Lithium Charging - replacing auto-detect WFCO converter/charger

[CasadeMike]

Moderator Note -- don't miss CasadeMike's outstanding follow up in post 13! A critical data point from his post:

Progressive Dynamics ...makes a direct replacement power center for the WFCO 8735-AD. It's called the PD4135KW2B. This unit has the same number of branch AC circuits and an additional DC circuit. It has a physical switch (novel concept) to change between Lithium and Lead Acid charging profile. It's only about $180.

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Hoping I can pick the minds of some electrical system experts here.

I have a GD 2023 21BHE. It came with the WF-8735-AD-GE "auto-detect" converter/charger. I have installed (2) 100AH Battleborn Lithium batteries.

I read that for your first charge, the batteries must be depleted for the auto-detect system to work. I drained my batteries until they were about 11.5V (according to the Furion Shunt Meter that came with the trailer). I wasn't totally comfortable draining them much further than that.

I plugged the trailer in and it failed to start charging at the required 14.4 to 14.6V (it hovered around 13.3V charging). Even after 24 hours the batteries were not charged to 80%. So basically I think it's slow charging on a Lead Acid profile.

I've read online that many of these units fail to "auto-detect" Lithium and even if they do, they often fall back to Lead Acid profiles after for no known reason.

Basically I'm assuming this converter/charger is junk. I'm also dubious that if it did work, it would charge at the promised 35 amps since by my calculations the wire run to the batteries from the converter is about 20 feet and the battery leads are clearly marked 8AWG. I'd love to be wrong here (I'm not an expert, just a proficient googler).

The converter is built into the electrical panel. Not a floor mount underneath or behind it. Space behind the electrical panel is limited - and I'm still not sure about the run length/gauge of my existing wires.

What are the options here? So far I've thought I could try and squeeze in something better behind the panel and hope the wire run is sufficient to at least charge at 30 amps. OR, I could buy charger only and mount it in the front storage and run higher gauge wire to the batteries and just plug it in using the plug in the front storage compartment.

What I'm unsure about is can I keep a lithium charger hooked up AND this WFCO converter (in its Lead Acid profile) or would that do damage. I'm assuming I still need some sort of converter when plugged into shore power, or would the Lithium charger provide enough power? I'm also unsure about doing this and bypassing the battery switch.

I'm open to any and all suggestions. Not afraid to spend money to just make it right. But my first choice would be using existing wiring.

Thanks in advance for any and all advice.

[Country Campers]

If you installed a lithium compatible charger/convert in the front pass thru and wired it to the batteries then the battery power would "back" feed thru the wires that comes from the factory converter/charger. I believe that there is either wires or a breaker that you can remove or turn off for the factory converter/charger. You do not want to have both converter/chargers on at the same time for sure. Installing the new converter/charger in the front pass thru, which you could mount on the ceiling if possible, then you can also install larger wires from there to the batteries for better charging. The wire size from the batteries to the power center should be fine and not need changed. Hopefully that is not too confusing.

Brian

[Jomani]

CasadeMike
Before you make the assumption that your current setup won’t work, you might want to contact WFCO directly. They may have a solution. I am not familiar with your trailer, but a lot of the newer models are coming with 12 volt refrigerators and a single solar panel. Does yours have a 12 volt refrigerator? Solar? Keep in mind that the converter/charger is not only responsible for charging the batteries, but also for powering all of the 12v loads. The converter sees the batteries as just another load on the system and will prioritize the output - battery charging is the lowest priority.

A couple of things to consider before heading down this rabbit hole. Making changes to the existing wiring will most likely void your warranty - at least on anything that is directly connected. Depending on your usage (dry camping vs full power) a 35 amp charger may or may not be sufficient. If you tend to use full hookups and only occasionally run off battery power, the primary function of the converter is to power the trailer. If, on the other hand you prefer boon-docking and need to a quick and easy way to recharge the batteries, I think you will find that a 35 amp converter will struggle. If you upsize the converter output, then yes larger wire is a necessity. If you simply want the existing system to work as designed, I would start by contacting WFCO and or Grand Design.

