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AAA or 4/5 AA option for Spice Series
01-30-2015, 02:38 AM (This post was last modified: 01-30-2015 02:39 AM by Sanjeev Visvanatha.)
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AAA or 4/5 AA option for Spice Series
I came across a HP 38C in very good condition for $10 CAD last week in a local sale. It was missing the battery pack and AC adapter. Since this was my first Spice series calculator, I could not even test it before purchasing it. The contacts were intact, and no signs of corrosion. The only damage is a crack in the screen that does not impede readability.

I wanted a relatively inexpensive battery solution using common AAA's or flat top AA's (both to be charged externally). Reading some more on battery solutions for the Spice series, I also got worried about breaking the battery contacts. This lead me to using AAA size or 4/5 AA size batteries.

Since the battery compartment is too long for either of these types of batteries, I chose to fill the gap on the non-contact side with a dual contact plate to establish the series connection, and some compressible foam. This is a similar arrangement as the 48sx battery compartment.

I plan on using 4/5 AA NiMH 1.2V batteries, which I will order. This will eliminate the need to add foam spacers between the AAA's, and also a foam piece over the AAA's so that the batteries do not get dislodged. I may have to add 1-2mm to the foam area to make up the difference of losing the button top.

Fig 1: View showing Contact Plate and Foam

Fig 2: View Showing Dual Contact Plate for Series Connection

Fig 3: View Showing AAA Batteries in the Compartment

Fig 4: View Showing Foam Spacers Between AAA Batteries

-- Sanjeev Visvanatha
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