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.

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.

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.

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.

See All (9) 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.

Jameson C.

7/17/2025

@Lee Yes this is correct.

Answer 1

Hey Nancy, yes the WFCO Auto Detect RV Converter and AC/DC Distribution Panel #WF96FR that you referenced is the correct replacement for your WF8735P that you have now and is compatible with lithium batteries like you need as well. This is same shape…

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Answer 2

Hey John! Yes, a 65A converter/charger like the PowerMax #PM64VR will work well with this setup. Your 30A shore service can easily handle it, and 4 AWG over a 12' run is a solid choice to keep voltage drop low. Just be sure to install a properly…

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Answer 3

Hello Ingrid, thanks for reaching out, and congrats on the new camper! The Velit 2000R Mini AC #VE69QV can only be installed horizontally. It can be installed on sloped roofs, but it must be less than 15 degrees. It cannot be installed vertically on…

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Answer 4

WF-8735P is a 35-amp panel model. To upgrade to a lithium ready system you will need the Progressive Dynamics #PD4135K Converter/Smart Charger rated for 35-Amp. this system includes a high voltage output to provide full, quick charge for your lithium…

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Answer 5

I spoke with Progressive Dynamics and they informed me that you cannot replace just the converter section and you would need a new panel, the Progressive Dynamics Mighty Mini AC/DC Panel and Converter/Smart Charger part #PD4045KA. The Progressive…

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Answer 6

Hi Darryl; the Velit 2000R Mini RV AC #VE49QV is designed to be installed horizontally, as in flat on the roof. Even on a roof the slope must be less than 15º. It cannot be installed vertically on a side wall. If you have limited space on the…

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Answer 7

Hey Brian, the PD4135K is no longer available but we have the current version of it from WFCO with our part number #WF96FR which is lithium battery compatible.

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Answer 8

It looks like the previous owner of the trailer had vehicle tires installed since there are very few trailer tire manufacturers that carry a 235/75R15 size. Even though it might work for a while, trailer tires are always better to use for trailer…

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Answer 9

Hey Danny, thanks for the pictures. The only replacement option I have for your WFCO WF-1835-P is the Progressive Dynamics 4000 Series Mini RV Converter w/ Charge Wizard and AC/DC Distribution Panel item #PD4045KA. I don't have a way to replace…

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Answer 10

Hi Ric; using a converter that is not rated for lithium is not recommended. Your existing WFCO converter won't be able to fully charger a battery like #34282738, it could overheat, and might trip the BMS which would shut the battery down until it…

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Answer 11

Hey Lance, thanks for the information! I don't have just a lithium compatible replacement converter for your WFCO 8735. The best solution I have is the Progressive Dynamics Mini Panel item #PD4045KA. This 45 amp panel will replace everything you…

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Answer 12

Hello Francisco, thanks for reaching out. You are correct that weight distribution (WD) hitches should not be used on vehicles with unibody frames. The frame is not made to handle the additional stress added by the WD hitch. I am sure there are…

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Solution to Replace WFCO 8735P to Charge Lithium Batteries

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