Start / House / Combine conundrum

[Portage_Bay]

I can't make heads nor tails out of this setup. New to me boat, still crawling around sorting things out. To be honest I'm close to admitting I'm in over my head and bringing in the pros.

• Twin engines, internally regulated alternators
• Port alternator 90 AMPs should charge start bank
• Stbd alternator 90 AMPs should charge house bank
• House bank FLA
• Start bank FLS
• Combiner switch. Blue Sea 3200
• Battery separator. Sure Power 1315-200
• ON / OFF switch between house bank and house bus
• Ignorant PO mislabeling things
• Creative wiring cobbled onto OEM wiring

It sort of works, mostly. Problems and possible solutions once I get my head around this mess.

• House bank not being charged when underway. Appeared during survey to be a faulty alternator. Was probably a blown fuse in the alternator output line mislabled "water maker" and too small at 60 AMPs. New fuse and holder on the way. Should fix that.
• During survey the start bank appeared to be dead. Probably was. Replaced. But wait, there's more!
• Combiner switch set to the PO's "Start" label the engines do not start. Assumption by surveyor and later on hired tech was the battery separator was dead. Had killed the batts.
• New Blue Sea ACR 7622 in hand to replace separator. Given this is an older boat with FLA banks I'm not inclined to go Balmar, Wakespeed or any other fancy gear as long as the FLA's live. Following Rod Collin's in Making Sense of the ACR where he says the two alternators can work together through bulk that is my current plan. After I understand this mess.
• The house bank ON / OFF switch does nothing. Absolutely nothing. With the combiner switch set to OFF and the house bank switch set to OFF two curious things happen. The engines start. Voltage from house bank bus to negative bus is still there. All the house circuits still work. Go figure.
  

Have a look at my DIY "Schematic" and combiner switch "logic". Maybe you can help sort it out.

 

[SteveK]

Your drawing, 1-2-B switch is all that is needed to combine manually, does that separator combine automatically?
The start battery drawn to the 'Both' is confusing. It suggest the house bat only works when switch is on both or all batteries.
Drawing also shows the house bank gets a direct charge from ALT, but you say not.

 

[Bmarler]

That looks goofy to me. A 1-2-both switch should have the 1 terminal to a battery bank, the 2 terminal to another bank, and the c terminal to the output. In this case the start buss. No idea what a separator is, or what it’s intended to do.

 

[High Wire]

Make sure you don't also have a 1/2/both switch for the bow thruster. That can bypass everything if set wrong.

 

[Bmarler]

According to your logic, 2 to b is made in the off position. That heats up the start buss as well as the house buss. That’s a huge problem. As was mentioned, look for another switch to be making mischief in the system. But really, those switches/combiners are not working as intended, or labeled.
You can simplify this easily.

 

[Portage_Bay]

Your drawing, 1-2-B switch is all that is needed to combine manually, does that separator combine automatically?
The start battery drawn to the 'Both' is confusing. It suggest the house bat only works when switch is on both or all batteries.
Drawing also shows the house bank gets a direct charge from ALT, but you say not.

I agree with your reading of things. However it does not work that way.

First, yes the combiner is automatic. Combines when either bank is above 13.2 volts. According to data I can find max capacity is 200 AMPs which tells me it cannot be used for combining start and house bank for starting. Only for charging.

Second the stbd alt not charging the house bank direct is almost surely do to a failed fuse in that circuit which will soon be replaced. That should solve the house bank charging issue.

Easy enough to understand so far. Note that in my continuity chart I have the columns
1 <-> 2 1 <-> B 2<-> B
B should really be labled C for common

Now things get wierd. Look at my continuity chart for the 1-2-Both switch. It's truly odd.

• I expect in position 1 there is continuity between 1 and C. And yes, there is.
• I expect in position 2 there is continuity between 2 and C. And yes there is. There is also continuity between 1 and 2 as well as 1 and C. The switch cannot be doing that. Something else is. The combiner?
• I expect in position Both there is continuity among all posts. And there is.
• In fact as far as continuity among the posts positions 2 and BOTH are the same. Yet the engines start in position BOTH. They do NOT start in position 2.

