Thread: P1900 alternative power supply for Mac Mini

Usually those bricks are OVERrated, so 90W should be ok especially since you will not be using the cpu at 100%, unless you like to compile stuff while you drive . Although the best way to test it is to go to RadioShack and get one of those current metters and meassure just exaclty how much current were talking about here, but my hunch is that 90W should be ok, since I have desktop PCs at home that draw less.

Originally Posted by johnsin

Mac Mini power brick is rated 110W, but from what I read on the web, it seems like Mac Mini is not drawing 110w even at maximum load. Do you think the 90W will be sufficient for Core Duo 1.66?

Yes. The brick has some reserve for FireWire and USB devices, you won't probably be burning DVDs in your car too often etc.

should work by connecting the hot and ground together, and also connect the isense wire to ground through 3.3K resistor. Is there anything else I need to watch out when doing this?

Not sure about Intel mini. I used 6k6 to be sure for my PPC one.
Some of these laptop power supplies tend to suck quite a lot of power even in idle mode.

I would still go with P1900 - it requires less power when in stand-by mode, gives you one or two extra outputs (+5V and +12V in my case) plus many other features (battery protection, startup/shutdown control etc.).

I tend to think the 90W should be OK. Anyway, I will test the car adaptor and post if it does a good job. Thanks.

Does the iSense wire require 13 volts on the Intel boxes, like the PPC, or will it work with 19?

As far as I know, the isense only required connection to ground through 3.3K resistor. Please correct me if I am wrong, thanks.

Just a quick update for all of you, the notebook auto adaptor with 3.3K resistor mod works well with my Intel Mac Mini. However, I still have no idea what the 3.3K resistor is for, maybe anyone with the knowledge could explain to us how the 3.3K resistor work with the grond connected. Thanks.

I have just done the same thing. I used the Kensington 72 Watt Universal Adapter.

I was able to determine that 72 Watts was more than enough because I have a Kill a Watt tester which plugs into the wall and then I can plug the Mini's power supply into it and it tells me the current and power draw.

I have the Core Duo 1.6 GHz and the power draw was never more than 22 Watts. It only hit 22 Watts while 3 USB devices were plugged in and it was playing a DVD. It idles at 16 Watts. So 72 Watts is definitely more than enough.

It amazes me that such a powerful machine can run on only 22 Watts.

I have no idea what the control wire is for, but I used a 2K ohm resistor and it did the trick.

I really wanted to use the Carnetix P1900 for it's startup/shutdown controller and to power my Lilliput, however I've been waiting for the P1900 for months. No distributor has it in stock and I'm sick of waiting.

MikesSwelch,
Nice to hear it works for you as well. I was going to use Carnetix P1900, but I also had encounter the same problem with you.

I usually put MacMini to sleep before I stop the engine. When the power to car adaptor is cut, MacMini automatically goes into deepsleep/safesleep/hibernate. With 'restart on power failure' enabled under the energy setting, it does wakeup the MacMini from deepsleep when car is ignited. The best part is MacMini is completely power up from deepsleep in just less than 10 seconds.

My biggest problem is sometimes the power to car adaptor is cut due to cranking problem during ignition. I am trying to get a time delay relay to delay power to car adaptor say 5 to 10 secs. It should do the trick to solve my cranking problem. Is your Kensington survived the cranking?

P1900 is supposed to come out out to the shelfs 11/15 at least that's what the posts on their message boards say.