The nominal pack capacity was used for reference SOC calculation owing to almost negligible battery attenuation in the almost one-year operation. This approximation is reasonable since the battery pack has an equivalent cycle number (ECN) of <150 compared with the total ECN of more than 1000.
The basic concept is that when connecting in parallel, you add the amp hour ratings of the batteries together, but the voltage remains the same. For example: two 6 volt 4.5 Ah batteries wired in parallel are capable of providing 6 volt 9 amp hours (4.5 Ah + 4.5 Ah).
It’s worth pointing out that many people accidentally connect batteries of different voltages in parallel every day. For example: If you mix brands even of the same labelled voltage – you can experience problems. Due to different manufacturing processes, the exact voltages of batteries from different producers can vary slightly.
Similar to SOC estimation, the battery pack capacity estimation methods can be divided into the direct calculation method , empirical method [, , ], model-based method [7, 26, 27], and data-driven method [, , ].
Battery pack configuration develops toward the series connection due to the high energy density of the individual battery cell and lower management difficulty. Therefore, the accurate and robust estimations of state-of-charge (SOC) and capacity for series-connected battery packs are greatly essential.
for secondary (rechargeable) batteries – the stronger battery would charge the weaker one, draining itself and wasting energy. If you connect rechargeable batteries in parallel and one is discharged while the others are charged – the charged batteries will attempt to charge the discharged battery.