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Classics Battery Holder vs. Battery Pack
05-10-2018, 03:53 PM (This post was last modified: 05-10-2018 03:54 PM by AndiGer.)
Post: #1
Classics Battery Holder vs. Battery Pack
Inspired by Mark Hoskin's battery holder for classics that take 3 AAA cells I built one myself.
But when I put it in an HP-67 with even freshly loaded AAA batteries that give together 4.1 V I get the low battery indicator on (650 mAh or 900 mAh cells, doesn't give a difference).
In contrary I lately re-designed a cell phone battery pack with 3 AAA 800 mAh cells in it and the low battery indicator does not appear also I measure only 3.95 V.

What is the difference here? Why do I get the indicator on using the holder but not with the pack? Different current flow given to the calculator?
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05-10-2018, 04:06 PM
Post: #2
RE: Classics Battery Holder vs. Battery Pack
Do you mean AA ? Anyways, it could just be a poor electrical contact someplace.
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05-10-2018, 05:24 PM
Post: #3
RE: Classics Battery Holder vs. Battery Pack
No AA but AAA batteries inside the holder and pack as well.

Search for "Alkaline Hewlett Packard Calculator Battery CASE HP 35, 45, 55, 65, 67 & 80" on TAS. It's Mark's offer.

OK, will try to connect from pack outside with some wires and measure whether contacts maybe bad somewhere.
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05-10-2018, 06:04 PM
Post: #4
RE: Classics Battery Holder vs. Battery Pack
Out of sheer coincidence I received a little package from Mark Hoskins only yesterday. Among other things it contained two classic batteries and one of his AAA battery holders for classics. The HP-35 that I used to try them out likes both of the packs equally well, I put rechargeable 800mAh NiMh cells into the AAA holder.
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05-11-2018, 04:25 PM
Post: #5
RE: Classics Battery Holder vs. Battery Pack
Today did a test to a small bulb.
As the AAA cells aren't new voltage under load drops significantly from near 4 V to near 3 V.
That makes clear the low bat indicator.
Voltage drop doing the same with the pack is 0.1 to 0.2 V.
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