It’s all about the Batteries

As a sailor, I understand the importance of reliable power on board to ensure a safe and enjoyable voyage. Whether I’m taking a short trip along the coastline or a longer journey, having enough battery capacity to power my electronics, lights, and other systems is crucial. To ensure I have the right amount of batteries for Luna, there are several considerations and questions I need to address.

Firstly, I need to determine the power requirements for Luna. This involves making a list of all the electrical devices on board, including their power ratings. I can find this information on the device itself or in the owner’s manual. If I don’t have access to the manual, I can use a multimeter tool to measure the consumption. By doing this, I can estimate how much power I need to run all of my onboard systems.

Another important consideration is the charging capacity of Luna’s charging system. The charging system needs to be strong enough to replenish the battery bank to its full capacity within a reasonable amount of time, usually 4-6 hours. If the charging system is too weak, it will take longer to recharge the battery bank, which could lead to a situation where the battery is not fully charged before the next use.

For Luna, which currently has two 12V 100Ah batteries, I plan to exchange these for two LiTime 12V 200Ah batteries to increase the total capacity from 2.48KWH to 5.12KWH. This should be more than enough for a boat of Luna’s size. However, the main reason for adding this much battery is to prepare Luna for a future hybridization. Being able to run shorter periods on electricity instead of diesel will in the long term save a lot of money

In addition to selecting the right amount of batteries, it’s important to manage power consumption to ensure that I don’t run out of power where there is no place to plug-in and charge the boat. Having multiple sources of power, such as solar panels, wind turbines, or a backup generator, can help ensure that I have enough power to meet my needs even in the event of unexpected situations. For now, I plan to stick with just solar, and running the engine as a backup since it can also be used to charge up the batteries. The boat is simply to small to fit a generator and wind turbine are to noisy.

To determine the size of the solar panel array needed to charge Luna’s batteries, I need to calculate the total capacity of the battery bank in watt-hours. This is calculated by multiplying the battery bank’s voltage by its amp-hour capacity. For example, a 12-volt battery bank with a capacity of 400 amp-hours would have a total capacity of 5.12KWH.

Assuming a 20% efficiency rating, the two 400W solar panels would have a combined maximum output of 800 watts, or 66.7 amps at 12 volts. To charge a 5.12KWH battery bank, we need to provide 5.12KWH / 12 volts = 426.66 amp-hours.

Therefore, the time it would take to fully charge the battery bank would be:
400 amp-hours / 66.7 amps = 5.99 hours

To calculate the time, it would take to fully charge a 5.12KWH battery bank with two 400W solar panels on a sunny day in the Bahamas in March, I need to take into account several factors, including the efficiency of the solar panels and the available sunshine hours. Assuming an efficiency rating of 20%, the two 400W panels would have a combined maximum output of 800 watts, or 66.67 amps at 12 volts (typical for a 12V battery system). According to data from the National Renewable Energy Laboratory, the Bahamas has an average of 6.4 peak sun hours per day in March. Peak sun hours are defined as the number of hours per day when sunlight intensity is equal to or greater than 1,000 watts per square meter.

Using these figures, I estimate that the panels will produce around 5.12 kilowatt-hours (kWh) of energy per day. However, this is a theoretical maximum output and does not account for any energy losses due to inefficiencies, In terms of managing consumption, there are several strategies that can help you prolong the life of your batteries and reduce your overall power usage. So, a more reasonable assumption is that I could recharge 50-70% of the batteries in a day.

However, it’s worth noting that this calculation assumes ideal conditions, and actual charging times may vary based on factors such as weather, panel orientation, and wiring losses.

Another important strategy for managing consumption is to be mindful of how you use your onboard systems. Turning off lights and electronics when they’re not in use, for example, can help conserve power and extend the life of your batteries. Similarly, avoiding unnecessary idling of engines or generators can help reduce fuel consumption and prolong the life of these systems as well. For someone like me that has never lived on a boat, that is going to be a big change.

In conclusion, selecting the right amount of batteries and managing consumption are key considerations for any sailor looking to maintain reliable power on their boat. By determining your power requirements, choosing the right battery capacity, and implementing strategies for managing consumption, you can ensure that you have enough power to meet your needs and enjoy your time on the water. And, by regularly maintaining and monitoring your batteries, you can prolong their life and avoid unexpected power outages. On Luna, my plan is to add two LiTime 12V 200Ah batteries to ensure I have enough power for my current and needs future, while also implementing strategies to manage consumption and regularly maintaining and monitoring my batteries to keep them functioning properly.

To end this I would like to ask anyone out there if they have any Experience of LiTime Batteries? Any suggestions regarding what solar panels to use is also appreciated.  Just leave a comment below.

My next focus is to find someone that can help me building a Targa arche combined for mounting solar panels and a dinghy davit. If you have a recommendation for anyone around Gothemburg, Swedens, drop a comment below or use the contact form?

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