Interstate L16 early failure
My 16 Battery bank got "stuck" in equalize for 12 days about 10 months ago. Reference topic "Boiling Mad" in Forum.
They did not run out of water, but the plates were all but exposed.
Since then, everything has been OK until last week. I noticed the system taking a long time to get thru absorb, and sure enough, battery #7 had a zero SG cell and was about 5 volts when all the rest in the string were 6.4 or so (trying to pull up #7 it seems).
Almost all the others are +/- 20 points SG. All the others voltages look within about 100 mv (in the dark of course).
The failed battery gave no symptom: SG's in May were good as they have been the 6 times a year I check them. These batteries NEVER discharge below 50%. They never are low on water. They do see high temps in their box. It was 106 in there last week. I seasonally reduce absorb time from 3 hours to two in the summer to reduce heat and bubbling. The set points appear below.
I removed #7 and plugged my backup spare Rolls L16 that is 7 years old but been charged routinely and is in good shape as an interim fix. My tech service guy came out and said " I don't know, but 4 year batteries shouldn't fail especially the way you take care of them. The posts on the Positive side on several are starting to swell the case up a little on some of them and my experience says they are not going to last a year".
What do you think is going on?
Why the sudden failure?
Any experience with bloating tops by the positive post?
Am I going to need new batteries soon as my tech said?
What batteries would be recommended? Deka??
Location: Northeastern AZ 5500 ft elevation. Full sun exposure 6 am to 7 pm midsummer.
48 volt system 16 Interstate L16 new in 7/2014 with water miser caps in Battery box with Auto exhaust
MX-60 Charge Conroller
Xantrex 5500(?) Inverter Charger
16 Kyocera 140 watt with Wattsun Tracker
900W Wind Generator
12 kw Kohler Propane Auto Backup Gen installed Dec 2015. It has come on automatically twice in this time due to low battery voltage. Batteries are in perfect condition 99% of the time.
The controller, wind gen, inverter are all original equipment 2007. The home is occupied 1/3 of the year. The power usage occupied is 5 kw per day, away is 2.3 kw per day. Generator has been used twice by auto on feature meaning thatthe batteries are 99.9 OK all the time.