Will battery replacements with more power hurt the system?

[Alma J Wetzker]

bof wrote:
> My laptop came with a six cell battery rated at 11.1 V, 4800 mAh with a 
> 3.0 hour life. When I went to buy a replacement from the manufacturer, 
> all I could find was an eight cell battery rated 14.4 V, 4800 mAh with a 
> 4.5 hour life. (No one else in the country seems to be making 
> replacement batteries for this system, so it would seem that I am stuck 
> with the manufacturer).
> 
> When I asked their Tech Support if the higher voltage of the eight cell 
> battery would hurt the computer, I was told it could damage the computer 
> and to make sure that I used ONLY a six cell replacement.
> 
> When I pointed out that the eight cell battery was being sold by the 
> manufacturer as a replacement, and that in fact they also offered a 
> twelve cell replacement, I was then told that the larger-celled 
> batteries would not hurt the system, just give a longer life. (It should 
> be noted that the larger-celled batteries cost much more, also).
> 
> So which is it? Will the additional power of the larger-celled batteries 
> hurt anything or not? It would be nice to have a longer life for the 
> system, but not if the higher voltage is going to hurt anything.

To the best of my knowledge, the computer uses voltages like 3.3, 5, and 
12.  (Not all laptops use 12)  So the battery voltage is being regulated 
down anyway.  The only possible harm is if the buck converter is at a 
fixed reduction factor.  That would be a truly brain dead engineering 
decision, so it is unlikely.

What happens with the higher voltage?  It takes less current to provide 
the same operating voltage, so you have greater operating time.  You MAY 
get a hotter system, but it would seem to me that most things would even 
out.  The conversion process is pretty efficient (better than 90% typical.)

The only other down side would be the charge circuitry.  Will it charge 
to the higher voltage?  And will it cut back to a trickle charge at the 
wrong voltage level, so you never get a full charge?  Who knows.

     -- Alma