Direct Answer
A 30 to 55 amp DC output converter is practical for a single 100Ah LiFePO4 battery bank. The lower end ensures the charging current stays within the manufacturer's recommendation, while the upper end adheres to the published maximum. The right size also depends on the total DC current your coach's loads consume while charging. Use the on-site converter sizing calculator once you know your load total.
This page details a specific example but is not a general method for all battery chemistries or configurations. A future pillar page will cover the full sizing method across different chemistries and coach sizes. This page focuses specifically on one 100Ah LiFePO4 bank, the relevant numbers, and how to read the Battle Born BB10012 manual figures that support these numbers.
Why Converter Amps Are a Battery-Side Decision
Converter output is measured in DC amps and serves two purposes: powering the coach's 12V house loads (such as lights, fans, water pump, and control boards) and charging the battery. If your house loads draw 15A and your converter outputs 40A, only 25A will go to the battery. The converter must be sized to accommodate both uses.
Charge current isn't just a simple calculation. The battery manufacturer sets the maximum safe charge rate. Exceeding this rate can trigger the Battery Management System (BMS) to disconnect the charging circuit as a safety measure. The battery ultimately dictates the maximum charging speed, regardless of the converter's output capacity.
The correct sequence is:
- Check the battery's spec sheet for recommended and maximum charge current.
- Estimate your DC house load.
- Choose a converter that can cover both without exceeding the battery's maximum charge rate.
The numbers below are from the Battle Born BB10012 and BB10012H manual (100Ah, 12V LiFePO4) and apply only to those models. For a different battery, consult your battery manufacturer's spec sheet for the appropriate numbers. LiFePO4 charge parameters vary by brand and model; do not assume one brand's values apply universally.
Battle Born BB10012 Charge Specifications
These figures come directly from the Battle Born BB10012 / BB10012H / BB10012i manual and datasheet, both verified against the manufacturer's own hosted PDFs on 2026-09-18. See the sources section for exact URLs.
Recommended Charge Current: .5C. For a 100Ah battery, this means 50A. Battle Born recommends this rate for normal cycling use.
Maximum Charge Current: 50A. The manual states that the BMS will disconnect if the current exceeds 50A. For this battery, the recommended and maximum charge rates are both 50A. Other batteries may have different rates.
Absorption Voltage: 14.2 to 14.6V. Your converter must reach this range during the bulk-to-absorption transition. A converter that only reaches 13.6V, typical for float-only lead acid profiles, will not fully charge a LiFePO4 battery.
Float Voltage: 13.4 to 13.8V. Once absorption is complete, the converter should drop to this maintenance voltage. LiFePO4 batteries do not require active float like lead acid batteries, but maintaining 13.4 to 13.8V does no harm.
Absorption Time: 30 minutes per 100Ah battery bank. For a single 100Ah bank, absorption voltage should last for 30 minutes before transitioning to float.
These figures apply only to the BB10012 / BB10012H / BB10012i. Do not use them for other brands or models. Always check your own battery's spec sheet.
A Known Discrepancy in the Battle Born Manual
The BB10012 manual contains an unresolved discrepancy. The BMS section heading reads "Low Temperature Charging (less than 25 degrees F / -3.9 degrees C)," but the body text states "The BMS will not allow a charging current under 32 degrees F (0 degrees C)." Both statements are present in the same document. Contact Battle Born directly if cold-weather charging is relevant to your situation. Do not charge a lithium battery below freezing without confirming the exact temperature cutoff for your unit with the manufacturer.
Sizing the Converter: The Worked Example
Setup: one Battle Born BB10012, 100Ah, 12V LiFePO4. Typical weekend coach, shore power at a campground.
Estimate your DC house loads while plugged in:
- Lights: 3 to 5A for LED interior lighting
- Water pump: 3 to 5A while running (intermittently)
- Control boards, slides, and accessories: 5 to 10A depending on the coach
- Refrigerator (12V DC mode): 3 to 8A depending on the model
A reasonable estimate for a mid-size coach on shore power is 10 to 20A of continuous DC house load. Use your own measured or estimated values; these are examples, not specifications.
Add charge current:
Battle Born recommends .5C on the BB10012, which is 50A on a 100Ah bank. This is also the maximum. The converter should be able to deliver this while the house loads are running.
Total converter output needed:
- DC house loads: 15A (midpoint estimate for this example)
- Battery charge current: 50A
- Total: 65A
A 55A converter would not be able to deliver the full recommended charge current while running house loads simultaneously. It will still charge the battery, but more slowly. A 60A or 70A converter can cover the full recommended charge rate plus typical house loads with some margin.
Most stock WFCO and Progressive Dynamics converters that ship with coaches in the 30A shore power class are rated at 30 to 55A. A 45A or 55A unit works for a single 100Ah LiFePO4 bank if your house loads are light. For heavier loads or adding a second 100Ah battery later, size up now.