This is honestly the strangest wiring I've seen and it makes no sense.

Don't know if I'm making sense. And I have to quit for the day. May not be able to get back to the boat until mid June. Thanks for trying to help

 

[Portage_Bay]

Make sure you don't also have a 1/2/both switch for the bow thruster. That can bypass everything if set wrong.

As far as I know the bow thruster is independent. Tow AGMs in the bow with their own charger.

 

[Portage_Bay]

According to your logic, 2 to b is made in the off position. That heats up the start buss as well as the house buss. That’s a huge problem. As was mentioned, look for another switch to be making mischief in the system. But really, those switches/combiners are not working as intended, or labeled.
You can simplify this easily.

Gotta agree with you. There are some as yet undiscovered switches. This appears to have been a 2010 add on to 1986 OEM build. And not well done.

 

[Portage_Bay]

According to your logic, 2 to b is made in the off position. That heats up the start buss as well as the house buss. That’s a huge problem. As was mentioned, look for another switch to be making mischief in the system. But really, those switches/combiners are not working as intended, or labeled.
You can simplify this easily.

And, don't know if I stated this in earlier posts. There is a main house bus on/off switch. House (+) to class T fuse to on/off switch to house (+) bus. When I turn that switch off I still see full voltage on the house bus measured between the (+) and (-) buses. Not good.

 

[Bmarler]

I think the 1-2-both switch is wired wrong. And I’d get rid of the automatic combiner in this scenario.
There’s already a way to manually connect in case of failure. Let each alternator do its own bank.

 

[Bmarler]

And, don't know if I stated this in earlier posts. There is a main house bus on/off switch. House (+) to class T fuse to on/off switch to house (+) bus. When I turn that switch off I still see full voltage on the house bus measured between the (+) and (-) buses. Not good.

I did see that. It looks like it must be coming through the combiner and the switch. It’s just not wired right. Off needs to be off.

 

[SteveK]

I think the 1-2-both switch is wired wrong. And I’d get rid of the automatic combiner in this scenario.
There’s already a way to manually connect in case of failure. Let each alternator do its own bank.

I agree and from there may come the other issues.
Both position would connect all three terminals regardless of what is connected to each.

 

[High Wire]

The way your drawing shows the start battery switch, placing the switch to #1 position will destroy your alternator diodes. It would be better to have the cable from the engines on "2" go to "B" and the cable on "B" go to "2". Then you could choose which bank to charge with the alternators. Do NOT switch with the engines running or you'll let the smoke out!!!
Also checking continuity with cables attached will give false readings assuming there is a battery charger wired into the scheme somewhere.

 

[Portage_Bay]

The way your drawing shows the start battery switch, placing the switch to #1 position will destroy your alternator diodes. It would be better to have the cable from the engines on "2" go to "B" and the cable on "B" go to "2". Then you could choose which bank to charge with the alternators. Do NOT switch with the engines running or you'll let the smoke out!!!
Also checking continuity with cables attached will give false readings assuming there is a battery charger wired into the scheme somewhere.

Please explain how running in position # will destroy the alternator diodes. The PO and I have run it that way without damaging diodes.

I'm aware of not switching while engines are running.

Thanks for the heads up regarding checking continuity with the charger on. The charger on might explain the full voltage on the house bus when the house main switch is opened.

 

[High Wire]

Sure. Per the drawing with the switch in position 1, the Port alternator coming in via terminal 2 is not connected to ANY battery. When the alternator loses its battery connection the internal voltage regulator sees low voltage and drives output voltage to max, which is beyond the ratings of the diodes and poof they fail almost instantly. There are ways to prevent that IF the installer is thoughtful with a ZapStop device or a Field Cut-Out contact. This is why you will see the warning message on battery switches not to switch with the engine running. A momentary interruption when the switch is moved is all it takes to kill an alternator. Soooo, if you used position 1 without blowing the diodes, my guess is the drawing doesn’t match the actual install. The starboard alternator would survive because it is directly connected to the house battery.

