Is one better than the other?
In: 7
In most contexts, “active” means forcing a change to occur and “passive” means letting it happen more naturally. I assume you are talking about batteries here, but the concept applies to other cases.
Batteries are typically made up of a bunch of smaller “batteries” that each hold a portion of the total charge. These smaller “batteries” are called cells. Think of this as a collection of buckets, each holding a specific amount of water. Each bucket has a hose that drains to the next bucket and you get water from the hose in the final bucket. As the buckets are drained, some buckets empty faster than others. Maybe the hose is bigger, maybe the bucket shape is different, etc. These inconsistencies can cause problems with the water coming out of the final buckets so it’s important that all buckets have a roughly equal amount of water at any given time.
Now to answer your question. “Passive” balancing involves you refilling buckets with new water as needed (while charging the battery), but you don’t touch any water that is already in a bucket. Afterwards, buckets are all at same level.
“Active” balancing involves you moving water between buckets in order to keep things balanced. You don’t need to charge the battery to do this, you can just take water from a full bucket and add it to a empty bucket. The allows you to more fully empty the battery before you need to recharge.
Both active and passive cell balancing are effective ways to improve system health by monitoring and matching the SoC of each cell. Active cell balancing redistributes charge during the charging and discharging cycle, unlike passive cell balancing, which simply dissipates charge during the charge cycle.
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