Sometimes, many of us consider when we fall short with a certain battery bank, add units until we have a sufficient power reserve for our needs. This seemingly innocent process can be very expensive. And this because we say it? Very simple, you have to avoid at all costs making parallel Battery Systems .
In a perfect theoretical electrical system there would be no problem, but this does not exist in real life. Batteries connected in parallel or series-parallel initially do not give any problem, but after a period of operation, and if it is intensive, after a few weeks the evidence of the faults that are generated begins to be appreciated :
- The load is not uniform . They go from being unloaded to being almost fully charged with an abnormally fast speed. This occurs because one of the batteries in the bank offsets the power reading made by the inverter / regulator.
- The capacity that we appreciate for its operation is lower than it should be . The typical question of: 'if I have so much capacity, I can't explain how I have so little autonomy'. This occurs because some of the Battery Systems in the bank are more worn than the rest and carry a very low energy reading that drops the voltage of the entire bank.
- Battery wear is accelerated . There are batteries that work much more than others since the conditions that must be met for us to be as close as possible to a perfect electrical system do not exist.
- The batteries have not been purchased all at once .
- The length of the cables is not identical .
- The internal resistance of the batteries is not identical (this is unavoidable)
- The initial state of charge of all batteries is never the same .
Broadly speaking, we can summarize that in a parallel system not all batteries are charged equally, from what we have just explained and that is why there is always a minimum transfer of energy between one battery and another, so Battery Systems connected in parallel they will never reach 100% charge , that is, the connection of the connected batteries greatly accelerates wear and tear and causes an installation with batteries in parallel to be condemned to give problems in a short space of time .
AutoSolar batteries have a two-year manufacturer's warranty, but if any of the purchased batteries has been connected in parallel, the manufacturer does not assume the replacement or repair of the same , therefore, when the battery is connected in parallel already the warranty does not cover you.
Obviously, the manufacturers in their laboratory do the convenient tests to study if the battery in question has been connected in parallel or in series, since with simple tests the type of connection made by it is clearly seen.
Our recommendation from AutoSolar is to avoid as much as possible the parallel connection , to use batteries only in series, and if we need more autonomy, use larger Battery Systems, which are for that, not to add smaller units, since the investment to the long is much more expensive.