Wiring Diagram for Lithium Ion installation

[smokey73]

Here is my wiring diagram for installation of a 314 AH WattCycle Mini Bluetooth Lithium Ion battery keeping the stock Hitachi Alternator. I realize this is suboptimal but I think at the moment that is what I'm planning on doing. Lets not get into a debate on going to a externally regulated alternator right now. I am only asking the experienced forum members to give me their feedback. This is based on MainSail simple diagram with a Victron XS DC to DC charger. All switches are simple BlueSea ON/Off (not 1-2-Both) switches. There is also an Emergency X-Connect to start the Generator in the case of a Start Battery failure or to power the DC Panel in the case of a House Battery failure. The Grounds are shown simplified - all go to the common ground buss.

I'm showing MainSail's diagram first followed by wiring diagram. They layout on my drawing draws from Rod's diagram and the locations on my specific boat and wanting to keep the loads with the potential for large inrush currents normally run from the start battery. Have at it with comments. I'm open to suggestions.

 

[Stu Jackson]

a Victron XS DC to DC charger

What size?

 

[Stu Jackson]

stock Hitachi Alternator

what size?

 

[Davidasailor26]

The one thing that strikes me is that the fuse between the charge bus and positive bus should probably be on the positive bus side of the wire, not the charge bus side. The battery is the source of unlimited current there, so you need to protect the wire from it, not from the current-limited chargers.

 

[smokey73]

what size?

Victron XS DC -DC 50 A
Hitachi 80 A

 

[smokey73]

The one thing that strikes me is that the fuse between the charge bus and positive bus should probably be on the positive bus side of the wire, not the charge bus side. The battery is the source of unlimited current there, so you need to protect the wire from it, not from the current-limited chargers.

There is a Blue Sea Class T Fuse (300A) within a 7 inches of the WattCycle 314 AH House Battery (same as on Rod's diagram)
I think I need a fuse on the line from the Start battery that feeds the Start Buss? There is none shown on Rod's diagram.

All comments are welcome.

 

[Davidasailor26]

There is a Blue Sea Class T Fuse (300A) within a 7 inches of the WattCycle 314 AH House Battery (same as on Rod's diagram)

The 300A class T can protect the 2/0 cables, but the AWG 2 cables have a maximum ampacity of 210 amps (assuming 105 degree rated insulation in a non-engine space). The 300 amp fuse wouldn’t adequately protect that.
Rod’s diagram does show fuses on some of the cables off the bus, and he doesn’t specify cable sizes.

I think I need a fuse on the line from the Start battery that feeds the Start Buss? There is none shown on Rod's diagram

Fuses are optional on start circuits, to avoid nuisance trips with high starter inrush currents.

 

[Davidasailor26]

Victron XS DC -DC 50 A
Hitachi 80 A

You’ll probably want to dial the XS down to 40 amps, to not overwhelm the alternator.

 

[dLj]

You’ll probably want to dial the XS down to 40 amps, to not overwhelm the alternator.

50% seems awfully conservative. 50 amps is a bit over 60% - I run mine alternators at about 80% which was the safety factor I'd been told at the time. They now have close to 2000 hours on them trouble free. Knock on wood....

dj

 

[Davidasailor26]

50% seems awfully conservative. 50 amps is a bit over 60% - I run mine alternators at about 80% which was the safety factor I'd been told at the time. They now have close to 2000 hours on them trouble free. Knock on wood....

dj

If I remember right you have temperature sensing external regulation though? The 50% rule of thumb is for dumb internally regulated alternators. See DC to DC charger size

 

[jssailem]

Smokie, I see the specifications for the positive wires. I do not see a specification for the ground wire.
If the positive conductor to the load is 2/0, the negative (return) should also be 2/0. They carry the same current. Matching size keeps ampacity, heating, and voltage drop the same on both sides of the circuit.

As @Davidasailor26 suggests (and I concur), when the wire size changes (is smaller), a fuse is used.

The lack of a fuse on the cable between the battery and the starter motor on an engine is an exception in the ABYC safety standard.

 

[smokey73]

Smokie, I see the specifications for the positive wires. I do not see a specification for the ground wire.
If the positive conductor to the load is 2/0, the negative (return) should also be 2/0. They carry the same current. Matching size keeps ampacity, heating, and voltage drop the same on both sides of the circuit.

As @Davidasailor26 suggests (and I concur), when the wire size changes (is smaller), a fuse is used.

The lack of a fuse on the cable between the battery and the starter motor on an engine is an exception in the ABYC safety standard.

I just showed simplified ground circuit. All Ground Wires are matched to the size of the hot wires for size. The 2/0 positive wires have similar (not exact though) length 2/0 ground wires or ground wires equal to the positive wire

 

[capta]

Before you dump any money into a complicated system with multiple parts, I suggest you look into the portable power stations. They have multiple charging ports, several very fast, multiple output ports, safety circuits, and have internal monitoring. Some are expandable to over 6kw.

