Discrete voltage reduction?

[HellTriX]

Suppose I have this 12 by 12volt battery bank for ~163v.
I have Mosfet that are going to be using this full voltage, but
my control circuity is rated to 18v max or something like that.

What would be a few ways to reduce this voltage to safe levels for the
Op-amps, 555s, etc?

One what I was thinking was a couple transistors used as a voltage divider.
Would a transistor oscillator used as a PWM signal for a Mosfet be acceptable
to drop this voltage?

I'd like to try to build my own for this rather than use a buck converter thing.

But I'm just collecting ideas at this point.

BTW the control circuity would be low current, less then 2-3amps max, and
if I needed to keep it fairly stable I could drop that to as low as 100-200mA
for the voltage divider to stay within safe limits. Oh, and I would like the
voltage to remain between 12 and 18v. I guess I could use a voltage
regulator after a voltage divider or something. But ya. I don't know..

tnx

 

[ericgibbs]

hi,
Are the individual 12V battery terminals accessable.?

If Yes, you could use the bottom 2 batteries, referenced to the common end of the 12*12.

This would give 24V which could drive the 18V control voltage regulator, maybe a LM317.

If you are concerned about balancing the charging of the 12 *12 battery bank it would be possible to additional recharge the lower 2 batteries with a 24V floating charger.

The way you are proposing to reduce the voltage by a divider would be very inefficient.

Do you follow this.?

 

[HellTriX]

The inefficiency was one of my concerns. But loosing a few watts to run the drive circuity would be trivial in the short term. I was away of the imbalance of trying to take power off one or 2 of the batteries so was just looking for ways around it.

Another option I considered was a triode step down transformer with some sort of oscillator. This would be what, 75-95% efficient? Compared to 40% or something of a transistor voltage divider. But weight is an issue. It would need to be a khz transformer to make it light enough to be beneficial, otherwise a resistive approach would be better.

But I'd really like to keep the battery load balanced and not add complexity and wear and tear on the batteries by adding floating chargers.