IMPORTANT! The BEQ1 products are discontinued.

The BEQ1 has been discontinued to redirect manufacturing resources to the Chassis Juicer and Motor Juicer. These are the products that Hot Juice Electric was incorporated to produce and it is time to pursue that endeavor.

We will continue to honor the BEQ1 warranty and provide service to BEQ1 customers. For more information see Ken's Blog.

Please feel free to contact us regarding other battery management options or any other related questions. Regards, Hot Juice Electric, LLC

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BEQ1 LiFePO4 regulator

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Note:The BEQ1 LiFePO4 is the original proof of concept test version. Due to market demand, the BEQ1 LiFePO4 is offered as a production product. The BEQ1 LiFePO4 is a minimal Battery Management System (BMS) that will keep a balanced pack balanced. It is not designed to balance a previously unbalanced pack.

How does the BEQ1 LiFePO4 work?

A characteristic of Lithium Iron Phosphate cells is their abrupt drop in charging current when they reach 100% State Of Charge (SOC). See graph below. This poses a problem when the cells are charged in a series string with a single charger. Even with a perfectly balanced pack, the cells do not all reach 100% SOC at exactly the same time. The first cell to reach 100% SOC will drop its current (see graph below). Since the cells are wired in series, this will also drop the current through all the other cells. Since the other cells have not reached 100% SOC their impedance will be lower than the 100% SOC cell. This will cause the voltage across the 100% SOC cell to exceed damaging levels in addition to preventing the remaining cells from completing their charge.

A BEQ1 LiFePO4 is installed across the terminals of each cell. When a cell reaches 100% SOC and its charge current abruptly drops, the BEQ1 turns on to continue the charging current across that cell and onto the remaining cells in the pack. This keeps the voltage across that cell within safe levels as well as completing the charge of the rest of the pack.

BEQ1 LiFePO4 Operation

When a cell reaches 100% SOC the BEQ1 will turn on and conduct up to 3 amps of charging current. The yellow LIMIT LED on the BEQ1 will illuminate indicating the BEQ1 is on.

The red OVER TEMP LED will illuminate if the BEQ1 temperature exceeds 100° C. This can occur if:

The cell’s impedance is too high (bad cell or lose terminal).
The State of Charge of another cell(s) in the string is too low compared to the rest of the cells in the string.
Another cell(s) in the string has internal leakage (bad cell).
Insufficient airflow around the BEQ1.

Once tripped, the OVER TEMP circuit reduces the shunt current and is latched on until the voltage drops below the BEQ1’s set point. This means the charger should be immediately turned down or off until the cause of over heating is determined.

Limitations:

The BEQ1 is a minimal Battery Management System (BMS). It is the original proof of concept test version. While it will keep a balanced pack of healthy cells balanced, it cannot compensate for compromised cells or restore balance to a previously unbalanced pack.

Instrumentation is limited to the LED’s on the BEQ1 itself. Careful observation should be practiced. You can assume proper operation as long as no red LED’s are lit. Charging should be aborted immediately if a red LED is observed.

Additionally, the BEQ1 cannot compensate for an inappropriate charger. The charger should have a constant voltage finish phase that equals 3.65 Volts times the number of cells in the pack. Or preferably, a 2 Amp, or less, Constant Current finish phase that begins before any cell in the pack reaches 3.6 Volts.

Specifications:

Absolute Maximum Ratings:

Max Terminal Voltage........................ +5 Volts

Max Reverse Terminal Voltage.......... -0.45 Volts

Max Operating Temperature.............. +125° C

Minimum Operating Temperature....... -40° C

Max Dissipation................................ 9.5 Watts continuous

Max Dissipation................................ 23.5 Watts for 2 minutes

Max Current during Over Temp.......... 600mA

Electrical Characteristics:

Turn ON voltage................................ 3.656 Volts

Turn OFF Voltage............................. 3.648 Volts

Hysteresis........................................ 8 mV

Shunt Current................................... 3.5 Amps

Switching Speed............................... 230 µS

Quiescent Current............................. 300 µA

Over Temp Limit Trip Temperature..... +100° C

Dimensions:

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