Welcome back to another blog post!
It’s been a while, and we’ve been busy gaining some hands-on experience at sea, which we will talk about very soon.
This week we wanted to talk to you about batteries.
Originally, there was an idea about utilizing a modern automotive battery system on board our all-electric yacht, Whio II. However, the engineers who worked on the preliminary design have advised that the chemistry preferred by the automotive industry is oriented towards providing fast charging and extremely fast discharge. This allows for the rapid acceleration and high performance demanded by the modern electric car. In our case however, the batteries are only going to receive a trickle charge for the vast majority of their life via the solar panels or from the impellor while cruising. The batteries’ discharge requirements are going to be limited by the engine size; roughly 20% of what an electric car motor might use.
Our engineers recommended a battery design based on industrial energy storage applications, manufactored by CATL. CATL is currently the largest battery manufacturer on Earth and is not solely focused on the automotive industry. By changing our apporach to battery selection, we have managed to improve the warranty period by more than double. This is achieved by a mixture of form and chemistry that is entirely suited to the more gradual nature of the charge/discharge and deep cycle that we will be able to exploit. The engineers specified a very large battery pack with a fantastic power-to-weight ratio. The reduced cooling requirement (fewer pumps and ancillary equipment) again improves reliability over the lifecycle of the system. It is hoped that this approach will extend the overall lifetime of the pack, and we will not need to consider changing the batteries for the entire lifetime of the boat, which is more than 20 years.
As mentioned in a previous blog, the arrangement of the battery pack may lead to an operating voltage of over 700v. This in turn reduces the current in the system, makes for smaller cables, and better heat management. This also reduces weight, simplifies the system, and improves reliability. With the battery pack and electrical system being a dangerous voltage, improved relability is important and a set of troubleshooting/safety procedures will be strictly implemented. Electronic monitoring of cells and a sophisticated BMS should provide all the safety we require.
We look forward to CATL being our preferred supplier and the lessons learned from this system being more widely implemented in the marine sector.
Stay tuned, as we’re back and will be updating you on all the recent activities we’ve had, here at home…
… and out at sea!