Saw on of my batteries get down to 2.6v recently

[jedics]

My 24v 2p 8s system got down to 20% soc recently and saw one of my battery pairs get down to 2.6v when the rest were at 3.2v which was probably caused by my system getting run to zero 3 times before I got things under control after I first installed it. Its been running fine for 6 years of daily use and because I have almost never run the batteries that low with my usage I never saw this until now. Obviously I am loosing some capacity which I dont care about that much but I would like to be able to get my moneys worth for another 4 years at least before upgrading. 

What would you guys do, take out the battery pair and find if one or both batteries is damaged and replace one or both, new or second hand?

Or just carry on as it is seeing I havent had a problem with the damaged battery in 6 years? (not ideal in winter to never be able to drain them below about 30% safely)

[Dacian Todea (electrodacus)]

I will like to see a photo of the SBMS screen. 3.2V can be just around 10 to 15% so the other cells where likely also almost discharged.

The issue is that your one cell that got to 2.6V should never have been there if the SBMS has control ON/OFF over all Loads and settings are are default with switching OFF all loads when any cell gets to 2.8V. Since it gets to 2.8V under load usually the voltage will recover to around 3V and will stay there with just the SBMS as load until the next day when sun should recharge the battery.

Likely the battery is fine and can last a few more years. You just need to setup the system so that no cell can get below 2.8V  (2.6V is not an issue but below 2.5V is a problem).

[jedics]

When I built the system the Giandel inverter I bought had the on/off switch that you must push and hold so the sbms couldnt control it which is why I had the draining to zero because the inverter stupidly has a 21v cut off that you cant change. Everything is charged up now so a pic probably wont help you now but here you go: