MPPT solar charger, lead-acid output (BQ24650)
TI BQ24650 synchronous buck MPPT charge controller for a 12 V lead-acid battery from a solar panel. Two NTMFS5C442NL MOSFETs, 10 µH 12.5 mm inductor, 22 mΩ Kelvin current-sense shunt. MPPSET divider, STAT outputs and a scaled PV-voltage output for the MCU ADC.
Key specifications
- PV input up to 28 V; MPPT point ≈ 18.3 V (R5 470k / R6 33k) for a 36-cell 12 V panel
- Charge voltage 14.14 V: VFB 2.1 V × (1 + R16 470k / R15 82k), both 1 % (12 V lead-acid absorption level; BQ24650 has no separate float stage)
- Charge current set by the 22 mΩ shunt (BQ24650: 40 mV full-scale → ~1.8 A)
This block is not available yet. It is released once its checks are complete. Planned price: €29.
Planned package contents
KiCad 10 design block
Schematic and PCB layout fragment; symbols and footprints embedded
BOM (CSV)
Manufacturer part numbers and LCSC codes
Schematic PDF + README
Interface, specs, population options and design notes
3D models
STEP models of the special parts; standard parts use KiCad’s 3D library
template.yaml
Machine-readable interface and limits
Planned: PCB Composer
Place blocks like this one as tiles and get them routed into one board, without opening KiCad.
About PCB ComposerDevelopment status
| Block ID | 0120 |
|---|---|
| Block name | 0120-mppt-solar-charger-lead-acid |
| Version | 1.1 |
| Status | Designed – Schematic and layout fragment done; ERC/DRC clean-up and hardware verification pending. |
| Open review items | 3 (0 blocking) |
| PCB layout | Layout fragment without board outline; DRC clean-up pending |
| Format | KiCad 10 design block (schematic + PCB) |
| Last change | 2026-10-18 |
Interface
Hierarchical labels the block exposes to the rest of your design.
| Net | Direction | Description |
|---|---|---|
| PV_INPUT+ | Power in | Solar panel positive input |
| PV_INPUT- | Passive | Solar panel negative / power GND |
| BATTERY+ | Power out | Battery charge output positive |
| DO_STAT1 | Output | BQ24650 STAT1 open-drain status output |
| DO_STAT2 | Output | BQ24650 STAT2 open-drain status output |
| ~{DI_BQ24650_EN} | Input | Charger enable — active low; pull low to disable charging |
| AI_MPPSET | Input | Analog MPPT voltage setpoint input (connected to VFB divider) |
| AO_PV_VOLTAGE | Output | Analog PV voltage output via resistor divider (for ADC monitoring) |
FAQ
Which KiCad version do I need?
KiCad 10. The files are saved in the KiCad 10 format and are meant to be placed with KiCad’s Design Blocks feature (schematic block, then “Apply Design Block Layout” on the PCB).
Do I need the Circuit Issues part library?
No. Symbols are embedded in the schematic and footprints in the PCB, so the block opens on its own. Parts carry manufacturer part numbers and LCSC codes.
Is the layout production-ready?
Not yet. The PCB part is a layout fragment without a board outline and its DRC clean-up is still open. The status above shows where this block is.
Can I use the template in a commercial product?
The licence terms are published together with the first release.
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