[chbot] Power for 12v / 5v solutions.

[Andrew Errington]

Hello Daniel,

I hope you get a range of replies to help you choose, however, these days
knowledge doesn't count for quite so much since everyone buys the same
modules from China.

A very common one is the LM2596, which appears in various guises. Here's
one from a local supplier, but there are several versions from various
places:

https://instantpanel.co.nz/products/2596-buck-converter-adjustable-switch-mode-module

That module is available in (at least) two physical sizes with different
PCB dimensions and different hole spacings. Don't ask me how I know.

There are also versions available with fixed output instead of the
adjustable pot. I have had several in the field (literally) powering
Arduinos and other modules for months with no problems.

Here's an article about the regulator itself, but you don't need to know
how it works in order to use it:

https://components101.com/regulators/lm2596-3a-step-down-voltage-switching-regulator

You do need to know the parameters of the rest of your system though,
however I suspect you will not need 3A current handling, and based on your
requirements you will not be generating much waste heat. What is the
current requirement of the dash?

If you want to bling up your rig then there are regulator modules with
7-segment displays for voltage and current, but they use power themselves
so might reduce your battery life.

Finally, I don't know about Ryobi battery packs, but you should check what
they do when they are getting low. If they keep going until they're
literally flat it's bad for the cells, but it's quite likely that there is
a low-voltage cutoff inside the pack so the power will just stop.

Aside from that, the project sounds really interesting. If you can bring it
(or part of it) along sometime I'm sure it will be well received. Or if you
want to arrange a private viewing off-list then please include me in your
invite.

Andrew


On Thu, 22 Apr 2021, 15:34 Daniel Powell, <danielvieway at hotmail.com> wrote:

> I've been playing with a remote battery powered dash for my race car based
> on a Mazda RX8 dash and ESPNow.
>
> I've successfully prototyped the unit using a couple of M5stack Atom's and
> external CAN Bus transceivers.
>
> The Atom is powered via USB and the dash (12v) via an external 240v power
> adaptor.
>
> I'm not looking to produce my own board (I'm not quite of that skill set
> yet) however want to integrate the unit into something somewhat more
> portable using a single Ryobi 18v battery as a power source. I was thinking
> two buck converters, one for 12v for the dash (thinking 18v might be a
> little much for the dash) and a second for the 5v logic.
>
> Would appreciate advice from those who are considerably more knowledgeable
> and exposed to modular power supplies than I am and could possibly point me
> in the direction of a more suitable or tidier solution.
>
> Cheers,
> Daniel.
>
>
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