RV Converters and LiFePO4: WFCO Auto-Detect, Progressive Dynamics and Charge Profiles for OEM Builds

When an RV builder or dealer swaps lead-acid house batteries for LiFePO4, the converter is often the part that gets forgotten. Most RVs have a converter/charger in the power center that charges the house battery from shore power, and many of them were set up for lead-acid. This guide explains what the two common North American converter families actually do in their lithium modes, according to their manufacturers’ manuals, and which charge parameters your battery supplier must put in writing.

WFCO and Progressive Dynamics products are typical market examples, not LJY products. Values below are quoted from their manuals as of 30 October 2026; always check the manual for the exact model and revision you install. Charge settings for any LJY-supplied battery come from that battery’s datasheet.

Short answer

• A converter only charges a lithium battery correctly if it runs a lithium profile that matches the battery’s datasheet. Check the mode, don’t assume it.
• WFCO Auto-Detect (WF-8900-AD series) picks a lead-acid or lithium profile by itself. In lithium mode it charges at 14.6 V for one to four hours, then drops to power mode.
• WFCO LiS models use a switch on the fuse board to select lead-acid or lithium.
• Progressive Dynamics’ two-stage lithium models charge at 14.4 V for at least one hour and up to eight hours, then idle at 13.6 V.
• Write the battery’s charge parameters into the OEM spec, and test the converter with the real battery bank before the pilot build.

Why the converter mode matters

A converter in an RV has two jobs: it powers the 12 V loads, and it charges the house battery. In lead-acid mode, WFCO’s manual describes a three-stage profile: about 13.6 V in power mode, 14.4 V in charge mode for up to four hours, and a storage (float) mode that reduces the voltage from 13.6 V to 13.2 V. A lithium battery’s charge voltage, how long it should be held and whether it needs a float stage are set by the battery’s datasheet and its BMS. If the converter’s profile doesn’t match, the bank may never reach full charge, or it may be held at a voltage the battery maker doesn’t recommend.

That is why the RV system design checklist should name the converter model and its lithium mode, not only the battery. Our RV lithium battery system design guide covers the rest of the charging path.

WFCO WF-8900-AD Auto-Detect series

The WF-8900-AD series manual (models WF-8935-AD to WF-8975-AD, including the WF-8955-AD) describes an “Auto-Detect” feature: the converter evaluates the battery’s charging cycle, decides whether it is lead-acid/AGM or lithium, and chooses the matching profile.

• Lithium charge mode: the output is raised to 14.6 VDC. The stage lasts one to four hours: at least one hour for a full battery, “which allows the lithium cells inside the battery the time required to balance”, and at most four hours for an empty one. For banks that need longer, such as banks above 200 Ah, the manual says cycling the power resets the timers.
• Lithium power mode: after charge mode, the output drops to the power-mode voltage and stays there until power is cycled. The manual’s text gives 13.6 VDC; its specification table lists 13.8 V for lithium power and storage mode. Check the label and manual of your unit.
• LED indicators: green indicates the lead-acid profile, blue the lithium profile, and red indicates bulk (fast) charging.

The manual also lists what can upset Auto-Detect or slow charging: long or thin cable between battery and converter, solar installed without a solar disconnect, high current loads during bulk charge, and converter size. If the battery is misdetected, the converter can detect it correctly on the next charge cycle once the cause is removed. For an OEM build, this means the first commissioning charge should be done with loads and solar disconnected, and the blue LED confirmed.

WFCO WF-8900LiS series

The WF-8900LiS manual (WF-8935LiS to WF-8975LiS) describes a fuse-board switch that selects lead-acid or lithium charging. In lithium mode, an LED marked LI lights, and a second LED shows the 14.6 VDC charge mode. When the converter drops from 14.6 VDC charge mode to 13.6 VDC power mode, the second LED goes off. For an OEM-fitted lithium build, the switch position belongs on the end-of-line checklist.

Progressive Dynamics lithium converters

Progressive Dynamics’ PD9100/9200 manual says the 9100L/9100AL two-stage models charge at a nominal 14.4 VDC and switch to idle at 13.6 VDC when the output current falls below a preset level. It also states that the 9100AL series is designed to recharge lithium iron phosphate batteries and must not be used to recharge lead-acid batteries.

