lithium ion battery charging Baofeng

[mkube396]

So i have 3 chargers 1 of them is busted.. I would like to make a circuit that will charge the lithium ion battery pack's for the radios.
They are 7.4v Li-ion 1800mAh to 3800mAh but more like 2600 i would guess you know "China".
From how simple the circuit is in the charging base i guessing there just dropping the voltage from 10V to 8.4v from pics on the internet of the battery's that are open it looks like they have a circuit board in with the battery's for Controlling the charge? Can i just put a Simple voltage reg in there to drop 10 or 12V down to 8.4v?
and is there away to add a done charging LED?

[Audioguru]

A lithium battery explodes or catches on fire if charged wrong. You are guessing about the little board on the battery that might not be a charger circuit.
A charger circuit limits the charging current and detects it dropping low then disconnects the charging. The charger also regulates the charging voltage and many of them sense over temperature then disconnects the charging. A battery discharged too low must be charged with a current much less than normal and its voltage is monitored. If the voltage rises then soon it is normally charged but if the voltage stays low then the charge is disconnected. Multi-cell batteries (7.4V to 8.4V have two cells)are balanced charged.

[mkube396]

that a look at the pics... I don't think them 2 10ohm  resistors are doing all that work..

In this video you can see the inside from what it looks like it is balanced charged

[mkube396]

will this work?


https://www.ebay.com/itm/TP5100-1S-2S-3-7V-7-4V-Lithium-Lipo-Li-ion-18650-Battery-Charger-Charging-Module/322655498326?epid=2163906507&hash=item4b1fc43056:g:6x0AAOSwfDhZgxLf&rmvSB=true