Greetings
Here's my 2 cents worth.
At 10 years old, or more, your Li-ion batteries are approaching end of life.
Performance will be at it's worst when it is cold, that is, when the batteries are cold.
If you are in Canberra, it is pretty cold overnight.
Start the machine, and leave it in balance mode, up against a wall, perhaps for 10 minutes or so.
This will slightly drain the batteries, but more importantly, it will warm the batteries internally.
Once warmed like this, you should get the most out of your aging batteries.
Cheers
Michael
www.dgbint.com