I'm in the process of upgrading the solar and electrical
systems on my 2019 Fountain Pajot Saba
. After extensive research, I've settled on a somewhat "atypical" design to overcome some single-point-of-failure concerns. I'm new to LFP systems and would greatly appreciate any comments or suggestions offered.
SV Ghost Electrical System Overview
In researching LFP designs I was troubled to learn that an entire battery bank can be shut down by the BMS due to problems with a single cell. If a single battery bank were used, this could result in the vessel going dark. This was not an acceptable outcome. Instead I chose a design that provides redundancy and fault tolerance with automated fail-overs should a battery bank shut down for any reason. To accomplish this, we split the AC and DC systems.
The AC side consists of 1000AH @ 24V Victron LFP driving 2 X 24V, 3Kw-230V and 2 X 24V, 3Kw-115V MultiPlus charger
inverters. The bank is maintained by shore power
or a 13.5Kw Genset through a 100 Amp Victron Autotransformer (to prevent leg imbalance) and 1850W of Solar. The system is sized to allow us to operate about 20K BTU of AirCons overnight and occasionally throughout the day (i.e. meal prep), sans GenSet. Plans exist for the addition of a 180AH 24V alternator
should; based on real world use and performance it be needed. This bank is responsible for the following potential loads,
24V Fault Tolerance and Fail-Over Rationale
- 6 AirCon Units – 60K BTU (3 @ 12KBTU, 3 @ 8KBTU fitted with SoftStarts)
- A theoretical maximum of 12Kw of combined 115V/230V inverting
- 280 Amps of 24V battery charging (6720W)
- 12V House Bank Charging - DC/DC 24V/12V @ 60 Amps
- Watermaker - Aquabase YK3 180 L/H (Alternate power source – Genset Primary ~2000W)
Should the 24V bank encounter a low voltage/SOC condition, the GenSet is configured to auto-start and auto-stop based on pre-programmed values.
Should the BMS shut down the 24V bank for any reason, all critical systems, (Navigation, windless, lighting…) continue to operate off the 600AH 12V bank. Additionally, the GenSet can be started to maintain all AC systems.
The DC system consists of 600AH of 12V Victron LFP. The bank is maintained by 60 Amps of 24V/12V DC/DC charging and the 2 engine alternators fitted with Wakespeed WS500 external regulators. This bank drives,
12V Fault Tolerance and Fail-Over Rationale
- All critical vessel DC systems including navigation, communication, autopilot, windless and lighting
Should the 12V bank suffer a BMS shutdown or low SOC, a relay routes all 12V loads to the Starboard 200AH AGM
start battery. The start/fail-over AGMS are charged via individual 24/12 DC/DC chargers. The starboard battery is also charged by the GenSet Alternator
(the Starboard engine shares the start battery with the GenSet.) This can also be paralleled with the Port side 200AH start/fail-over battery if needed.
European Power (230V/50Hz) Solution
For shore power
use when in locations using 230V/50Hz power, a manually activated system diverts 50Hz shore power only to the pair of 24V/230V MultiPlus charger
inverters which charge all battery banks and provides pass-through to the AirCons and watermaker
. The 24V-115V MultiPlus’s operate in inverter-only mode supplying 115V service
to the vessel.
Wherever possible we prioritized Victron components as we had extensive Victron equipment
already onboard and to maximize interoperability.
5 X Sunpower X22 370W Solar Panels
= 1850W (we're working on ways to install additional solar)
5 X Victron SmartSolar MPPT
5 X Victron 200AH 24V Smart LiFePO4
2 X Victron 300AH 12V Smart LiFePO4
2 X Victron BMS300200000 VE.Bus BMS
2 X Victron MultiPlus 24V/3000W/70A-50 120V
2 X Victron MultiPlus 24V/3000W/70A-16 230V
1 X Victron Autotransformer 120/240 - 100A
2 X Victron Orion-Tr Smart 12/12-30A (360W) Isolated DC-DC charger (Paralleled 12V House bank)
2 X Victron Orion-Tr Smart 12/12-18 18A Isolated DC-DC Charger (Start/Fail-over)
2 X 200AH 12V AGM
2 X Wakespeed WS500 12V External Voltage Regulators
2 X Sterling Power Alternator Protection Device for 12v (AP12D)
1 X Genset Autostart Functionality (Onan 13.5Kw)
3 X MICRO AIR - ASY-364-X07 EasyStart 3 Ton
3 X MICRO AIR - ASY-364-X36-IP EasyStart 3 Ton
1 X Victron - BPP900450100 Cerbo GX
1 X Victron - BPP900455050 Cerbo Display
2 X Victron - LYN040102100 Lynx Shunt VE.Can
2 X Victron - LYN060102000 Lynx Distributor
XXX PACER - 4/0 AWG Black/Red Battery Cable (more feet then I care to count)
Numerous Blue Sea Systems, Merlin Gerin and E-T-A Fuses
, Relays, Switches and Breakers
Battery Tables Created Using 80/20 Extruded Aluminum
There are a few areas yet to be determined such as monitoring. We currently use a Color Control GX and are adding a Cerbo GX with the GX Touch 50 controller. The hope is to transition all to the Cerbo, but it is unclear if it supports multiple BMS.
Thanks again for putting up with such a long post - I truly appreciate your time and any comments or suggestions.