The Winnebago Solis 59P comes with two Group 31 AGM batteries for running the house power and eventually, those batteries are going to need to be replaced. I found that it seems to be possible to replace these with LiFePO4 batteries, which likely have some advantages.
I won’t go into to many details, but AGM (absorbed glass-mat) batteries are lead acid batteries that are sealed, don’t require maintenance, and don’t need to be upright. Oh, and the Group 31 size that the Solis takes are heavy AF. LiFePO4 (or LFP) batteries are made of lithium iron phosphate, and also don’t require maintenance. The have longer lifetimes, more cycles, charge quickly, and have slower self discharge. And… they weight about 25% of the AGM battery. The downside? Traditionally they are way more expensive. However, when looking for replacement AGM batteries, I found these Redodo LiFePO4 batteries were as inexpensive as some of the least expensive AGM batteries, so these are a clear win! Well, assuming they work.
As far as I could tell. the things to consider in swapping the battery types are the WFCO WF-8955PEC power center that handles the conversion of power from when you plug in to AC, and the Xantrex Solar Charge Controller 30 that charges batteries using solar from the solar panels. The Xantrex was pretty simple to work out, there is a setting for LFP batteries, so you just need to change that and life is good. Unfortunately, the website for WFCO power center states that it is not a lithium ready solution and directs one to a new power center purchase. However, I stumbled upon this post suggesting that the 8955PEC specs are comparable with LiFePO4 charging requirements, so I decided to let go, let Glob and take the plunge.
Physical Battery Replacement
The house batteries are underneath the Solis on the rear right, and I was able to get enough access to work by driving onto two rows of bricks (rustic jack stands). Taking the old batteries out was a struggle only because of the weight (see “heavy AF”, above) and my pinky is still healing from being crushed against the concrete as the first battery came out of the tray. Once out, it was time to install the brand new LiFePO4 batteries…
First, OMG dealing with the LiFePO4 batteries was a dream compared to the AGMs, as they have about 25% of the weight. They were way easier to lift, position, and manipulate. The only challenge in installing the new batteries was the post bolts are a little short and the front battery has three leads on the positive terminal, so lining up all connectors on thick cables coming from different angles took some effort.
Finally connected, tightened up, and secured, I enabled the house power and… let there be light! As far as the basic, you have one job, supply power aspect, everything seemed to work. I changed the battery type on the solar charge controller to LFP and, we’re done! Hopefully.
Diagnostics
The bar was pretty low of my first diagnostic test… do the LiFePO4 batteries power the Solis? Yep, they do.
While I purchased the same model battery for each replacement, one of the batteries I purchased has bluetooth capability, so I was also able to confirm a few other things. For one, the batteries do go into a “charging” state from the solar panels even when the main house power is turned off (I’ve seen conflicting posts on whether house power needs to be on for the batteries to charge). I also confirmed that with the house power off at night, the battery in an idle state (no power in or out), so that seems right.
Oh, I also verified that my Solis has not spontaneously combusted, which is also a good sign.
There a few other things I need to test and I’ll update this posting when I have more results (or share photos of a Solis on fire).
First, I need to test charging from AC. I almost always do dry camping, so I need to run special test for this, and I think this relies on the WFCO power center to do the right thing, so there is some risk it won’t do what I’m hoping.
Additionally, I need to test the charge from the van’s electrical system (when I a driving, does it charge the batteries properly).
Finally, I need to do a little more research on the LiFePO4 lifecycle and ensure the charging / discharging patterns are doing all the things to ensure the optimal lifespan.
Been here, done this or have other suggestions for me? I’d love to hear about it and learn from your experiences…please leave a comment, below!