While a modern yacht has lots of great systems on board to make life easy and comfortable - communications gear, autopilot, refrigeration, powered winches etc - they all require power. The generation, storage and usage of power becomes a constant source of worry!
When the small, rarely used generator on Coconut gave up in 2022, we decided that rather than pay to replace it, we would instead invest in a system that would allow us to rely as much as possible on renewable energy, reducing pollution, running costs, and reliance on finding diesel fuel for charging. Over the winter of 2022-23 we fitted solar panels and a wind generator which did a great job of keeping us powered last summer, but there was always more solar energy available on good days than we could store. We therefore decided to fit a much bigger battery bank over winter 2023-24 before our big trip.
Our house battery bank was 4 x 76Ah AGM batteries giving a nominal capacity of 304Ah, with a usable capacity of about 150Ah. We now have a house battery bank comprising 4 x 280Ah LiFePo4 batteries, total 1,120Ah nominal capacity, usable capacity of about 1,000Ah, so we've increased our usable energy storage capacity by a factor of nearly 7.
We selected Fogstar Drift Pro LiFePo4 batteries based on them being UK based and having a responsive customer service team, good reviews online, a competetive price point, good energy density (low volume and weight per Ah), quality cells, quality, Victron compatible BMS, metal cases, and dimesnions that suited the available fitting location.
However, replacing batteries with Lithium is not as simple as swapping one for the other. Old charging systems are not usually compatible with lithium batteries which require a different charge profile, and alternator regulators for conventional batteries will allow an alternator to overheat if charging a Lithium bank, which can draw more charge for much longer.
Some of the electrical system, being original, required replacement anyway, but we were also concious of not wanting to spend more than necessary. In the end, we have elected to combine the original house and start batteries into a very large AGM start bank which will be charged by the alternator and then charge the Lithium bank through a DC-DC charger, avoiding the requirement to change the alternator and regulator. We hope that we'll have sufficient wind and solar that we won't be running the engine just to charge. If we find that we are, we may fit and uprated alternator and regulator in future.
The original charger and inverter had become tempremental, so these have been replaced with a Victron Multiplus combined charger and inverter. The Multiplus can accept 50 or 60Hz but can only output at the input frequency. Therefore, we have also fitted a multi voltage, multi frequency victron charger so that in 110V/220V 60Hz regions, we can use that to charge and have on board power at 50Hz through the Multiplus inverter. A dedicated 250W inverter ruins the Starlink so that the Multiplus does not need to be running to power this small load that is mostly left on.
Orion Smart DC-DC chargers will charge the house bank from the start bank when the alternator is charging the start bank, charge the start bank from the house bank when solar or wind are charging the house bank, and charge the thruster bank from the house bank.
Power supply from the LiFePo4 batteries and distribution to the systems is taken care of with Lynx power in and distributors, with consumption monitored by a Lynx shunt. The Solar panels were already charged and monitored with a Victron Smartsolar MPPT. A further Victron shunt monitors the start batteries, and data from all the Victron components is monitored with a Cerbo GX and GX Touch screen. The data from the Cerbo can be monitored on board on the Axiom MFDs and remotely through the Victron VRM app.
At the same time as installing the new equipment, we took time to remove redundant cabling, tidy and improve the general installation, remove instances of poor practice (multiple cables now run to bus bars rather than to several ring connectors on a terminal!) and document and label the installation to make future torubleshooting and modification much more straightforward.
Huge thanks are due to Cameron Springthorpe of Yourskipper Ltd Marine Electrical who helped enormously with the planning and design of the system and undertook much of the installation work.
