QuantEnergo:

Greetings Robi. Thank you for the extensive description of the current situation and your requirements. It would be good to know the power of the refrigerator you have and the power of the microwave you want to use. However, we will assume that it is a smaller ship’s refrigerator, which has a daily consumption of approx. 1100Wh. Since you use the boat in the summer, we can assume that night use is less than 40%. Other uses are, I suppose, lights, phone charging, various screens, and kitchen utensils. From experience, we conclude that a 100Ah battery would already cover your needs, but we recommend installing a 150Ah so that you can switch off the solar panels at night and thus prevent the battery from charging in the morning. The chargers have built-in cooling fans, which are quite loud in the quiet of the morning. During the day, however, the sound will not be noticeable. Considering the power requirement at 220V AC, however, a 1000W solar inverter should be sufficient. If you want to use several different, more powerful kitchen utensils at the same time, decide for the more powerful 2.2KW model.

Installs the following components:

• Battery storage QE150, 12V 150Ah (https://www.rvbattery.eu/product/qe150-12v-150ah/)
• Solar inverter: 2200W Hybrid Solar Inverter (https://www.rvbattery.eu/product/2-2kw-12v-hybrid-solar-inverter/) Enables battery charging from solar cells, from the 220VAC network and conversion from 12VDC from the battery to 220VAC power up to 1000W, long-term 600W.
• Solar cells: 1 pc, Trina Solar Vertex S (415Wp), which will be sufficient for daily use and charging the battery during the day.

We recommend binding as follows:

When connecting the solar cells and the Solar Inverter, we recommend the additional installation of an off switch.

Please note that this is the installation of a LiFePo4 battery, which is not compatible with a Lead-acid battery. So you have to have a separate system for starting the engine, a separate Lead acid battery. You also have to additionally install a DC – DC inverter if you want to charge this battery with the engine alternator. Direct connection will cause alternator failure and shorten the life of both batteries.

QuantEnergo:

Hello Milan. You are thinking correctly. You need two accumulators, which must be separated. That way, you can never run out of lead-acid motor battery. The LiFePo4 battery storage (https://www.rvbattery.eu/product-category/lifepo4-batteries/) is, in our opinion, the right choice. You must separate the system so that the two batteries are not connected. The motor part must be completely separated from the living part. To ensure the charging of the LiFePo4 battery storage 100Ah (https://www.rvbattery.eu/product/qe100-12v-100ah/), we suggest that you carry out two options. One is charging from an alternator, where you need to connect a DC-DC constant current LiFePo4 Charger (https://www.rvbattery.eu/product/dc-to-dc-constant-current-lifepo4-charger/). You must not connect the battery directly to the alternator, as this would cause the alternator to malfunction. We suggest adding a LiFePo4 Battery Charger 220V. In our opinion, the capacity of 8A would be sufficient for your needs (https://www.rvbattery.eu/product/lifepo4-battery-charger-146v-8a/). So you will have both options covered, both charging with the engine while driving and charging from the mains.

QuantEnergo:

Hallo Anton. Thank you for Question. The size of the battery depends entirely on your decision, your needs, or also to the entire electrical system that you have installed.

First of all, you need to calculate your daily electricity consumption.

An example!

The next step is the system you have.

Do you provide charging only from the engine and the network, in this case the decision of how long you want to provide energy, is it one day, two…

Another option, installation of solar cells. In the case of installing solar cells, the battery must ensure at least night use, or, due to the possibility of cloudy days, we suggest at least 2/3 of daily use. However, this is definitely the decision of the individual, who will decide based on the method of use and also the time of year of use, what kind of autonomy he wants to achieve without charging. If we follow the decision to cover 2/3 of the daily consumption according to the above data, then we would need approx 2000Wh battery. In the case of a 12V system, this capacity is provided by a 150Ah LiFePo4 battery – 1920Wh. The investor must decide whether he will install a larger battery or whether even a smaller battery storage will be enough for him.

Hello Jan. Yes, there are many providers of LiFePo4 batteries, and this is also why we decided to produce our own battery, as we had bad experiences with quality. We tested different batteries at the university and found that, despite promising the same lifespan, the performances were different and, according to the researchers, most batteries would not reach the promised lifespan under any conditions due to the high internal resistance of the cells.

The quality of the battery storage depends on three things that are influenced by the manufacturer and one that is influenced by the customer.

1. Cell quality – only class 1 cells can guarantee a lifetime of 6000+ cycles. Unfortunately, the quality of the cells can only be recognized in the laboratory by measuring the internal resistance at high currents. Customers recognize the quality only after a few years, when the battery capacity begins to decrease.
2. BMS – battery management unit – is the electronics that ensures the operation of the cells within the parameters. A bad BMS does not protect the cells well enough, resulting in a shorter lifespan. Based on our review of BMS suppliers, we can recommend one thing. Buy a battery pack with Bluetooth 5,0 functionality. The Bluetooth 5.0 feature is a bit more expensive, but we haven’t seen a lower-end BMS that offers Bluetooth 5.0 functionality. So, if you buy a battery with a Bluetooth 5.0 function, you have a better chance of buying a battery with a quality BMS.
3. Housing – composition – The composition of the battery and the housing must be designed in such a way that it can dissipate the excess heat that is generated during heavy loads. Manufacturers of inferior batteries save on production costs, and when assembling the cells in the battery, they fix them with  the foam, which is an insulator and prevents excess heat from escaping. Unfortunately, most batteries are in plastic glued housings and you can’t see how the insides are assembled. Our battery is assembled in such a way that there is a metal casing inside, which takes care of fixing the cells and at the same time allows excess thermal energy to be dissipated away from the cells.
4. The customer influences the lifetime through use. The lifetime is guaranteed in accordance with the UN Manual of Test and Criteria, Part III Subsection 38.3. To put it as simply as possible, the BMS is programmed in such a way that it allows the customer to use the battery even outside of these conditions, for example 100% DOD, higher currents… For example, our batteries also allow higher currents in the case of higher force, which enable the engine to start. However, this is intended for a higher force, failure of the lead-acid battery. Such use shortens the life span. Also discharge 100% charge 100%… is intended for extreme circumstances. Everyday use means that we have a battery system designed in a way that exceeds our needs. And in this way, with a quality battery system, we can achieve 6000+ cycles, which means much more than that. Our battery storage units are designed in such a way that they allow servicing, which means that in case of some normal use in 20 years, you could also replace a cell or two and continue using the battery storage unit…

I hope that we have managed to explain to you in a comprehensible way what affects the quality of the battery and made your decision easier.