SunnyParys

Appreciated Gerrie and Coulomb. Wish I found this site earlier then I wouldn't have had to just go on "trusting the installer".
I've found a better installer since and would pass the recommend test on to them. I truly believe you two are correct, the batteries are faulty. But, I didn't want to buy Pylon just to find there's a problem with the inverter. New at this, so just took guesses at what can be wrong. It took me by surprise to see the good battery test results since they're behaving oddly. 
I do however have two concerns on Pylon Tech. Our routine, after dark the only higher load we use is a microwave, for around 3 times 1 minute. Can a Pylon handle that kind of load? Secondly, if Pylon is just used as back up for if Eskom fails, how tough is a cold start really on them? Lets say, winter time and the Utility fail at 6am and the 'back up battery' wakes. It gets pretty cold in the garage where they would be.
These questions had me wondering, should I get enough batteries to carry through the night to avoid cold start? If they can't handle heavier loads, that would not be a good idea since there's an early morning kettle too. Then I'll rather just get one 3.5kwh for back up at night and support during the day when a cloud blows over. But, then that one battery is exposed to a cold start.