I don't know about efficiency. The Macally ac adapter says it uses 1.5 amp at 110-240vac and puts out 24v at 2 amps, BUT my Kill-A-Watt meter says it's using 15-18 watts with the battery fully charged. If I close the lid, my Apple suspends itself automatically, and the wattage goes up and down for a few seconds, then drops to 3.
The car adapter is Micro Accessories (APD) model DC-72A24. It put out up to 3 amps at 24v. With the battery fully charged, my CenTech (HarborFreight) multimeter says there is about 1.25 amps being used. The battery voltage was 13.1, which works out to 16 watts, same as the MacAlly. The car adapter load senses, too. If I disconnect it from my laptop, the current draw drops to .03amps.
Both adapters are after market. The original Apple adapter is usually left in the box. It has a slightly bent plug, but still works. It also uses 16 watts according to the Kill-A-Watt meter. The bent plug and dinged up laptop shell were from the original owner, who dropped it. The new Apple ac adapters have a magnetic plug, rather than RCA jack, for safety.
I had to replace the hard drive recently because it had accumulated damage from the original fall (lots of bad, unrepairable sectors).[ Parent ]
Thurmond [ Parent ]
It has a full wave bridge just above the big round cap on the upper left. I plugged it into 13.2 volts dc from the Harbor Freight pdu and it seems to work fine.
I'm posting using it now. If I get desperate for power, I'll do it that way. What does 10.5 vac work out to full wave rectified? Is 13 dc underpowered?[ Parent ]
10.5 * 1.414 = 14.8470
But there's also "droop" due to current pulled from the cap between the peaks. DC doesn't droop.
There will be a regulator or two downstream to reduce the voltage to what is actually used. So you're probably just fine.[ Parent ]
