# What is the most convenient way to make/buy step 66V DC down to 12V DC?

There is a big battery that I have which has 64-67 volts, and I need constant 12 DC volts from it.

I tried ebay, but the best buck converter that I found had limit of 55 volts. My local electronic parts store doesn't offer what I want either.

I have some basic skills in soldering, I have some resistors, diodes and MOSFETS, I know how this all work separately, buy is there a way for me to make a converter that I need? Or where to get one?

Update:

For instance, can I use transformer-type of this-other-pulsing-type 220 AC - DC 12 converter, but with 66V DC input?

Update:

Can TPS2490DGS help me with it? I don't understand english well, but from what I can tell from the datasheet, this thing can control two external MOSFETs providing nice custom current and voltage outputs. But how to use it? It has 10 pins...

Update: The max current on the output I need is 4A.

• You haven't written what current you need on output. – Janka Oct 25 '16 at 21:47
• How much access do you have to electronics lab gear? (oscilloscope, etal) – ThreePhaseEel Oct 25 '16 at 22:19
• Look for 36to72VDC input converters, there are various sizes available, you may have to order online if local suppliers have no stock. An AC input device will not always work with your DC battery supply though some will, the peak and RMS AC voltages values are also not the same so take care if you go that route. – KalleMP Oct 25 '16 at 22:22
• @KalleMP thank you, that was what I was looking for! Can you write it as an answer? – AgentFire Oct 25 '16 at 22:35
• Is this by chance a locomotive battery supply? Those can run up to 74VDC during charging... – ThreePhaseEel Oct 25 '16 at 22:38

• 128$us or 2$/W