Connect MPPT to Isolator?

[cal40john]

Originally Posted by zuzullo

The alternator I dont know but the CTek battery charger I got an email from them saying that I should connect it to the Isolator. I cannot find any specs about the Isolator itself. Here is a picture of it attached to this message. As you can see on the picture, some loads were actually connected to the isolator instead of the battery. I have moved them all to the bus splitter. This is correct, right?


Yes, there is a big fuse on the main cable right after the battery, on the wire going to the first bus splitter.

I could not find documentation on your separator. If it were a diode separator for 55 amps it should have a large heat sink, so I am guessing it isn't. So probably what you have does not have the issue I was talking about and there is no significant voltage drop.

(The problem with an email from your charger company is that if you give incomplete information you can get the wrong answer. If you had had a diode splitter and told them about it, their answer probably would have been different.)

The big fuse on the main cable is sized to protect that size cable. It won't prevent a fire in the smaller cables. You should have a fuse to protect the smaller wire where it begins closest to the battery.

(Your switch board with fuses is doing that for the circuits on that part of your system.)

[Zil]

On your new diagram; You need a fuse on the wire to the fused switch panel, near the split bus. Sized to protect the wire. You don't really need a fuse between the panel and controller. But, you do need a fuse between the controller and battery. At the battery.
The approximate 10 awg you show from the controller is only safe up to about 60 amps. At 15 amps you would face over 4% voltage drop. Not good on a charging circuit. I would recommend at least 6 awg (13mm) with a large fuse at the battery. 6awg is safe at 100 amps, and small fuses add more voltage drop.

[hellosailor]

Get rid of the isolator. They were a great idea in 1950, but they create a voltage drop, prevent the alternator's voltage sense lead from being properly used, and have no real excuse to still be around. Instead, lead all charging sources to the house battery, and connect that to the starter battery with an "Echo Charger" or Yandina/West Marine "Battery combiner". A small box with a relay that connects both batteries to charge when the alternator is at power, and separates them when the engine is off. If that removes 1/2 volt of voltage drop from the charging circuit, that's removing roughly a 3-4% energy loss from your charging system. There's no downside to this.

You can connect the MPPT "load" side to your stereo or tv, to play live music sunrise to sunset, if you want.(G)

[cal40john]

Originally Posted by hellosailor

Get rid of the isolator. They were a great idea in 1950, but they create a voltage drop, prevent the alternator's voltage sense lead from being properly used, and have no real excuse to still be around. Instead, lead all charging sources to the house battery, and connect that to the starter battery with an "Echo Charger" or Yandina/West Marine "Battery combiner". A small box with a relay that connects both batteries to charge when the alternator is at power, and separates them when the engine is off. If that removes 1/2 volt of voltage drop from the charging circuit, that's removing roughly a 3-4% energy loss from your charging system. There's no downside to this.

You can connect the MPPT "load" side to your stereo or tv, to play live music sunrise to sunset, if you want.(G)

Look at the picture of his isolator. I don't see how that little box with no heat sinks could be a 50 amp diode isolator. Be nice to find a reference to it to find out exactly what it is, but I haven't yet.

[hellosailor]

Good question, John. A quick search for the part number (Skiljerela) actually found me a higher amperage model MADE BY BLUE SEAS so there may be more than a plain (diode) isolator here. They are calling it a "separator", no an isolator, for whatever that's worth.

The Blue Seas label calls it (the SKILJERELÄ 12V/140A DVSR) an "automatic charging relay, but that's a very different package.

But note this one says "Generator max. 55A" indicating that it can only handle a 55amp total load. Given that low a capacity, two good diodes mounted directly to a heavy metal case could very well be in there, possibly two 30A stud-mounted diodes? Also acting as the terminals?

I suppose the OP could always use a DMM or take a peek inside the case to find out for sure, if Skiljerela doesn't have a phone number.

[john61ct]

Spänningsstyrda skiljereläer: 7611

https://odelco.se/laddningsfoerdelni...aeer/7611-info

No matter what, charge output direct to bank.

If possible the House bank.

Then combiners / ACRs whatever can charge other bank(s)

If only Starter low amps is OK, even just Echo Starter

[john61ct]

Use a good DMM to check voltage levels at each bank, fat wiring to ensure low drop levels.

