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Philip Perkins

Block battery for laptop?

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Does anyone know of a block battery usable directly w/ a Mac laptop?  That would mean 24 VDC, right?  It seems like it ought to be possible, but haven't seen anything suitable.  I'm referring to a "movie style" battery built into a Pelican etc, maybe with a charger etc..

Philip Perkins

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I shouldn't think it would be necessary to build a special 24 volt block (movie-style) battery to run a Mac laptop. Except for the Mag-Safe connector problem (the new MacBook and MacBook Pro --- more later) there are lots of so-called auto adapters that are designed to connect a laptop to a standard 12 vdc source. So, any standard 12 vdc block type battery would then serve your need. When Apple introduced the Mag-Safe power connector (a really good idea but not compatible with anything else out there) all the companies that had produced all the accessory power connections (for airline hookup, car adapters, etc.) were S-O-L. I am not up on the current state of affairs in this area although I know that Apple has made available an airline adapter with the new Mag-Safe connector on it --- this is a standard Apple accessory now and possibly that could be adapted in some way. I did see that some company is again making power adapters (auto, airline, etc.) that uses the Mag-Safe connector, but I don't remember what company is doing that.

Regards,  Jeff Wexler

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I shouldn't think it would be necessary to build a special 24 volt block (movie-style) battery to run a Mac laptop. Except for the Mag-Safe connector problem (the new MacBook and MacBook Pro --- more later) there are lots of so-called auto adapters that are designed to connect a laptop to a standard 12 vdc source. So, any standard 12 vdc block type battery would then serve your need. When Apple introduced the Mag-Safe power connector (a really good idea but not compatible with anything else out there) all the companies that had produced all the accessory power connections (for airline hookup, car adapters, etc.) were S-O-L. I am not up on the current state of affairs in this area although I know that Apple has made available an airline adapter with the new Mag-Safe connector on it --- this is a standard Apple accessory now and possibly that could be adapted in some way. I did see that some company is again making power adapters (auto, airline, etc.) that uses the Mag-Safe connector, but I don't remember what company is doing that.

Regards,  Jeff Wexler

OK, but they DO need 24 VDC right?  I mean my G4 laptop PSU says that it makes 24v.  I've almost always made up my own batteries, and would like to do that for this purpose, and wondered if anyone had done it already.  I guess for the Mac end of the connector you'd have to cannibalize something.  You cats using Mac mins on yr carts--are you running an invertor for them or did you do a DC mod?

Philip Perkins

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OK, but they DO need 24 VDC right?  I mean my G4 laptop PSU says that it makes 24v.  I've almost always made up my own batteries, and would like to do that for this purpose, and wondered if anyone had done it already.  I guess for the Mac end of the connector you'd have to cannibalize something.  You cats using Mac mins on yr carts--are you running an invertor for them or did you do a DC mod?

Philip Perkins

The Mac Minis want 18V DC and so do (I believe) the Macbooks and Powerbooks.  Most folks just put an 18V regulator inline from a 12V (or 24V) battery, but there's another grounding circuit needed called "iSense" for the macs which makes the wiring a bit more complicated.  Regardless of voltage, you'll want a regulator as Macs don't like fluctuations in voltage.  Check out www.carnetix.com for their mods -- they make prebuilt setups for the Mac Mini and have wiring diagrams there.

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I made a cable to put two 12vs in series to run a G4 laptop, and it works great. There are actually two seperate conductors in the pin of the adapter where it plugs into the laptop. If I remember right, one, the inside one (the ring of the inside pin), "switches on" the power supply when it's connected to the outer ring. This keeps connector from shorting out or shocking someone when it's unplugged from the computer but still plugged in. Once again, make sure before you do it, but I'm pretty sure it's positive for the tip of the inside pin and negative for the outer ring, and you can just ignore the ring of the inside pin. Good luck with it. --John Bucher

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I made a cable to put two 12vs in series to run a G4 laptop, and it works great. There are actually two seperate conductors in the pin of the adapter where it plugs into the laptop.

John Bucher

Remember this description only applies to the old style connector (round with a center pin) and does not address the Mag-Safe connector. All current Mac laptops have the Mag-Safe connector. I don't remember if the original question stated whether this was a powering solution for a current model (MacBook and MacBook Pro) or the older ones.

Regards,  Jeff Wexler

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Thank you Brian for posting that. I knew someone had done this with the Mag-Safe connector. From the looks of it, this is the way to go for anyone wishing to power a MacBook or MacBook Pro from a 12 vdc source.

Regards,  Jeff Wexler

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