 

[smokey73]

Capta, not sure what you mean by "portable power stations?"

 

[Stu Jackson]

Thx for the answer. You may have an issue. Here's why I asked and why the issue may occur: Your DC/DC would well allow 50A to flow into even a somewhat depleted house bank of Lith. This means the alternator will see a constant load of 50A, which is a pretty fair percentage of your 80A Hitachi alternator. As we all know, Hitachi alternators are designed with internal temperature compensation which should, I say should reduce the output to keep the alternator cool enough. But it does so by reducing the voltage to reduce the current. If this "works' with your DC/DC unit AND the voltage required by the Lith bank, then all is fine. I just suggest you check its operation and components carefully. I just want you to be aware of this. If you are already, great. All the best, Stu

Victron XS DC -DC 50 A
Hitachi 80 A

 

[dLj]

If I remember right you have temperature sensing external regulation though? The 50% rule of thumb is for dumb internally regulated alternators. See DC to DC charger size

Yes, you are correct. I do have temperature sensing externally regulated alternators.

Wow, that's quite a power hit...

dj

 

[shemandr]

For those who like to peruse wiring schematics - I'm not one who does - Wooden Boat Magazine's current issue has what must be the Mother of All schematics. It is in an article about the electric refit of a classic wooden sailboat. To say the author went to town would be an understatement. But that's not criticism really. I'm just struct by the complexity of the project. I'd post a pic but I think that might be a violation of some sort.

 

[dlochner]

There is no need to have a separate charging and DC+ bus. All charging and loads can be on the same bus. Each wire coming off the bus should be fused to protect the wire leading to the load or charge source. Doing this will eliminate one switch.

I would move the Lewmar winch and the windlass to the house bank. This keeps all the DC loads in one place. The Epoch 314ah battery has a continuous discharge rating of 250a and a peak discharge rating of 750a (5 seconds) which is more than enough to support the windlass and the winch, unless both are being used at the same time. One caveat, watch the amp ratings for the bus bars to be sure they can support the max load.

The Yacht Rigger has a cool Class T fuse holder that mounts on top of the battery. Saves space and makes installation easier.

Take a look at BEP Pro installer series of switches and bus bars. These are all surface mounted and use link bars to connect switches and bus bars. Simplifies installation.

 

[smokey73]

Thanks @dlochner for the tip on BEP Pro installer.

I actually don't have the Epoch but rather a WattCycle 314AH Mini as recommended by @Maine Sail. My wiring scheme is set up to avoid potentially large "in-rush" current which, as described by Rod as potential problems for the BMS system of Lithium battery banks. This places the loads with the potential for "in rush" current onto the Start Battery. In particular the "in-rush" is not the same as "continuous" or even the "peak discharge current." The in-rush current last only for less than a second but can play heck on the BMS system. Here is the link to his discussion. Hopefully @Maine Sail will comment not only on the proposed diagram, but the topic of in-rush current. Maybe I'm overly concerned with this.

The following exerpts are from Rod's primer on Drop-In Lithium batteries and considerations in their proper care and use.
______________________________________________________________________________________________________________________________________________---
From:
Drop-In LiFePo4- Be an Educated Consumer

DC Motor In-rush

The reason most drop in batteries cannot be used for starting is the in-rush current. The in-rush of large DC motors looks like a dead short to the FET’s. Imagine sitting there and intentionally shorting your battery multiple times each day…..That is what starting your motor, running a windlass, electric winch or Bow thruster looks like to the FET’s. There are LFP batteries that can be used for starting but they are very expensive at this point in time.

Starting a 40HP Westerkeke takes=640A!!!!



Know your loads before you buy!

The critical load data you need to know is the in-rush current for all DC Motors .This includes a windlass, electric winches or a bow thruster. You also want know your inverters Pre-charge in-rush. Unfortunately most DC Clamp meters cannot properly capture DC in-rush current. We own three DC clamp meters that claim to do in-rush but all except the Fluke meters fail miserably. The image below is one of our Fluke 376 meters capturing the in-rush current for a Lewmar V2 Windlass. This customer ruined his FET BMS (seen in an image above in this article) by using his “direct from China” drop-in battery to power his windlass. Warranty? Ha-ha now that’s funny….



The image above is a prime example of how drop-in battery bank went wrong for this customer. he wanted to lighten the load in the bow of his sailboat so he installed a single drop-in battery to power his windlass.What he failed to understand was the BMS’s current handling rating . In just a few short weeks he destroyed his drop-in battery with his windlass when he failed to account for what the peak in-rush current handling of the BMS., Warranty? Not covered!

 

[capta]

Capta, not sure what you mean by "portable power stations?"

Google; portable power stations