[hellosailor]

Interesting. That one is yet another BS product but clearly labeled as their automatic charge relay. I wonder if they are sourced from Sweden? Or, resold under Swedish label" there?
Good sleuthing.

[john61ct]

The conglomerate that owns Blue Sea

http://www.marincopowerproducts.com/en/brands

is the 800lb gorilla, I doubt much is manufactured in high-cost jurisdictions anymore.

Just got acquired itself last week by Brunswick Corporation (NYSE:BC)*

[zuzullo]

Still working on it after your tips. I just found that the fridge has the positive (+) wired to the battery and the negative (-) wired to one of the bolts on the engine (!). Why is that? See photo 1 attached.
I am keen on rewire and make it go through my switchboard. It that ok?

Then I also see that some instruments have 2 fuses. One on the black wire and another on the red wire. Is there a specific reason for that? Having one on the red wire is enough, right? See photo 2 attached.

[hellosailor]

After a gut rewire, we found the lights on the pedestal compass didn't work. No one remembered particularly when they'd last worked or not, so, it was off to Radio Shack for some new LED lights to replace the presumably burned out bulbs.

Nope. Turned out some OP had run the compass lights under the deck, over the engine space, out to the breakers, using household ZIP CORD simply twisted and taped as an extension. And during all the movement or whatever, those twists had come undone.

And at the same time, we found another run of zip cord, with a toggle switch in the middle of it. Traced it out and found it was a secret ignition [sic] kill switch in the engine wiring. Fortunately, we found it before it went bad! And out it came.

While it does pay to ask "Why would someone have done this?" because sometimes, "it" was done for a reason, more often than not it it because someone was cheaping out, or didn't know better, and if you have the whole picture (like "a refrigerator") it pays to not even ask why things were done that way, but to just do it all over again--the right way.

Even General Motors has used two fuses, in series, for electrical parts in cars. I remember one fine day crawling behind a bulkhead to check an evil fuel gauge-only to find it had been fused TWICE. Once on the breaker panel, a second time buried behind the bulkhead, for no really good reason, and that was the one that ha invisibly blown.

Sometimes you fuse both leads in order to prevent possible ground loops or an overload when a main ground has come loose. It is a rare but real possibility. If they look "factory" and OK, it might pay to leave them alone until you're sure of the bigger picture. If they look like Bozo just spliced them in...by all means, make it conventional (one proper fuse) again.

While you're cleaning up wiring, use a plain old pencil and big sheet of paper, create a schematic of what you do and what you've found. In the future it is almost certain to come in handy.

[pcmm]

Originally Posted by zuzullo

Should I connect the MPPT charger to the battery isolator?
If I do so, then the MPPT will only deliver energy and we wont be able to keep it connected to the Switchboard, as it is now.
Please see the diagram of the current setup in the sailboat (attachment). And if you see anything wrong let me know as well
Thanks in advance

No, connect the MPPT directly to the house bank. Get rid of the isolator and install a battery combiner between banks. That way you don't have to deal with the 1v drop across the isolator.

[pcmm]

See edited diagram

[zuzullo]

Originally Posted by hellosailor

While it does pay to ask "Why would someone have done this?" because sometimes, "it" was done for a reason, more often than not it it because someone was cheaping out, or didn't know better, and if you have the whole picture (like "a refrigerator") it pays to not even ask why things were done that way, but to just do it all over again--the right way.

THANKS! Thats exactly what I thought, but since it seemed so odd to connect a fridge to a bold on the engine, I had to ask afraid that there could be a crazy logic to it. I am gonna rewire today.
As for the fuses, I will remove them from the negative leads (picture 1) and I have just created a bus (picture 2) to split the black wire leads correctly (without fuses).

[Albro359]

Originally Posted by pcmm

No, connect the MPPT directly to the house bank. Get rid of the isolator and install a battery combiner between banks. That way you don't have to deal with the 1v drop across the isolator.

There are now available battery isolators that use FETs rather than diodes and the voltage drop is almost unmeasurable...VICTRON is one supplier...there are others.
We had one on our last boat and because its solid state it is much more reliable than most relay based battery combiners.
Cheers
Alan