The main PCB for the charger is a single sided, 1.6mm tick printed circuit board. The DC/DC converter is now integrated within the charger in order to allow the charge of high number cell packs. The people that charges only few batteries (12Vdc supplies sufficient) can not mount the components for the DC/DC converter saving the money of this part. The DC/DC converter part is a generic step-up converter, capable to deliver 7.5A and an output voltage of 24Vdc, starting from a 12Vdc supply. The main parts are the following:
- PWM controller UC3843 very cheap and easy to find
- Power inductor from Bourns, type 2306RC (27uH, 15A), Farnell 1167731
- The power diode is a schottky type,and a N-type mosfet can be generic: all the two components are in case TO-220
Universal Charger: [Link]
This charger has the same hardware of the Advanced Charger but can charge/discharge up to 19 cells. The advanced charger HV is based on a hardware pratically identical to the non HV version: for this all the material (from the schematics to the PCB) can be dowloaded from the Advanced Charger version. Some of the features of the HV advanced charger are:
- Power supply with a 24V source (Current equal to maximum charge current).
- Change the R6 with 12 KOhm, 1% value.
- Heat sink the 7805 regulator.
- Change the fan cooler with a 24V model.
- Reprogram the PIC with the newch_HV.HEX file (see “files” section).
- Start the charge/discharge of your 14-cells pack!!!.
NiCd Advanced Charger HV: [Link]
This charger is a more complex one than the others available over the internet, and among its features are:
- All the parameters for charge and discharge can be entered directly in the charger.
- The PC is useful only for PIC firmware patch and for output graphic plotting.
- A second P-channel mosfet is added for up to 10A charge current or for no self-powering diode.
- Integrates a 16×2 lines LCD display
- Integrates up to 7 different charge/discharge profiles
- The batteries can be charged,discharged or cycled (charge after discharge)
- Parameters for each battery profile:
- Number of cells (from 1 o 7)
- Cell capacity (useful for automatic timeout calculation)
- Cut-off voltage per cell
- Delta peak per cell
- Charge current (up to 10A or 5A plus the diode)
- Discharge current (up to 30A)
- Peak control inhibition
- Timeout in function of the cell capacity.
- Support for costant voltage supply (motor test) with adjustable output
- Fast current control (200Hz) and low noise values (1mV resolution for batteries)
- Display during charge of current,voltage,peak voltage,delta peak, capacity, time
- Display during discharge of current,voltage,peak voltage,cut-off, capacity, time
- Acoustic buzzer for end of operation signaling
- Automatic recovery in case of power supply failure
NiCd Advanced Charger: [Link]
The LiPo balancer cell acts like a big and very accurate zener diode; when the cell voltage is under a threshold fixed by the user the system is in “idle state” and watch only for the voltage with a equivalent resistance of some KOhm and a negligible current shunt. When the voltage reaches the threshold the balancer element will start to shunt current from the cell with an internal power resistor: the amount of current sunk by the element is proportional to the cell overvoltage with respect the user “safe” threshold.
LiPo Balancer Element: [Link]
Most of todays AVR programmers don’t support the high voltage mode the only widely available possibility beeing the STK500 from ATMEL. HVProg is a redesign of the original STK500 without all components of a development board. It is based on the original ATMEL schematics that are freely available on the net (i.e at avrfreaks.net). The main target was to keep all nessecary functionality to programm all available AVR controllers in every programming mode that the STK500 supports.
I never need-ed high voltage programming so far, so the fact that my AVR MK II doesn’t support high voltage programming doesn’t bother me, because i don’t need it.
HVProg Parallel and serial High Voltage Programmer: [Link]
