Before I ask for help, here is what I did and what I lost.
In April 2015, I installed this setup at my home.
- 2 x 180watts Yingli solar panels
- 40A Ep solar MPPT charge Controller (CC)
- 1 Osaka IPS 800 battery
- Homage 1000VA ups
Exactly after 8 months the battery was dead. The dealer, who knows nothing about solar etc, told me that one cell was dead and another one was also dying. He recommended not to replace the cell but get a new battery. According to him, the battery died due to over-charging.
Well, it seems true to me. Usually I turn off WAPDA to UPS at day time and turn it on at night, but this doesn't happen always. So when the WAPDA to UPS is on all day long, the battery used to get about 30A (10 from UPS and 20 from MPPT at mid-day). This might be one of reasons due to which battery was dead so early. In fact I was expecting above 2 years life of battery due to Solar at day time.
What I have concluded is there might be two reasons due to which battery dies so early.
- The battery was getting high current during charging.
- The CC was chargeing the battery till 14.4volts. Then it keeps the battery at that volts for exactly 2 hours and then return to 13.8 volts (floating charging). I think Osaka IPS 800 was not made to be charged till 14.4 volts.
Now I need to know what should I do??
- Should I get a battery of ~200AH so that it is not damaged by the solar 20A current??
- Or should I replace the MPPT CC with simple PWM CC, so that it doesn't charge the battery up to 14.4v for two hours?
I have read in the forums that Millat batteries can be charged up to 14.4V. If it is so, then should I get this battery for my current setup??