I bought a fairly inexpensive
battery charger that I just clamp on to the car. I've never had a problem as long as I have everything turned off (fan, interior lights, headlights, radio).
You've got one hell of a power supply if can supply 23 amps @ 12 volts. Typical battery chargers adjust the current while charging the battery and offer protection against overvoltage and overcurrent. I still prefer my automotive charger but you're probably ok with the power supply since the battery is disconnected and the car's not running. Keep an eye on the current so you don't smoke your nice power supply.
Most (all?) diagnostics still work with the car running. Just have somebody with a laptop in the passenger seat and drive to a beach that's 2 hours away.