[AZMike]

According to the manual for my convertor (WFCO-8950L2-MBA) it will remain in lithium bulk charge mode for a maximum of four hours. After that, it will revert to an absorption charge. The input power will have to recycled to initiate another four hour bulk charge cycle. I am not sure if this is the same across all of the WFCO lithium products.

[howson]

According to the manual for my convertor (WFCO-8950L2-MBA) it will remain in lithium bulk charge mode for a maximum of four hours. After that, it will revert to an absorption charge. The input power will have to recycled to initiate another four hour bulk charge cycle. I am not sure if this is the same across all of the WFCO lithium products.

Yep--that's a nuisance. We'd come back from a day of sightseeing and my buddy's camper would only be at 80% SoC. (We actually plugged his 297RSTS into mine so my solar/inverter setup would charge his system...my setup generated more than enough power to charge both our campers!) It took us a bit to figure out, but it was the WFCO's timeout feature coupled with the relatively slow (low amperage) charge from the WFCO that was the culprit.

The WFCO is a decent option for a small systems (like maybe 1ea 100aH lithium battery) but anything over that...IMHO it's time to look for a charger with more capacity and no time limitation.

One more note--the WFCO rep my buddy talked to said that newer WFCOs will not have the time limitation. I can't elaborate any further with details or even confirm if that is true.

Howard

[Jomani]

According to the manual for my convertor (WFCO-8950L2-MBA) it will remain in lithium bulk charge mode for a maximum of four hours. After that, it will revert to an absorption charge. The input power will have to recycled to initiate another four hour bulk charge cycle. I am not sure if this is the same across all of the WFCO lithium products.

A four hour time limit on a 35 amp charger connected to a 200 amp hour battery bank could certainly be problematic. I think most, if not all of the RV converters have a built-in bulk charge time limit. I know my Progressive Dynamics limits bulk charging to 8 hours. My PD has an optional pendant that will allow me to force it into bulk mode without cycling the power.

howson
I certainly hope the major manufacturers like WFCO start to realize that the trend with many RVers is to upgrade to larger lithium battery banks. I have to imagine that the bulk charge time limit is at least partially for self preservation - a lot of heat is generated when operating at full capacity.

[glennco]

The distance from the converter to the batteries could also be a concern. I believe the wire run from the factory is like 12awg. I don’t think that is enough to carry 50amps 10ft. So, unless you relocated the batteries closer to the converter you could have a problem carrying all that current.

[ncitro]

The distance from the converter to the batteries could also be a concern. I believe the wire run from the factory is like 12awg. I don’t think that is enough to carry 50amps 10ft. So, unless you relocated the batteries closer to the converter you could have a problem carrying all that current.

The factory run from the distribution panel (where the converter ties in to the batteries should be 6AWG.

[Bobsrv]

Can leave the dc wires connected to the PD 9260 and unplug it from service panel and run a 12 gage extension cord to front storage and connect a Pd 9260ALV to the batteries without causing problems

[Jomani]

This response gets a little off track from the original question in that I have a different setup to start out with. I do think my research (in theory) is applicable.

I have a Progressive Dynamics PD9160AL (lithium only) ready to go in as a replacement for the stock PD9260C (non-lithium) that came in my 5th wheel. My plan all along has been to do a simple swap and leave the new converter in the same location as the old one. The more I think about it, the more inclined I am to leave the old converter installed and connected and simply add the new one to the front battery compartment. For normal usage (plugged into shore power) I will leave the circuit breaker for the old converter turned off. When I need a quick charge (say from a generator while boon-docking), I will turn on the circuit breaker and run both converters at the same time.

I did reach out to the Progressive Dynamics support team to verify that this will work. They did verify that my plan (using multiple converters simultaneously) will work and offered that adding a Charge Wizard pendant to both converters will allow me to better control the modes they are operating in. They did caution me that operating both 60 amp converters simultaneously could potentially draw 4000 watts of power. That would be problematic if plugged into a 30 amp service or attempting with a generator with less than a 4000 watt continuous output.

[ncitro]

This response gets a little off track from the original question in that I have a different setup to start out with. I do think my research (in theory) is applicable.

