UPGRADE - Lithium Rig
- Dan Goetzman
- Sep 7, 2020
- 6 min read
Tripper is now a "Tripper-L" model!
After running for the first two years with a single 100 Ah AGM "house" battery, we decided that during the 2020 "pandemic" we would convert to a "lithium" battery subsystem with increased capacity and functionality. Our main goal was to be able to run the roof mounted A/C for ~2 hours as we like to make stops along the way, be it for lunch or dinner at a restaurant, or to visit interesting places along the way. And leave our traveling buddy Tripp safe in the RV.
We have a Yamaha EF2400iSHC generator we have been using for this purpose. It's an inverter type generator, which means it's quiet as generators go. And designed to start any 13K BTU RV A/C system. But we wanted something that made no noise, didn't need to be started first to run the A/C and would allow us running our A/C for ~2 hours so our RV namesake "Tripp", our toy Australian Shepard that LOVES to travel in "his" RV, would be comfortable during our many stops along the way. We also have remote temperature monitoring and remote cameras connected to our iPhones to make sure Tripp is "OK".
Our DIY "house" power sub system now looks like this...
Our new "house" battery bank is now using four Battleborn 100 Ah LiFePO4 batteries. Each rated at 1200 Watts (or VA if you prefer) for a total of 4.8 KVA. With all the advantages of "LiFePO4" (Lithium Iron Phosphate, AKA LFP) batteries;
- Can be 100% discharged to Zero SOC (State Of Charge)
- Fast recharge, if you have a charger that can deliver 100+ amps
- Rated for 3000 discharge cycles
- Light weight
Note: The Battleborns internally have more than 100 Ah capacity, so that allows discharging to 100% of the rated 100 Ah capacity. They also have an internal BMS (Battery Management System) that will shutdown at "Zero" SOC to protect the batteries from damage.
The heart of the system is a Victron Energy "MultiPlus" inverter/charger. Victron Energy makes best in class electric energy components. They are used in many RV and Marine installations, often with Solar energy as an additional power source.
We used the popular MultiPlus 12V-3000W-120A Charger/inverter. A list of its multiple features include;
- AC Switch: "Shore" line is directly connected to the MultiPlus
- AC Current Limiting: Allows restricting AC current, IE 15/20 AMP "shore" power
- 3000 WATT Pure Sinewave Inverter: That syncs to the AC input "grid" power
- UPS: Inverter takes over if grid power is lost
- PowerAssist: Inverter can help supply power if grid power is insufficient
- Charger: Up to 120 AMP at 12 VDC
All the 120 VAC circuits in our RV are connected to the output of the MultiPlus. This allows all VAC outlets to be hot all the time, either from shore power or the inverter assuming it is turned on. The current limit feature we normally have set to 25 AMPs and any input power not used by devices is used by the charger to charge the battery bank. The adjustable current limit feature is handy if you need to connect to a regular 20 AMP feed. Set the current limit to say 13 AMPs and the MultiPlus will handle the load for you and NOT trip the circuit breaker! And if you need more power, for example a coffee maker or to run the microwave with the A/C running, the MultiPlus will provide the extra power from the inverter using it's "PowerAssist" mode. Even if you are only on a 20 AMP shore power feed!
The MultiPlus is really MAGIC!
And once installed and configured, its all controlled by this simple operator panel.
The panel on the right! The left panel is the BMV-700 Battery Monitor, also very cool as it counts electrons going in or out of the battery bank to tells us our usage and estimated time remaining based on our battery "State Of Charge" (AKA "SOC").
The "Multi Control" has a simple rotary knob to set the current limit as needed. And the main switch to enable "Charger Only" mode, Off, or On (Charger and Inverter). And key status on both the Charger and Inverter operating state.
While the MultiPlus can generally charge the LiFePO4 battery bank in 1 to 2 hours, depending on battery discharge level, we also wanted to have the chassis alternator help charge when we are traveling down the road. Normally for a AGM house battery system, you would just hook up a simple switched feed from your chassis battery. Either an old style relay or a solid state switch. We were using a "Battery Doctor" solid state switch before switching to a Lithium house battery bank. The problem with direct connecting your chassis system to a lithium house battery bank is the amount of charge current the LiFePO4 batteries can consume from your alternator. Lithium batteries have a low impedance compared to lead acid (AGM) batteries and direct connecting them can draw 100+ AMPs and risk burning out you alternator under certain conditions, like low state of charge when starting up the chassis as you depart own the road.
We ordered our ProMaster chassis with the optional 220 AMP alternator, just because we knew it as going to be used as an RV and the 220 AMP alternation added little to the cost. However, I don't want to put a heavy load on the chassis alternator with the lithium house battery bank, so we added another Victron Energy device known as a Orion-TR Smart DC to DC Convertor.
Normally a DC to DC convertor would simply take the chassis battery voltage, say 13.6 volts on the input side and convert it to the needed 14.6 volts to charge the lithium battery bank. However the NEW "Smart" version of the Victron Orion series from Victron Energy also supports a charger mode. This means it knows how to safely charge the batteries using Bulk, Absorption, and Float modes instead of outputting a fixed DC voltage. And it detects the chassis running state to automatically isolate the house battery bank from the chassis when the chassis is not running.
And last, the important feature I needed, is to restrict the AMP draw to 30 AMPs from the chassis battery/alternator to the house battery bank! Yes, we only get 30 AMP charge rate into our 400 Ah house battery bank. And Yes, we have the 220 AMP alternator but I really didn't want to run the alternator anywhere near 100% duty cycle! 60 AMPs would be nice, and as the Orion-TR Smart DC-DC Convertor allows parallel operation, I may add a second one in the future... You know what they say? It's only money! On the subject of spending more money...
Once the base system was installed and operational, I decided to spend a few more dollars and add the optional Venus GX management and monitoring system. Strictly optional but it provides centralized management and monitoring.
The real reason I added it is that it supports Victron Energy's VRM (Victron Remote Management) platform where I can monitor and control our RV's electrical system from their internet web portal and/or using the VRM app on our iPhones.
It's nice to be able to check the estimated run time remote on our iPhones when have the A/C running for Tripp and we are outside the RV nearby.
The Venus GX device also has a console that can be accessed both remote from the VRM portal as well as local on our WiFi network in the Tripper;
Note: Console showing status while plugged into shore line and running A/C, while also charging battery bank in absorption mode at 1.1 AMPs.
A rather nice display giving us status of our system at a glance. The remote console also allows changing settings as needed to the Victron components.
The Venus GX device also transmits status and usage to the VRM Portal if our WiFi hotspot is connected to the internet. This is very useful to see status and power usage over time.
There's actually a ton on information available via VRM, and that would require another posting on it's own to show all the features available once connected to VRM. I even added a GPS receiver to the Venus GX and we get location data reported to VRM for example.
That's an overview of our new lithium LeFePO4 based power sub-system we have installed in our Tripper RV. All DIY after doing a ton of research. Using Victron Energy systems made it easy and we get features like PowerAssist, Smart automation using both our iPhones in addition to the VRM portal.
Summary: We now have the capacity of 400 Ah battery bank driving the 3000 watt inverter allowing us to run our standard Coleman Mach 10 13.5K BTU A/C unit for about 3 hours. With the additional bonus we can now use our Keurig coffee maker and/or the microwave at any time! And have plenty of 12 VDC power available for the RV lightening circuits and our Nova Kool refrigerator. All with out needing to start the generator!
In fact for most trips, we probably will now leave our generator at home! As its mounted detachable to our rear receiver hitch.
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