How to step down DC voltage efficiently?

boomerboomer Posts: 5Registered Users
I have read a lot here about advantages of using a 48V battery bank instead of 12V. One thing I don't understand (and I have read and searched) is this:

Assuming a 48V battery system in an off-grid system, how should one step down the voltage to feed common 12V DC loads such as appliances, lights, etc? I thought it was quite inefficient to step down DC voltages with a voltage regulator, voltage divider, etc. because the extra voltage gets wasted as heat. Is there a more efficient way?

Comments

  • CariboocootCariboocoot Posts: 17,615Banned ✭✭
    Re: How to step down DC voltage efficiently?

    Buck-converter power supplies are fairly efficient. This is what you find in things like MPPT charge controllers and DC to DC converters. They are not, however, cheap.

    Cheap is: big resistor + Zener diode which = power lost to heat just as you say.
  • BB.BB. Posts: 27,788Super Moderators admin
    Re: How to step down DC voltage efficiently?

    It becomes almost a wash between a DC to DC down converter vs just converting all of your DC loads to 120 VAC and using an AC inverter.

    If you have DC native loads that you have to run that way--There are a few DC to DC down converters (and products) that can work fine (some will charge a 12 volt battery so you have backup/reserve 12 volt power)--Just need to know the details on the size of the loads.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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