Woodstock Li-ion Battery

[jjohnson873]

Has anyone thought of designing a rechargable L-ion woodstock battery that will fit into a woodstock battery case with a USB-c connector? It seems as if the NimH batteries only last so long and then they won't hold a charge any longer. Using standard alkaline cells is one solution, but they also run down quickly. I love using LED calculators, but would like a portable power source that will last several weeks without recharging that fits the woodstock form factor.

[teenix]

(07-03-2024 01:02 AM)jjohnson873 Wrote:  Has anyone thought of designing a rechargable L-ion woodstock battery that will fit into a woodstock battery case with a USB-c connector? It seems as if the NimH batteries only last so long and then they won't hold a charge any longer. Using standard alkaline cells is one solution, but they also run down quickly. I love using LED calculators, but would like a portable power source that will last several weeks without recharging that fits the woodstock form factor.

I use them for my Woodstock CPU board replacement with inbuilt LiPo charger.

The voltage is 3.8V which is way higher than the 2.5V that the original Woodstock used from NiCads. You could probably drop some voltage with 2 x 1N4002 diodes in series on the +ve battery terminal.

cheers

Tony

[Steve Simpkin]

Here is one.
https://hackaday.io/project/189308-hp-wo...ttery-pack

[jjohnson873]

(07-03-2024 01:12 AM)Steve Simpkin Wrote:  Here is one.
https://hackaday.io/project/189308-hp-wo...ttery-pack

Awesome Steve! I've contacted the hackaday developer. Next iteration should be integration of a Qi charger so the battery can charge wirelessly eliminating the USB-c connector.

[Maximilian Hohmann]

Hello!

(07-03-2024 01:02 AM)jjohnson873 Wrote:  Has anyone thought of designing a rechargable L-ion woodstock battery that will fit into a woodstock battery case with a USB-c connector?

Forgive me if my answers are already included in the other replies...

Regarding the topic there was this thread here: https://www.hpmuseum.org/forum/thread-18315.html

Then someone (who unfortunately we have never seen here before or after) presented the perfect solution: https://www.hpmuseum.org/forum/thread-16924.html
He never disclosed his circuitry but does not try to manufacture his battery packs either which means that they are even more "unobtainium" than a working HP-29C in good cosmetic condition. If you scroll down that thead a litte bit you can see that I was able to put together something similar - alas without some protections and the low-battery warning - from cheap off-the-shelf components. Works very well.

But honestly, since the price for 1,5V USB rechargeable Lithium based AA batteries has dropped to something like 3 Euro/$/GPP a piece I don't bother. I just use two of these and pull them out for charging, exactly as I have been doing forever with NiMH cells: https://www.hpmuseum.org/forum/thread-20284.html (here is a sample link to the last ones I ordered from Aliexpress, the brand name is "Litokala": https://de.aliexpress.com/item/100500670...ry_from%3A)

Regards
Max