batteries, series, charging, etc.

ok so. There's a lot that I'm thinking about. With the new high voltage amps out like the Stetsom or even just the older 18v amps, I was wondering how you'd go about charging batteries properly at these stupid high voltages. I seen amps with 12 volt rails and 250 volt rails, by Stetsom. Uhm. I thought if wiring 5x48v batteries in series to get 240 volts, but how the hell do you charge that kind of battery bank? and and, what about current draw? I mean naturally it would get smaller right? and well. another question i had was. is it safe to mix like a 12v battery and a 48v battery in series? or any configuration for that matter? What is going on here with these new amps? There was more I had to ask but it escaped me. Sorry if this isn't the right section. and as for getting 18 volts. you'd have to wire like 3 6 volt batteries in series? and run like a modified alternator and just a standard alternator? run two alternators for separate charging? I am clueless, please help me. I know all about the series, series/parallel, parallel configurations. I just don't know how i would go about charging properly. or what might get hot or not.

To charge any battery bank you need a generator (and voltage regulator) that outputs a higher voltage than what you're trying to attain.  So if you have a 48V battery you need a 48V charger, and it will likely be capable of putting out about 60V.  Yes, you can wire a 12V and a 48V in series to result in a 60V bus, but unless you have some sophisticated monitor and control setup, be sure the batteries are the same aH capacities or you will deplete one first and run into issues.  Actually this is true for ANY series setup: be sure the capacities of the batteries are matched.  Now as far as setting up an 18V bus to power higher voltage amplifiers, you must keep this sort of system completely separate from your 12V vehicle electrical system or you can run into problems, and you will need a dedicated 18V charging system to support it.  SOME vehicle electrical systems might be able to handle 18V, but MOST will stop working after you fry the ECU or the voltage regulator or some other computer in the system.  It is not a good idea to run higher voltage in a vehicle unless you know exactly what you are doing and that the vehicle can handle it.Support the12volt.com

As per DYohn, matching batteries is essential for series connections. But this means more than their AH, it means their full behavior. Therefore "matched" batteries - same age, size, history etc. Hence it is unlikely - or probably impossible - to mix different voltage batteries. As they say with simple non-rechargeable batteries - DON'T mix new and old or dissimilar batteries. And that's merely for discharging without the complexity of recharging! The exception to the above is if recharging them all in parallel or individually. IOW, forget it. Forget a 48V or n00 Volt DC battery. The answer is YOUR normal voltage system with a dc-dc converter (SMPS). The intent of any new vehicular high volt amps is what audio amps should have done years ago - separate power from the amps. Hence instead of the traditional sucker's system with the 12V to HV PSU in the amp and hence end the resulting big copper, extra batteries, caps, distribution blocks, gold plating, dual/multi-battery systems, etc etc rip-offs; you locate the 12V-HVDC nearer the alternator etc and run 2 or 3 thinner cable to the amp (namely +V & -V with maybe an optional ground). If indeed HV amps are finally here, we may finally see an end to the high-current 12V distribution market. Then again, caps are still surviving... The new amps may also be for the long suggested 42V etc car systems, but even that will begin the end of the 12V distribution was some will want to use the new amps (and hence front-end SMPS) and others will see the benefits. PS - what a pity they still stick to low-Ohmage outputs, but maybe that's an HV-DC certification issue? (Ok, so SMPS#1 to 120VDC to an internal amp SMPS. LOL - Does that mean a +120, 0V & -120V, or +/-60VDC limit (58kW RMS vs 14kW RMS)?

Guess I'm just going to have to get creative if/when I decide to put a high voltage stereo together. and avoid mismatching batteries. getting the right alternators for the right jobs, etc. Thanks!

IMO the solution is a dc-dc converter(s) to obtain the required amp voltage(s). IMO that's how high power amps should be designed (as I wrote above). Otherwise it's matched series batteries (with the usually series problems) and an alternator to match.