Its technical note on the two-stage lithium PD91xxALV models describes the “Charge Wizard” profile:

• charge voltage 14.4 VDC and idle voltage 13.6 VDC
• charging continues for at least 1 hour, and up to a maximum of 8 hours if the current stays high
• on long-term shore power, a top-off charge every 3 weeks
• a large bank, high RV loads, or alternator and solar charging can influence the Charge Wizard; solar or alternator voltage can make the bank appear full
• an optional PD92201 remote pendant shows the mode and allows a manual mode change

Comparison: what the manuals say

Converter (typical market examples, not LJY products)	How lithium mode is selected	Lithium charge stage	After charging
WFCO WF-8900-AD series	Auto-Detect (blue LED = lithium)	14.6 VDC, 1–4 h timer	Power mode 13.6 VDC in the manual text; 13.8 V in the spec table
WFCO WF-8900LiS series	Switch on the fuse board	14.6 VDC	13.6 VDC power mode
Progressive Dynamics PD91xxALV two-stage	Dedicated lithium model	14.4 VDC, at least 1 h, up to 8 h	Idle 13.6 VDC; top-off every 3 weeks on shore power

Whether any of these profiles suits a particular battery depends on that battery’s datasheet. Compare the converter’s charge voltage, the time it holds that voltage and what happens afterwards with the battery maker’s recommended charge voltage, absorption and float settings.

Other chargers on the same bus

Most RVs have more than one charging source. Both manufacturers point out that solar and alternator charging can interfere with the converter’s logic. Set solar charge controllers and inverter/chargers to profiles that match the same battery datasheet, and use a charging method for the alternator that the battery maker approves. If the battery also reports over a data network, see our RV-C lithium battery integration guide.

OEM spec sheet: what your battery supplier must state

1. Charge voltage and the tolerance the BMS accepts.
2. Absorption or hold time recommendation, and whether the battery needs a float stage or prefers none.
3. Maximum continuous charge current per battery and for the bank.
4. Low-temperature charging limit and how the BMS reacts below it.
5. BMS high-voltage cut-off, so you know the margin above the converter’s charge voltage.
6. Recommended settings for each converter, inverter/charger and solar controller model in your build.
7. Proof: a charge log from your actual converter and bank, recorded before the pilot build.

Dealers can use the same list when they advise customers on a retrofit; see the RV lithium battery dealer buying guide.

Where LJY fits

LJY Energy is a Shenzhen supplier and OEM/ODM coordinator for LiFePO4 batteries, not a manufacturer. For RV programs we coordinate battery configuration, documents and samples with qualified manufacturing partners. Charge parameters for each model come from its datasheet and are confirmed in writing per project. See our RV battery solutions, the 12V LiFePO4 battery series and our page for RV and caravan manufacturers.

FAQ

Will my WFCO converter charge a lithium battery?

WFCO’s Auto-Detect (WF-8900-AD) models choose a lithium profile when they detect a lithium battery, shown by a blue LED. LiS models use a switch. For any other model, check its manual for a lithium mode before relying on it.

How do I know which mode a WFCO Auto-Detect converter is in?

By the LEDs: green indicates the lead-acid profile, blue the lithium profile, and red indicates bulk charging.

Why does my WFCO stop charging before the bank is full?

The lithium charge stage has a one-to-four-hour timer. The manual says large banks, above 200 Ah for example, may need the power cycled to reset the timer, and that loads, solar and cable length affect charging.

What voltage does a Progressive Dynamics lithium converter use?

Its two-stage lithium models charge at 14.4 VDC for at least one hour and up to eight hours, then idle at 13.6 VDC, per the manufacturer’s technical note.

What absorption and float voltage should I use?

Use the values on the battery’s datasheet. Converter settings should be checked against them, not the other way round.

Sources

• WFCO WF-8900-AD series product manual
• WFCO WF-8900LiS series manual
• Progressive Dynamics PD9100/9200 installation and operation guide
• Progressive Dynamics: Understanding the PD91xxALV two-stage lithium converter/charger