Suggestions on DC2DC charger setup.

Currently, all charging sources go to my House Bank. I have three DC2DC chargers that then send current to my Start Battery, Genset Start battery, and Thruster bank. The Thruster bank feeds the bow and stern thrusters as well as the windlass. Balmar Duo-Chargers are used for the Thruster and Genset battery. A Xantrex Echo-Charge is used for the Start battery. FWIW, the Engine Start battery uses the Echo-Charge because the Cummins electronics don't play well with the Balmar Duo-Charge but the Echo-charge works great.

So that has worked very well except for one problem. There have been three times that I can recall, where the high amp draws from the Thruster bank have caused the Balmar Duo-charge to try and send more than 30 amps to to the battery bank, blowing the 30amp fuse. The Duo-Charge is only rated to deliver 30amps and doesn't seem smart enough to not give more than the battery is asking for. It is easy to replace the fuse, but unfortunately I only notice the problem when the thrusters or the windlass fail to work due to a low battery after the thrusters and windlass had been run for a while with no recharging of the battery. So I want to make a change.

I just changed up my layout so that the alternator is charging the Thruster bank. I then made the Thruster bank the source for the DC2DC chargers to the Start and Genset batteries and reversed the Duo-charge so that the Thruster bank is feeding the House bank. This will work but I don't think it is ideal. This will limit the charge to the House bank to only 30amps from the alternator. FWIW, the alternator is a stock Cummins (Delco) 130amp alternator that kicks out a constant 14.0v.

I am looking at the option of buying a Victron Orion 12v 50amp DC2DC charger. This has a number of advantages, chief among them being able to charge at 50amps instead of 30amps. The other option is that it would work well for me if/when I decided to move to a LiPo house bank.

Currently, there are two ways I could do it. I could go back to the way the system was setup before but simply substitute the Victron for the old Balmar Duo-charge and have it feed the Thruster bank from the House bank. I would then direct the alternator feed back to the House bank. This would give the Thruster up to 50amps of charge from the house bank. Likely not when idling unless the sun is giving me a good solar boost, but still better than the Balmar and I wouldn't have to worry about it blowing a fuse like the Balmar.

The second option is to leave it all setup as it is currently only with the Victron feeding the house from the Thruster bank instead of the Balmar. This would have the advantage that the Thruster bank would be getting the full alternator feed when using the thrusters and windlass and the rest of the time when under way, it would be feeding the house at close to 50 amps when under way.

So of those two options, what might you all chose?

I think sharing a couple of diagrams of what you have today and what you are considering would help draw more feedback. Even if roughly drawn block diagrams. By your text description there are a lot of pieces to the puzzle.

READY said:

I think sharing a couple of diagrams of what you have today and what you are considering would help draw more feedback. Even if roughly drawn block diagrams. By your text description there are a lot of pieces to the puzzle.

Click to expand...

Good point. I'll see what I can come up with.

Here are the two options I am thinking about.
Option #1

Option #2

Dave. this device is new to me so I found the manual which I attach. It appears to work as a DC2DC.
From the read if the demand is greater than 30A the DDC is supposed to shut off, not blow the fuse, 1st failure. It is limited to 30A so 2nd failure. I am going to say the DDC is past the best before date and should be discarded.
You say you have three DC2DC charges. What are the amps per DC2DC. Is this DDC one of the three, or a second charger to thrust (before the change).

Option 1&2 only has a trickle charge to start battery.
Where are the 3 DC2DC?

The Xantrix echo-charge is a form of a DC-DC charger. As you say, more of a trickle charger. There are two of the Balmar Duo-Charge but I would like to replace the one that is currently serving the thruster bank with the Victron Orion.

You may be right that the Balmar has failed. It was on the boat when I bought it 7 years ago.

I think you need to step back and have a good think about what are the needs, what do you have and where should that go to best satisfy the needs.

For example I've owned boats all my adult life, now 50 years, and never had the genset Start battery charged with anything but the puny permanent magnet (there is no electrical feed to the field coil) alternator, that produces maybe 5 amps that is mounted on the genset. Never in those 50 years have I had a flat genset start battery, with the existing battery now about 6 years old. Seldom have I turned the battery switch off. I expect a few more years of use yet.
These batteries have a much easier life than the battery in your car. How many echo chargers or DC2DC's do you have in your car? Yep, though so.
I'm an advocate of keeping the genset battery completely isolated from everything else, having a small stand alone ac charger in place and as the ultimate back up, jumper cables. If I really need it, the battery is not going to be the thing that stops it from starting.
Never been without a genset at the turn of a switch.