 

[Portage_Bay]

Sure. Per the drawing with the switch in position 1, the Port alternator coming in via terminal 2 is not connected to ANY battery. When the alternator loses its battery connection the internal voltage regulator sees low voltage and drives output voltage to max, which is beyond the ratings of the diodes and poof they fail almost instantly. There are ways to prevent that IF the installer is thoughtful with a ZapStop device or a Field Cut-Out contact. This is why you will see the warning message on battery switches not to switch with the engine running. A momentary interruption when the switch is moved is all it takes to kill an alternator. Soooo, if you used position 1 without blowing the diodes, my guess is the drawing doesn’t match the actual install. The starboard alternator would survive because it is directly connected to the house battery.

I understand that switching the charging circuit off while charging will blow diodes. That is not what is happening. The switch is not changed while the engine is running. An alternator is not harmed by running with no load from startup.

Regarding the drawing being incorrect I'm confident I have it right.

 

[Bacchus]

I dont believe fusing alt output is common... at least not on my Mainship single Yan eng.
The issue is if/when fuse blows you will likely damage the alt... its just like switching under power.
Starter cables are also generally not fused and many tie alt output back to the starter lug and use the start cable to charge the batty.

 

[Portage_Bay]

I dont believe fusing alt output is common... at least not on my Mainship single Yan eng.
The issue is if/when fuse blows you will likely damage the alt... its just like switching under power.
Starter cables are also generally not fused and many tie alt output back to the starter lug and use the start cable to charge the batty.

I think you are correct that it is uncommon. However it is recommended by some. Calder, Cote and others. The fuse is 1.25 the max output of the alternator near the battery or where it connects into the bigger cables / bus / starter lug. At 1.25 max output it won't blow. The concept is that the alternator won't develop enough power to burn it's wire. However in a dead short to ground the alternator's cable will be exposed to full battery current possibly starting a fire.

 

[High Wire]

If you reverse the labels for “2” and “B” the drawing will work, the engines will start and charge properly. As it is now with the switch in position “1” the engine starters and port alternator are connected to nothing.

 

[Bmarler]

If you reverse the labels for “2” and “B” the drawing will work, the engines will start and charge properly. As it is now with the switch in position “1” the engine starters and port alternator are connected to nothing.

Agreed. I said it in post 3. And I’d lose that combiner. As long as both alternators are working, everything’s fine and automatic. If an alternator fails, the battery switch will make the connection to charge the other bank by using the 2 or both position. Simple.

 

[Bmarler]

I dont believe fusing alt output is common... at least not on my Mainship single Yan eng.
The issue is if/when fuse blows you will likely damage the alt... its just like switching under power.
Starter cables are also generally not fused and many tie alt output back to the starter lug and use the start cable to charge the batty.

Mine is fused as well. It’s a 225 amp balmar on 4/0 cable. Probably 12-14 feet to the positive buss. I wouldn’t want that un-fused.
I have a zap stopper on the alternator that should protect it, but I guess I won’t really know until there’s a catastrophe.

 

[Portage_Bay]

If you reverse the labels for “2” and “B” the drawing will work, the engines will start and charge properly. As it is now with the switch in position “1” the engine starters and port alternator are connected to nothing.

I think you're right. The start buss would be fed from the Both position. House bank goes to 1, start goes to 2. Then the 1-2-Both switch works as designed. And the isolator is right also. Certainly easy enough to swap the two cables at "2" and "B" for a test.

Other issues remain:

1. Why is the house (+) buss live when the house master switch is off. Very likely you are correct that the charger was still on.
2. Why do the engines still start when the combiner switch is in position "1" and the house master switch is "OFF". That still makes no sense. It must be solved. There are still mysteries in this 1986 / 2010 system.
3. The port alternator should go straight to the start bank. Easy cable run.

