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Lithium Polymer (LiPO) Cell Chemistry Over-Discharge Protection Circuit Board

Price: 15.00 (USD) with Red LED Alarm
17.50 (USD) With Buzzer Alarm

Independent Product Review at AirsoftMechanics.com


ORDER FORM AVAILABLE HERE. (Save the PDF File to your computer, then you can fill out the interactive form, save the data, and email it to me.)

The image shown above is of a LiPO PCB Lite with connectors for a 2 Cell LiPO Pack (I will send you whichever connectors you need for your requested configuration), prior to connection of the battery cable, connection of the Alarm, and enclosure in heatshrink. This is done to allow for image clarity. Unlike the PCB V3.X, there is no power configuration needed to use this PCB.
An example of a completed LiPO PCB Lite is at the bottom of the page.

ITEMS SHOWN IN THE IMAGE ABOVE: (Starting at the center and working clockwise from 7 o'clock)

LiPO PCB Lite board
Heatshrink for the board after soldering all wires to the board
Male JST XH Connector with wires (Connect this to the G, B1+, B2+, B3+, and B4+ pads on the board as required, see the manual.)
Heatshrink - 1/16" x 4" 2:1 Black
Female JST XH Housing (Put the pins in this, this will replace (or be in addition) your LiPO Pack's current balance port.)
JST XH Pins with wires (Just bend back and forth to break the pins off of the carrier strip.)
A United States Quarter (For size comparison)
A 6mm BB (For size comparison)
Buzzer Alarm with ~12 inches of wire. (Only one alarm will be supplied with your order.)
Red LED Alarm with ~12 inches of wire. (Only one alarm will be supplied with your order.)


Nominal Size = 0.90 x 0.65 x 0.22 inches (23 x 16.5 x 5.6 mm) (L x W x H)
Operating Range = 2, 3, and 4 Cell LiPO Packs (7.4, 11.1, 14.8 VDC Nominal Pack Voltages) (Packs fresh off of the charger can be higher voltage, the PCB will be fine.)
Operating Power Consumption = Less than 5 mA Idle (Pack OK) and Less than 50 mA when Indicating Weak or Dead cells (The alarms use 35 mA (Buzzer) and 20 mA (LED))
LEDs on the PCB for User Information = Yellow (Pack Weak)
Red LED Alarm = Digikey #754-1254-ND 800mcd Super Bright, Slides perfectly into a 1/8" hole (You might want it a bit off angle from your face unless you like being blinded in the middle of the day).
Buzzer Alarm = Digikey #102-1285-ND 2.73KHZ 80dB 9.6mm Diameter (You can hear it inside your AEG while firing).


1. Per Cell Voltage Monitoring, Ensures that no single cell will overdischarge below acceptable charging limits.
2. Design optimized for super small spaces, will even fit in an AK battery tube space with a LiPO Stick battery. (Always check your AEG for space first!)
3. Ultra low power consumption keeps power where you need it, on the motor.
4. User reconfigurable for different LiPO packs. See the manual for details.
5. Low profile design allows for placement in battery bay alongside monitored pack, can also fit in present fuse holder space with a MOSFET Trigger such as SW-COMPUTER.
6. All wires and connectors needed are supplied with your order.
7. Can be used with any LiPO Pack and ANY MOSFET Trigger (the PCB and the Trigger never see each other, so nothing special needs to be done)

How It Works:

1. The PCB constantly measures the voltage of each cell in your pack.
2. When the voltage of the pack spikes downward from firing, the PCB ignores these data values for a short time. (The PCB only cares about steady state cell voltage.)
3. When any cell drops below a steady state of 3.2 volts, the AMBER LED on the PCB Board will turn on. (You will not see this since it is inside of the AEG)
4. The PCB continues to monitor the cells, looking for when any cell drops below a steady state of 3.0 volts. The Alarm (Red LED or Buzzer) will then Flash/Chirp, indicating a Dead Pack..

1. The PCB requires at least a 2 Cell LiPO pack to function, 1 Cell simply doesn't have enough voltage to run the CPU (or fire your AEG nicely).
2. The PCB functions to prevent Over-Discharge NOT Over-Current draw, a Fuse does this perfectly.
3. To prevent over-current draw (and the resulting thermal runaway which typically results in a fireball), use a LiPO Pack that is rated for 20 Amps or greater continuous discharge.
4. If at any time the AEG jams, DO NOT continue to attempt to fire the AEG, this will only cook the FETs, blow fuses, and/or risk damaging the LiPO Pack.
5. Do not leave the PCB connected to your battery pack when not in use, the PCB constantly draws a small amount of current and can over-discharge your pack if left connected for a long enough period of time.

Not intended for use with conventional (NiCD/NiMH/SLA) cell chemistry packs, failure to comply can damage the PCB and VOID ALL WARRANTIES.

If your LiPO Pack does not have balancing taps and you want to use a PCB, contact me and I will see what I can do about adding a balancing tap to your pack.

Quick Start Guide (Refer to the Manual for details, there are more things going on than I list here):

1. Connect the Balancing Port to the PCB, the PCB will Flash/Chirp some startup codes, see the manual for details.
2. Connect the Main Power for the AEG.
3. The AEG is Ready to Fire.

To Shutdown your AEG:

1. Disconnect the Main Power connection.
2. Disconnect the LiPO Power Tap connection used to monitor cell voltage. Do not leave PCB connected to your pack indefinitely!
3. Remove the battery pack from your AEG.

I accept payment via paypal. Send payment to sales@projectwolfdragon.com

Warranty Information

Factory Configured Example (Personal DEMO/Proto Unit - Board may vary from current production) PCB Lite:

Questions? Please contact: sales@projectwolfdragon.com

Special Notes:
This product assumes that the buyer is able to disassemble and reassemble the AEG and/or mechbox fairly easily.
Rewiring and soldering will be needed for installation of this product.

If needed, please contact me to arrange for custom work.

©2009 WolfDragon Contact