minimal overnight voltage conversion

blueskies

Hi all,

I have a cabin style situation.  All high loads run off the 24 v system but i have a couple panels that go through a midnite solar unit that runs small loads.  This was against other advice but i wanted both a 12 and a 24 v system separate for different needs.  Anyway, while I am sleeping, I want the small 12v system to run some simple things like alarm clocks and low watt fans.  These have been selected and purchased to use a power source of 5v dc - the same as most phone and usb devices.  In my experience, using an inverter for something like this is over the top and draining.  Anyone know of a device that will provide the 5v dc from 12 v batteries without draining them more than necessary? PS  I turn off ALL inverters when not in use.

Photowhit

Someything like this, claims 96% efficiency;

https://www.amazon.com/SMAKN-Converter-Power-Supply-Module/dp/B00CXKBJI2

You might also charge a lithium 'power bank' during the day, and run things off that. Here's a 10,000 mah bank next to my cell phone and a usb fan That will run a couple days on low;

blueskies

Thank you, photowit.  Your advice is always good.  I will have one of these.  

blueskies

at the price, 2 or 3, one for a backup

BB.

I am not a big fan of cigarrette lighter plugin devices... But Anker does make some 12/24 VDC usb "car" chargers:

https://www.anker.com/products/variant/powerdrive-speed-2/A2228011

Input: 12V/24V

Here is a search of their website that may list more of their 12v/24v devices (I did not go through the results in detail):

https://duckduckgo.com/?q=site%3Aanker.com+12v%2F24v&atb=v122-1__&ia=web

Or you can use Google/Bing/etc. with this search term using the "site:" tag (limits search to one website:

• site:anker.com 12v/24v

Another option is to use a buck mode switching DC to DC power supply... 24 volts in, 12 volts out (adjustable for many). There are lots out there and usually do not waste very much energy. Lots on Amazon/eBay/etc... Lots of different current/voltage/features and options available.

https://www.amazon.com/s?k=dc+to+dc+buck+converter

This one can output 12 volts @ 5 amps max:

https://www.amazon.com/DROK-Adjustable-Converter-Transformer-Protective/dp/B07JZ2GQJF

And use this to power a 12 volt USB converter.

-Bill

blueskies

Thanks Bill!   Future researchers - you can"t beat BB and photowit for advice.

blueskies

ps. but have a pencil ready - if they still make those - for Bill / BB.  very thorough.

blueskies

ps ps here is a website to determine how much awg you can get out of combining insulated wires to get the awg you want.  this is not to meet standards for houses.  https://www.wirebarn.com/Combined-Wire-Gauge-Calculator_ep_42.html