| kaaoszx |
| im trying to install a new battery in a mp3 player and had a different capacity one on hand. can i use the same protection circuit for the higher capacity battery? im guessing that the higher capacity batery wont work with a lower capacity circuit? anyone know where i can find information on building your own lithium ion charging circuit? |
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| I_Forgot |
SparkFun Electronics has a $15 Li-Ion charger kit (well, assembled PCB) that gets power from either a wall wart or USB port on a computer.
I_F |
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| Mailliw |
Assuming the lithium-ion charging circuit detects when the voltage reaches a specified value (Wikipedia), the capacity change shouldn't matter.
What's the worst that could happen, a small fire? :) |
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| Pjotr |
Hi,
Li-ion batteries have almost the same charging profile as lead acid batteries: That is, constant current / constant voltage.
But there is a big difference: They cannot stand overcharge. When the cell voltage becomes higher than 4.2 V the electrolyte will be destroyed permanently rendering the battery useless then. Therefore they need a battery management system (BMS) when more cells are in series to watch each cell. So no one will be overcharged.
Putting a new single cell battery in with a just higher capacity means only charging will take a little longer. Provided the current charger is in good working order.
Here is some good reading: http://www.batteryuniversity.com/
Cheers ;) |
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