I have a Progressive Dynamics PD9160AL (lithium only) ready to go in as a replacement for the stock PD9260C (non-lithium) that came in my 5th wheel. My plan all along has been to do a simple swap and leave the new converter in the same location as the old one. The more I think about it, the more inclined I am to leave the old converter installed and connected and simply add the new one to the front battery compartment. For normal usage (plugged into shore power) I will leave the circuit breaker for the old converter turned off. When I need a quick charge (say from a generator while boon-docking), I will turn on the circuit breaker and run both converters at the same time.

I did reach out to the Progressive Dynamics support team to verify that this will work. They did verify that my plan (using multiple converters simultaneously) will work and offered that adding a Charge Wizard pendant to both converters will allow me to better control the modes they are operating in. They did caution me that operating both 60 amp converters simultaneously could potentially draw 4000 watts of power. That would be problematic if plugged into a 30 amp service or attempting with a generator with less than a 4000 watt continuous output.

Not sure where they are getting 4000 watts, it will be a fraction of that. 60 amps x 2 x 14V is 1680 watts, which will be around 14 amps of 120V, plus losses. Put another way two at 60A is what my Multiplus charges at (120A) and its draws about that.

[Jomani]

Not sure where they are getting 4000 watts, it will be a fraction of that. 60 amps x 2 x 14V is 1680 watts, which will be around 14 amps of 120V, plus losses. Put another way two at 60A is what my Multiplus charges at (120A) and its draws about that.

Seemed high to me as well. I think they are just being cautious in their response since my question to them was specific to using a generator. They did specify “peak” output. Below is the exact text from their email:

They will work together. It would be best to have the PD92201 Pendant to press the button to give maximum charge.
In your case 2.
Technical-library/Two-stage-lithium.pdf


Both of these 60 amp chargers require 2000 watts from a generator. If your generator is 4000 watt peak or larger it should be OK.

[CasadeMike]

Thanks to all who posted. In the interest of perhaps helping future searchers of this topic. I thought I'd write up a little outcome.

1) WFCO Auto Detect Converter - watched multiple YouTube videos, read many forum posts, talked to Battleborn and other electrical RV techs. I came to the conclusion that WFCO Lithium auto detect is unreliable and often does not work. IF it does work, it won't work for long and will randomly switch back to a Lead Acid profile. Many corroborating stories on this–they're just totally unreliable. Even WFCO themselves have a YouTube video on "tricking" the converter into a Lithium profile (that says a lot in my books). This was disappointing because having a Lithium capable converter was one of the check marks for purchasing the trailer.

2) Talked to Battleborn tech - In regards to my additional Victron charger idea. He said since I was running two batteries, I "could" hook up the additional charger. They said it should work but was not recommended. And if I was only running 1 battery, this setup would toast it. Nuf said, eliminated that option.

3) Talked to Grand Design - They were friendly as always - but said to call WFCO or take it in to a dealer (I despise my dealer so that wasn't going to happen). Grand Design rep generically said there was "no reports" of any issues with that Converter. But I think a lot of people just don't know or are not actually checking.

3) Progressive Dynamics - Battleborn told me to talk to Randy at bestconverter.com. (apparently he's a trusted vendor for them). He informed me that Progressive Dynamics makes a direct replacement power center for the WFCO 8735-AD. It's called the PD4135KW2B. This unit has the same number of branch AC circuits and an additional DC circuit. It has a physical switch (novel concept) to change between Lithium and Lead Acid charging profile. It's only about $180.

The prospect of re-wiring my whole power center was a little daunting. But I just took it slow moving one circuit over at a time. In the end it wasn't that hard. My old breakers were not compatible with the new panel, so I had to purchase those. But all in all the project costs was about $250 total (new panel and new breakers).

My old converter was charging at 13.6V and max amps I was getting to the battery was about 8. (took multiple days to charge and only to 80%)

My new converter charges up to 14.5 V and max amps I am getting to the battery is about 18. (now charges to 100% in about 5-6 hours).

The investment was minimal and I had to run no additional (or higher gauge) wires to the battery. I now have a reliable system that will charge fast enough off a a generator if we are boon docking.

I'm a happy camper now - pardon the pun! 😀

[howson]

CasadeMike -- superb follow-up and information. Thank you! Added the Reference Library and Modification tags to this thread. I also added a very brief summary to post 1.

-Howard