I have just spent the last 10 minutes lying on the floor roaring with laughter. I am still wiping the tears away as I type, so excuse the smeary typing.

I think the best solution is a compact thermo-nuclear reactor which should keep the voltage up when you draw over 250A simultaneously from your charge system. Make sure you use enough lead shielding: Crutchfield do a range of economy stick on shield packs, and they throw in a film-based exposure badge for free with each pack You will need to remember to change the film every 24 hours and keep an eye on your daily microRAD count.

Alternatively, a Mr. Fusion compact reactor unit with a flux capacitor may suffice - it does give you the added benefit of time travel as well, but they've been having QA problems recently so make sure you get the extended warranty and don't travel (back) too far.