Dear Dave,
I switched from two regular batteries to two LiFePO4 batteries. I have a 2020 Salem Hemisphere 26BHHL trailer. Can my trailer converter maintain/charge these batteries? (I’ve asked questions before and got no answer… Redeem yourself!) Also, can I cut a hole in the floor in a remote area for a small 4-inch computer fan to shove extra heat under the floor to keep the lines from freezing? — Jim, 2020 Salem Hemisphere 26BHHL
Dear Jim,
Ouch. I posted the original question just as I received it [with Diane’s slight editing], since you stated that I should “redeem” myself because you got no answer when you wrote to me previously. I apologize for apparently not replying to you. While I try to answer every question I get, I have received more than 6,000 emails with questions, and have just surpassed 1,000 posts.
About lithium iron phosphate batteries
Most lithium iron phosphate (LiFePO4) batteries have a charging profile of 14.6 volts for a much shorter period of time. From what information I can find on your Forest River Salem, it has an all-in-one distribution center/converter located under the refrigerator.
Forest River typically uses the WFCO WF 8930/50 model distribution center, which is available in a 30-amp or 50-amp application. Both models produce 13.6 volts when there is a low or no battery indication, and then drops to 13.2 volts for a maintenance charge once the battery reaches 12.6 volts. This is the preferred charging profile for a flooded lead acid (FLA) battery but will not fully charge a lithium battery. It will charge the batteries—however, only to about 60%.
Most owners replace the original FLA batteries with 100 AH lithium batteries, which can be drawn down to almost 100%. That means you most likely have 200 AH. Even at 60% charge, you still have more available AH than your previous batteries, but you are not getting all you paid for.
Some people believe they will supplement the charge with solar panels, which technically is true. However, that is only for the portion of the day when the panels are exposed to the sun.
Better option is dedicated converter/charger
The better option would be purchasing a dedicated lithium iron phosphate converter/charger such as the Progressive Dynamics PD9300 series.
Another issue with your lithium batteries is the output of the alternator in your tow vehicle. If it has a high voltage output or two alternators, it will send more voltage through the “pigtail” connected to the tow vehicle. A DC-to-DC charger will limit the amount of voltage going to the RV batteries and also protect the tow vehicle alternator and charging system from a draw coming from the RV.
Heating under floor
Next, you ask if you can cut a hole in the floor of your Forest River Salem to add a computer fan. Yes, if you can identify the wood framework that typically runs from the outer perimeter framework across the floor. Most Forest River trailers are 1/2” plywood or thicker and some have block foam sandwiched inside, as well. Use a residential stud finder and you should be able to locate any cross members and avoid them without jeopardizing structural integrity.
You might also enjoy this from Dave
Is one 300 Ah lithium or three 100 Ah batteries better? What size converter?
Dear Dave,
I decided to go lithium and am familiar with the install, but I have a question on batteries. Currently I have four 6-volt golf cart batteries and am okay with power availability, but slightly more would be better. I see a lot of batteries at 270-300 amps, but I cannot get a clear answer on what’s best: one 300-amp or three 100-amp lithium batteries? I have room for either. I’d like to hear your views and ideas. Thanks again. —Alan, 2018 Winnebago Vista 29VE
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Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”
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Dave, I don’t think you need any “redeeming!” In fact, considering the complete lack of details you many times seem to receive, and all the work that creates for you to look things up just to formulate a valid response, I think you are a saint 😇 who deserves three big gold stars! 💫💫💫
Keep up the great work! 🙂
Hooahh
Thank you, Dave, for reminding us that rarely is introducing lithium iron phosphate batteries as simple as “old batteries out, new batteries in.” Have a great day and safe travels!