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2 layers41 × 33 mmFlowsense charger, the printed circuit board in 3D

Flowsense charger

n0skill/SolarCharger1

A wide(r) voltage and current range solar panel LiPo Charger

Size
41 × 33 mm
Copper layers
2
Thickness
1.6 mm
Parts
38
Nets
26
Pads
145
Tracks, vias
168, 17
Pours
2
Routed
Yes
KiCad
KiCad 9.0 (file 20241229)
Created
2 Jun 2025
Updated
20 Jan 2026

Overview

Flowsense charger is an open-source printed circuit board by n0skill, from the n0skill/SolarCharger repository on GitHub. It is a 2-layer board of 41 × 33 mm with 38 parts on 26 nets, routed with 168 tracks and 17 vias.

It is built around the TPS61230DRC. Its parts include 10 resistors, 9 connectors, 6 capacitors, 2 ICs and 1 switch. It belongs with the power boards of this library.

Main components

1

README

README.md

SolarCharger

3d render of the charger 3d render of the back of the charger

This is a Lithium Ion / Lithium Polymer chemistry battery (4.2V) solar charger.

The goals are

  • To allow the use of a wider range of PV panels
  • Ampere-level charging current (currently max. 1A, goal is around 3A)
  • To provide a regulated voltage output (3.3v or 5v) at >2A (currently 3.125A)
  • To provide an unregulated output
  • To provide an USB port output (micro usb) - might change to USB-C in the future

This is done by

  • Allowing the use of a larger range of PV solar panels voltages (3.6-18V)
  • Bigger charging current capabilities with a goal of around 3A (currently 1100mA)
  • Bigger input current.

Caracteristics

The goal of this small circuit is not necessarily to be the most efficient. The primary goal is to be able to support a large variety of panels, while also being able to provide >2A of 5V to the device to power.

Solar panel support

The supported panels just have to be within the support of the main IC, the BQ25185. Therefore supported PV panels MUST provide BETWEEN 3.6 AND 18V at a MINIMUM of 500mA.

Then, depending on your PV panel current capabilities, you HAVE to solder ONE AND ONLY ONE of the solder jumpers (on the back of the circuit)

  • If your solar panel provides 500mA < solar panel current < 1100mA, you HAVE TO solder the 500mA jumper. This will limit the input current from the panel to the circuit to 500mA.
  • Else, if your panel is able to provide >1100mA, you can still solder the 500mA jumper (this will limit the current). If you wish for more current, you can solder the 1100mA jumper.

Battery

This circuit is designed to work with single cell Li-Po batteries ONLY This means cells with charge a nominal charging voltage of 4.2V. For the LiPo chemistry, this ONLY works with 1SXP configurations.

A later version will allow a 4.1V charge option to improve cell life at the expense of capacity.

Charging current

This circuit provides 500mA or 1000mA (default) charging current capabilities. Please double check your cells current charging capabilities.

Your cells MUST be able to sustain a continuous 1A or 500mA charging current. The charging current is set to 1000mA by default. To set the charging current to 500mA, cut the JP1 solder jumper on the front right of the board.

Things left to do

Maybe we should use a BQ24074 instead ? This allows for 1.5A charge current What about MAX77787 ?

Parts

38
QtyValueFootprintReferences
3TestPointTestPoint:TestPoint_Pad_D1.0mmTP1, TP2, TP3
22.2kResistor_SMD:R_1206_3216MetricR8, R9
2600 ohmResistor_SMD:R_1206_3216MetricR3, R11
2Conn_01x02_PinTerminalBlock_Phoenix:TerminalBlock_Phoenix_MPT-0,5-2-2.54_1x02_P2.54mm_HorizontalJ6, J9
2Conn_01x02_PinConnector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_VerticalJ3, J8
2LEDLED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolderDS1, DS2
2SolderJumper_2_OpenJumper:SolderJumper-2_P1.3mm_Open_Pad1.0x1.5mm500mA_4.2v1, 1100mA_4.2v1
11 uFCapacitor_SMD:C_0805_2012MetricC1
1100kResistor_SMD:R_1206_3216MetricR7
110nFCapacitor_SMD:C_0805_2012MetricC4
110uFCapacitor_SMD:C_0805_2012MetricC2
113 KohmResistor_SMD:R_1206_3216MetricR1
118 KohmResistor_SMD:R_1206_3216MetricR2
11MResistor_SMD:R_1206_3216MetricR5
11uFCapacitor_SMD:C_0805_2012MetricC6
11uHInductor_SMD:L_Coilcraft_XxL4020L1-XFL4020-102MEB1
122 nFCapacitor_SMD:C_0805_2012MetricC3
122 uFCapacitor_SMD:C_0805_2012MetricC5
1230KResistor_SMD:R_1206_3216MetricR4
1402kResistor_SMD:R_1206_3216MetricR6
1BQ25185Package_SON:WSON-10-1EP_2.5x2.5mm_P0.5mm_EP1.2x2mmU1
1Jumper_3_Bridged12Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_VerticalJP2
1LOADConnector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_VerticalJ2
1LOADTerminalBlock_Phoenix:TerminalBlock_Phoenix_MPT-0,5-2-2.54_1x02_P2.54mm_HorizontalJ4
1SJ2Jumper:SolderJumper-2_P1.3mm_Bridged_Pad1.0x1.5mmJP1
1SOLARConnector_JST:JST_PH_B2B-PH-K_1x02_P2.00mm_VerticalJ1
1SOLARTerminalBlock_Phoenix:TerminalBlock_Phoenix_MPT-0,5-2-2.54_1x02_P2.54mm_HorizontalJ7
1SW_PushButton_Switch_THT:SW_PUSH_6mmSW1
1TPS61230DRCPackage_SON:Texas_S-PVSON-N10_ThermalViasU2
1USB_AConnector_USB:USB_Micro-B_Molex-105017-0001J5

Questions

How big is the Flowsense charger PCB?

It measures 41 × 33 mm and has 2 copper layers, 1.6 mm thick.

What parts does the Flowsense charger use?

38 parts, built around the TPS61230DRC. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.

Where can I download the Flowsense charger KiCad files?

From the n0skill/SolarCharger repository on GitHub, at the commit this page was made from: the board is flowsense_charger.kicad_pcb and its schematic flowsense_charger.kicad_sch. PCBKit opens the board in the browser, with nothing to install.

Can I use the Flowsense charger design in my own project?

Its repository states no licence, so its author keeps all rights: ask n0skill before reusing the design.

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