Many readers have shown interest in the upgraded E-system aboard TWO B so we decided to create a dedicated post to this subject.
We didn’t want propane on board since it can be outright dangerous. Secondly, gas-applyances heat up the saloon in summer and bring extra condensation in winter. Thirdly, getting propane tanks refilled can be a hassle in some countries. (With our first boat we have experience with our tanks being rejected). Even the BBQ is electric. Well………….try to keep your gas BBQ lit in windy conditions.
The propane locker is now used to store fuel cans. The locker is well ventilated so we have no gasoline vapors in the boat.
Te following equipment is powered by 230V: Siemens induction hob – Siemens oven/microwave combo – Coffee maker – Toaster – Hot water kettle – Kenyon BBQ – Foodprocessor – Bosch washing machine – AquaBase watermaker 180 ltr/hr – Bauer junior dive compressor – Isotherm boiler – Airconditioning – Vacuum cleaner – Hairdryer – Kaercher pressure washer – TV – chargers and other small stuff.
Below is the E-diagram of the main 12-Volt system. Click the button for a downloadable .pdf
Drawing left. Being a catamaran, the boat has two VOLVO engines, each with its own Optima starting battery separate from the main Li-ion house bank. The power generated by the standard 115 Amp alternators is fed to a programable DC/DC convertor that does the following: 1) it takes 50 amps of alternator current, converts it to Li-ion charging requirements and sends it to the Li-ion house bank. 2) the remaining power is send to the Lead-Acid starting battery. 3) It protects the standard alternator from overheating (frying). Below an image of the converter installed in each engine bay.
Drawing top middle. Shore power comes in via a 3.6 kW Victron autotransformer that automatically switches to either 115V or 230V incoming voltage. Outgoing voltage is set to the 230 volts boat system. Al equipment on board can handle both 50Hz and 60Hz. We can plug into shorepower anywhere without worrying about a mismatch. A second reason for the transformer is the galvanic isolation of the boats earthing system. We do not have to be afraid for stray currents causing excessive corrosion to (engine) parts or rapid erosion of the zinc anodes.
Drawing top right. The brains of the system are two Victron Quattro inverter/chargers wired in parallel. We decided for 2 x 3Kw over 1 x 5 Kw to have a redundant system. Both shore power (AC2) and the generator (AC1) have a dedicated input. The Quattro selects the active input with the generator (AC1) having priority. A second reason for two inverters in paralel is that we can now charge the batteries with 2 x 120 amps (in reality closer to 2 x 100 amps), reducing the generator running time and increasing the load on the diesel engine of the generator to keep it happy.
A drawback of two inverters is the high “zero load” or idle power consumption of 40 Watt or 70 Amp-hours (in reality closer to 90 Ah) per 24 hours.
The auto transformer and the two quattro’s are installed under the bed in the port forward cabin. The original FP installed inverter is against the starboard bulkhead in the engine room, just inches from our heads when sleeping which we think is not a good idea. The port forward cabin is seldom used.
Via the control panel we can limit the incoming shore power to prevent tripping the breaker on the dock. The “power assist function” of the Quattro increases the output of the system to match the demand in case of limited shore power.
Drawing bottom richt shows a third and smaller inverter, a Victron Phoenix. This inverter powers three Bluesmart 4-Amp battery chargers for the optima starter batteries. We switch it on when the main system is shut off when we would be absent from the boat for a longer period. The “zero load” of the quattro’s could drain the main battery bank in a week if the solar panels cannot produce enough charge like in prolonged overcast skies.
We took out the FP installed inverter behind the TV and reused it for this purpose.
The two relais disconnect the Li-ion batteries when the SOC (State of Charge) drops below 20%. Contrary to common believe that Lions can be discharged to 0%, you will inflict damage to the batteries if the SOC is 0% for a few days or longer. Note that these relais are latching relais (bistable). The contact turns ON or OFF when an input signal is received and maintains that status even if the input signal is cut. Also note that the terminals of the relais are interconnected. This is to compensate for the difference in voltage drop over the cables and to ensure both relais turn at exactly the same time.
The Li-ion batteries are protected by the VE.bus BMS. This programable device does five things;
- It disconnects the batteries when the SOC drops below 20%.
- It disconnects the solar charges when the SOC is 100% to prevent overcharging.
- It balances the individual Lion cells in the batteries to ensure they all have the same SOC after a full charge.
- It generates the start signal for the generator at 30% SOC of the batteries.
- It generates the stop signal for the generator at 90% SOC of the batteries.
The main battery bank consists of 6 x 150 Ah = 900 Ah. Discharging to 30% gives us a usable capacity of 630 Ah. With sunny conditions at anchor in the Mediterranean we run the generator once every three days for 3 to 4 hours to make water and to recharge the batteries.
The batteries are installed under the settee at the nav station. To keep the balance of the boat we have not installed them in the original battery bay at starboard since we added a dive compressor in the stb. engine compartment and installed a second fuel tank under the master bed (Courtesy of Cote Mar).
The batteries are monitored via the BMV-712. Our default display is the SOC.
We added 6 solar panels to the original array of 4 and gave all 10 panels their individual MPPT controller to maximise efficiency. We installed three panels on the hardtop over the bridge and three on the port side cabin top since we did not want to spoil the look of the boat.
After two years sailing and living on the boat with 8 months spend at anchor we know now that we should have installed more solar capacity. We believe that investing in solar capacity is the best investment in your boat for liveaboards, especially with a heavy electrified boat like ours. In future we might instal an arch at the stern of the boat and replace the original panels with the biggest ones we can safely install. Added benefit would be additional shade over the dinghy. If properly designed it doesn’t look bad at all as we have seen on other cats.
We opted for Sunbeam TP106 x 54, TOUGH+ series, 116 Watt solar panels. They are light – high efficiency, flexible and have consistent high reviews. However out of the six panel that are installed, one did not meet output specifications. That was easy to identified with the individual controllers. It was replaced under warranty. About two months ago another panel developed a blister and then died. This will also be replaced under warranty. Replacement her means that you get a new panel for free. Removal / Installation costs are not covered under the warranty.
Each of the 10 solar panels has its own dedicated MPPT controller. This is the best way to optimise the charging capacity of the whole array. An added advantage is that you can monitor the performance of each panel and see when one goes bad and needs to be replaced.
The Octo GX is the communication-centre for the system. It connects the components and ensures they are working in harmony. The Octo can handle many MPPT Solar Chargers, as it has 10 VE.Direct ports. The device is programmed to auto-start/stop the generator. We can log in to the device via wifi and get te same screen as you see on the Victron Color Control. Victron themselves can also remotely log into the system for trouble shooting if that were required.
A Smart Battery Protect BP 220 is used to disconnect the solar arrays from the batteries to prevent overcharging when the SOC is at 100%.
Brilliant post. Wish I had the money for all the gadgets. But will start with a Smart battery protector as per advice. Have been thinking about this when I see battery at 14v plus. I often turn everything(kettle, water heater etc) on just to use up excess voltage.
CYCLADES, Greece. Was a fantastic read. Didn’t feel long at all. I can almost feel I was there. The chasing for Homer resting place is a good treasure hunt.