[ltp] a30 voltage tolerance

[Andreas Kemnade]

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On Tue, 02 Mar 2004 21:36:14 -0500
Brian Beattie <beattie@beattie-home.net> wrote:

> I read an article on making an auxilary battery.  According to the
> article 12 Alkaline cells, a nominal 18V, is what you need.  What I'd
> like to know, before I plug this sucker in, is does anybody know
> anything about the circuit on the A30 (presumeably all current
> thinkpads).  Can the circuit handle 18v, can it handle lower voltage
> with out damage?

I can give you some experiences with that on a 560E which I had some time ago
which might help you
but I cannot guarantee that it works with yours. So you are on your own risk.

I have connected the input jack of a 560E, where I usually plug the ac adapter
in, to a solar panel with some extra overvoltage protection so the voltage goes
under no circumstances above 16V (the same value, the ac adapter uses).
When the voltage was lower, apm gets a bit confused. It says that ac is off and
displayed a high discharge time (multiple days! would be glad if that time was true ;-) ). When the voltage drops,
the displayed discharge time drops, too, until it reaches the time which is
displayed without any input. I have also connected a selfmade DC/DC connector with 16V output for some time, which worked reliably. With that adapter I could
use almost everything I found as power source (8-10 NiMH akkus, Pb akkus, other
LiIon akkus). I have not tried that with my current thinkpad. I guess it might
be the same. Look what is quoted on your ac adapter and try to generate that
voltage, too.  On my current thinkpad (X31) the output voltage of
the ac adapter is 16V, too. So using 18V might be a bad idea. 

Greetings
Andreas Kemnade

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