Our DIY Lithium Battery Upgrade PT 2

Mike 7 minute read

In Part 1 of our DIY Lithium Upgrade series, I explained why we chose to power our Airstream with Li-ion batteries instead of lead acid and the advantages of doing so. Along with the different options on the market.

If you haven’t read it yet, you’ll want to do so to get an understanding of lithiums.

During my research and planning I decided to break my own build up into three phases. This way I could adjust my build to our needs while testing the system.

Phases one and two are solid. But Phase three is my maybe I will, maybe I won’t phase. I plan on observing our power use over the next to months to make that decision.

The three phases of my plan are as follows:

Phase 1

  • Install 400Ah of lithium batteries & Battery Management System
  • Installation of Inteli-Power® PD9145AL 45-amp lithium ion converter/charger
  • Upgrade Solar Charge Controller to Blue Sky Energy SB3024IL
  • Upgrade various wires sizes for the new system
  • Installation of 300 Amp fuse bus for Inverter
  • Installation of 50 Amp breaker to isolate Airstream’s 12V

Phase 2

  • Installation & Addition of one 100 watt solar panel on roof; bring the roof total to 505 watts
  • Slave my original Blue Sky Energy 2512iX to SB3024IL
  • Installation SAE Port on side of Airstream which will be contact to the BS 2512ix
  • DIY a 300-watt ground deploy solar panel using two 150 watt Renogy panels.

Phase 3

  • Upgrade 600-watt inverter to Magnum 3000 watt Hybrid Inverter
  • Installation of secondary AC panel to separate fridge

System Over-view Diagram

These are the plans for my system that I drew up to give you an idea how how the whole system is wired.

System Diagram

Getting the parts

I mentioned in Part 1, we needed batteries NOW. So the first phase of this project would focus on getting the battery bank installed. So over thanksgiving I picked up the 4 batteries, sense boards and BMS from Starlight Solar in Yuma. And placed a large order with Amazon.com and Wireandcabletogo.com

Below is everything I purchased in my setup for this project.

Battery Hardware

4x - GBS-LFMP100AHX Li-ion Batteries

4x - Elite EMS-4SB-V7 Sense Boards

1x - Elite EMS-CPU BMS unit

1x - Dragonpad 7” TFT LCD

1x - 25ft RCA Composite Cable

Wire & Connectors

12ft - 2/0 Welding Cable Class K

60ft - 4 AWG Welding Cable Class K

40ft - 2 AWG Welding Cable Class K

11x - Forney 60098 Copper Cable Lugs, 2/0 Cable with 3/8-Inch Stud Size, 2-Pack

2x - Install Bay Copper Ring Terminal 4 Gauge 25 Pack

2x - Install Bay Copper Ring Terminal 2 Gauge 10 Pack

5x - ATC Fuse Holder 16 Gauge 5

2x - 12 Volt 40 amp 4-prong relays

System Components

1x - Blue Sea Systems 9012 Solenoid Switch L-Series 12-24V

1x - Blue Sea Systems m-Series Mini On-Off Battery Switch with Knob

1x - Blue Sea Systems ANL Fuse Block with Insulating Cover - 300A

2x - Blue Sea Systems 5133 300A ANL Fuse

2x - Insulated Battery Power Junction Post Block 3/8 Lug

1x- Ulincos® Momentary Pushbutton Switch

Solar Re-Wire

So, the first thing I did was rewire my combiner box. I went from 6 AWG to 4 AWG. (Something I now realize was completely unnecessary. I could of stuck with the 6 AWG based on the length of my run.)

My cable run to the charge controller is pretty short. It runs down the back of the bathroom here:

And exits out right next to the batteries.

Building The Battery Box

Lithiums don’t like the cold or extreme heat. So they are best installed inside. I decided to place ours at the front of our twin bed.

The first thing I did was determine the layout of the batteries. And take some measurements.

Next I removed the steel bands and plates that hold the cells together. These are in place to prevent the batteries from swelling during charging. Since mine were going to be in a tight box, that won’t be an issue. And I can save a few inches of space.

I built my battery box out of 1x6x6 and 1x1x4 select pine. The battery box is approximately 5 1/2 inches from the Airstream curbside wall. I secured it to the Airstream floor with contractor wood screws that are 1 1/2 inches long.

After building the box, the next step was to install the sense boards and terminal connectors.

After that, I proceeded to wire my batteries into parallel using class K 2/0 AWG welding cable. Copper bar across the terminals would be better here. But I couldn’t source any in my timeframe.

On the wall here I mounted a piece of 1/4 sanded plywood. I decided this is where I would mount the shunt, BMS and the older 2512ix solar controller.

The first thing I mounted and wired was the Shunt. The shunt is wired off the negative terminal opposite of the bank from the positive terminal.

I then constructed a lid for the top of the battery box, that just sits a few inches above it. It does not cover the entire box, and leaves one end open for airflow.

Also I planned to use the top to mount most of the positive side components.

Power comes off the positive side terminal from the batteries and goes into a 12v continuous duty solenoid. The BMS controls the solenoid acting like a battery disconnect. This provides over-voltage and under-voltage protection by disconnecting the battery.

From the solenoid the power flows to a master system On/Off switch. From the switch it flows to a terminal stud and a 300amp fused bus bar for the inverter.

I took the opportunity to rewire the Airstreams power distribution bus and isolate the Airstream with a 50amp breaker switch. I installed a second ground bar, as the original was over loaded and two new bus bars for things that are isolated outside the Airstreams disconnect but need constant power.

I upgraded most of the wiring, and repositioned a number of things.

Below are a series of photos from the install.