Help needed for building LI-Ion 9volt battery charger

bwolf

Member
2015-12-01 11:37 am
how to build charger circuit for
9 volt li ion battery.600mah
I read somewhere on the net
you should not charge a battery with a higher voltage than its capacity.
so it must be< 8 - 9V
??charging batteries with 10% of their current. Is this true? Should I be resisting my current to 60mah? my battery capacity 600mah.

external adapter 15v 1.5amp, I have Linear voltage 9v regulator but I dont know how to control current / limit it to 60 mah??

sorry for my bad English

Thank you :)
 

bwolf

Member
2015-12-01 11:37 am
thanks for the Circuit diagram
frnd can you explain Io = (VO/R1) + Io Bias current ??? with my requirements pls
how to get desired out put current with above circuit ?

in general how to get desired out put current??
 
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Stay with lead/acid or NiCad or Nimh if you want easy to charge batteries
Yes, that circuit is what I used with Ni/Cd many years ago.
I wouldn't mess with Li-ion because it's very over-my-head
( I've been looking for anything related to electric bikes last year...some sites were displaying some circuits -most ready-made/available on the market -and were intended for RC cars/planes)
 

basreflex

Member
2007-10-09 7:30 pm
LI-ion 9V are most likely dual cell batteries at 8.4V (2x4.2). applying a current limited voltage higher than 8.4V will destroy the cell or shorten it's life considerably.
so a precision current limited voltage source is needed. a standard 9V NIcd cell charger will not do the job as that one has a much higher voltage. one option is to build a precision shunt using a TL431set at 8.4V, and charge using a voltage with series resistor as limiter.
 
If you're not experienced with Li-Ion charging I would recommend getting a charge controller for them, you can buy them really cheap on eBay. Lithium cells are pretty intolerant of bad charging, so if you don't understand their charging cycle it's definitely not recommended to build your own charger.

If you want to learn more about LiPo charging I highly recommend you to watch this EEVBlog video.
 
Are you using a LM317? If you are all you need to do is look at the example circuits in the datasheet and you'll find the formula for setting voltage and current.

I would just like to stress this again, lithium charging is a very tricky thing, the cells are not tolerant of overcharge and if you just use a LM317 you won't have any termination of charge, so it'll just continue charging until you remove the battery. I highly recommend you to buy one of those chargers from eBay, or a lithium charging module, or use a dedicated charging IC.

Sent from my STV100-4 using Tapatalk
 

bwolf

Member
2015-12-01 11:37 am
:)

I finally found below circuit but it is for 1 cell 4.2v
how to modify this to 8.4 2 cell battery ...thank you
 

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Do not build a charger!

My serious advice:
Do not build a charger!
Buy a dedicated charger as these type of batteries need a special charger.

I bought on Ebay two 9V Li-ion batteries with dedicated charger for allmost zip.

Exploding Li-batteries is no fun.
Beware.
:hot:
 

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If you're not experienced with Li-Ion charging I would recommend getting a charge controller for them, you can buy them really cheap on eBay. Lithium cells are pretty intolerant of bad charging, so if you don't understand their charging cycle it's definitely not recommended to build your own charger.

If you want to learn more about LiPo charging I highly recommend you to watch this EEVBlog video.

100% agreed.