The rest of this applies only if you have all the same battery chemistry and that your alternator is the primary charge source while underway.

The engine start batteries, connected to the alternator is really all they need, again just like your car. Nothing and I mean nothing else other than the engines, their control and gauges are powered from these batteries.

The thruster batteries are much the same as the engine start battery, as the alternator is spinning when you are using the thruster, connecting it to the alternator will charge it quite easily. Again nothing else connected. No 30 amp fuses in line, let the battery accept the current that it needs. A 100 amp fuse and the appropriate conductor size, ampacity wise, would be my choice.

House, there should be no restriction on what the alternator can pour into the house battery other than alternator capacity or a depleted battery need.

All of this means that all you really need are those 100% efficient 1, 2, all switches you took out when someone sold you those expensive 85% efficient DC2DC gizmos.
Or if you don't want to throw switches down near the ER, a couple of the 100 % efficient ACRs with the remote switches wire up to the helm.

It is always a good idea to have the ability to charge all of the batteries with an ac powered charger, One charger and time, along with the switches or the ACR's would do the job. The genset as noted above has its own ac charger which could, using jumper cables provide redundancy in a pinch.

If your battery chemistry differs then you have to start looking at how you are going to charge at all of the required voltages, but the alternator should always produce the right voltages for and be connect to the house batteries as that bank requires the most energy to replenish and you are a power vessel with at least one spinning alternator.

Here, your DC2Dc's come into play to modify the charge voltage sourced from the house battery to what is required by whatever the engine start or thruster battery needs. Here it's ok that they are only 85% efficient as they really don't do much work. 10 minutes after you start they are idling.

If you have solar, program the mppt to whatever voltage the house bank needs and connected to the house bank.

I need to add one more thing.

You need to get your head around the fact that the battery is never asking for any amount of current. A depleted battery will accept every bit of current and more than what your 130 A alternator will produce.
Batteries of all types accept current, the amount of which varies depending on their state of charge. A more depleted battery will accept more current. The amount they will accept when depleted is huge.

Alternators on the other hand produce current, generally controlled by how readily the battery accepts the current, but limited by the capacity of the alternator.
This, run the alternator at full tilt into a huge depleted bank, over time is what cooks alternators. You have to be careful not to do that.

It's kind of like my relationship with my wife. I'll accept as much s_x as she is able to produce, Or wait a minute, maybe its the other way around?

Luna #8:
“You need to get your head around the fact that the battery is never asking for any amount of current. A depleted battery will accept every bit of current and more than what your 130 A alternator will produce.”

This is not correct. Flooded lead acid (FLA) batteries will only accept about 20% of their capacity (0.2C) depending on the manufacturer. AGM’s will accept more, thin plate pure lead (TPPL) AGM’s will accept as much as 0.7C but the charging source will probably be reduced by a temperature sensor on the battery, if fitted. Lithium iron phosphate (LFP) batteries will accept 1.0C but all reputable manufactures recommend to charge a <0.5C.

Lead acid batteries; FLA, AGM and TPPL charging rates are limited by their internal resistance. Counterintuitively, as the state of charge increases, the resistance of these batteries also increases thus reducing the amount of current into the battery. Ohm’s Law in action.

The only batteries that you have to mindful of not overworking are the TPPL and LFP because they have such a low internal resistance and therefore a high charge acceptance rate. The TPPL’s do have the same characteristic of resistance increasing as they become charged; LFP’s do not. This is why an owner needs to be mindful of alternator load with TPPL’s and, more importantly, with LFP’s.

Finally, I won’t install TPPL’s or LFP’s without an alternator and battery temperature monitor controlling an alternator external regulator.

WRT blowing the 30a fuse - the chargers are typically rated at output voltage, which can be several volts higher than the input source. It's not unusual to exceed 30a input for a 30a output charger

I had this issue and switched from 30a to 40a breakers for the chargers. Problem solved.

luna said:

I think you need to step back and have a good think about what are the needs, what do you have and where should that go to best satisfy the needs.

For example I've owned boats all my adult life, now 50 years, and never had the genset Start battery charged with anything but the puny permanent magnet (there is no electrical feed to the field coil) alternator, that produces maybe 5 amps that is mounted on the genset.

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I have wondered the same thing. I am not even sure there is any type of alternator on my Genset. The Genset battery had a DC to DC charger connected to it when I bought the boat. If there is, I'd be very happy to let that charge the Genset battery. Time for me to do some digging.

