RPI3B+ disable HDMI

[Stefan Parvu]

Thank you all for answers. Will experiment with these. 

At least we got a basic 12hrs run on a single charge, running Kronometrix data recorders (1 recorder up), ethernet cable on.

Stefan

> On 1. Nov 2020, at 4.22, bob prohaska <fbsd at www.zefox.net> wrote:
> 
> On Sat, Oct 31, 2020 at 09:59:38PM +0200, Stefan Parvu wrote:
>> Hi,
>> 
>> We have started now testing our product using FreeBSD 12.2 on RPI3 and 3B+. 
>> 
>> I have a question how one can start to disable things from the board which are not needed, to save as much as possible power. For example starting with HDMI port. I am trying to do some basic tests running our data recorders with FreeBSD 12.2 only on batteries. (4 x 18650 Li-ion 3500 mAh). Would it boot from batteries. Has anyone tried before this?
> 
> At one time ISTR that no monitor in the HDMI port on powerup turned off
> the port, at least to the extent that if a monitor was subsequently plugged
> in it got no signal. Not sure if this is still true, nor whether it actually
> reduced power consumption. 
> 
> hth,
> 
> bob prohaska
>