Variable dc power supply from a car battery?

Off-topic Chatter
1

Is this realistic or am I dreaming?

Could you potentially make a variable dc power supply from a 12v battery?

The idea being it seems silly to convert DC to AC just to have an inverter convert it back.

Plus I just love to tinker.

What I’m thinking is a 12v battery along with DC-dc converter to charge batteries and run various DC electronics. I also want to hook up a few USB ports.

I want a portable way to charge a huge variety of things without bringing a ton of charging cables and an inverter.

Put it in a battery enclosure and I have mobile variable power supply I can use for pretty much anything.

This summer we are doing a lot of travel and camping. I’d love to be able charge my li-ions, lipos for RC, USB for phones,camp lighting all from a simple power pack and be inverter free.

Like I said it seems to be a huge waste to do a dc-ac-dc tapdance when a little ingenuity and solder may just work.

I’d love to hear some ideas to make this happen.

2

There are lots of hobby chargers that run on both Ac and Dc input

3

most hobby chargers can run on 12v, even the ones with 110 plug, still have DC in jack.

4

Would I need some kind of voltage regulator between the two? It’s my understanding that car batteries can show a great deal of variance in voltage, especially under load.

A hobby charger would be able to charge 90% of what I need it to.

5

I don’t understand, there is a cigarette plug in your car, why not use that?

6

Many battery chargers with 12V input can be used with a car adapter.
For chargers with usb input get a good multiport car usb charger, you can find a few in my tests: index of USB equipment

If you need other voltage, you can get busk and boost converters from ebay for cheap, they just need to be put into a box with some connections.
For ideas check you-tube Julian Ilett, he runs just about all his experiments from car batteries, power banks and a few primary batteries, using buck and boost converter to adapt the voltage.

7

Most hobby chargers can accept a range of voltages and work. I think my turnigy brand charger (accucel 6) will work down to around 9V. I measured it but I can’t remember now. It might be stated in the user’s manual.

8

Just get a dc-dc voltage power supply?
There are plenty of cheap buck/boost ones.
Just keep in mind that most batteries should not be charged by just connecting them to a power supply, they require monitoring and regulation, not just constant voltage.

9

I tried the working voltage range out on the SC608 here… https://youtu.be/IQFA-miJcSg (About 4.5 minutes in)

That little unit is pretty versatile and very compact but reasonably powerful, great for sticking in a glove box.

10

Thanks for the ideas guys.

Bear in mind this is more of a fun project than practical…

I have to carry a spare battery when I camp anyway for my CPAP, so why not use it to run all my other stuff as well?

I’m liking the idea of using a buck boost converter inside a battery enclosure, throw in some USB ports a nice led display.

I’ve seen lots of plans for power packs using car batteries, just not one that is adjustable.