Edit: OK there should be an alternator on the non-service side of my NL M673L generator on the non-service side. I think I have only looked at that side once, years ago. When I can get back to the boat in another week or two, I will take a look. It looks like it should be a 14amp alternator. I suppose that I can check the voltage at the battery before and after starting the Genset and see if the voltage increases. I really should get a clamp amp meter.

CharlieJ said:

Luna #8:
“You need to get your head around the fact that the battery is never asking for any amount of current. A depleted battery will accept every bit of current and more than what your 130 A alternator will produce.”

This is not correct. Flooded lead acid (FLA) batteries will only accept about 20% of their capacity (0.2C) depending on the manufacturer.

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Ya, you are right, for FLA batteries 20% is about the charge current limit.
What I should have wrote was the same sentence with these few words added.

After the word depleted, add the word…..house.

After the word battery add the words…..bank typically found in a boat of your size.

I think that fixes my error as the statement would now apply to all flavours of house battery banks that would be reasonably expected to be found in a boat of this size.

I’ll see if the current program will allow an edit at this late date.

Getting more test equipment is usually a smart move, but to see if the alternator is working, a voltage reading at rest and while running will tell the tale.

I would get to that non service side (is that what it’s called?) of the genset so you can have a good look at things and adjust belt tension if required which usually is done by relocating the alternator.

My preference is to keep the genset’s start system separate from all other things.
In a well implemented system there is nothing wrong with tying the genset’s start system into whatever battery bank that you chose.

Dave, what do you use to make those drawings for options.
I would like to make one of those to map my setup.

I wonder if you sent the engine ALT charge to the thruster bank and reversed the (faulty) Balmor to go from thruster to house may solve your problem.

SteveK said:

Dave, what do you use to make those drawings for options.
I would like to make one of those to map my setup.

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I used an online design tool that tries really hard to sell you on a subscription. It is possible to use it for free however what the some limitations. Not perfect, but a bit better than using Paint.

I wonder if you sent the engine ALT charge to the thruster bank and reversed the (faulty) Balmor to go from thruster to house may solve your problem.

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That is how I have it setup now after my last misadventure. It works, and I like the fact that the alt will be feeding into the Thruster bank when I'm docking or raising the anchor, although with the bank at full charge it never is an issue.

I do plan on upgrading that Balmar anyway to the Victron Orion. It would feed more power to the house bank than the Balmar. i also am thinking about upgrading my house bank to LiPo at some point. The Victron Orion would work to feed that new bank from the AGM thruster bank. My solar MPPT and Inverter/Charger are capable of charging LiPo batteries so with the Victron Orion in place it would be a relatively easy swap.

sounds like you have a setup that works now and will adapt to LFP.

I do need to follow up on luna's suggestion on just using the Genset alt for the Genset battery. In doing some other work quite a while ago, I had disconnected the Duo-Charge from the Genset battery. I happened to notice on Thursday that the Genset battery was at 12.3 volts.

Since I have used the Genset a number of times a few weeks ago on my very rare outing, I figure it must be getting some charge from its own alt. I am going to be away for a week, but I will check when I get back.

Update: I got back from a week away and went down to the boat to check on some things.

I am getting a charge on my genset start battery from the Genset onboard alternator. So I removed the Balmar DC-DC charger that was put there by the PO.

Today I ordered a Victron Orion 12-12v 50a DC to DC charger. I will use this to feed a charge from the engine alternator via the thruster bank to the house bank.

The 2nd sentence in the first post says that you already have 3 DC2DC Chargers. You have correctly made the determination that the Genset battery does not need one.
That leaves 3 battery banks, house, thruster & start.

Why do you need a fourth DC2DC?

dhays said:

Update: I got back from a week away and went down to the boat to check on some things.

I am getting a charge on my genset start battery from the Genset onboard alternator. So I removed the Balmar DC-DC charger that was put there by the PO.

Today I ordered a Victron Orion 12-12v 50a DC to DC charger. I will use this to feed a charge from the engine alternator via the thruster bank to the house bank.

Click to expand...

I`m not a fan of the genset battery only getting a charge from the genset alternator, when it runs. My current boat has a feed to the genset battery from the main batteries, my previous boat had a dedicated solar charge for the genset battery. If you use the genset frequently then it should be ok, but if less so, maintaining the battery makes sense to me.

BruceK said:

I`m not a fan of the genset battery only getting a charge from the genset alternator, when it runs. My current boat has a feed to the genset battery from the main batteries, my previous boat had a dedicated solar charge for the genset battery. If you use the genset frequently then it should be ok, but if less so, maintaining the battery makes sense to me.

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I will see how it goes. I am hanging onto the Balmar so I could reinstall it if required.

