Perko 4-way switch

[mitiempo]

Maine beat me to it.

The saving is usually the total price of the Dual Circuit switch as most boats already have the 1/2/all switch.

Whatever switch you have it makes more sense to run alt output to the house bank and take care of the start/aux battery with either an Echo Charge or an ACR. This eliminates the chance of someone switching to off and blowing alt diodes. It also means that whatever position any switch is in both banks will be charged. Not a PITA to use as you only have to switch to #1 and back to off when leaving the boat. Couldn't be simpler.

The aux battery should be exercised occasionally.

As far as using all of the Dual Circuit's functions, I can't think of any time I would want to combine banks.

The one unlikely scenario? Boats should be engineered electrically so you never have to rewire batteries under way - whatever the circumstances.

[SEMIJim]

Originally Posted by mitiempo

The aux battery should be exercised occasionally.

Maybe so, but will it be? My guess is, in most cases: No.

We have a saying in engineering: "Make something more idiot-proof, and God will build a better idiot." The point being: In any design, the more you can take dependence on humans doing it right out of the equation, the lower your failure rate. That is the point of the Blue Sea switch and ACR or Echo Charge solution: To take the human error out of the daily operational equation.

Originally Posted by mitiempo

As far as using all of the Dual Circuit's functions, I can't think of any time I would want to combine banks.

For charging, in case of Echo Charge or ACR failure?

Originally Posted by mitiempo

The one unlikely scenario? Boats should be engineered electrically so you never have to rewire batteries under way - whatever the circumstances.

Given proper maintenance, which your and Maine's design also requires, the unlikely scenario probably fades to a probability so low as to be effectively a non-issue.

Your and Maine's designs have their disadvantages. Mine has a different one. In any event: We're obviously neither going to change the other's mind, so I guess I'm done with this thread.

Jim

[mitiempo]

If the Echo Charge fails and you have a 1/2/both switch all you need to do is put it in the both position to parallel battery banks for charging. But you still retain the use of either bank for any purpose.

[Omatako]

As far as knowing what the state is of the secondary (start) bank, a decent battery monitor should suffice. I have a Xantrx Link20 that monitors both banks and tells me at a glance what the state of charge is.

I also have another system connected to the secondary bank - I have a pair of wires that run from these batteries to the bow where the battery is located under the anchor winch. When the start batteries are charged, so is the anchor winch battery.

That's one of the original reasons for this thread. I thought that if there is no charge going to the start bank then there is also no charge going to the anchor winch battery. Anyway, as with SEMIjim, I think this thread has run its course for me, thanks for the ideas.

[Maine Sail]

Originally Posted by SEMIJim

Maine, given the your experience vs. mine, I'm usually disinclined to disagree with you, but this would be one of those rare instances...

Disagreement is always good as it leads to good conversations!

Originally Posted by SEMIJim

As an aside (not the main point I wished to make): Haven't you just obviated the cost advantage of the traditional switch over the DCP?

Btw: About the cost thing: A traditional Perko switch runs about $25-$35 U.S. A Blue Sea Dual Circuit Plus appears to run about $15 more, on average. Not a real budget-buster, I would think?

I suspect part of the problem is that you are looking at this from a DIY perspective and I need to look at things from an installers point of view.

Most of my customers already have a perfectly functional 1/2/BOTH/OFF switch so the cost of the switch is free. Many of these switches are already mounted directly in a custom electrical panel or expensive teak bulkhead. The DCP switch does not mate up to many of the 1/2/BOTH/OFF switches cut out sizes and customization is very often required at my customers cost. This can often exceed an hour or two of labor depending upon the location, access or whether a new custom blanking plate needs to be made. The cost of the switch can be but a small portion of the swap out.

Originally Posted by SEMIJim

Anyway...


So should you go to use it in an emergency, you've no idea whether it'll actually perform?

I always advise my customers to test the #2 bank a few times per season. Starting an engine really does not "exercise" a bank all that much but it does tell you the bank is working. Cycling down to 99.5% state of charge, after starting, is not much of a work out for a battery in good shape but does confirm it is working.

Originally Posted by SEMIJim

Still liking the separate start/house circuits, both of which whose batteries get cycled regularly.

Jim

And your decision is a good one for your comfort level and that is what matters. I would argue though that you have one bank that gets cycled and one bank that you merely confirm is working well enough to fire up the engine..


I have a customer who decided a few years ago to go with a dedicated start and house bank with two independent on/off switches, one for start and one for house and a third for "emergency" combine. I gave him the pro's & cons against & for this and he knew it left him with no redundancy to take a bad battery bank completely off line and still have one to power everything to get home. He was very confident in his system and his choice in batteries so made his choice and went ahead with it..

FF three years to last spring. He launched his boat and the AGM starter fired up the boat. He took it to his mooring and came back three days later only to find a dead, as in, click, click, starting battery. He called me from the boat to ask for advise.

His 6V bank could not fit in the start battery location to connect them there and re-running the start cables to the house bank was not doable nor was it doable by moving wires on the switches he installed due to the custom nature of his boats interior. Being a rather sudden and catastrophic failure he chose not to "combine" the banks with the jumper switch for fear of starting a further problem like a fire. I would not have combined them either as the battery went from starting the boat to sitting at about 9 volts with zero loads on it all in just three days which could be indicative of an internal cell failure.

