Victron RV upgrade, MultiPlus inverter especially
My family and I are getting ready to escape the Florida summer heat and visit friends and family we haven’t seen in much too long. We’re taking our RV, and we’re planning a mix of campgrounds, parks, friends’ driveways, and Harvest Hosts for our trip. This mix of stops means sporadic availability of shore power, and that makes for great testing opportunities. I’ve been planning to install my DIY LiFePO4 battery to get some real-world testing in. But, to test any LiFePO4 battery, I needed to ensure the inverter and charger systems would coexist nicely with lithium chemistries. Plus, I wanted to upgrade my monitoring capabilities to see everything happening within the 12-volt system. What follows is the first entry on updating the electrical system and getting everything ready for LiFePO4.
Our RV is a 2016, so it’s pretty recent and has a pretty well-designed electrical system. But that won’t stop me from tearing out some perfectly good equipment and replacing it with the latest and greatest. Harvey (I can’t keep saying our RV and I’m used to naming my boats, so from Have an RV I get Harvey) came from the factory with a Magnum Energy MS2000 2000 watt inverter/charger. Unfortunately, my inverter was made before Magnum had LiFePO4 charge profiles. The inverter is upgradeable with a remote that has the correct profiles. But, my remote doesn’t have those profiles and would need to be replaced. Plus, I want to pull data out of the inverter to understand the system’s performance better.
Ultimately, faced with spending quite a bit on upgrading the Magnum, I decided to replace the Inverter and install a mostly Victron-based system. I chose Victron in part because I know their equipment well and think it offers a good blend of performance, quality, and value. However, the data and insight offered by VRM, Victron’s management portal, pushed me over the edge to a Victron system.
Frequent Panbo readers have certainly read plenty of praise for VRM mainly from Ben Ellison (some here, here, and here). I’m also impressed by VRM’s deep insight and easy integration of Victron equipment. Eagle-eyed readers might note the name of this installation in the screenshot above, Harvey Venus-Pi. I’m running VenusOS (Victron’s monitoring system) on a $35 Raspberry Pi, but more about that later.
My family is used to me using our boat (and primary home) as a floating laboratory, and they’re remarkably forgiving when my tests inconvenience them. But I sure don’t want our travel plans ground to a halt by my testing. I’m familiar with Victron’s equipment and confident it will work well and deliver the monitoring I desire.
The last bonus for me is the opportunity to directly compare the all Mastervolt system installed on Have Another Day with the new system on Harvey.
Victron has been steadily rolling out new inverter and inverter/chargers with a new industrial design and updated internals. The new designs are also taller and thinner than the older, somewhat squat models. All of the new models start with MultiPlus-II — except the MultiPlus 2000VA I installed. I’m especially intrigued by the MultiPlus-II GX and EasySolar-II GX models with built-in system monitoring controllers and, in the case of the EasySolar, a built-in solar charge controller. Currently, they’re only available in 24 and 48-volt models so not appropriate for my 12-volt applications.
Out with the old, in with the MultiPlus 2000VA
The new MultiPlus 2000VA produces a maximum of 2,000 volt-amps or 1,6000 watts of continuous AC power while the Magnum can produce 2,000 watts. Additionally, the Victron has a smaller, 80-amp charger. But, based on my potential loads, I’m confident the new inverter is plenty.
Although the Victron is a little smaller, it’s also more efficient. At idle, with the inverter on but no load, the Victron draws 10 watts and the Magnum draws 25 watts. Two and a half times! At 12 volts the Victron will draw a little under an amp and the Magnum just over two amps. Over a 24 hour period that’s more than 25 amp hours or 360 watt hours! Plus, the Victron’s 93% peak or maximum efficiency is noticeably greater than the 90.6% rating of the Magnum.
Installing the new inverter
Similar to many cruising boats, the inverter/charger is the heart of Harvey’s 12-volt DC house power system. The Inverter charges the house batteries and is, by far, the largest potential DC load. So, swapping the inverter is a big change and probably the most complex step of this project. Unlike on a boat, there’s no engine room with a bulkhead on which to mount the inverter. Instead, the inverter hangs from the ceiling of one of the storage compartments under the RV.
