I know what my thoughts are, but looking for more input etc.

I had issues last year with a lot of strange electrical gremlins that stopped when I charged my battery with mains charger.

It took considerably longer than the normal 12hrs or there abouts for a depleted battery as I understand it.

I've since charged it a few months ago and done again this weekend taking and it's taken best part of 24hrs.

I have a new rectifier with 14.5v set point and a reading at the terminal of 14.2-14.3v which should be good enough to keep it charged.

Give us ya thoughts guys.

How long it takes is going to depend on the charger, so maybe your charger is dying?

Were you charging the battery out of the car? If so, it sounds like it's about to become a spare...

What was the voltage of the battery before you started recharging? As Richard says, could be the charger (if you have another you can try ?), else it does rather sound like the battery is on its last legs. The trouble with the high cap batteries is that they don't get properly recharged if the car is not used enough. Maybe leave less time between trickle charges - a few days of discharge can be fatal. Have you measured your quiescent current draw - BeCM off and awake?

Charger is nearly new.
Battery is showing about 12.3 to 12.4 v which suggests a cell is dead. It can sit for weeks without problem apart from above voltage.

My thoughts were dead cell in battery.

Car gets used every day.

Looks like a new battery needed :(

The old alternator only ever really charged at about 13.6 to 13.8 hence the new alternator regulator I fitted. I think that's what cooked the battery.

Oh and left on charge overnight and still only up to 90%.

My voltage slides below 12.0 sometimes and then I give it a good top-up, but I have a V8 which is probably more forgiving than a diesel.

Yeah, no glowplugs and high compression, but still need good battery :)

12.4 doesn't sound like a dead cell to me - at least not when it isn't loaded anyway...

If it has dropped a cell, then I'd be expecting to see around 10.5V at the battery after it's been left standing for awhile anyway. My old one which has gone faulty on me would show charging voltage - well ish - and hold it for a little bit just after disconnecting or turning the RR off, but then it would keep dropping to 11.7/11.8 with no real load on it.

If you're seeing 12.4 then whilst it's not fully charged, it probably isn't a total write off just yet.

Also my batteries get a fairy hard life in the fact that often my RR will sit around for 3-4 weeks at a time without being started - when I'm away working. My last main starting battery lasted just under 4 years - which was a MF31-1000. The previous MF31-750 I had lasted about 4 1/2 years and was only totally flat after I had been away for 8 weeks without the RR being started.

Tanis, do you have a charger that will do a de-sulphation cycle? My latest acquisition does and it can work minor miracles with tired batteries.
This is the one I have but there are many others: https://www.amazon.co.uk/gp/product/B00E907PWS/ref=ppx_yo_dt_b_asin_title_o06_s00?ie=UTF8&psc=1

That one is available quite reasonably now as there's a new range out from that company.
Here's the 5A version https://tinyurl.com/y8e9q6u3 at Hellfrauds

I haven't but it needs to be minimum 10amp charging current.

Thanks for the links. I'll look later. :)