Hello DIY Solar folks, I'm a n00b looking for some better understanding.
I understand that it's a bad idea to mix old and new batteries, but I'm wondering what the reasons are, besides the basic idea that capacity is reduced over time, so mixing an old battery rated at 120Ah with a new one rated the same Ah is a no-no. But I'm wondering if there's more to it.
Here's a scenario (partially hypothetical for simplicity/clarity):
I understand that it's a bad idea to mix old and new batteries, but I'm wondering what the reasons are, besides the basic idea that capacity is reduced over time, so mixing an old battery rated at 120Ah with a new one rated the same Ah is a no-no. But I'm wondering if there's more to it.
Here's a scenario (partially hypothetical for simplicity/clarity):
- I have a 12V flooded lead-acid deep cycle battery rated at ~120Ah that is more than one year old.
- I tested the actual Ah, and determined that the battery now has a 100Ah capacity.
- I need to add an additional battery to reach the capacity I need for my inverter/load.
- Is it safe to add a brand new 100Ah battery in parallel with the older battery, since their capacities match, or are there other factors to consider?