Rechargeable 9v Battery: Charging & Safety Tips

[Tesladude]

I have a very small project which requires a typical 9v battery for mobile use. But to keep from having to replace the battery I would like to put in a rechargable 9v battery and use a 9v output from a dc power plug to charge it. I have charged batteries with solar panels before and all that is needed is the diode on posotive. But is this the same for what I am wanting? Will the battery not have enough resistance to keep a safe low amperage? or will the battery consume only what it needs? or must a resistor be put in series with the diode?

 

[davenn]

it depends on the type of battery to what the charging requirements are
for example LiPo's require very specific charging circuits. Others require specific voltages and or currents

Pretty much all of them need some sort of circuitry to make sure that the battery isn't overcharged
causing it to bulge, explode, catch on fire etc

so determine what type of battery you are going to use, then do some google searching on charger circuits relevant to that style of battery.
If you find an appropriate charger circuit, then post a link to it on here and let the guys here check it out to make sure its fit for the job :)

Dave

 

[Tesladude]

Its a 300mah Ni-Mh 9v battery. I was looking at this one.
http://www.circuitdiagram.org/automatic-nimh-battery-charger-circuit.html
I was thinking, ignore the 5v regulator and set it at a 100ma current?

 

[sherrellbc]

Well for one, that circuit design makes use of 230V AC. Do you have access 230V mains or, for that matter, an appropriate step-down transformer?

 

[Tesladude]

I am going to use a 9v output dc charger. such as one of these from 110v

http://www.google.com/imgres?um=1&s...pg&w=395&h=395&ei=69f2UaIDkoHJAebxgbAC&zoom=1