Ok it seems now that is a cable to charger issue.
Changed things around and got a number of different readings.
The last one was back to normal. So I think the batteries are ok
Run a couple more tests, one with the current cable and another with the other and see what you get. Chances are the resistance is coming from the cables.
See if you can do a continuity check with your multi meter on the old cables.
If you can and you see high numbers you probably have fractured wires in the cable.
Charged my Goblin packs, IR was 0.9omhs across the board.
So the only difference is the main charge lead, and of course the age of the batteries.
I'm going to clean the plugs on the charge lead, and give it another go.
I have never cared for the charger based ESR meter. The worrisome part is if you try and balance charge that thing you could end up with some odd results.
These Revolectrix batteries are really good. The IR on them is perfect.
0.9ohms is two batteries in parallel.
The Gens Ace are a little random, but seem to be settling back to a normal reading.
Even the worst one that wouldn't finish balance charging, now balances and finished its charge cycle correctly.
I think it was just a resistance in the connection.