Yes, you need a difference in voltage to 'move' the charge from the supply to the battery. Maybe the charger is labeled so that you only use it on that battery.

You could hook it up to the battery and then measure the voltage going to it, it should be higher than the battery. Although, Li-ion chargers are generally pulsed on a logarithmic scale but its worth a shot.

 

Ya ,I am wondering how mathematically you can determine what voltage/current you need to supply a rechargeable battery based on it voltage/current ratings on it....

Because this adapter works great in chargeing this battery...
But both say 9volts ...etc
I know the adapter is like 11.5 or so not load but ....
But curious to know how to determine how much more voltage you need to charge a specific battery in this case 9volts....

And I also want to beable to determine the max voltage so I won't exceed it and explode/kill the battery ....etc

Could you ever charge a rechargeable battery with a source voltage of less then the battery voltage? Definitely not fully but maybe partially if it was depleted enough?

 

There's something called a "C rating" that dictates the recommended/max charge and discharge rate. it is a multiple of the maH rating of the battery. i.e. 1c means you can safely charge/discharge a 1000maH battery at a current of 1000mA. 10c would mean 10x that, etc. Id say that most personal electronics are closer to 1c.

The answer to your last q is... no. Obviously, you can do what you wish in this life but realistically, a battery is designed to put out a certain voltage and the range is quite narrow. If you charge a 9v to float 7 or 8, you still have a "dead" battery.

Batteries give folks a lot of confusion because we tend to think that a dead battery is one that has no volts left. Take a AA that stopped working in a device and measure the voltage, it will be closer to the 1.5 than 0.

 

The answer to your last q is... no. Obviously, you can do what you wish in this life but realistically, a battery is designed to put out a certain voltage and the range is quite narrow. If you charge a 9v to float 7 or 8, you still have a "dead" battery.

Batteries give folks a lot of confusion because we tend to think that a dead battery is one that has no volts left. Take a AA that stopped working in a device and measure the voltage, it will be closer to the 1.5 than 0.

the term they like to use is "discharged" battery.
as in a wet lead cell battery, about 2.1 volts per cell is considered a
fully charged battery and about 1.75-1.80 volts per cell is considered a discharged battery.
a discharged battery is discharged and a dead battery is, well...dead.

what is the tiger thing about? or is that a nunya?

 

This is why I often use " " in my posts. It completely removes me from having to be accurate or factual and as an added benifit, automatically references the infamous "they" with plausible deniability. " " is a "win-win"


As far as tiger goes, it was on yahoo homepage a few days ago and I thought it was funny because it was obviously a reaction to a bad hit, but yahoo was using it as a link to his more recent indiscretions. About sums it all up in one expression, me thinks.

 

well stated

 

so for a 9volt 500mA , 800mAH rechargeable battery can I use any 9/10 volt source to recharge it to its full potential....

I know the adapter used to charge say's on it 9volt , 400mA and this charges it perfect...

 

No, don't do that. Unless you plan on adding circuitry between it and the battery.

If its a Li-ion battery, its even more precarious and extra steps need to be taken to ensure proper charge. Search around on the net or here for Li-ion battery charger schematics and you'll be sure to understand better.