Run Your Desktop off DC Power
You want to run your desktop computer off battery power directly without an inverter? Maybe an inverter is a little too much overhead for you? Maybe you are in a remote location and need every amp-hour you can get? Whatever the reason, you don't necessarily need an inverter to run the PC.
Contents
Steps
- Replace your computer's power supply with a similar DC/DC power supply. If your computer has an ATX power supply, a web search for 'DC ATX POWER' will turn these up.
- Select a power supply that matches the voltage of your battery bank.
- Consider the effect of high current draw and the life of your battery when using 12V.
- Replace the LCD monitor's 'wall wart' with a 'DC/DC converter'.
- Do a web search for 'DC-DC Converter', too.
- Look at the monitor's 'power in' plug. Is it a standard, everyday plug you could get an adapter for at a 'Radio Shack', or something odd-looking?
- If it's a standard-looking connector, get a DC/DC converter that is rated for an input from 10.5VDC to at least 15 volts DC, that has EXACTLY the same voltage as the monitor is expecting as an output. It must put out at least as much current (amps) as the original AC adapter. There are some 'universal' DC/DC adapters with switchable output voltage but their current (amps) ratings tend to be too low.
- If it's something 'odd' (i.e. more than just positive and negative), you have more reverse-engineering work cut out for you than can be outlined in a little 'how to' list.
- Items which use more than two voltages will need to have it's own converter for each voltage used.
- If it only has an AC power plug, then it's simpler to just use an inverter to power it. (High voltage DC is also possible, but keep in mind that only half of the bridge rectifier will be used, so make sure the current draw isn't too high.)
- Do the same DC/DC thing with any necessary peripherals (such as hubs, routers, speakers).
- Some items which originally run on low voltage AC will not run properly when powered by the same voltage in DC. A very simple unloaded DC supply will convert 12 VAC from the transformer into ~15.6V (inclusive of the voltage drop across the bridge rectifier). In that case for an item powered by 12 VAC from the adapter, use 15 VDC.
- This method will not work for items that require AC to produce positive and negative rails, as in the case of some speakers (the amplifier requires them).
- Hook it all up to the batteries.
Tips
- Notebook power supplies can also be replaced with (correctly matched) 12 volt DC-DC adapters, similar to how it's done with monitors, but the maker of the notebook/tablet will generally sell you a 12 volt adapter they had made for it.
- There is still loss for using a DC-DC converter, but far less loss than using an inverter to ramp it up to 'something like' AC power and then use that original power supply to re-convert that noisy signal to DC again.
- Alternatively, buy a laptop and the matching Car Charger (12v DC charger), its smaller, simpler and more energy efficient.
Warnings
- Shorting big batteries can cause messy, acid-filled explosions, with disfigurement, blindness and death as possible consequences.
- Don't take electrical/electronic things apart or handle big batteries with jewelry on. Jewelry can become a 'heating element', so rings can burn off fingers, bracelets burn off hands, etc.
- Big batteries have big current, and that's enough to hurt or kill you on its own.
- Even dropping a metal tool on 'live' DC terminals can literally burn it in half pretty much instantly, and that's if you're lucky.
- Many desktop manufacturers including Apple, Google and Microsoft don't recommend running a desktop off battery power.
- You can fry expensive stuff if you don't do it right.
- Mind polarity on DC/DC adapters (input AND output), especially 'universal' ones.
- It only takes momentary contact with the battery cables reversed to blow things up in a flashy, irreversible way
