Can I mix flooded and AGM batteries in one solar system?

Cycle Life Comparison

When mixing flooded and AGM batteries, it’s essential to consider their differing cycle life expectations. Flooded batteries typically have a 300-500 cycle life, while AGM batteries can last for 500-1000 cycles. To minimize the impact of mixing battery types, it’s recommended to use a single battery type throughout the system. However, if you must mix battery types, prioritize the lifespan of the AGM batteries, as they are more sensitive to deep discharges and high charge rates.

Charging Strategy

When charging a mixed flooded and AGM battery bank, it’s crucial to adopt a charging strategy that prioritizes the needs of the AGM batteries. This typically involves a three-stage charging process: bulk charging, absorption charging, and float charging. During bulk charging, the charge current should be limited to 10-20% of the total battery capacity to prevent excessive heat buildup in the AGM batteries. During absorption charging, the charge current should be reduced to 5-10% of the total battery capacity to ensure that the AGM batteries are not overcharged. Once the batteries reach the float charge stage, the charge current should be reduced to a trickle charge to maintain a stable state of charge.