[turbotel]

Do I need a stabilised power supply/maintainer when using ista D for diagnostic only or will a well charged battery be sufficient.

[Tambohamilton]

For diagnostics you just need a functional battery...assuming you mean just reading and clearing codes, etc.

You only need a maintainer when flashing (programming), and even then I've done plenty with nothing in place. Often just a decent 5a charger is sufficient to keep voltage steady. I have built myself a power supply from 2 server PSUs though, which I occasionally use.

[Tunafish]

Its always a good idea when messing around with the module to have a charger hooked up unless you know its going to be a quick job. But as long as you got power then all is well, its when power goes below a narrow threshold that things go bad..