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diy solar

DIY Lifepo4 on 39' Privilege Cat (with Boat Rewire)

With regard to your installation in the engine room. What we know about lifepo4 and heat. 25degC is perfect for lithium. 35degC constant ambient temperature will half the life. 45degC will half it again. We cruise the Caribbean in winter and the batteries sit at ambient most of the time plus a bit if we are charging. So the lowest we see at the moment with the battery box lid permanently off whilst at anchor is 27degC. This can creep up to 29degC. By comparison, our engine room gets to 40degC with the engine running and the ventilation on. This is air temperature. Radiant temperature off the engine block that sits at 80degC when running with raise the temperature of anything in there further. Although you won't see the high temperatures on the batteries permanently due to the engine heat, it will be high temperature. This will have an effect on battery life.
The impact of high temperature on lifepo4 is not talked about much but its real. I am working on a liquid cooled lifepo4 commercial project at the moment. For tropical locations we expect 25% increase in battery life and the ability to charge and discharge at high rates with no impact on battery life.
I've slowly been wiring up various circuits. It's really a slog and much more time-consuming than initially anticipated. I'm about 60-70% complete with the wiring.

Back of Power Wall.jpg

*** Main Breaker Panels ***

Since my last post I added in the battery monitor and 3 switches. Also wired in the Color Control. Those 3 switches are all salon lights.


*** Breaker "Splitter" Panel ***

How to layout the breakers was a topic of some thought. There are many ways to organize the power flow throughout the boat. In the end, what I came up with is 2/0 Cables feed into 7 breakers which in turn feed 7 panels.

In the picture below, the 2/0 input cables from the batteries are coming up from the bottom. They first go through a 150 amp breaker, then various circuit breakers that feed various panels.

Splitter Breakers.jpg

The empty spot in the wooden panel above is where the 110 AC breaker panel will go.

For reference, here is what it looked like before I started:

Wiring Before.png

*** Layout for all the breakers ***

Main Panel 1 - Lights, Auto Bilge, Misc (40 Amp Breaker)Breaker SizeUnit
1Automatic Bilges30amps
2NMEA 20005amps
3Anchor Light / Tri-Color / SOS2.5amps
4Fwd Nav Lights2.5amps
5Steaming Light2.5amps
6Deck Light2.5amps
7Stern Light2.5amps
Main Panel 2 - Manual Bilges (50 Amp Breaker)
9Bilge, Port Forward Locker5amps
10Bilge, Port Midships (Main)5amps
11Bilge, Port Engine5amps
12Bilge, Port Head5amps
13Bilge, Starboard, Forward Locker5amps
14Bilge, Starboard Midships (Main)5amps
15Bilge, Starboard Engine5amps
16Bilge, Starboard Head5amps
Main Panel 3 - Accessories (70 Amp Breaker)
17Victron Color Control5amps
18Nav Station USB10amps
20Refrigerator, Port15amps
21Refrigerator, Starboard15amps
22Fresh Water Pump15amps
23Saltwater Pump20amps
24Propane Solenoid & Sniffer5amps
Main Panel 4 - Operational (50 amps)
26AIS / Splitter / GPS5amps
27Chart Plotter10amps
28Helm Station10amps
Main Panel 5 - Compartments (70 Amp Breaker)
33Staterooms, Forward5amps
34Stateroom, Aft Port10amps
35Salon, Port10amps
36Salon, Starboard10amps
38Engine Room, Port, Sub Panel20amps
39Engine Room, Starboard, Sub Panel20amps
*** Sub Panel in Starboard Head which has Toilet only *** (100 Amp Breaker)
4312V Charging Hallway10amps
44Aft Stbd Cabin10amps
45Starboard Hallway2.5amps
47Head Bilge5amps
48Head Lights2.5amps
*** Sub Panel in Fwd Starboard Locker (i.e. water room) ***
49Light & Fan, Stbd Fwd (2 amp)3amps
50Light & Fan, Center Fwd (2 amp)3amps
51Light & Fan, Port Fwd (2 amp)4amps
52WM Feed Pump (5 amp)6amps
53WM High Pressure Pump Relay (1 amp)4amps
54Bilge Pump6amps
*** Sub Panel in Port Engine Compartment ***
55Light (Main)10amps
56Lighs (Aft)3amps
*** Sub Panel in Starboard Engine Compartment ***
61Light (Main)10amps
62Lighs (Aft)3amps

*** Batteries in the Engine Room ***

@TimE, you're correct that the life of the batteries will be shortened some by the heat of the engines. However, I don't anticipate running the engines that much in comparison to the life of the batteries. Perhaps a few hours per week. So hoping the impact will be negligible.

