Question on charging battery

[jason280]

I have a lithium ion battery, 7.4v 800mAh, which needs to be charged. Problem is, I have lost the charger for the battery. Best I can tell, the charger was a 8.4v 1.7a unit, all though I can't confirm this.

The battery is for a small camcorder, so I am curious as to what type of charging requirements will be. I have a couple of plugs I can use, both of which are 9v DC (one is 300mAh, the other is 450mAh). Here is my question, will either of the plugs be sufficient to charge the battery?

 

[Externet]

Your battery pack should have a charge controller inside for the individual cells in it, and a 9V source adapter should be able to be managed by the controller.

Adding a silicon diode in series to the 9v adapter to bring its output to 8.4V should be a good action to take anyway.
The reduced ampacity of the 'new' adapter will charge the pack in a longer time.
Miguel

 

[blueroomelectronics]

You probably need a smart charger for the battery, the camcorder may have built in charger circuitry.

Your 9v 0.3A supply is not going to work. Check eBay for a replacement charger.

 

[jason280]

Thanks for the information. I have actually been able to charge the battery with the charger from my Sony camcorder (this is a Samsung). That's why I *think* the charging requirements are 8.4v at 1.7a. However, I never had the original charger, so I cannot confirm this.

Your 9v 0.3A supply is not going to work

Not to be argumentative, but why exactly wouldn't it work? I have a very limited understanding of these kinds of things, and would greatly appreciate a chance to learn something new!

 

[blueroomelectronics]

LiON batteries require special conditions to charge properly & safely.
How to charge Lithium Batteries.

 

[bountyhunter]

Your battery pack should have a charge controller inside for the individual cells in it, and a 9V source adapter should be able to be managed by the controller.

The charge control ICs we made that Sony and others put in the pack "control" the charge by popping the FEts open when the battery voltage is overcharged by a significant amount. Using that for charge termination will shorten the battery life severely, that IC is simply a fail safe for protection.

You need a regulated 8.400V output constant voltage charger with current limiting at about 1A.