Luckily he was already on his home mooring and simply replaced the battery and moved on. He now however has a lot less confidence in his system and has expressed to me he now wishes he'd kept his 1/2/BOTH switch. If he was off cruising he was basically dead in the water. While these types of failures are not very common I do see them more than I'd like to. Perhaps he could have combined them and not caused any damage but the battery was confirmed dead and could have had a bad cell. He now carries a "jumper pack"..

There is no one right system but I see a lot of people dismiss the venerable 1/2/BOTH switch which does offer complete redundancy and the ability to completely isolate a bad battery bank and take it completely off line while still 100% being able to power the vessel.

If that customer had been of cruising and had called me with a re-wired 1/2/BOTH switch I could have easily talked him through it and got him going, though he could have done this on his own too. With his system which was electrically very similar to the DCP there was not a lot we could do.

I wire things many ways, and have installed a DCP, but I just feel there are other options that are ultimately safer and more redundant.


The ONLY thing that matters is that YOU are comfortable with YOUR system. I often install things that go against my own suggestion because it makes the owner more comfortable right, wrong or indifferent.....

[Stu Jackson]

It's also a bigger PITA to use during normal use.

With the Dual-Circuit Plus there's no getting it wrong: You turn it on: Starting battery's connected to the starting system, house battery is connected to everything else. You will always have starting battery.

Unless, as previously conceded, it dies due to old age.

There's no messing with things like "Well, we started on both, so we need to remember to switch to 1 after we shut the engine off... or did we use 1 last time? Maybe we should switch to 2?" You remembered to do one of those, but operated long enough to drag the battery down to below starting reserves, so you switch to the other and start up. Now you have to remember to switch to both to charge the drained one, and cross your fingers in the hope the switch hasn't degraded to the point where it breaks before makes, which could fry your alternator.

To add to Maine Sail's contribution, that's simply not the case. IF, I say IF, you have removed the alternator ouptut (AO) from the C post of the -1-2B switch, and ONLY use it to determine battery output, as Brian has described, then you simply don't go through this nonsense.

This "messing with the switch" position was back in the dark old days when the AO was put on the C post of the 1-2-B switch, and thus the switch served TWO purposes: where the charge current WENT when the engine was running, and the which battery it came FROM when the engine was off.

If you move the AO, that "issue" just goes away, and you run the system as Maine Sail and Brian and I have described.

The dual circuit switch is stupid.

[SEMIJim]

Originally Posted by Stu Jackson

The dual circuit switch is stupid.

Stu, a hint: That "argument" is no more convincing now that when you made it the first time.

Jim

[Stu Jackson]

Jim, sorry about that. Perhaps I feel strongly enough that situations such as what Maine Sail just described, are rather unnecessary. I also just posted a link to this discussion on our C34 message board, in my "Electrical Systems 101" topic, and noted this:

It gets into, yet again, the stupid Blue Seas dual circuit system. For those of you who have the DC switch, take heed of Maine Sail's advice: if you like what you have, and understand how it works, and its limitations, then you're just fine. Simply understand that there are different, and I believe, better ways to set up a boat electrical system.

Sorry to use that word again, just copying & pasting, and I promise that I'll stop using it here on this topic.

[mitiempo]

Yes, illogical, but not stupid. And it is very well made.

[Maine Sail]

Originally Posted by mitiempo

Yes, illogical, but not stupid. And it is very well made.

I too would disagree with Stu that it is "stupid" as there are boats that can benefit from such a switch I just don't personally like the lack of features and safety/redundancy that you lose by installing one on a sailboat.

And yes Blue Seas makes some of the best marine electrical stuff out there. The switch does exactly what it is intended to do and does that very, very well. I just am not a huge fan of the "intentions" without a potential customer knowing all of or the "rest of the story".

As long as a customer or potential customer knows the whole story, and they still decide it is right for them, then I'll install what ever they want. I will not simply take someones money though without giving them all of the options and pro's & cons. So far I have only had one customer bite on the DCP switch after weighing all the pros and cons and that particular installation was a decent application for that switch.

She was a center console fishing boat that did not want the fishing electronics dropping out every time they started the 300HP outboard. The boat had room for just two group 27 batts one for engine and one for house. The engine was shut down and re-started 10-30 times per fishing day with little charging time in-between. One of these batteries could not support the 300HP starting loads and electronics without shutting down the Furuno system. This type of application is very well suited for the DCP.

I am installing a $160.00 Blue Seas volt meter later this week for a customer. The owner insists he needs it and does not want a battery monitor even though my cost to him is the same.

Personally, I think he is wasting his money but he does not want to "learn" a new device so his comfort lies in what he knows/wants. I even explained that he could leave the Victron on the voltage setting and use it just the same as the Blue Seas digital volt meter but his mind was made up. Money was not the issue, personal comfort with what he wants was. He does fully understand and knows the voltage tells him little to nothing at a simple glance, and he knows this, but still wants it. The real reason behind his decision was a failed alternator that he never knew about until the batts died in a bad spot.. He simply wants to see his alternator voltage from the cockpit which is about 10 feet away. Fair enough and the Victron won't do that as the numbers are significantly smaller. He got all the options, understood them well, and still wants what he wants and that is great!

He also replaces batteries every three years and could care less. He did not even want to hear that I could to likely double his bank life because his comfort level is in replacing them every three years for "piece of mind".

Nothing is "stupid", just different, and every system has its pro's and con's.. As far as I am concerned I have not yet seen the "perfect" sailboat electrical system and don't know that it exists though I have been trying.......