Calling all Mac guys. G3 restore?

[NxB]

Re: Calling all Mac guys. G3 restore?

Even newer laptops will work with under/over psus. Most laptop chargers will either charge the battery or power the laptop or both. The plug is the annoying part. Putting os9 is like putting 98 on it.

[Logistics]

Re: Calling all Mac guys. G3 restore?

So I can't use this old AT supply that has 1.6A min, 9A max on the +12V and 0.1A min, 1A max on the -12V?

Can you mix rails? Like +12V - -5V or +5V - -12V?

I have no desire to use a PC PSU to power the laptop itself, only to charge the battery. I can either get as close to 24V as possible and hook up to it's actual power port or close as possible to 14V and hook directly to the battery.

[Wizard]

Re: Calling all Mac guys. G3 restore?

Again,

Like I said, the -Ve supplies on these PC PSUs are woefully underpowered (1A at most due to thin windings and 1A diodes, and often many PSUs uses -5V regulator off the -12V supply.

What I mean is put on thinking cap and learn about PSU how it works and how much turns it needs for a 12V for example either split the 12V into two windings and put in series (12V supply often is wround with 2 to 4 copper wires in parallel). or add more turns on to reach 23-24V. The regulation feedback is tapped from 3.3V or 5V so leave that alone.

I had to trace and create a schematic of my suitable PSU to find correct resistors and change couple resistors to raise 12V to 15V and stripped all other wires out leaving the 15V and ground wires so I can power my notebook.

Cheers, Wizard

[momaka]

Re: Calling all Mac guys. G3 restore?

I have no desire to use a PC PSU to power the laptop itself, only to charge the battery.

Well, I only suggested using a PC PSU as an idea, perhaps an experiment for a rainy day. But if you really want this laptop working without risking of breaking it, I'd just suggest you get a laptop PSU with a similar voltage to your battery. Also, don't forget you're dealing with lithium batteries. Unlike Ni-Cd and Ni-Mh, lithium batteries can be quite destructive if something goes wrong (i.e. burn your laptop in seconds if a cell overheats).

Question (and I don't meant to be hijackign the thread) - is it possible to take the +12v and ground AC output from the traffo of the PC PSU, and with 4 diodes (or a bridge rectifier), 2 resistors, and 2 16v capacitors make a voltage doubler (like the primary side of a PSU with a voltage switch)? Perhaps if this idea works, maybe you can make a 24v supply that way.

[Wizard]

Re: Calling all Mac guys. G3 restore?

Do not apply power direct to the battery's contacts. Ever. Use the notebook to charge these batteries. So need to get 24V sourced.

Cheers, Wizard

[Logistics]

Re: Calling all Mac guys. G3 restore?

Again,

Like I said, the -Ve supplies on these PC PSUs are woefully underpowered (1A at most due to thin windings and 1A diodes

Yeah, but the specs on the battery cover say to use a 24V 1.875A Maximum, anyway. But it's okay, I'll just get one of those power supplies off eBay.

So okay, everybody do those power supplies that come up on eBay for the M2453 for roughly $16 look okay? Or do you think I need to get one of the more expensive ones?

Note: I hadn't planned on having to use the laptop with the power supply plugged in. I had planned on letting it charge up and then using it without, but in the case this battery ends up being too weak to holds it's charge then I suppose I'll have to keep it in all the time so tell me if those $16 ones look adequate or if they are time-bombs.

[NxB]

Re: Calling all Mac guys. G3 restore?

I've seen li-ions get really hot and start burning up. Power to battery is the LAST resort. Nimh is a little beter but still kind of shaky.

[HWgeek]

Re: Calling all Mac guys. G3 restore?

Nice score! Since you are in San Jose, CA. you should stop by either halted electronics santa clara (http://www.halted.com/) or weird stuff. http://www.weirdstuff.com/sunnyvale/html/index.htm

Weird stuff probably will have the exact charger for your ibook in stock, they handle lots of mac stuff. Halted will have a generic used charger that you would just have to put the right end on to use.
Try to get the right voltage (V) and same or greater amperage (A) rating. The switching supplies in side the laptop will only have so much swing to them. IE they might be able to handle +/- 10% voltage change. You can always go higher on the amperage, as that is a function of how much draw the laptop wants. so if it wants more than what the power supply is rated for, the power supply will start to heat up too much.

Regarding the LiIon pack. If it was down to zero volts some of the cells are probably bad on it. Aka decreased battery life etc. a 14.4 pack is probably either 4 cells (3.6 -3.7 v nominal) or 8 cells (depending on overall size) and current capability (mAh, usually 3300/4000 ish).
Charge on one cell is 4.2V to fully charge, so 4 cells, charge @ 16.8V charge. And you have to manage the current draw or the cells will heat up and blow up. Literally. (search the web, lots of RC car/plane guys blow up LiIon/LiPoly packs regularly, its ugly!)
Safest way is to either find a used battery charger off of ebay for that battery (they were made by VST) or get a power supply for the laptop and hte laptop will charge the battery correctly.

You can run 10.2 but will need to max up the memory. Or try ubuntu.
read this: http://forums.macosxhints.com/archiv...p/t-70109.html
and this http://forums.macrumors.com/showthread.php?t=231721
www.xubuntu.com

As always, the web search is your friend :-)

[Logistics]

Re: Calling all Mac guys. G3 restore?

Thank you, very much! I'm going to run out to Weird Stuff today, in that case. I've always wanted to go there, anyway. I like playing with funky stuff that's just old junk to most people. I'm not interested in trying to run OSX. I understand it's pretty in comparison, but I'm not concerned about that.

I'll also see if I can find some 350W+ PSU's for my blade servers.