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Installing An RV Lithium BIM Battery Isolation Manager LI-BIM 225

Unowix LiFePO4 100ah battery

If you want to upgrade your RV to lithium batteries it's usually more involved than just replacing the old lead acid with new lithium batteries. You can check out my article on Upgrading the RV to Lithium Batteries. I have also included the videos below of how I completed the upgrade. The last part of my upgrade was to install a lithium-compatible BIM or Battery isolation manager.

RV BIM Forest River Motorhome.

A BIM is a device that allows both the RV's coach batteries and chassis battery to stay charged. It does this by monitoring the voltage of both sets of batteries and allowing charging power to the specific battery as needed. When attached to shore (120v) power, if it senses the chassis battery is low it will allow the RVs charger/converter to charge the chassis battery. In turn, when the RV is running and it senses the coach batteries are low it will allow the alternator to charge the coach batteries. This is typically between two banks (the chassis and coach), of lead-acid batteries. They both charge and maintain similar voltage. After replacing the coach batteries with lithium, the coach and chassis will charge and maintain voltage at different rates. The BIM should be replaced with a lithium-compatible battery isolation manager to properly charge both sets of batteries and not overwork the RVs alternator.

Precision Circuits LI-BIM 225

I chose to replace my RVs current BIM with a Precision Circuits LI-BIM 225. The wiring was straight forward but the new BIM was not a simple swap. The location was tight and not specifically designed for the shape and size of the new LI-BIM 225. It took some time to make everything fit in the location of the old BIM. I also needed to purchase some 9-inch battery cables and a few nuts and bolts to complete the installation.

Precision Circuits LI-BIM 225 install

After struggling for two hours I got it all to fit. It works just as designed and now can differentiate between the coach's lithium batteries and the chassis lead acid battery. This is important so the chassis battery is not overcharged by the RVs charger/converter and the RVs alternator is not overworked by charging the coaches batteries.

I included some literature below from Precision Circuits in PDF form. It outlines the specifications and how it works. You can watch how I installed the LI-BIM 225 into my RV below. I have also included links to everything I used. This was the most difficult step in the Lithium battery conversion. It really depends on the space you're working with and making it all fit. Overall, I love the upgrade, and at the same time, I'm glad I'm done.

Watch the installation of the LI-BIM 225

Watch the introduction to the RV LiFePO4 upgrade

Watch the video below to see installing the AiLi Battery Monitor

Watch the video to see the RV Converter/Charger Upgrade Install

Watch the video to see the RV Lithium Battery Upgrade Install

Precision Circuits LI-BIM 225 Specification Sheet

Precision Circuits LI-BIM 225 Quick Guide

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