BankManager™ System

Combine Lithium (LiFePO4) and Lead-Acid Batteries in the same system, and charge everything optimally. Introducing the BankManager.

BankManager™ technical manual and user information here

Click here for Frequently Asked Questions (FAQs)

Click here to buy a BankManager™

In January 2021, Clark posted a video about how we combine our lithium (LiFePO4) batteries and lead-acid (Pb) batteries in the same system aboard our boat. After receiving a lot of questions and doing research, he concluded that while simply hooking batteries together does work, the batteries don't get charged optimally. In fact, it seems that there is no way to charge lithium batteries optimally using any charge controller currently available on the market. So he invented what we now call a Battery Bank Management System (BBMS), aka the BankManager.

Many people are familiar with a Battery Management System (BMS), which should be installed with every lithium battery. A BMS monitors the voltages of the individual lithium cells inside a battery and has the ability to shut everything down in an emergency. A BBMS, on the other hand regulates the charging of the lithium batteries. A BBMS does NOT replace a BMS, but when used in tandem with a BMS, it optimizes lithium batteries for smarter charging and longer battery life. Best of all, it allows you to gain many of the benefits of lithium batteries, without upgrading your entire electrical system. Instead, you can simply add one or more lithium batteries to your existing lead system. You don't even have to change your battery charge controllers.

Since launch, Clark's BankManager™ BBMS units have been installed on SV Temptress and SV Tla Hla. We have also sold more than 100 units to boaters, RVers, and other off-gridders. In that time, 98% of units have functioned perfectly from the initial installation. The remaining 2% have received updated boards designed to accommodate peculiarities in their systems. This required a small change to the software, and we've updated the software on all future versions of the BankManager™. This page has more information about how the BankManager works and how to buy one. If you have specific questions about your system and whether the system is right for you, please feel free to send us an email and we can find a time to chat.


Anyone interested in obtaining one of these units is invited to place and order here:


Introducing the new BankManager™ Generation 2.0

We’ve just finished the 2.0 version of the BankManager™. The biggest change you’ll notice is the new custom 3D-printed case. This case isn’t like 3D prints you’ ve probably seen that look like spaghetti formed into a nice shape. These are professionally printed in a process that uses UV light to harden resin for a really smooth, high resolution finish. With this new case, it’s now possible for us to pre-assemble and test each device with its screen and rotary encoder installed. This case also has a better quality screw terminal bank, which makes installation much easier. No need to ever open the case, as all terminals are accessible from the outside!

The new 2.0 software includes better Percent Of Charge (POC) tracking (aka coulomb counter) so you have a better indication of the available charge left in your LiFePO4 battery. It also provides a new function which allows you to set a minimum POC.(Note: this new feature, as of the current software version (v. 2.1) has a known bug. It's recommended that you leave this feature turned off.) When your LiFePO4 batteries deplete below that level, the BankManager™ will stop them from discharging and run your system on Lead until the LiFePO4 charges back up.

Generation 1.0 is still available, while supplies last. We are still offering the Generation 1.0 BankManager™ units as long as we have stock. (Though our inventory is limited!) These 1.0 units have been upgraded with the same 2.0 software and functionality. But they are a bit smaller, making them easier to install in a cramped battery compartment. As before, they do require some assembly.

We now have Generation 1.0 stock available in the EU. These units are fully imported and with VAT prepaid. If you are in the EU, this is a much easier and quicker option for delivery. We are preparing an order page soon, but until then, please email emilyandclarksadventure @ to request a unit. Include your address, phone, and what kind of system (12/24/36/48V) you have, an whether you want a contactor.

For the rest of the world outside the US, we still suggest you use a forwarding service such as to get your orders. Many BankManagers™ have arrived safely using this method, and it comes out safer and much cheaper than direct mail. 


To function properly, your BankManager™ will need the following:



*A contactor is basically a relay, rated large enough for your installation. It can be a device that is normally closed, normally open, or bi-stable. The BankManager™ is quite flexible, but it's probably best if you check with me to verify if the contactor you choose is compatible. 

I offer a 300A bi-stable contactor (manufactured to the BankManager™ specifications). These will be the same type of contactor that I used on SV Temptress throughout the testing phase of this project, and is the best device I've found at this price point. If you would like to receive one of these contactors with your BankManager™, please add it to your cart with your BankManager™ order.




