Finally ready for review: 1.7kw solar, 48v LifePo4, 2x3kw Split Phase for boat

TLJester

New Member
Think I have got most of this plan sorted.
Wanted to have some other expert eyes take a look and see what I am missing or any glaring issues :)
(FYI its for updating a catamaran ;) )

Screen Shot 2021-05-17 at 11.23.14 AM.png
 

Yes day

New Member
looks great to this newbie. I sent you message to ask some questions. I really like how you still have 12V after upgrading to 48V. I plan on doing the same and feeding the 12 V fridge and freezer with 48V - 12V converter and windlass an leaving all 12V as is on its own system charged from 48V to 12V dc to dc charger.
 

TLJester

New Member
looks great to this newbie. I sent you message to ask some questions. I really like how you still have 12V after upgrading to 48V. I plan on doing the same and feeding the 12 V fridge and freezer with 48V - 12V converter and windlass an leaving all 12V as is on its own system charged from 48V to 12V dc to dc charger.
Hi
Great questions !

I am leaving the existing system in place, and instead feeding the old AGM 12v battery bank from the new LifePo4 bank via (I think) the old MPPT that is already charging them.
Also going to add a 48v DC to 12v DC convertor "puck" as a backup to directly feed the existing 12v circuits from the new LifePo4 bank
(bottom left on the diagram)
 

Yes day

New Member
I am trying to draw or configure a diagram but am not getting anywhere with a website or program. I still have pen and paper. I have called a handful of marine electricians and they all try to convince me of going 12 V everything and have a separate panel for the items I want to run.
 

TLJester

New Member
I am trying to draw or configure a diagram but am not getting anywhere with a website or program. I still have pen and paper. I have called a handful of marine electricians and they all try to convince me of going 12 V everything and have a separate panel for the items I want to run.
What do you have today ? Assume you already have a 12v circuit with 12v only devices (windlass, etc) ?
If not then consider 24v!
Im going 48v as the charger/inverters ONLY support 48v battery banks, hence why i need to step down convertor to feed my existing 12v system.
However i am trying to remove much of the 12v devices (but not all), a perfect example are the fridge and freezer. Going to replace those with 110v standard home models. Also replacing the French standards oven and stove with 110v electrical models. to mention a few things. My windlass, electric winches etc are 12v so still need to keep that system running, and would rather not spend more money replacing those items that are working just fine.
 

rickst29

Solar Addict
Your use of the previous MPPT charger, as a voltage converter/battery charger form the 12v systems is very clever, but I don't know if this will require you to keep at least one AGM battery in place (to power the MPPT electronics 24x7). Aside from powering the "old" MPPT electronics and slightly stabilizing the output as a filter, it just sits there as a 'pass-through' device on the way to the terminals of the 12v panel.

I have three wiring comments and one MPP Voltage concern: First (WRT wiring), your "50A" generator is going to need much larger wire on the 120-VAC side, into the MPPs. If you fuse the circuit at 60A, then your wire size needs to be AWG-6 or even larger. You can use either a fuse or a Circuit Breaker, but the safety limiting device must be smaller than the wire's capability.

The same applies to the shore power 120-VAC limiting device: Although they will always have an AFCI/GFCI at the "shore" plugin, your wires and cords need to handle everything which their plug is willing to dish out. (If you size for 30A, then you need AWG-10 or larger).

My third AC wiring concern is with your "Downstream", where you use AWG-8 (40 amps max) but provide a 150A breaker/fuse from each MPP. The MPP's, if rated at 3Kw continuous and 6Kw maximum, are officially incapable of exceeding 60A in any situation (that's 7200 watts). I would want to increase the wire size of these "mains" into the port and starboard mini-boxes to at least AWG-6, and I'd cut the fuse/circuit breaker rating down to 60A.

Second, I'm a bit concerned about running Zone-1 into the MPP at a voltage which is so close to the MPP's maximum rating. I prefer to design with V(oc) no higher than 80% of the rated limit on the MPP's 'Solar Input' Voltage.

Your plan otherwise looks great to me, carefully designed and beautifully drawn for consideration by members of this forum.
 

Yes day

New Member
What do you have today ? Assume you already have a 12v circuit with 12v only devices (windlass, etc) ?
If not then consider 24v!
Im going 48v as the charger/inverters ONLY support 48v battery banks, hence why i need to step down convertor to feed my existing 12v system.
However i am trying to remove much of the 12v devices (but not all), a perfect example are the fridge and freezer. Going to replace those with 110v standard home models. Also replacing the French standards oven and stove with 110v electrical models. to mention a few things. My windlass, electric winches etc are 12v so still need to keep that system running, and would rather not spend more money replacing those items that are working just fine.
Yea I am playing with 24v because my fridge freezer compressor are dual 12v 24v. I plan on keeping small 400ah 12 V system and 1600 ah 24v or 48v system. Trying to find someone help me with these things is like pulling teeth. Most are brainwashed at 12v
 

Yes day

New Member
Yea I am playing with 24v because my fridge freezer compressor are dual 12v 24v. I plan on keeping small 400ah 12 V system and 1600 ah 24v or 48v system. Trying to find someone help me with these things is like pulling teeth. Most are brainwashed at 12v
 

TLJester

New Member
Im only keeping the 12v AGM setup as the batteries are less than a year old. So using them as a buffer between my main LifePo4 bank and the 12v system. Eventually I will probably get another 48v bank and replace the AGM's completely, using only the 48v-12v step down puck. (or keep 1 battery for that for when the Windlass or winches are used and draw a LOT of amps in one go !)

Is this info helping?
Happy to answer any specific questions you have :D
 

Yes day

New Member
yes thank you for communicating with me. I had another member I am not going to mention names but it was “another guy not a mod” he said I should start my own thread so your thread is not confused. Is that something you want me to do ? Am I confusing your thread 🧵? Anyway I don’t have great memory and can’t follow every single rule 24/7 and apologize if “other guy “ is confused or projecting confusion. I
Just trying to learn and get my ah installed safely.
 
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