional but a system with THREE types of 1/2 controls just seems like a problem waiting to happen. And from the schematic, it looks like the Combiner isn't hooked up properly at all. And the starting battery has been wired up so it only will be charged from the charger, since the only other power connection to it is via the "start" switch, and that's open whenever the engine is running.
Ooopsie?
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