My project for this month is a universal battery charger, that is, load all types of batteries (NiCd, NiMh, LiPo (or LiPoly) SLA, Lithium, etc), all intelligently controlled by the PIC 16F877A to ensure care for the life of the battery and obtain maximum efficiency.
source I'm doing for now, I show you a picture preview:
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Analysis of charge / discharge of NiCd and NiMH batteries
Loading is the process of restoring the original capacity battery discharged. To achieve a longer life, it must bear the appropriate method.
Various methods are used to charge rechargeable cells:
1. Fast charge current: 1CmA (fast charge temperature: 0 C to 40 C). To gain control and stop the fast charge, we recommend charging over but less than 1CmA 0.5CmA. Battery charging over 1CmA can cause it to activate the safety vent for increased battery internal pressure, causing leakage of electrolytes. When the battery temperature is detected by a thermistor or other sensor, and its temperature is below 0 C or above 40 C at the beginning of the load, must perform a floating charge, rather than a fast charge. A quick charge should be stopped when any of the values \u200b\u200bdescribed below reaches the designated level:
- upper voltage limit control : Approx. 1.8V/celda. This method is changed to a floating charge if the battery voltage reaches approximately 1.8V/celda due to problems or malfunction of some kind.
- value dV / dt (or delta peak cut) : 5 to 10mV/celda. When the battery voltage drops from its peak 5 to 10mV/celda for fast charging is to be stopped, and the charging method should be changed to float.
- value dT / dt (or cutting temperature) : 1 to 2 C / min. When an increase in battery temperature per unit time is detected in the thermistor or other temperature sensor for fast charging, and the temperature rise is detected by the sensor, fast charging should be stopped and charging method changed to float.
- Timeout: 90 minutes.
2. For charging excessively discharged, first apply a floating charge current to flow, and then proceed with rapid charging once the battery voltage rose.
initial fast charge voltage: Approx. 0.8V/celda with a current of 0.2 ~ 0.3 MAC.
Requirements:
- initial Wait 10 minutes. This prevents detection circuitry dV / dt is triggered by the specified time at the beginning of the fast charge. However, the detection dT / dt can be active in this period. This is necessary for batteries that were left unloaded for a long time or were too loaded, etc.. The initial wait is necessary to prevent the load stops (to prevent malfunctions) due to pseudo dV / dt. Current
- floating or maintenance : 0.033 to 0.05 MAC. When the current flow is high, the battery temperature increases, causing the battery characteristics deteriorate.
- Fast-charge time: 60 minutes.
- Total time: 10 to 20 hours. Overloading a battery NiXX, even floating charge or maintenance, causing deterioration in the characteristics of the batteries. To prevent overloading the floating charge or any other method, you must provide a timer to regulate the total charge time.
Analysis of charge / discharge of SLA (Sealed Lead-Acid) Lead-Acid
Unlike NiXX batteries, these batteries are charged to fixed voltages instead fixed current.
Charging Method:
1. Check the battery.
2. If OK, start the constant current charging capacidad/10.
3. When the voltage reaches 2.55V/celda switch to constant voltage charging 2.45V/celda.
4. If the current falls below capacidad/20 then switch to float charge.
5. Upload 2.25V/celda shaped floating indefinitely (recommended maximum 20 hours).
Requirements:
An SLA battery should not be downloaded unless 1.5V/celda.
maximum battery voltage is 3V/celda SLA.
Analysis of charge / discharge battery LiPO (lithium polymer) and LiIon (lithium ion)
Charging Method:
1. 1C to constant current until the voltage reaches the 4.2V/celda.
2. 4.2V/celda constant current until the current drops to the capacity / 15.
3. Floating load capacity / 30 for 30 minutes.
Requirements:
a LiPo battery should not be downloaded unless 2.5V/celda. Maximum voltage
LiPO battery (lithium polymer) is 4.5V/celda.
Based on these recommendations, I designed the magazine with the following characteristics:
Default Description
Maximum charge current: 0 to 5A
Maximum discharge current: 440mA (I = V / R -> R = 12/27 -> I = 0.444mA)
Modes: 0: NiMh, 1: SLA, 2 : NiCd, 3: LiPo, 4: LiIon cells
Capacity: 3000mAh
Number of cells: (1 to 19) 6
Load: (0.1 to 25.5) (10) -> 3000 * 1.0 = 3A
Download: (0.1 to 25.5) (40) -> 3000 * 4.0 = 12A peak delta
Wait: 10 minutes
Court Low Voltage (per cell) NiCd
(0 to 2550) 800mV
NiMh (0 to 2550)
1000mV LiPo (2500 to 3500) 3000mV
SLA (1500 to 2500) Delta
2000mV peak (0 to 255):
NiCd NiMh 5mV 10mV
maximum voltage per cell: 1680mV
NiCd NiMh LiPo
1680mV (3500 to 4500) 4200mV
SLA (2000 to 3000) 2500mV (2.5V x 6 cells = 15 - maximum voltage of 12V SLA)
final current (% of initial charging current, 0 to 255):
LiPo (5 %) -> 3000 5 / 100 = 150mA SLA
(5%) -> 3000 * 5 / 100 = 150mA
NiCd and NiMH Timeout 65 min at 1C, 130 min 0.5C, etc.
Total time: 20 h
Universal Battery Charger
0.01
0.98 Universal Battery Charger
functionality is 80%
Refactoring ...
PC Software
SLA Battery Charge 1200mAh 6-cell at 0.1C
Loading
LiIon battery (cell) of 1-cell 920mAh 0.3C
LiIon battery
Download
NiMH Battery Charge 2500mAh 2 cells at 0.5C
Updated
It's all you need to make the charger!
Schematics, PCBs:
http://www.4shared.com/file/133419765/847fc88d/MultiBatteryCharger-pub.html
The PCB did not publish it because I had a lot of manual corrections. 09/18/2009
IMPORTANT UPDATE!
sensed
an error in the charging algorithm and LiXX SLA, and I corrected and updated the file from 4shared
charger 09/19/2009 Full documentation (in PDF) version 0.1
http://www.4shared .com/file/133948247/924ef203/BatteryCharger-doc.html
schematic Update 22/09/2009
The diode D3 which appeared as 1N4148, 1N4007 was changed and it was already updated the file from 4shared. 10/29/2009
PCBs Availability Available in 4shared PCBs boot thanks to our friend The Forum Fluf uControl :
license files and images on this site are available under the Creative Commons ( Attribution-Share Alike 3.0 Unported )
running Boot Video:
* Videos.
Security Advisory
overload Li-Ion and Li-Poly can be explosive:
If they are testing, please do it with NiCd or NiMH failing, and then move to the SLA, at last, with those based on lithium ion
complete project documentation
2/12/2010 - Publication of source code and compiled
http://www.4shared.com/file/-cg4Mfit/ BatteryCharger-src.html
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