devo 10 battery drain problems

Well, I did say I would report back...

TL;DR
Took cells out and charged individually - and it seems all is OK?

The long version......
what I think I have found is 1 or possibly 2 issue(s)

I took the cells out of the tray/holder and popped them on charge individually
They were pretty much flat (1.2v a cell) - and when they were fully charged a few hours later I took some measurements
They had charged to 1.4v a cell fresh from the external individual cell charger - 1 did take a good few minutes more than the others

Popped them (still warm) in their tray and popped it into the TX - powering up showed 5.46v

I left the cells in the TX (not powered up or charging) overnight
In the morning I turned the TX on and it showed 5.3v on screen once it had settled

I flew a V911 for 5 mins (HiSky protocol - NRF module) at 1mw

When I got the timer beeps and landed the screen showed me I had 5.2v in it
I took the cells out of the sled and I had the following readings
1.337v 1.343v 1.347v 1.340v

I put the cells back in the battery tray and turned the TX on and looked at the screen and wiggled the red connector
I could make the voltage change quite alarmingly - and worryingly also power off completely! - by wobbling the connector slightly
I did pop the connector in and out a good few times (to try and "wipe" any oxidation/dirt off the connector contacts)

After I did this I went to the last ever local indoor heli club meet
(I am so going to miss my evening sessions and really hope they find somewhere for us to fly again)

I took a set of spare fully charged cells with me (just in case) and I managed just over an hour of solid flying and came home with volts to spare with the cells I went out with installed in the TX (TX showing 5.04v right now a day later)

I am wondering if the connector issue I seemed to have has confused the internal charger circuit?
I am wondering if my internal charger circuit is working correctly for the NiMh cells I am using in there?
I am also wondering about the PSU I use to charge the TX with (12v 1a) - maybe the batts are not getting a 'decent' charge?
I know the side where the regulator lives gets warm when its plugged in - I will see if I can find a 9v one here to see if 12v is actually too much for it?

The rear power connector is very handy and very convenient and a nice touch - but maybe I /should/ be charging the cells individually?
(at least it means the little red connector and the battery to tray contacts get wiped when removed/refitted and shuffling the cells around a bit in the tray to even out the wear - sure I read somewhere about this being a GOOD thing to do otherwise they can 'wear' unevenly)

I will plug the TX charger in and see what it brings the cells to after 2-3 hours
(Never seen any specs on how long it /should take- maybe 3 hours is NOT enough and its operator error?)

Regards
Rob

And as promised
- overnight on a 10v 1.2a charger into the TX

Woke up this morning and checked - I have 5.35v showing on screen

Out of the battery tray ...individual cells are showing
1.389v
1.385v
1.386v
1.390v

All looks fine to me
Happy to leave it charging overnight I suppose as they seem to have been looked after OK

I am wondering if the red battery tray connector wasn't pushed all the way home since the first time I loaded it up with batteries and installed it .... months ago
It seems to push in further now and voltages seem more stable and the individual battery voltages are telling me they have had a full charge
(so I'll chalk up my "issues" to operator error for now )

Regards
Rob

Edited to say
I flew a total of 5 cells in an array of micro helis (mcpx, hcp80, hfp80 and V955) all at 1mw and did a little fiddling in the field so I possibly had the TX on for about 1/2 to 3/4 of an hour and came back with just under 5v, not sure if this is good or not