Put that trickle charger (echo) on the genset, smallest DC2DC to start and then rest to the house

SteveK said:

Put that trickle charger (echo) on the genset, smallest DC2DC to start and then rest to the house

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Cummins electronic engines are finicky. It doesn't mind the Echo Charger on the Start battery but can't handle the Balmar.

dhays said:

Cummins electronic engines are finicky. It doesn't mind the Echo Charger on the Start battery but can't handle the Balmar.

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forgot that, ok then leave it on start bat. Put a smallest DC on gen since you have them. You do want as much as you can go to house of course

dhays said:

Currently, all charging sources go to my House Bank. I have three DC2DC chargers that then send current to my Start Battery, Genset Start battery, and Thruster bank. The Thruster bank feeds the bow and stern thrusters as well as the windlass. Balmar Duo-Chargers are used for the Thruster and Genset battery. A Xantrex Echo-Charge is used for the Start battery. FWIW, the Engine Start battery uses the Echo-Charge because the Cummins electronics don't play well with the Balmar Duo-Charge but the Echo-charge works great.

So that has worked very well except for one problem. There have been three times that I can recall, where the high amp draws from the Thruster bank have caused the Balmar Duo-charge to try and send more than 30 amps to to the battery bank, blowing the 30amp fuse. The Duo-Charge is only rated to deliver 30amps and doesn't seem smart enough to not give more than the battery is asking for. It is easy to replace the fuse, but unfortunately I only notice the problem when the thrusters or the windlass fail to work due to a low battery after the thrusters and windlass had been run for a while with no recharging of the battery. So I want to make a change.

I just changed up my layout so that the alternator is charging the Thruster bank. I then made the Thruster bank the source for the DC2DC chargers to the Start and Genset batteries and reversed the Duo-charge so that the Thruster bank is feeding the House bank. This will work but I don't think it is ideal. This will limit the charge to the House bank to only 30amps from the alternator. FWIW, the alternator is a stock Cummins (Delco) 130amp alternator that kicks out a constant 14.0v.

I am looking at the option of buying a Victron Orion 12v 50amp DC2DC charger. This has a number of advantages, chief among them being able to charge at 50amps instead of 30amps. The other option is that it would work well for me if/when I decided to move to a LiPo house bank.

Currently, there are two ways I could do it. I could go back to the way the system was setup before but simply substitute the Victron for the old Balmar Duo-charge and have it feed the Thruster bank from the House bank. I would then direct the alternator feed back to the House bank. This would give the Thruster up to 50amps of charge from the house bank. Likely not when idling unless the sun is giving me a good solar boost, but still better than the Balmar and I wouldn't have to worry about it blowing a fuse like the Balmar.

The second option is to leave it all setup as it is currently only with the Victron feeding the house from the Thruster bank instead of the Balmar. This would have the advantage that the Thruster bank would be getting the full alternator feed when using the thrusters and windlass and the rest of the time when under way, it would be feeding the house at close to 50 amps when under way.

So of those two options, what might you all chose?

Click to expand...

So I would suggest you question the choice of a 30A fuse on a DC2DC converter capable of supplying 30A. My general understanding is that fuses, circuit breakers and wires are typically rated to operate at 80% of maximum expected current. A web search reveals "According to the National Electrical Code, you cannot exceed 80% of a circuit breaker's limit. This means that the above load of 18 amps exceeds the limit of 16 amps on a 20-Amp breaker." This is oriented towards AC applications. So it's reasonable to figure your 30A capable DC2DC charger should have a fuse of at least 30A/0.8=37.5A. And the wiring should be capable of 30A continuous too. Perhaps someone who knows the code better for marine DC could weigh in.

dqking said:

So I would suggest you question the choice of a 30A fuse on a DC2DC converter capable of supplying 30A. My general understanding is that fuses, circuit breakers and wires are typically rated to operate at 80% of maximum expected current. A web search reveals "According to the National Electrical Code, you cannot exceed 80% of a circuit breaker's limit. This means that the above load of 18 amps exceeds the limit of 16 amps on a 20-Amp breaker." This is oriented towards AC applications. So it's reasonable to figure your 30A capable DC2DC charger should have a fuse of at least 30A/0.8=37.5A. And the wiring should be capable of 30A continuous too. Perhaps someone who knows the code better for marine DC could weigh in.

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You are right. While Balmar calls for a 30 amp fuse, I ended up putting in a 40a fuse and then had no issue with nuisance blown fuses. However, the question is mute since I have replaced the Balmar DC/DC charger with a Victron Orion XS 50amp DC/DC charger.