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Looking for 6F22 ("9V") 3S (not 2S) LiFePO4 batteries (need 9.6V nominal)

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BILLPOD:
Looky here:  https://www.ebay.com/itm/253372126102?chn=ps&var=555428525886&_trkparms=ispr%3D1&amdata=enc%3A18S4WF-rSQr6igsaRIZQnOw58&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=555428525886_253372126102&targetid=&device=c&mktype=pla&googleloc=9005066&poi=&campaignid=17597089569&mkgroupid=&rlsatarget=&abcId=9300988&merchantid=101688389&gclid=Cj0KCQjwjbyYBhCdARIsAArC6LJEWEquyA3eQVMrvkMvUgFMtSTAhLWQ0gj92585qhZ6lsxsirMOH9IaAv1HEALw_wcB

tunk:

--- Quote from: BILLPOD on August 31, 2022, 08:12:26 pm ---Looky here: 

--- End quote ---
That's a 2S li-ion, not a 3S LiFePO4.

tunk:

--- Quote from: tobyinlu on August 31, 2022, 06:19:54 pm ---What is the maximum voltage of a traditional 9v bloc?
Most vendors offer only a graph... using my magnifier I can estimate something like 10V.
What can I expect that most appliances will tolerate?
The just arrived LiFePO4 have 3.25V => 9.75V.
I expect the voltage to be higher immediately after charging.
Do I have to discharge the cells to be on the safe side?

Any suggestions welcome
Tobias

--- End quote ---
A new 9V alkaline is around 9.6V (assuming six cells at 1.6V).
A fully charged LiFePO4 is 3.6V, i.e. 10.6V.
If this is too high depends on the application.

thm_w:

--- Quote from: tobyinlu on August 31, 2022, 06:19:54 pm ---I hope someone is still following this thread.

My approach is to use 3 AAA LiFePO4's and to design an adapter.
If my measurements are correct they should fit into a standard 9V enclosure.
The advantage would be to be able to charge the three batteries separately.

What is the maximum voltage of a traditional 9v bloc?
Most vendors offer only a graph... using my magnifier I can estimate something like 10V.
What can I expect that most appliances will tolerate?
The just arrived LiFePO4 have 3.25V => 9.75V.
I expect the voltage to be higher immediately after charging.
Do I have to discharge the cells to be on the safe side?

Any suggestions welcome
Tobias

--- End quote ---

Any drawing of the adapter?


--- Quote from: tunk on August 31, 2022, 08:47:11 pm ---A new 9V alkaline is around 9.6V (assuming six cells at 1.6V).
A fully charged LiFePO4 is 3.6V, i.e. 10.6V.
If this is too high depends on the application.

--- End quote ---

3.3V is 90% state of charge, so you could stop around there if you were worried, should be safe for almost anything.

tobyinlu:
It's been a while... now I have a prototype. The upper part consists of 1 mm PCB, the lower part of 1,5mm PCB milled down to 0,5mm to keep the
length within max 48.5mm.
The contacts a of phosphor bronze, the top buttons fit into holes in the PCB.
The negative contact might have short with one of top buttons. I added added an insulation ring. I think I should flip one cell for a next version.
I tried to upload more images, but  a 356kB file is too large.

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