Re: cd player remote turn ons
If he can build you a 140A alternator, it will take the pull. If for a brief moment (ie: big bass note) you are demanding more current than the alternator can give, you have a reserve, the battery that's in the car. Trying to charge a second battery with the same alternator will increase the load on the alternator all the time. It will have to run the electronics and keep both batteries charged, therefore working harder.
About 12 years ago I went to an Autosound 2000 seminar (Richard Clark & Dave Navone, the guys that get a check anytime someone says 'stiffening capacitor' becasue they patented the term.)
They had a bicycle with a generator attached to the rear wheel. a volunteer rode the bike and it charged a battery and ran a light. Richard then asked what should we do if we want to run more lights. Everyone in the room thought or said, 'add another battery'. An unlucky engineer from Kenwood was the first to give the answer. They had him operate the bike and without adding a light at first. Then they added another battery as he was already moving and the light dimmed. The poor guy was pedalling his a$$ off and could barely keep the light on. The reason is a capacitor wants to store energy, we were told to think of current as water and a battery as a pool. The water source or alternator is a garden hose. That garden hose has limited capacity and if you tried to fill 2 swimming pools while watering your lawn you would see a drop in water pressure, only fill 1 pool and your alternator will have to work less.
Use another vehicle, get a good set of heavy gauge jumper cables, start your car turn on the headlights and then connect the cables to the other car but don't start the engine. Your headlights will dim the second the other battery is connected and that battery isn't powering anything. And this still doesn't address the potential problems with a 2nd battery. There is ZERO benefit to putting an extra battery in your car, unless you need engine off power or large quantities of CCA to start the thing.