battery woes

[regw]

Last September I bought a new 091 100AH type battery for the galaxy 1.9TD
Initially it seemed to be fine but from earlier this year it
was often too flat to turn over the engine when I went out to start it.
after a period standing idle.
What with it not being used daily and lockdown keeping me at home a lot
I attributed it to this and kept a spare battery to hand to 'wake it up'

Now I'm considering buying new one but wanted know if
A: I killed it due to neglect/ low car useage
B: Parasitic drain and/or quiescent current from the alarm/stereo etc was too high
C: I cheaped out and at Ã,£67 delivered it was case of 'buy cheap buy twice'
D: all of the above

The quiescent current fell within the levels I got from Mirez tutorial
thanks Mirez !
Battery and fuse box terminals all clean and tight
The 2 onboard voltmeters in the USB sockets and stereo plus my fluke meter all agreed the charging voltage was consistently around 14-14.2V near as.
Most car van batteries have lasted me for a good few years so
somewhat miffed.

I'm obviously reluctant to buy/ruin another battery and have been mulling it
all over and doing some research and idly read up on Calcium batteries.
I'd seen it written on the battery and TBH never took much notice of it
until now when I read

"The ideal charging voltage for a calcium battery is 14.8V for the recombination process to properly occur"
and
"Silver calcium batteries generally require more charging voltage (14.4 to 14.8 V) and deteriorate rapidly in vehicles which do not provide the required voltage range. "

What?
Borrux! my alternator has never been fully charging the thing!
so A B & C above plus optimum Calcium charging voltages being out of range
means it was bound to struggle.
I considered the idea of taking my alternator apart to
see if could mod the regulator to pump up the output voltage
but will probably just get a quality lead acid type.

[regw]

Err thats a  019 type not not 091

[SirDavidAlhambra]

How often was said vehicle started and left running for at least 20 mins please?

It could just be lack of use that made it go flat and broke the cheapo battery perhaps, they donââ,¬â,,¢t like going completely flat

[johnnyroper]

Yeah lead acid battery is way forward silver calcium are for smart charge systems really as they can handle the higher voltages those systems put out.

I would also periodically put a charger on if vehicle not being used much.