Prevents Overcharging

Lithium batteries are extremely sensitive to low-current overcharging. A BMS does not prevent this, but the BBMS can.  It is not only possible but likely that you could overcharge your batteries when using any of the lithium-enabled solar charge controllers out there.  This low-current overcharge phenomenon causes permanent cumulative damage to your lithium batteries.  The BankManager™ can charge your lithium bank of batteries to 100% without fear of overcharging.  

Doesn't Cause "Memory"

LiFePO4 batteries can develop memory if charged repeatedly to a point below 100%.  This makes it difficult to get the battery to take a full charge in the future. The BankManager can accurately charge LiFePO4 batteries to 100% without creating this type of "memory."

Extends Battery Life  

The BBMS ensures that every battery in your system is utilized in a way that is appropriate to its longest life. It monitors the voltage and charge of each bank, and disconnects and reconnects individual banks when necessary to optimize your batteries. 

Facilitates a Lithium(LiFePO4)/Lead-Acid Hybrid System

A BBMS like the BankManager™ allows you to safely combine LiFePO4 and lead battery banks.

Saves Money

With the BankManger™, you can upgrade your lead-acid system with as few as 1-2 lithium batteries, rather than replacing all your batteries. In addition, the BankManager™ allows you to keep your existing charge controllers. 


The BankManager™ user interface allows you to fine-tune your charging levels and methods to your needs.



Why does the BankManager™ matter?

The problem is, charging to voltage alone (as a traditional battery charger does) will not safely or fully charge a LiFePO4 battery bank. 

For example, if you only consider voltage, charging a 12V, 100A battery bank to 14.6V could mean several things:

On a boat—where cloudy or windless days can effect the power available, and varying loads are being applied to the system—the charge current is always changing; you cannot rely on charging at exactly 50A (or any particular amperage). Therefore, charging to a cutoff voltage (as a traditional charger would) is neither safe nor effective! In fact, charging at low current to a set voltage will likely cause permanent damage to your batteries. 

In contrast, the BankManager™ senses the state of your LiFePO4 battery bank many times per second and reacts quickly to its needs.  This allows you to charge your batteries safely and optimally. 

In either case, if your charge controller tries to restart a charge cycle when your bank is already charged to the level you want, the BankManager™ will "mark" your LiFePO4 battery bank as charged, and prevent it from being charged again until its voltage falls beneath a threshold you set. 

In fact, if your LiFePO4 bank is quite large and your nightly needs are modest (as is the case for our friends on SV Tla Hla), you may be able to go multiple days between charging your LiFePO4 bank, while your Lead bank continues to charge daily. 

In short, the BankManager™ allows you to monitor and charge EACH of your battery banks in the safest, most optimal way based on its chemistry. 


Jack and Lisa live aboard their Hunter 410, "Shore 'Nuff" and have been happy with their system since installing it in January 2022:

Simon in the UK had a rather complex installation, but worked with Clark to incorporate the BankManager™:

Mark Z aboard "Zee Cat" recently installed the BankManager™ BBMS on his boat with a single 100Ah LiFePO4 battery in SW Florida. He is routinely seeing 13.1 or 13.2V first thing in the morning!

Andrzej developed his own approach to mixing lead and lithium batteries, but decided in the end that the BankManager helped him create a more hands-off system. 

Dustin and his family live on an offgrid homestead and have combined the BankManager with their Growatt Inveter charges. This system shows the BankManager's ability to handle very large power levels. 

If you have installed your BankManager unit and would like to share your story, please email


If you're interested in adding a BankManager™ to your boat, RV, or other offgrid system, we recommend you place an order ASAP to reserve your unit. We have a higher influx of orders in the months before peak sailing season. Global supply chain issues can often interrupt production, so we generally have fewer than 100 units on hand at all times, and often less than 50. 


My good friend Conrad Grillo (who lives aboard his sailboat, SV Tla Hla) has taken the lead in testing the BankManager™ unit on his own battery system since 2021. He has been instrumental in the development of the BBMS. Conrad has written up some thoughts and research to share with you. You may access his notes as a PDF file here