The on-site converter sizing calculator lets you enter your actual house loads and battery configuration and returns a recommended output range for your specific numbers.
Voltage and Amperage Mismatches to Avoid
A converter below roughly 30A DC output will charge the battery slowly. The BB10012 BMS limits incoming current regardless of converter output, so a small converter means slow charging, not a safety hazard.
A converter that cannot exceed 13.6V is a more serious mismatch. The BB10012 absorption target is 14.2 to 14.6V. A converter that cannot reach this range leaves the battery in a partial state of charge after hours on shore power. Lead acid-only converters typically float at 13.2 to 13.6V and are not compatible with LiFePO4 without modification.
A converter rated at 100A or more is not better for a single 100Ah battery. The BMS disconnects if charge current to the battery alone exceeds 50A. Repeated BMS trips are unnecessary stress. Target 50 to 70A total output for this setup.
Charge Profile Compatibility Matters as Much as Amps
Output current isn't the only factor. The converter must support the absorption voltage range your battery needs. The BB10012 requires 14.2 to 14.6V during bulk-to-absorption charging. Check these points on any converter you're considering:
- The maximum DC output voltage is at least 14.2V.
- The lithium charging profile is either built in or can be selected via a jumper or switch.
- The converter doesn't maintain a continuous high-voltage float above 13.8V.
Converters marketed as lithium-compatible, such as the Progressive Dynamics PD9100L series and WFCO WF-8955-AD series, are designed with these requirements in mind. Check the specific model's spec sheet, not just the series name. For example, the PD4600 series supports LiFePO4 only after an internal jumper is set by a qualified technician. Auto-detect units like the WFCO WF-8955-AD set the profile automatically based on the battery chemistry detected at startup.
Temperature and the BMS
The BB10012 manual states a charge temperature range of 25 to 135 degrees F (noting the internal discrepancy described above). Below the low-temperature threshold, the BMS will not allow charging current. If your battery is not accepting a charge at a cold campsite, check the temperature before assuming a converter fault. Never bypass the BMS; it's a safety device.
Summary: Practical Converter Range for One 100Ah BB10012
- Minimum useful output: 30A (slow charging, adequate for light house loads and overnight recovery)
- Good working range: 45 to 55A (covers house loads and charges the battery at a healthy rate)
- Ideal with margin: 55 to 70A (covers house loads plus delivers close to the full recommended .5C charge rate)
- Avoid: converters that cannot exceed 13.8V output (incompatible charge voltage for LiFePO4)
- Avoid: converters whose total output regularly exceeds 50A delivered to the battery alone (BMS will disconnect)
To determine the right converter for your specific load profile, use the converter sizing calculator. These figures come from the Battle Born BB10012 / BB10012H / BB10012i manual. If your battery is a different brand or model, the numbers will vary.
Sources
- Battle Born BB10012 / BB10012H 100Ah 12V LiFePO4 Manual Primary manufacturer manual for the Battle Born BB10012 and BB10012H. Proves: Recommended Charge Current .5C, Max Charge Current 50A, Absorption 14.2 to 14.6V, Float 13.4 to 13.8V, Absorption Time 30 minutes per 100Ah battery bank, charge temperature range 25 degrees F to 135 degrees F, BMS high-temperature cutoff above 135 degrees F, and the internal discrepancy between the section heading low-temperature threshold (25 degrees F) and body text threshold (32 degrees F). Verified live 2026-09-18. Authority tier: manufacturer manual.
- Battle Born BB10012i Datasheet (11-21-24) Manufacturer datasheet for the BB10012i variant. Confirms the same charging specifications as the BB10012 manual: Recommended Charge Current .5C, Max Charge Current 50A, Absorption and Float voltage targets. Verified live 2026-09-18. Authority tier: manufacturer datasheet.
- Progressive Dynamics PD Converter Lineup Progressive Dynamics converter product lineup page. Confirms the PD9100L LiFePO4 series including the PD9160ALV as lithium-targeted units. Referenced to support the statement that PD offers lithium-profile converters. Verified live 2026-09-18. Authority tier: manufacturer product page.
- WFCO WF-8955-AD Power Center Specs WFCO product page for the WF-8955-AD Power Center. Confirms the auto-detect lithium profile capability and output specifications. Referenced to support the description of auto-detect converter behavior in the charge profile compatibility section. Verified live 2026-09-18 via browser (WAF returns 403 to curl; page content confirmed real). Authority tier: manufacturer product page.
- Progressive Dynamics PD4600 Jumper Settings Progressive Dynamics installation document for PD4600 series lithium jumper configuration. Confirms that the PD4655V supports LiFePO4 via an internal jumper set by a qualified technician, not automatic detection. Referenced to accurately describe the PD4655V and PD4600 series limitation in the charge profile compatibility section. Verified live 2026-09-18. Authority tier: manufacturer installation document.
Published 2026-09-18. Electrical specifications are model-specific: confirm every figure against the manual for your exact equipment before acting on it.