PARALLEL-CONNECTED LITHIUM BATTERIES
We connect lithium batteries in parallel to get the right capacity in the battery bank.
There are lithium batteries that can't be connected in parallel or have limited possibilities for parallel connection.
The reason is usually that the BMS, Battery Management System, is cheap in order to create the cheapest possible battery.
It's easy to save up for fantasies that compromise on quality and opportunities.
Published Friday 24.11.2023 - Written by: Johan Fr. Bruenech
How do I connect lithium batteries in parallel?
Makspower lithium batteries have a very robust BMS that has no limit on parallel connection
In practice, this means that you can build as large a battery bank as you need. In our own demo boat SØNDAG, Oceanis 50, we have 12 x Makspower 100 Ah which together is approx. 15 Kwh.
We have enough power to heat hot water from an inverter, lie still for a week without recharging and charge with 250 amps from two dynamos.
Some tips for choosing lithium batteries
More BMSs means a more robust battery bank
The BMS, Battery Management System, determines how much power can go in and out of the battery bank.
The more powerful the BMS and the more BMSs you have determines how much power the battery bank can deliver.
If you buy a large battery with a BMS to save money, you may have made a bad purchase when the need for more power arises.
Expand the battery bank later
Think about what you're going to use the battery bank for now and possibly in the future. A Makspower battery bank can be expanded later, unlike lead-acid batteries, which should preferably come from the same pallet.
How much power should I be able to draw from the battery bank now and later?
When you discover how efficient lithium batteries are in terms of how quickly they can be recharged and that they give you freedom and better vacations, you may want to take advantage of the possibilities of 230 volts in your boat now or later.
This is easily achieved with an inverter or combined charger and inverter like Victron Multiplus.
That's why we recommend installing several smaller batteries with multiple BMSs, which together form the most robust battery bank possible that can supply enough power for a powerful inverter.
One large lithium battery or several small ones?
If you only have one battery and you're unlucky, you're without power.
If you have built your battery bank from several smaller batteries, such as 100 Ah batteries, you will hardly notice that a battery has failed.
The price per Ah (ampere hour) for several smaller batteries is essentially the same as for one large battery. In other words, you get more for your money by buying several small batteries.
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