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sv-the-dream avatar image
sv-the-dream asked

Sailing yacht conversion to LiFePo4

I’m trying to finalise the brainstorming and diagram to convert our sailing yacht from lead acid to LiFePo4, I‘ve used one of Victron schematics to help me visualise the system and understand how things are connected before embarking on this journey but I need some assistance and all the so called marine electricians we’ve found so far are hopeless and don’t even seem to be aware of the standards for connecting batteries (I tested them with a few questions and their answers are literally text book Victron wiring unlimited the what not to do section). So I need help.


Existing system and equipments:

  • 12v
  • Multiplus 12/3000/230 50hz 16A
  • MPPT 150/100 - TR
  • Colour control
  • BMV 712
  • "dumb"110A alternator
  • Battery isolator
  • 3x390watts LG bifacial solar panels
  • engine start battery Victron AGM 12-165


Questions:

  1. Does the Orion DC to DC protect my "dumb" alternator from overcharge/burnout by the LiFePo4 demands? Thinking on limiting the charge to 30A / 1Orion unit but possibly add a second unit later. The main source of power will be the solar system.
  2. currently the Multiplus is connected with 2x50sqm cables of same length and under 5m, each cable with a 200A fuse and a 300A switch (one of those big red ones on the diagram below). Is this ok or we should really wire it like in this diagram with one 400A fuse then a switch and then the 2 cables?
  3. cannot find the Cyrix Li Charge 230 for sale anywhere. As this product been discontinued? What’s the alternative?
  4. what size fuses are recommended for the locations I’ve marked?
  5. Can we use the Victron super packs or is it better the Victron lithium smart? We do run some high loads so I’m worried about the limitations of 70A maximum discharge current and maximum charge current of the super packs. Our solar system can deliver up to 98A. (I’m assuming that if I have 2 batteries with a 70A maximum discharge current each it means I actually have a total of around 140A maximum discharge current on my bank, please correct if I’m wrong its quite important)

Thanks

df242e0b-01ea-4665-a721-222444582315.jpeg


Lithium Battery
df242e0b-01ea-4665-a721-222444582315.jpeg (1.1 MiB)
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2 Answers
Paul B avatar image
Paul B answered ·

Hi, Really you should do a diagram of your existing system, and take the diagram to the people you are buying the batteries from and ask them for advise.

the questions you are asking are quite simple to a point but there are variables and this takes time to do.

as a example you are correct re the batteries with inbuilt BMS systems having max current limits, and maybe you should be looking for different bms setups and Batteries that have external BMS control so that you loose those max current limits to a point , and that suit the equipment what you already have.

So could I suggest that you do a detailed diagram and then get some advise from someone that you are conformable with and formulate your systems design, as there are lots of different options and variables out there , and how far do you go, to get a perfect system that covers everything you do,

or do you take some risk yourself ie the 110amp alternator do you install a external smart reg with temp control, or take the risk that it overheats, you have to get you head around all aspects.


happy to help you out on other questions if you want but a diagram of what you have is also quite helpfull




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sv-the-dream avatar image sv-the-dream commented ·
Hi Paul, this diagram is actually based on our system except for the addition of the Lithium’s in place of our lead acids, the Orion, the bms, and the smart battery protect. So the necessary adjustments were done to accommodate the needed equipments to run the lithium’s.
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drlbradley avatar image
drlbradley answered ·

I've just installed a very similar system in my motorhome. 2 x 200Ah Lithium Smart in parallel, using a VE.Bus BMS to control load (all my load is connected to a BP65 which the VE.Bus BMS can turn off if needed) and charge is regulated with Cyrix-Li-Charge 12/120A (controlled by the VE.Bus BMS) - The 230A Cyrix is part number CYR010230412 if that helps you source it.

I also used an Orion Isolated 30A DC-DC connected to my engine battery, the output of the Orion (and the solar controller) go (via breakers) to the input of the Cyrix-Li-Charge

Central to this build is my Multiplus 12/3000/120. It can draw a theoretical max of 800A from my 2 batteries if it really needs to (I haven't given it that much load yet!) The most I've seen is approx 130A with a hairdryer!

To simplify wiring I installed a Victron Lynx Power Distribution, this gives me the Positive busbar (with integral fuses), and a negative busbar. On the positive busbar, the batteries connect in, and the multiplus connects out - all fused inside the Lynx.

I have a SmartBMS 500A installed on the negative busbar, the batteries connect to one side of the busbar, and all my other negatives connect inside the Lynx. The SmartBMS then connects to a Cerbo GX via a VE.Bus cable.



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sv-the-dream avatar image sv-the-dream commented ·

I’ve revised my diagram after a bit more study.

highlighted in green is the new equipment to be installed to suit the LiFePo4 needs, the rest of the system is as per currently installed missing only a few sensors from the alternator and starter motor that connect at the battery isolator from cristec.70552BD8-FF07-4D94-AD30-7ABCA28DA47B.jpeg

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