Precision Circuits Battery Isolator Manager

The Precision Circuits Lithium Battery Isolation Manager (Li-BIM), product code 00-10041-260, is an intelligent battery isolator that manages the house battery and the engine/starter battery in an RV, motor-home, or fifth-wheel. This prevents loads in one system from discharging both. It also connects the two battery systems together during charging. Both batteries are charged if either is being charged: The house battery is charged while driving and the engine battery is charged while plugged into shore power at a campground.

The Li-BIM is microprocessor based, and much more intelligent than your average battery isolator. It monitors battery Voltages over long periods of time, and is not just Voltage dependent. The Voltage settings of the Li-BIM are such that it works well with a lead-acid engine battery and lithium-ion house battery (though a lead-acid house battery will work too).

The Li-BIM monitors the battery voltage of both the lead acid engine and lithium-ion house batteries over long periods of time. If it senses a charging voltage, it connects the two batteries together. It will both charge the house battery from the alternator, as well as the engine battery from shore power, depending in where it sees a charging Voltage. It will disconnect the house battery if the alternator exceeds 14.4 Volt, to prevent overcharging of lithium-ion batteries. The Li-BIM will charge the house battery for 15 minutes when it sees a charging Voltage on the engine side, then disconnect for 15 minutes to allow the alternator to cool down, and repeat that cycle until the house battery is full.

For the engine battery the Li-BIM will monitor the battery Voltages on both sides, and charge from the house battery if it sees a Voltage of 13.4V or more there, and 12.6 Volt or less on the engine side. It will charge for a maximum of 1 hour this way, then disconnect again to take another Voltage reading (and repeat if needed). If the house/coach battery drops below 13.3V while both are connected the Li-BIM will disconnect 10 minutes later from the engine battery. There is no way to entirely prevent charging from the coach to the engine battery, the Li-BIM will always follow this procedure.

The ignition terminal on the Li-BIM is used to detect that the engine is running (and that it can potentially charge from the engine to the house battery). If the ignition is turned off the Li-BIM immediately disconnects. The “dash switch” terminal is optional. If it is connected to either ground or the battery positive (either one works, whichever is easier to wire up) the Li-BIM will immediately connect through, regardless of the battery Voltages. This is meant for use with a momentary switch, to temporarily connect the house battery and engine battery together (for example to crank the engine in case the engine battery is low). It will disconnect as soon as the switch is let go again.

It draws no current in the on or off states. It supports currents of 225 Amp continuous, and 1,200 Amp for 30 seconds. Please note the spec sheet (in the “documents” section) is wrong; it states 160A for this version of the Li-BIM, while the unit really is made for 225A continuous.

Works great in combination with the Precision Circuits Battery Guardian, especially for lithium-ion batteries!

Features

• Approved for installation in battery compartments, ignition proof, meets SAE J1171
• Waterproof, IEC 60529, IP66 IP67, ASTM B 117 96-hours salt spray
• Isolates batteries to prevent discharging or overcharging
• Provides emergency start with dash switch
• Weighs under 1 pound