Need automatic charger schematics for 9v block battery.

[liteon]

Dear all.
please look at the attached the pictures of a battery that i need to recharge.Its Ni-mH 200mA 9v battery made by camelion in germany.
Why need to make a charger myself?
Well special chargers for this battery are available in the market where i live and are made by camelion (very nice ones) but every one of them is whopping high priced(could buy 10 of these batteries for the price of 1 charger).
As one of the image shows the actual voltage of battery to be 8.4v and size 9v block.
A charger based on Some microcontroller like pic or atmel will be much appreciated.
I got one schematics here.

blank.

Can i use it by setting it to charge 8 AA batteries.


Thanks a lot.

 

[DeepOne]

Possible use MC33340 chip for this.

If it is necessary certainly on microcontroller, that here is -
https://radiokot.ru/lab/controller/31/
(archive with .hex at the end of the article)

 

[liteon]

If it is necessary certainly on microcontroller, that here is -
ÐàäèîÊîò :: Çàðÿäíîå óñòðîéñòâî äëÿ Ni-Cd è Ni-MH àêêóìóëÿòîðîâ íà ìèêðîêîíòðîëëåðå.
(archive with .hex at the end of the article)

DeepOne thank you very much for the link.As the web page is in russian so translated it with google is not of much help.Further i looks to me like a charge for three 1.2v batteries in series.So 3.6 volt is not going to recharge 9v battery.If the web is giving some guide to modify it then google translation is not helping much.Discharge before charging is a nice feature any way.On the other hand my personal experience with russian,commercially available equipment says they are robust and more than very well made.I love russian makers.

Sorry my bad.I missed it to be 3.6 volt.It must be higher to charge 3 of 1.2v batteries.Can you explain the functioning of this charger to me please.

 

[DeepOne]

Hi, Liteon.

Can i use it by setting it to charge 8 AA batteries.

I think 8.4V s equivalent to seven 1,2V element.

So 3.6 volt is not going to recharge 9v battery.

yes, but number of cells ajustable by selecting value of R5, R4. (R5/R4 = 1,86*N - 1)

russian,commercially available equipment says they are robust and more than very well made.

Regrettably this not always. But this subject not for this forum.

Can you explain the functioning of this charger

Ok, i try to do it.
So, picture to avoid misunderstanding.

this charger uses principle of the charge by stabilized at 0,1C current on 15h timer. If supplying voltages disappearing, time is stored to EEPROM. After recovering, charge lasts until remained amount of time does not end.
Current is defined by value of R16
I = 1,25/R16. So, for 200mA battery I=0,02A, R16=62 Ohm.
Discharge current is depend from value of R12 and for 200mAh 9V battery R12 possible put 51 Ohm.

If R4=100k, for 7 cell R5=(1.86*7-1)*100k >> 1M2.

Voltage of power supply is around 20V for charging 9V battery . And else it is necessary to correct R1 in accordance with feeding voltage.

 

[liteon]

Thanks a million friend.
I happen to not have an attiny13 in my reserves.Just placed an order with an online supplier.Hope for them to arrive in 4/5 days.In mean time i going to attempt to make one with pic12F675 to see how it works.