2021/2022 Updates on 48v for main system bus

[mcarling]

Originally Posted by mako

@mcarling, you're putting an interesting configuration together, but your's is an interesting boat

Thank you.

Originally Posted by mako

*I assume you'll have a generator onboard for powering your drives when the batteries are depleted. It will need to be large, but say it's 30kW, can you load it up adequately (min 50%) on a weekly basis for a couple of hours to keep it healthy?

No hydrocarbon fuels onboard. 4-5KW of solar (2-2.5KW separately for each hull's 48V battery bank, each of which is planned to be 25-30Kwh). I'm sure someone will tell me that motoring range will be limited. Yes, it will be a sailboat, not a motorboat. Battery capacity will be in excess of what should be needed to motor into or out of any marina, even several miles up a river. I would like to believe that my seamanship is sufficient to not have to ever worry about clawing off a lee shore in a gale, but battery capacity will be sized for that contingency.

Originally Posted by mako

*I don't like mixing up too many systems on a boat (like electric, hydraulic) and try to avoid too many voltages as well. Since you need 12v for your navigation electronics, then avoid the 24v bank.

I agree about trying to avoid too many voltages. I won't have any hydraulics onboard. It's not clear that I would need 12V for navigation electronics. 24V navigation electronics are not difficult to source. I expect that within three years, new NMEA OneNet compliant products will be available and that standard is 48V, so I may or may not then be able to buy 48V rather than 12V or 24V navigation electronics. I'm at a loss to think of anything I would need that's available in 12V but not available in 24V.

Originally Posted by mako

*Two to three years from now you may be able to source 48v bilge pumps, and if you can't then you can fabricate them. Otherwise go 12v.

Yes, I know how to rewind a 24VDC motor to be 48VDC. I'm not convinced it's worth the time or expense. Even 4000GPH bilge pumps run well on 24V, though 48V would of course be better. I'm not sure whether three years from now I'll see rewinding motors as tedious or a fun project. I'm not seeing any advantage of 12V bilge pumps over 24V bilge pumps.

Originally Posted by mako

*Why do you need two inverters? If it's just for redundancy then keep a spare one in a small metal faraday box, with your other electronic spares.

That's a good suggestion and I may do that. I'll need an MPPT controller in each hull and probably will choose one that includes an inverter (for example, Victron EasySolar-II GX). If not, I'll go with your suggestion.

To clarify, if I will have a 24V battery for 24V bilge pumps, then of course any other 24V loads would be powered from the 24V battery. If I will have 48V bilge pumps and no 24V battery, then I'll run 48V wiring to any 12V or 24V loads and use a small (appropriately sized) DC-DC converter adjacent to the load (or cluster of loads), so that all DC breakers will be 48V. I don't want to risk any confusion about which wires are 12VDC, 24VDC, 48VDC, or 230VAC.

[mako]

Originally Posted by mcarling

No hydrocarbon fuels onboard... I would like to believe that my seamanship is sufficient to not have to ever worry about clawing off a lee shore in a gale, but battery capacity will be sized for that contingency.

Cool, youz got gutz. A suggestion however, just make sure there is space someone for a little Kohler generator in a sound box to be installed, especially for future resale. This shouldn't be difficult to accommodate.

You also may wish to pre-plumb a small diesel tank to feed two bulkhead drip heaters, one in each hull, or just a large single with hydronic piping networks to each hull.

[mcarling]

Originally Posted by mako

Cool, youz got gutz.

Thank you.

Originally Posted by mako

A suggestion however, just make sure there is space someone for a little Kohler generator in a sound box to be installed, especially for future resale. This shouldn't be difficult to accommodate.

The technical compartment (I hesitate to call them engine compartments because there won't be engines and the propulsion motors will be outside the hulls) in each hull will be in the lazarettes, separated from the accommodation spaces by watertight bulkheads. In each one, below the waterline, will be a tank that for me will just be a void space with secure buoyancy in the event of a hull breach, but which could be used by a future owner as a diesel tank. Also in each technical compartment will be a shelf on which a genset could be mounted. So it would be very easy for a future owner to add one or two gensets.

Originally Posted by mako

You also may wish to pre-plumb a small diesel tank to feed two bulkhead drip heaters, one in each hull, or just a large single with hydronic piping networks to each hull.

I'll have air conditioning that can be run backwards as a heat pump. I really, really, really don't want diesel onboard.

BTW, I'm not sure whether the dinghy will be 24V or 48V. Either way, it won't be a problem to charge its battery from one or the other 48V main batteries.

[mcarling]

Nigel Calder's own boat has a 48V house bank. He mentions it starting at 10:15 in this video:

https://www.youtube.com/watch?v=Ds1Jmy9ykNA

Very few other details. He has an 8KW inverter and no air conditioning.

[codingparadox]

Made an updated post with the current status of our 48V house system, in case anyone's still watching this thread and thinking about it. Still loving it.