*** Fuse Boxes ***

There will also be a number of fuse boxes throughout the boat in addition to all these breakers. It's enjoyable putting it all together, but it does take time. One nice thing is actually seeing things start working around the boat as I get each circuit hooked up.

*** Victron Color Control ***

The Victron Color Control came with the boat so I'm using it. However, there are only 2 USB ports and 2 VE.Direct ports. I'm using a powered USB splitter to get more ports. Here's how I have things laid out:

VE.Direct #1 - Solar Charge Controller 1
VE.Direct #2 - Solar Charge Controller 2
USB Port #1 - Batter Monitor (VE.Direct to USB Cable)
USB Port #2 - Powered USB Splitter

USB Splitter Port #1 - Solar Charge Controller 3
USB Splitter Port #2 - Solar Charge Controller 4
USB Splitter Port #3 - Wifi Dongle

The charge controllers are about 30' of wiring distance from the Color Control so I've had to daisy link VE.Direct lines and also the USB cables. Fortunately it all works.

The new Cerbo VX has more ports, which would be nice.


  • Back of Breaker Panels.jpg
    Back of Breaker Panels.jpg
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And the AC main panel is now wired.

AC Panel.jpg

Front of AC Panel.jpg

And, for reference, here is the same area before:

AC Wiring Before.png
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For record keeping, I've made a spreadsheet that shows which wires run through every transit (PVC pipes) on the boat. This should be handy in the future for any troubleshooting.

I took a stock overview diagram of our boat and labeled in the transit locations:


Here is a representative sample from the spreadsheet, just to give an idea of how tedious all this record keeping is.

Transit F - K (Starboard engine room to distribution panel / Inboard PVC transit)Description of WireEnd A End B
These 7 are bundled and go up to the Victron Color Control:
Solar Charge ControllerBlack VE.Direct Solar Charge Controller WireSolar Panel Charge ControllersColor Control
Solar Charge ControllerBlack VE.Direct Solar Charge Controller WireSolar Panel Charge ControllersColor Control
Solar Charge ControllerBlack USB Wire (Converts to VE.Direct in port engine room)Solar Panel Charge ControllersColor Control
Solar Charge ControllerBlack USB Wire (Converts to VE.Direct in port engine room)Solar Panel Charge ControllersColor Control
Battery shunt wireSmall grey wire, 24 awgShunt at batteriesBattery Monitor at Nav Station
Inverter Control Cat5 WireBlue Cat5Victron InverterInverter Control Panel at Nav Station
NMEA 2000 BackboneBlack WireStarts in the starboard area by fridge compressorEnds in port enigne room.
These 10 are bundled and go the Nav station just fwd of the bundle above.
Bilge Wire for Starboard EngineLarge Dark Grey, Round, 14 AWG w/3 conductors (Black, Red, Brown)Bilge Distribution PanelStarboard Engine Bilge
Bilge Wire for Port EngineLarge Dark Grey, Round, 14 AWG w/3 conductors (Black, Red, Brown)Bilge Distribution PanelPort Engine Bilge
Auto-Pilot10awg Ancor 2 strandDistribution Panel, OperationalPort Engine Room
Chart Plotter12awg, 2 strandDistribution Panel, OperationalPort Engine Room
Aft Port Cabin12awg, 2 strandDistribution Panel, CompartmentsPort Aft Cabin Closet (through Port Engine Room)
Propane Solenoid & Sniffer14awg, 2 strandDistribution panel, AccessoriesPort Engine Room (splits to 2 wires for sniffer & solenoid)
Helm Station14awg, 2 strandDistribution Panel, OperationalPort Engine Room - splits to fuse box for powering various helm station items
NMEA 2000 (inject DC power in port enigne room)14awg, 2 strandDistribution Panel, OperationalPort Engine Room
Cockpit14awg, 2 strandDistribution Panel, CompartmentsCockpit (through starboard engine room) has a terminal strip that splits to dinghy light & cockpit
Stern Light16awg 2 strandDistribution Panel, LightsAttached to aft end of solar. passes through Starboard Engine Room

Never fear, I'll get to the Lifepo4 installation at some point!
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As I've re-wired everything, there has been project creep galore. The starboard bilge was a mess when I bought the boat so I cleaned it up while running all new wiring.

Here is a before:

Bilge Before.png

And after:

Bilge After.png

I still need to install the bilge pump and some hoses, but the wiring is much cleaner. Also painted the bilge area with two coats of primer and one coat of exterior latex exterior paint.

Notice that before there were 3 transits full of messy wires, and now I'm only using 2 that are better organized.