Getting the old inverter out wasn’t too difficult, but I was a bit perplexed about how to hang the new 15 kg / 33 lb inverter while I secured it. Eventually, I came up with the setup you can see above. I hung the inverter from two zip-tie slings and then worked a bottle jack in. I was able to jack the inverter up a bit, tighten the zip-ties and repeat until the inverter was snug on its mounting rails. The best part was that I didn’t drop it on my face while laying under it to secure it.
The rest of the inverter install required connecting the battery cables and the 110-volt input and output leads. It’s an adjustment for me to see solid conductor wires on an RV, and I’m reminded that I prefer to work with stranded cables. The last connection is the VE.Bus Cat5 cable that ties the MultiPlus into VRM via a VenusOS monitoring system.
The MultiPlus 2000 I installed is a new model for Victron. It utilizes Victron’s new industrial design for their inverter/chargers and offers increased efficiency. In speaking with a Victron representative, he explained that the new models use slightly smaller transformers carefully matched to the loads they’re designed to serve. The biggest specification difference appears to be an increase in maximum efficiency from 92% for the older units to 93% for the new ones.
Venus OS on a Raspberry Pi
I’m a big fan of Victron’s presence in the open-source community and their openness to tinkerers and experimenters. Victron sells an entire line of devices that can collect and report on data from their devices. Victron calls them GX devices and they run a Linux-based operating system Victron calls Venus OS. I use a Cerbo GX on my test bench to report on the status of devices while I’m testing them and have been really pleased with it. While exploring some release notes, I noticed a link to a version of Venus OS that runs on a Raspberry Pi. I have a lot of Raspberry Pis floating around, so grabbing one and a MicroSD card to try it out only took a few minutes.
My investment of time yielded a fully running GX device and data uploaded to VRM. I used a $28 VE.Direct to USB cable connected to Harvey’s SmartShunt and had data on the RV’s batteries nicely displayed in VRM. Buoyed by my initial success, I mounted the Raspberry Pi in the inverter compartment. The solar charge controller also connects to my Venus Pi via another VE.Direct cable and the inverter uses the $69 MK3 VE.BUS to USB module at the bottom of the picture.
The Cerbo GX and Venus GX are both right around $300. The solution I’ve implemented above was a total of about $180 by the time I’ve paid for the Raspberry Pi, cables, and random bits. If I had fewer components it would have been cheaper, and if I had more, the cost would go up. With enough devices, it could be cheaper to use one of Victron’s own devices. The GX devices are very reasonably priced themselves, but the option of starting with a $35 computer can make it even cheaper.
It makes me smile that the most recent editor of the GitHub entry on Venus OS on Raspberry Pi is MPVader. I do believe that would be Matthijs Vader, Victron’s managing director. So, this isn’t some unauthorized skunkworks, but the boss himself working to make Victron’s code work on a system they won’t make any money selling.
Failed LiFePO4 install
I’ve spent a lot of time prepping the DC system to install LiFePO4 batteries. The plan was to install them prior to leaving for our summer travels. But, I’d been planning on using the DIY battery I made and wrote about and another DIY battery that I’m planning to make. Unfortunately, the parts for the second battery haven’t arrived and I’m just about out of time before we leave. So, now I’ve been debating installing one battery. With 280 amp hours and around 220 amp hours useable capacity I’m not too worried about capacity. But, the BMS in this battery is rated for 120 amps, well short of the inverter’s peak potential load. Plus, especially with a BMS-controlled battery, I prefer two batteries so a single fault doesn’t take out our 12-volt power.
I considered a hybrid LiFePO4 and FLA topology but just couldn’t get comfortable with what I know so far. It’s possible more research would get me comfortable with the idea but I’m not there yet.
No matter what I decided I know I want my DIY battery in a battery box to protect any exposed terminals from accidental shorting. It turns out that when I put the battery in a group-31 battery box I managed to catch the very thin wires for the temperature sensor and yank them off the BMS’ circuit board. Courtesy of this mistake, the BMS shows a low temperature fault and won’t allow any charging because it believes the battery is very cold. The good news is I’ve seen proof the BMS’ temperature protection works. The bad news is I think I might have ruined this BMS.
Regardless of what happens with the BMS, the path is pretty clear. I’m not going to be installing this battery before we leave in just a few days. So, the early portion of the trip will continue with the flooded lead-acid batteries. But, I might have another idea for LiFePO4 batteries for the RV. So, stay tuned for future updates. But, in the meantime, I’m looking forward to putting the new components through their paces.