Why did my battery die.
I'm asking this question to find out what went wrong and how to correctly maintain solar charging of AGM VRLA type batteries in a mobile scenario.
Setup purchased Dec 2018 (14 months old)
2 x HGL-120 -12 PRO SERIES EXIDE VRLA AGM.
1 x Victron 75/15 mppt
1 x Victron battery temp sence
1 x 100 watt solar panel.
Batteries are in parallel, charge cable from mppt is connected to + on one battery and - on the other.
The mppt settings from new have been, absorption 14.3v float 13.7v. Having some concerns over this near default setting about 3 months ago I changed these and made a new user defined standby setting which allowed the battery to achieve a float without major charge. info here
https://community.victronenergy.com/questions/29395/firmware-update-v142-causing-different-charging-ti.html?childToView=29432#comment-29432
The van has been used very little, 3 camping trips, a week each time and 10 other times overnight all with minimal discharge from a 45 watt fridge and a few other small gadgets.
January last was the third week trip to forster, it's then I noticed my discharge was more than normal down to 12.7v and charging back to float was hard to achieve, a bit concerned I started to wonder what was happening.
today with settings on default the voltage wouldn't rise above 14.1v and bulk charged up to 6 amps through the day, after chasing symptoms on line I physically checked the batteries and found the one without the victron temp sencer was hot hot hot, cooked. The other with temp sence was warmer than normal at 35 degc, I suspect it's been warming by leaking power to the dying one, I disconnected the batteries and checked voltage cold battery 13.19v the hot one was12.9v and checked an hour later 12.6v.
I must say I have spent hours of research trying to do everything for this not to happen and here I am, so I ask the question why did my batteries die.