Out of interest only, when we got the Jaguar XE we had a problem failing to start, unlike any other car this had some complex engine management, and we it failed we go nothing, engine did not even try to turn over, turn off every thing we could, wait a bit, re-try and it would start, and again unlike any other car the problem seemed to happen in the middle of a long run, not after being laid up for some time, so I suspected some thing with engine management, the car never stopped at junctions.
The garage said it was the battery, which was changed, but we kept the old battery to use on the caravan. To be fair after the battery was changed no further problems, so it did seem garage was correct, however moving house so old battery was charged and abandoned for a good 6 months, when it was collected and brought to new house and put on charge again, very quickly the smart charger reported it as charged, I had a few batteries to charge so this VRLA battery was again put to one side, with the idea of swapping it for the battery now in the caravan, however the virus stopped that happening, so once all other batteries were charged, I put the old Jag battery back on charge, but selected motorcycle on charger, as just wanted to top up.
Now every other battery charged with that charger has slowly gained voltage even when charge rate is 0.1 amp, and has in fullness of time caused the charger to fully turn off, unless there was a fault with the battery, in which case once disconnected the battery would lose charge and after 6 months would be near enough fully discharged. So this battery did not loose charge, so would seem OK, but when put on charge the voltage has remained rock solid at 13.4 volt, been on charge nearly a week, voltage neither fallen or risen.
It does not matter it is only for stand-by, but I wonder why, this battery has not behaved like any other battery I have worked with, and I have worked with 1000's of lead acid batteries, as to if being adsorbed glass mat or valve regulated lead acid I don't know, largest VRLA in the past was 12 AH where this one from size I would guess around 90 Ah, and in the past VRLA have been designed as traction or stand by batteries, not engine starting, but still seems odd, the charging voltage staying static would make me think internal drain, but it sat for 6 months or more with no charge and did not require charging for more than an hour before the charger (3.8A) reported fully charged. So any ideas on this?