After 3 years it was time to replace our factory deep cycle batteries. We had always toyed with the idea of switching to lithium iron phosphate (LI). But we waited until we actually had to make the change. The advantages of LI batteries are too long to list them all. However, the two most important advantages are the weight savings and the longevity of the batteries. The batteries have a life cycle of 4000 charges! Even after 4000 charges, the battery should still be 80% charged.
We chose a Power Queen LiFePO4 100Ah battery (PQ). If you live in a colder climate and want to charge at colder temperatures, self-heating batteries are now available. This battery was purchased directly from Power Queen. Shipping was fast and free!
Isn't she pretty?
Our original Renogy Rover MPPT solar controller that we installed is compatible with LI batteries. We only needed to create a custom charging profile. This is well documented in the Power Queen manual.
Upgrading was pretty easy. Electrical work doesn't scare us, especially on 12 volt systems. We removed the factory installed NOCO charger as it was not compatible with LI batteries. The 7-pin charging cable has been removed as charging directly from the vehicle does not provide the correct voltage for a LI battery. Power Queen's recommended 20Ah LI charger is used in its place. We swapped out the alligator clips for an XT60 quick connect connector. This allows the charger to be stored elsewhere and used only when needed.
This charger can charge a fully discharged battery to 100% in 5 hours. We rarely expect the battery to fully discharge.
The original deep cycle batteries weighed 62 pounds each. This new PQ LI battery only weighs 24 pounds! Since we don't generally run our fridge in the caravan, we didn't see the need to install 2 batteries. If we feel like it, we can run an SAE extension cord from our 4Runner to the trailer to run the fridge through this new facility.
Test location and charger
It's hard to make the wiring look nice. There are 4 positive and negative wires that need to be connected directly to the battery. Everything else is on the BlueSea fuse block. While a better inverter/charger could have been installed, we rarely use our inverter. For us, the benefit would have been negligible.
All reassembled. Quick connector for charger shown, it will get a cap/cover for when not in use. Yes, our pendant needs a bath!
We can't wait to try it in practice. A quick 3 hour test, running our Truma fridge at 40 degrees for 3 hours, showed a 0.1 percent battery drain. We didn't connect an ammeter to get a more accurate number. An off-grid test is required at the weekend. We did a quick solar charge test with our 100 watt panel. The results were excellent. The battery didn't discharge when the fridge was running and even recharged itself to go into trickle mode. Again, more testing is needed, but we should have no problem keeping this battery charged! We also have a 220 watt EcoFlow panel setup if required.
Renogy iOS App
The cost of the battery was very competitive with a 100Ah AGM battery. The long-term cost is much lower considering most AGM batteries have a lifespan of around 300-500 charges depending on the make/model. The greater ability to discharge a LI battery compared to an AGM battery must also be considered. The weight saving is always helpful, and the better discharge profile of a lithium battery is a big plus. We are in the early stages of planning an off-grid power supply for our cabin. This micro setup will help us assess what we will need. We will probably start with 2 of these batteries connected in series to create a 24 volt system.
We'll edit this article with some updated numbers once we've had a chance to run this facility for a few days.
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