DC-DC Car Power for Mac Mini

**ePiFaNT** · 01-25-2005, 09:03 AM

Would it be possible to set OS X to shut the Mini down after x seconds/hours/days? I`m currently running OS9 on my pismo, so I can`t find out ;o)

How big of a problem will the current draw pose to a system with a second battery? Will the battery lifespan be significantly decreased? After all, i use my car at least once a day...

**MikeH** · 01-25-2005, 09:11 AM

Would it be possible to set OS X to shut the Mini down after x seconds/hours/days? I`m currently running OS9 on my pismo, so I can`t find out ;o)

I'm going to have to admit....I am not a Mac guy

...so others will need to answer this.

How big of a problem will the current draw pose to a system with a second battery?

A second battery would prevent your main battery from draining. However, the problem will be a reliable way to keep it charged. This is been debated to death under the power supply section of ths forum. There may be a way to do this, but it gets a little messy. I guess it depends on how much you want the Sleep functionality.

**DMB-RSX** · 01-25-2005, 10:24 AM

I wonder how long it would take for a sleeping mac to drain a secondary battery in a battery isolation setup. My powerbook could sleep for many days before it's battery would drain.

**MikeH** · 01-25-2005, 11:17 AM

I guess the calculations are pretty straight forward. Amps x hours = AmpHours... So if you drain .2 amps out of a 60 AH battery you would get approximatley 300 hours or 12.5 days....if the battery were new and fully charged. Your mileage will vary.

The battery isolation setup is a pretty good way to do this, however, the casual user probably doesn't want to hassle with putting one in.

200mA may be OK for the main battery, but I think it will eventually put a strain on it's useful life. I guess it will be a tradeoff.

**Alric** · 01-25-2005, 09:58 PM

Anyway, I use my PC on standby, not hibernate, and I can leave it like that for days. I am sure the current draw on the Mac Mini while on standby will be similar to that of a powerbook, which can sleep for weeks without recharging.

In my experience sleep on the Mac is more similar to hibernate on the PC. Which makes the instantaneous wake from sleep even more impressive.

**randyb** · 01-26-2005, 01:17 PM

[QUOTE=ePiFaNT]Would it be possible to set OS X to shut the Mini down after x seconds/hours/days? I`m currently running OS9 on my pismo, so I can`t find out ;o)

There used to be an option in the Mac OS 9 sleep control panel called "Shut down instead of sleep". You could then set your sleep timer to 10 minutes. After 10 minutes of inactivity, it would shut down. Unfortunately this is not a feature of Mac OS X.

**NiN^_^NiN** · 01-30-2005, 06:13 PM

Sorry Mike i've been looking at the websites but havent found any of the cables yet

I have a few more to check when I get enough time so I'll keep you updated

**MikeH** · 01-30-2005, 08:23 PM

I'll keep you updated

Great.. let me know what you find.

**old_lou** · 01-30-2005, 08:45 PM

Originally Posted by NiN^_^NiN

Hmm maybe you could have the mac mini sleep for 10mins then after 10mins it cuts ALL power off?

How about the psu powering down automatically if the volage drops below X for longer than Y. This means if your battery is below say 12v it shuts down in 30 seconds. The Y bit stops it shutting down when cranking. This will let the Mac sleep but safeguard against a flat battery. If X is settable the user can decide when the battery level is safe.

**MikeH** · 01-30-2005, 08:56 PM

Lou,

How about the psu powering down automatically if the volage drops below X for longer than Y.

The P1900 already does this (where x=10.6V and Y=10 seconds). If X is below 10.6V when you attempt to initially boot, the SSC will prevent the computer from starting. X is resettable thru field upgradeable firmware.