Aim of the project
Why a fast battery charger?
This charger of NiCd and NiMH batteries has been designed for radiocontrolled model cars and airplanes when pilots have a tight schedule to perform a full charge of their batteries.
From a technical point of view the fast charges are reliable and harmless for batteries. However it requires a performant monitoring system because we often reach the maximum ratings of the specifications for the batteries in terms of temperature rise and current flows.
Some chargers pretend to take care of any battery with no information on it, but fast charges can sometimes produce unexpected results such as explosion when the system fails to stop the charge on time for example.
As a consequence it is safer to rely on the user parameters, which brings even more efficient charges.
That is why almost every monitoring parameters can be set according to the user choice.
Features of this battery charger
| Features of the fast battery charger | |
| Maximum number of cells | Up to 7 max with a 12V car battery Up to 15 cells with the step up DC-DC converter |
| Discharge current | Constant current only Up to 12A with 100mA steps |
| Charge current | Constant current only Up to 12A with 100mA steps |
| protections | For battery and heatsink overheat For battery overvoltage A timer ends up the fast charge when others failed |
| User interface | 3 command buttons 2 lines of 16 chars LCD screen Parameters updated and displayed every 10s |
| Power supply | Can be connected to the mains supply 220V 50Hz Can be connected to a 12V car battery Can be connected to a 24V truck battery |
| Recorded parameters | An EEPROM enables 4 hours recording of voltage, current and temperature |
| Recorded user choices | 26 different programs can be recorded and called back with a letter from A to Z |
| Heart of the system | Based on a PIC microcontroller 16F877 running at 4MHz... |
the battery charger on the left and the step up DC-DC converter on the right
Designed and built by Fabrice Lucas
more information: fab.lucas@free.fr
06/2001
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