Hi
I have 200Ah, on the 20hr rate, of deep cycle VRLA batteries. Well that is what I bought I've had them approaching 2 years, They are on a 24V system and originally I had a stand alone 1.5KW inverter with a separate MPPT charge controller. It worked well but at 1.5KW it was lacking in the power I needed, so I bought a hybrid 3Kw inverter with UPS facility and that provided with sensible use all the power I needed. I expanded My solar to 2.1Kw and again throughout the period of sun from around 9am to 17.00pm it happily ran the house including cooking. In fact I spent a couple of weeks stuffing a freezer with home made MREs and prepared food for over some of the winter.
Then as the days shortened I noticed the capacity started to fall away and though I can happily pull 600W with little problem for 20 mins or so they won't supply 55W overnight. I can only assume that until I programmed the UPS function on the inverter to cut in at 24.5V the batteries were allowed to drop below 24V once too often, as on a couple of occasions I saw the wrong side of 23V. The maximum charge rate on the UPS was set to 20A so doubtful I've been pushing that too hard.
All very annoying. I am thinking of replacing them with initially 100Ah of LiPo4 which hopefully the BMS should protect and 100Ah of Li should perform similarly to the 200Ah of lead acid and much lighter. I will go for a single 24V battery not two 12V batteries so I'm not having to fit battery balancers. 3000W at 24V is only 125A and I doubt I will be pulling more than 2.5 to 2.7Kw 100 to 110A should be within the BMS as a lot of them have 150 to 200A BMS limit.
Briam.
