Solution to Replace WFCO 8735P to Charge Lithium Batteries

Question

Question:

I have just installed a 200Amp hour lithium battery in our 2019 Aliner. I need to upgrade the WFCO 8735P convertor the a model that will charge Lithium batteries. I am considering the Progressive Dynamics PD4135K. Will this unit charge the battery from the tow vehicle? If not what are my options? Is there a power control center that has this ability incorporated into it? By the way, I also charge the battery using solar. Thanks for your help

asked by: Russ S

0

Expert Reply:

I have a solution for you because as you know what you have now cannot charge Lithium batteries. You will need the Progressive Dynamics # PD4135K which is designed to replace your WF-8735P and is compatible with Lithium batteries. When this is connected to your tow vehicle power source it will help charge the batteries. This will not interfere with your solar charging setup either.

expert reply by: Jameson C

0

Steven

1/25/2025

You said the 8735 p doesn’t charge lithium batteries but that manufacturer says it will. I would like a straight answer on this as I am consider lithium batteries as a change.

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Jameson C.

1/27/2025

@Steven At one point it did not but in recent years they have been updating the part numbers to have lithium profiles since the are getting more popular.

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Sean

4/10/2025

@Steven - I have the WF-8735P in my trailer running a single 80amp deep cycle AGM and 200 watts solar. I recently bought two 100amp lithium batteries for it before knowing that the converter could be an issue. My 8735P converter manufacture date is Jan 2020. I spoke with a tech at Western WFCO yesterday. I can only relay what I was told in the phone call but what he told me was..... A- He said it would charge my Lith batt's but only up to 70-80% while plugged to 110. B- My solar would charge above the 70-80% though. C- 200 amp was the upper limit of the converters ability. D- He also said that unlike AGM batteries, Lith batt's can be drawn down further than the AGM 50% recommendation and that they have a built in range safety feature. Keep in mind, I'm only stating what I understood from the the phone call. @ Jameson and I forgot to ask about about vehicle charging. I plan to eventually swap out my converter but might do some trials at the house before our next trip. Most our trips are just 2-3 nights, light power use anyways. @jamesonc Please correct me if I am wrong in any of this. Thanks in advance.

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Jameson C.

4/10/2025

@Sean did he say the reason it would charge past a certain point because it doesn't have the lithium profile? That would check out but figured I would ask. It is true lithium batteries can be ran down further and they will work super strong as well as will bounce back better. They really are great batteries.

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See All (7) Replies to Steven ∨

Lee

7/17/2025

The converter has nothing to do with the tow vehicle. It is a 120V to 12V converter for running the camper and charging the battery. The reason the WFCO 8735P won't charge Lithium is because the lithium discharge voltage profile means the lithium battery voltage will be well above 12.8 v even when discharged, and the 8735P, thinking its a lead battery, will immediately go to float at 13.5 which will not charge lithium.

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Jameson C.

7/17/2025

@Lee Yes this is correct.

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Solution to Replace WFCO 8735P to Charge Lithium Batteries

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