Attached is a drawing of your suggested changes and a concept of a "clean" twin engine system with a combiner switch and an ACR. Base drawing taken from Marine How To Making Sense of the ACR

 

[Portage_Bay]

Agreed. I said it in post 3. And I’d lose that combiner. As long as both alternators are working, everything’s fine and automatic. If an alternator fails, the battery switch will make the connection to charge the other bank by using the 2 or both position. Simple.

The plan is to replace the isolator with a Blue Sea ACR. This is an older boat with brand new start bank and new-ish healthy house bank. Both FLA. The boat will only be kept for about 3 yrs so I'm resisting huge changes to LifePo4. Quoting from Collins article Making Sense of the ACR

What about twin engine boats?

On twin engine boats one alternator, usually the largest and most capable, can feed the house bank directly and one can directly feed the start bank directly. The addition of an ACR means that both alternators will contribute to the house bank charging during bulk. Without the ACR the start bank alternators full capability is just being wasted by feeding a few amps at best to the start battery. By adding an ACR we can make much more effective use of both alternators and charge the house bank faster.

It won't be ideal but it will be far better than what's there now.

 

[Bmarler]

Both of those drawings do the same thing. The second one is cleaner with less cabling to the battery switch.
I will concede the use of the combiner if the alternators are small.
I looked again at the first sketch. I wonder if the switch position indicator really matches the terminal number on the back. Or if the banks are on opposite terminals than you think they are. That could easily cause the start condition you’re talking about.

 

[SteveK]

Others have said it and OP is agreeing. I would like to add that B is not a terminal. You have input #1, input #2 and output. In your drawing the output is called B for both 1&2 combined to output, but B is not a terminal, it is internal combiner switch.
The selector on #1 closes terminal #1 and output, #2 closes only #2 and output, then B closes #1, #2 and output.
The above is for two inputs, one output.

Then you can have one input and two outputs, for one ALT to two batteries. The B is just a position of the switch and should not be shown as a terminal.

 

[Portage_Bay]

Agreed. I said it in post 3. And I’d lose that combiner. As long as both alternators are working, everything’s fine and automatic. If an alternator fails, the battery switch will make the connection to charge the other bank by using the 2 or both position. Simple.

Yes you did say that in post #3. Thank you. It didn't sink into my thick frustrated skull yesterday.

 

[Portage_Bay]

Both of those drawings do the same thing. The second one is cleaner with less cabling to the battery switch.
I will concede the use of the combiner if the alternators are small.
I looked again at the first sketch. I wonder if the switch position indicator really matches the terminal number on the back. Or if the banks are on opposite terminals than you think they are. That could easily cause the start condition you’re talking about.

Regarding the combiner. Yes the alternators could be bigger. 90 AMPs each with a substantial running load. More current during bulk would be helpful.

Regarding the switch position indicator matching terminal #s on the back. Time to pull it off the board and have a look.

 

[Portage_Bay]

Others have said it and OP is agreeing. I would like to add that B is not a terminal. You have input #1, input #2 and output. In your drawing the output is called B for both 1&2 combined to output, but B is not a terminal, it is internal combiner switch.
The selector on #1 closes terminal #1 and output, #2 closes only #2 and output, then B closes #1, #2 and output.
The above is for two inputs, one output.

Then you can have one input and two outputs, for one ALT to two batteries. The B is just a position of the switch and should not be shown as a terminal.

Agree. Switch posts are not terminals and should not be used as such. Poor quality work on the part of the installer.

 

[Portage_Bay]

To all who have jumped in to help. Thank you. In the clarity of this morning along with all the posts I now have a better idea of how to solve the base issues with the switch and combiner. I still need to understand the rest of the antique DC system and it's apparent strange behaviors. I won't be back to the boat again till mid June.

 

[Bmarler]

How big is the house bank? Was it mentioned previously?