Lithium ion 50g

About a year ago, somebody made a post to this group about modifying their 
calculator to use a lithium ion battery.

I see that someone else has done the same with the 50g, but this time posted 
a bunch of nice photos and detailed instructions.  This was not written by 
me; I don't know if the author reads this group, but it wasn't yet posted 
here so I felt I should post it:

 http://www.**--****.com/ 

Regards,

Eric Rechlin 

My opinion:

Pros:
-2X battery life (theoretically, not thoroughly tested).
-Rechargeable through USB.
-Don need a battery charger anymore.
-An achievement feeling if you DIY.

Cons:
-You can kill your expensive calculator in the process.
-Takes time. Time is money.
-LiPo batteries are dangerous to tamper with.
-Not available everywhere as NiMH AAA.
-When batteries die (be it aging or too many cycles) you have to hack
your HP again (time consuming, risky).
-If, for some reason, your batteries die in a situation when you
really need your HP, you're fried, you can't just take out a fresh
pack of NiMH AAA and replace batteries. USB ports or AC outlets are
not available everywhere.

You can go easily through many 4 hour long exams with a fresh low self-
discharge AAA NiMH package. Notice "low self-discharge", normal NiMH
probably won make it due to high self-discharge rates.
Plus, who wouldn check battery status prior to an exam?

Contrary to the author, I consider devices with standard batteries are
more convenient, since standard batteries are always available
everywhere.

I guess the hobbyist felt warm and fuzzy when he got that hack to
work, but would you really trust a battery company that advertises
12,000mAh when it's really (or maybe doubtfully) 1,400?  You could
cause some serious damage to the calc (if only cosmetic) trying to
open it for the sake of a 40% improvement over 1,000mAh AAA cells.

I use NiMH batteries in the calc, my photoflashes, flashlights, etc,
and they're all normal types, not low-self-discharge.  I've never
noticed any problems.  Besides, slipping in another set of batteries
sure beats hacking the calc open again when the internal lithium cell
dies.

Bill

I totally agree. Standard batteries will be available in the future
(or at least be much more accessible than custom Lithium cells). They
are also widely available no matter where you are, so you can buy a
replacement set of batteries nearly anywhere if need be.

For important exams, either
(a) check battery status of the NiMH cells
(b) charge NiMH cells the night before
(c) invest in 4 alkaline cells that you know are fully charged

Or, do all three and use the alkalines as a backup.

S.C.

 >About a year ago, somebody made a post to this group about modifying their 
 >calculator to use a lithium ion battery.

Yes, that was me. And I had to charge it last month.

 >I see that someone else has done the same with the 50g, but this time posted 
 >a bunch of nice photos and detailed instructions.  

Pah! I dont cut an ugly hole in my SX....

Olaf

Aye.  When I added a lithium polymer to my 49g+, I kept the battery
bay intact and added a switch to allow the use of standard AAAs on the
fly.  You can see what I did on my page:
 http://www.**--****.com/ 

-Jonathan