The only non-off-the-shelf thing in here is my custom solution on top of the Calex converter for charging your 48V house from the 12V alternator setup, but I'm working on making this into an extensible marine platform and will have something out the door in the next year, but if anyone wants to test (or contribute) in the meantime, we have two boats running the solution flawlessly right now.

https://www.highwind.fun/2022/09/25/...ystem-updated/

[Harris Marine]

Originally Posted by codingparadox

Made an updated post with the current status of our 48V house system, in case anyone's still watching this thread and thinking about it. Still loving it.

The only non-off-the-shelf thing in here is my custom solution on top of the Calex converter for charging your 48V house from the 12V alternator setup, but I'm working on making this into an extensible marine platform and will have something out the door in the next year, but if anyone wants to test (or contribute) in the meantime, we have two boats running the solution flawlessly right now.

https://www.highwind.fun/2022/09/25/...ystem-updated/

That’s pretty cool CP!! Do you mind telling us how much the Capex 12/48v converter cost?

I thought the WS-3000 was simply a rebadged Safiery Scotty 3kw. Reading your blog it would appear not.

[codingparadox]

The WS-3000 is a rebadged Safiery Scotty.

The Calex board is ~775$ + shipping. https://power.sager.com/48s12-3k0bca-5921212.html for example

[Nor]

I have a 12v system with only 280ah batteries and planning to add a separate 48v 300ah system just to run the inverter, and to do efficient 48v charging from solar.
I'll keep the 12v system as is and just run the 230v 12v charger when needed (or 24/7) to keep the 12v system topped up.
This seems much simpler and cheaper compared to changing the whole boat 12v system. I'll use the Victron multi rs 48v for charging 4 X 49v panels in series and its 6000w inverter.
It seems much more efficient than 1200ah 12v batteries. What am I missing, why aren't more people using 48v battery banks?

[markcouz]

I do exaxtly that and it works very well.

48v 200Ah (10kWh) Lithium bank charged by solar (and suitcase gen if required), 12v 400Ah (5kWh) Lithium charged by 48v bank using 2x Victron 100/30 mppt (and alternator when motoring if required).

[mako]

Originally Posted by Nor

…a separate 48v 300ah system just to run the inverter… and its 6000w inverter.

I recall the rule of thumb is to size the battery bank (kw-hr) to 4X the inverter size. I assumed this was to account for voltage drop in traditional FLA batteries.

How does this guideline apply to lithiums now?

[Nor]

Originally Posted by markcouz

I do exaxtly that and it works very well.

48v 200Ah (10kWh) Lithium bank charged by solar (and suitcase gen if required), 12v 400Ah (5kWh) Lithium charged by 48v bank using 2x Victron 100/30 mppt (and alternator when motoring if required).

I looked into a 48 to 12v dcdc which would be a little more efficient than a 230v 1wv charger. However I already have the 230v charger, so it seems very easy just to stick with that. All the heavy loads will be from the inverter anyway.

[markcouz]

Originally Posted by mako

I recall the rule of thumb is to size the battery bank (kw-hr) to 4X the inverter size. I assumed this was to account for voltage drop in traditional FLA batteries.

How does this guideline apply to lithiums now?

I prefer not to exceed 0.5C on my LiFePO4 banks by design - my 5kW inverter will draw 100amps at max load (I rarely exceed 3kW), 100amps being 0.5C on my 200Ah 48v bank.

For my 400Ah 12v bank I like to stay below 200amps - the heaviest load is the windlass at 100amps which is supported with 60amps from the 2 mppt's - I never get anywhere near 200amps.

Engine start is via a separate 24v agm bank, which has no other task.

[Nor]

Originally Posted by markcouz

I prefer not to exceed 0.5C on my LiFePO4 banks by design - my 5kW inverter will draw 100amps at max load (I rarely exceed 3kW), 100amps being 0.5C on my 200Ah 48v bank.

For my 400Ah 12v bank I like to stay below 200amps - the heaviest load is the windlass at 100amps which is supported with 60amps from the 2 mppt's - I never get anywhere near 200amps.

Engine start is via a separate 24v agm bank, which has no other task.

How would you calculate this with regards to temperature? The Victron Multi RS inverter is 6000W but only 4400W continuous at 40C. Not sure the rating at the expected ~35C or so, maybe closer to 5000W. Is the max draw from lithium affected by temperature?

[jojo5]

After studying off grid home system, as an electrician. I decided to go with nominal 48v battery bank with dual multiplus inverters running my AC systems ( waterrmaker & Air conditioners) on my catamaran.
For now i am uding a victron dctodc converter to run my 12v frig & nav but it won't run my winch.
My dilemma is how to the run winches because . They draw too much for the victron converter.
I am at a lose because I don't want a dedicated battery bank for winches.
Jodi

[Nor]

Originally Posted by jojo5

After studying off grid home system, as an electrician. I decided to go with nominal 48v battery bank with dual multiplus inverters running my AC systems ( waterrmaker & Air conditioners) on my catamaran.
For now i am uding a victron dctodc converter to run my 12v frig & nav but it won't run my winch.
My dilemma is how to the run winches because . They draw too much for the victron converter.
I am at a lose because I don't want a dedicated battery bank for winches.
Jodi

Would a single 12V battery (together with the dcdc) be enough to power the winch?