kurt-braun avatar image
kurt-braun asked

System Design (Marine)


I am designing an upgraded electrical system for my 32' sailboat to LiFePo4 batteries with built-in BMS. If anyone would be willing to review/provide feedback, I would really appreciate it. This design does not incorporate a multi-plus that is in many of the example designs. This is due to limited space, but if it's required please let me know, and maybe I can cram it in somewhere! Thanks!

My main question is how to best control the Orion so that I don't drain the starter battery. I have a Cerbo GX (not shown), maybe this can monitor the starter voltage to shut it off below a certain voltage? Or I could wire a manual switch to turn it on when the engine is running I guess too.


system designmarine
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3 Answers
techie4hire avatar image
techie4hire answered ·

Hey @Kurt Braun! My wife and I spent 10 years on cruising sailing boat -- 32 countries, 50K nautical miles, westabout circumnavigation.

It's been 15 years since we got back though, so technology has changed significantly.

You didn't say what type of sailing you're planning to do, but the first thing that jumps out at me is the single solar panel. I'd suggest going much bigger there, though I'm sure space is an issue. How about mounting panels on top of a dodger and/or bimini? Some friends of ours actually had lightweight foldable panels attached to their lifeline/stanchion setup.

Also, if your LiFePO4 batteries can handle it, I suggest doing away with your dedicated starting battery. It keeps things simple having a single dual-purpose battery bank, allowing additional investment in panels and house batteries. :-)

We had a single 800Ah gel cell battery bank, and it had no problem starting our 50HP Perkins Diesel. The only time we ever had a problem starting the boat was due to a failed starter, not the batteries.

A couple of final suggestions:

Invest more in fewer systems whenever possible. Fewer systems to know, and spare parts to carry. Redundancy is important though -- so, "two is one, one is none" was one of the mantras that served us well.

Up your voltages, to reduce wire size and weight where possible. For example, run your panels in a series at say 72V for a 4x 18V panel array.

Have fun!

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Sarah avatar image
Sarah answered ·

Hi @Kurt Braun the config overall looks sound. Check to make sure everything is fused - not to protect the devices but to protect the cabling. With regard to the Orion it can be controlled using the engine detection feature which is configured using preset charge threshold voltage - additional options include hardwiring the auxiliary inputs on the Orion to the ignition to enable charging.

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Kevin Windrem avatar image
Kevin Windrem answered ·

Your main shunt should be between the house battery and EVERYTHING else. Otherwise it won't calculate state of charge properly. The battery monitor shunt needs to see all charging and discharging currents.

If you want a second shunt for your loads, that's fine but as shown in the diagram the DC load shunt won't see the Windlass and anything else connected to be busbars.

You want to make sure the Orion is a charger, not just a voltage converter. Otherwise it won't charge the house battery bank properly.

There is not much to control on the Orion chargers. They will automatically sense the alternator running and turn on only when it is. You can also connect a remote on/off switch to the Orion so you can manually control energy transfer from your starter battery to the house battery.

Cerbo is mostly inverter/charger centric but will provide useful information without one. There's no interface to Orion or the Blue Smart chargers however. You'll see power from the MPPT, battery status and DC loads.

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Sarah avatar image Sarah commented ·
Good point regarding the shunt location! The Cerbo can also be useful on a boat for doing tank levels, temperature, and bilge alarm integration along with remote VRM reporting.
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kurt-braun avatar image kurt-braun Sarah commented ·
Thanks to everyone for the suggestions, very helpful community here!

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