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#1
posted to rec.boats.electronics
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Inverters DC to AC Battery help!
Good points John.
Typical rated power to the AC adapter for a laptop is close to 150W, but output to computer is in order of 65W. Explains why the damn things get hot. Direct power may well be worth investigation, rather than using DC to AC to DC. surfnturf -------------------------------------- "John Weston" wrote: Watts = Volts x Amps snip If your laptops are so inefficient as to require the full 300W of available input power from the inverter then yes, that equates to at least 25A at 12V. If it requires less power, then the current drawn from the 12V battery drops to that necessary to provide the power. It doesn't matter that the laptop is being supplied at 120/240V from the inverter (and so the output current will be around 2.5/1.25A), you'll still need more than 25A at the input to the inverter if it needs the full 300W. If that is the case, you wouldn't be using a 300W inverter, since they don't like running at their maximum output for too long. Typically, with computers, the rating of the power supply is based on the expected maximum power requirement of the peripherals and circuits, plus a bit for reliability. What is actually drawn from the power source depends on what you are doing with the computer. I'd expect a computer on a boat to draw a *maximum* of around 100W (depending on its design) so your cigar-lighter socket should be OK at around 8A. However, if you ever try to power 3 or 4 working laptops, then your fuse may blow, if the inverter doesn't quit first... snip John |
#2
posted to rec.boats.electronics
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Inverters DC to AC Battery help!
Typical rated power to the AC adapter for a laptop is close to 150W, but
output to computer is in order of 65W. Explains why the damn things get hot. So don't bother with DC from the batteries to AC and then back again. Get a laptop power supply that has a 12V input. The iJuice (aka iGo) adapters work well. Then it's just a matter of using a cigarette lighter outlet. |
#3
posted to rec.boats.electronics
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Inverters DC to AC Battery help!
Bill Kearney wrote:
Typical rated power to the AC adapter for a laptop is close to 150W, but output to computer is in order of 65W. Explains why the damn things get hot. So don't bother with DC from the batteries to AC and then back again. Get a laptop power supply that has a 12V input. The iJuice (aka iGo) adapters work well. Then it's just a matter of using a cigarette lighter outlet. All these little adapters work well on a regulated voltage, but with an alternator running, the voltage can be far from regulated. |
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