Best way to tap 5V out of my scooter batteries!

[George.F]

Hi again,

As a project to revive my old electronic skill (been turned into a programmer) I have a little sideproject where I will build some cool stuff (unneccesary) stuff to my electric scooter. To start with I just wanted to hook up an Arduino board and som nice sensors to it, just for fun.

But the Arduino wants up to 12V as a supply to operate best, and I have some other thoughts where the components want to be fed with 5V. The batteries are 36V so I need to get it down from that to my levels?!

I know that it is possible to get 5V from the Arduino board, but I would like to avoid that. I was looking at an ordinary Linear Voltage Regulator, but I can't really find any that can cope with that high voltage in? As I have measured the voltage from the batteries can be as high as 43V when fully charged.

What is the best approach for this? Any ideas?

Thanks,
George.F

 

[crutschow]

You can use an LM317HV linear regulator for low currents, which can tolerate up to 60V maximum input voltage. You will need to put in on a heat sink, the size determined by how much current you need. The regulator power dissipation will be about (36V-5V) x I where I is the load current.

 

[dick_freebird]

First, you don't necessarily need to take the full battery voltage;
sounds like you have a 3x12V stack and you could take the
trivial current required, from only the lowest one (closest to
Gnd). That would let you use common "12V" point of load
converters, brick or module or a board design, real cheap.
Like ten bucks on eBay kind of cheap.

2 batteries, 28V converters; 3 batteries, 48V telecom
converters. All of these are overserved markets with
fully bottomed pricing if you stay away from the "high
reliability" gold plated end of it.

If you want the 12V straight then I'd take it off the
bottom battery through some decent filtering and
call it a day.