Electronics > Beginners
9V LiPO charging circuit
Audioguru:
All the low dropout regulators I have seen need a certain fairly high value output capacitor to avoid oscillating. The LM2940 needs at least 22uF with very short leads.
all my 2S Li-PO batteries for my RC model airplanes are charged safely with a balance charger.
2 cells in series might develop one cell weaker than the other. If charged in series without balancing then the weak cell will become charged higher than the 4.2V limit which will cause a fire or explosion.
alex-sh:
--- Quote from: Audioguru on February 15, 2019, 12:31:51 am ---All the low dropout regulators I have seen need a certain fairly high value output capacitor to avoid oscillating. The LM2940 needs at least 22uF with very short leads.
all my 2S Li-PO batteries for my RC model airplanes are charged safely with a balance charger.
2 cells in series might develop one cell weaker than the other. If charged in series without balancing then the weak cell will become charged higher than the 4.2V limit which will cause a fire or explosion.
--- End quote ---
There is protection in place for overcharging / cut-off.
The problem is that without breaking the battery I cannot have access to balance charge it. There are only two wires "-" and "+" as on any PP3 battery. That's it. Balance charging is not an option with this battery.
Zero999:
--- Quote from: alex-sh on February 15, 2019, 12:54:15 pm ---
--- Quote from: Audioguru on February 15, 2019, 12:31:51 am ---All the low dropout regulators I have seen need a certain fairly high value output capacitor to avoid oscillating. The LM2940 needs at least 22uF with very short leads.
all my 2S Li-PO batteries for my RC model airplanes are charged safely with a balance charger.
2 cells in series might develop one cell weaker than the other. If charged in series without balancing then the weak cell will become charged higher than the 4.2V limit which will cause a fire or explosion.
--- End quote ---
There is protection in place for overcharging / cut-off.
The problem is that without breaking the battery I cannot have access to balance charge it. There are only two wires "-" and "+" as on any PP3 battery. That's it. Balance charging is not an option with this battery.
--- End quote ---
Each cell should already have built-in protection to prevent fire.
I'd be more worried about over-discharging, then trying to recharge it, which can cause fire. Again there should be a built-in protection system, but it might be a one-shot: once the battery voltage drops below a certain level, the cells will go open circuit and no recharging possible, without dismantling the battery. The circuit or power supply should have a separate undervoltage cut-off circuit which activates before the battery's built-in protection system.
Peabody:
I've found a lot of tutorials on balanced charging, parallel charging, etc., but they basically start with an already existing charging device, and pretty much only deal with how to connect batteries to them. Does anyone know of a good tutorial that deals with what actually happens, including circuits if possible? So for example, how does the device in the picture work?
Nusa:
Try this to give you an idea how they might work.
https://www.electronicdesign.com/power/look-inside-battery-management-systems
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version