[@Crimmy]

Below are answers that I think are reasonable to I thik all of your questions and if you agree I'll find places to plug them in

Charge time: 15-20 seconds, but I think I can accept anything under a minute.

Cannon strength: I'd like to have them be able to punch through on mech and be able to keep going to wreck at least another target.

They charge up a huge amount of energy and then fire a concentration of lightning blow through enemies.

blast radius for an arm probably 20-30 meters.

blast radius for the core... 200 meters sounds fine.

The explosion will send shrapnel of the mech everywhere, but more important to worry about is the shear force of the blast which would definitely kill you if you aren't protected. Not sure how protected pilots are against that sort of thing, but if the answer is not really then even if they don't get hit by shrapnel then they could just instantly die when the explosion meats them. If the answer is yes then they just needs to avoid large chunks of mech flying at them.

Fast mechs should be able to move out of the way with warning, which will be sent out with the push of a designated button or the release of the ejection seat. Slow mechs should not get close. Note its not dangerous while its off.