Basic DC (direct current) theory and practice for newbies

hey everyone, as you may have guessed - i'm a newbie to DC theory! Backstory: after graduating i said 'forget it' to a proper job and moved to Australia to travel. i bought a converted camper van that has an auxillary battery for (whatever), and it looks like it runs off 12 volt dc! the Question: how does DC power work, for me and all those newbies out there putting along on the other side of the planet! -cheers, adrian

kadris310 years ago
that's a big assignment. i'll give u some basics and you can ask specific questions as the need arises.
use only stranded wire :red for plus;black for minus; that is big enough to handle
the current the device is using. since u will have to park a lot of the time(fuel is getting expensive) consider a photovoltaic array to keep it charged. replace all incandescent dc lights w LEDs as they use very little electricity. obtain a self contained portable jumper so u can start the vehicle if u drain the battery. on mains power u mostly use higher voltage(117vac or 208vac) and a low current. car power is low voltage 12vdv and higher amperage(think big wire)
to get the job done. forget toasters,heating devices, and most everything that requires lots of power. if u need "ac" for a computer or something, u need and inverter to "convert" the dc to the type of juice a computer can use and charge up the computer battery. cell phones and electric razors my also need to be charged. get a good quality one. modified sine wave or true sine wave only. do not skimp here. get only as big a one as u need. typically 200 watt or so will be more than adequate. i have used 75watt and gotten away w it. p=ei
power=voltage x current. 200 w = 12v x 16.66 AMPS(big wire). u need to be under power fr this to be used. when ur rolling charge ur gear. 100 watts = 8.3amps and 75 w = 6.25 amps. here little is better. u need to save juice.
the car alternator charges the batt and runs things when rolling. when u stop its all on the batt. running the alternator puts out 13.8 vdc but when u stop the
batt output is 12 vdc. any LEDs need to be biased for 13.8vdc if it is used when the charging circuit is in use(alternator or photocell). a constant 13.8vdc
will cause batts to boil and lose water. add only distilled water!!!!!!!!!!!do not overfill. voltage regulators in cars minimize boiling of electrolite but photocells
can be a problem as batts become nearly charged(voltage increases). the use of small cells(probably all u can afford anyway) and large batts eliminates the need fr solar regulation.

you are the envy of 50% of the people on this site. everyone wishes they had the guts to do what ur doing. have fun and enjoy life. everyone else waits until they are an old fart and too busy keeping themselves alive to enjoy it. good luck.
adritek (author)  kadris310 years ago
thanks very much for your info -- sorry this reply finds you late, australia is pretty big (and very remote on the inside).

we're on the fast track now armed with lots of great info and even bigger ideas!
we'll put up an instructable on solar/traveling or something
thanks again for all your help - come on down and we'll go surfing!

-adrian and dayleadrian and dayle
kadris3 adritek10 years ago
glad i could help some. as questions arise feel free to contact me if ur near a whimpernet connection. i know the outback can be vast and without services. best of luck to you and your wanderings. X
MrPopkins10 years ago
Oooh. You've not Googled this?
Rather than try and explain, how baout here?