Ok and thanks for your information. Here's what I can deduce.
Polo. It seems to have an exceptionally high power consumption of 24 CCA/month, far greater than all the cars that I have tested todate. Or maybe that is VW standard thingy, I don't know.
Gen2. Now I think I know what you are trying to say. However if I had guessed it correctly, the Gen2 high power consumption 16 CCA/month.
Here's the thing, one has to factor in power consumption as well in determining battery lifespan. The higher the power consumption, the shorter will the lifespan be, and vice versa. I know for sure that cars that runs only during the day, their batteries last longer than cars that runs at night. Simply because there is no load on the battery from the lights on day cars. Since you mentioned about frequent midnight jobs, that could be your very reason.
My sister-in-law gatal-gatal when to install a huge entertainment unit etc etc and then asked why her battery cannot last long. Now in order to say money on the DIN55 battery, now she never turns on the entertainment unit anymore.
A good friend of mine came in a new Odyssey and said that the battery dies after a year period. With the 2 huge automatic sliding doors, USB ports throughtout the car for charging 5 phones dan lain lain lagi, macam mana tak mati ?
I met a Chinese lady yesterday, whom is interested in attending my talk next month. She said she tries not to use the air-con where possible, just to save money on batteries and she managed to push her battery lifespan longer than before. I commended that it was very wise of her.
If anyone were to run 2 simple test, using 2 new batteries & let it self-discharge by itself sitting on the floor. The higher powered unit will certainly out last the lower powered unit accordingly based on CCA differences by the same proportion.
No no, if you read carefully my comment, my Gen2's original Ramcar DIN 45R battery should have lowest CCA of all, but it was lasted 3 years and ongoing. Bosch also another lower CCA of about 400 CCA when new, also lasted almost 3 years and ongoing. So you can't take assumption of my Gen2 was consuming high CCA/month just based on the Ce***** kaput case.
also experienced relative low battery lifespan for Ultraman battery. I remember saw his was dead just before mine, just passing 2 years life itself. My another friend's 2017 Honda City also had Ultraman NS60S battery death within warranty period, meaning below 21 months.... The problem lies with the quality of Ultraman battery itself I think, not due to CCA rating or my car's current draw consumption. FYI, I don't use radio or fancy alarm system on this car.