Direct Answer
For a single 100Ah LiFePO4 battery bank, a converter rated at 30 to 55 amps of DC output is the practical working range. The lower end keeps charge current within the battery manufacturer's recommended rate; the upper end stays within the published maximum. The exact right size for your coach also depends on how much DC current your house loads draw at the same time the battery is charging, so use the on-site converter sizing calculator once you know your load total.
This page works one specific example in detail. It is not a general method for every battery chemistry or bank configuration. A future pillar page covers the full sizing method across chemistries and coach sizes. This page is narrower on purpose: one 100Ah LiFePO4 bank, the numbers that matter, and how to read the Battle Born BB10012 manual figures that back them up.
Why Converter Amps Are a Battery-Side Decision
Converter output is rated in DC amps. That output goes two places at once: it powers your coach's 12V house loads (lights, fans, water pump, control boards) and it flows into the battery as charge current. If your house loads pull 15A and your converter outputs 40A, only 25A reaches the battery. Size the converter to cover both.
But charge current is not just a math problem. The battery manufacturer sets the maximum charge rate the battery can accept safely. Exceed that rate and the battery's Battery Management System (BMS) will disconnect the charge circuit as a protective measure. You cannot charge faster than the battery allows regardless of converter output.
The correct sequence is:
- Confirm what your battery's spec sheet says about recommended and maximum charge current.
- Add your estimated DC house load.
- Select a converter whose output covers both without greatly exceeding the battery maximum.
The numbers below are from the Battle Born BB10012 and BB10012H manual (100Ah, 12V LiFePO4). They apply to those specific models only. If you own a different battery, look up your battery manufacturer's spec sheet and use those numbers. LiFePO4 charge parameters vary by brand and model. Never treat any single brand's numbers as universal LiFePO4 values.
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. On a 100Ah battery that works out to 50A. Battle Born states this as the recommended rate for normal cycling use.
Maximum Charge Current: 50A. The manual lists 50A as the maximum the BMS will accept before it disconnects. Note that for this battery, the recommended rate and the maximum rate converge at 50A. Other batteries have different relationships between their recommended and maximum figures.
Absorption Voltage: 14.2 to 14.6V. Your converter must be capable of reaching this range during the bulk-to-absorption transition. A converter that tops out at 13.6V (float-only lead acid profile) will not charge a LiFePO4 battery fully.
Float Voltage: 13.4 to 13.8V. After absorption is complete, the converter drops to this maintenance voltage. LiFePO4 does not require active float the way lead acid does, but a converter that maintains 13.4 to 13.8V causes no harm.
Absorption Time: 30 minutes per 100Ah battery bank. On a single 100Ah bank, plan for 30 minutes at absorption voltage before the converter transitions to float.
These are BB10012 / BB10012H / BB10012i figures. Do not apply them to other brands or models. 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)" while the body sentence in the same section reads "The BMS will not allow a charging current under 32 degrees F (0 degrees C)." Both statements appear in the same document. Contact Battle Born directly if cold-weather charging applies to your situation. Do not charge a lithium battery below freezing without confirming the exact cutoff for your unit with your battery 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 common practice for LED interior lighting
- Water pump: 3 to 5A while running (intermittent)
- Control boards, slides, and accessories: 5 to 10A depending on coach
- Refrigerator (12V DC mode): 3 to 8A depending on model
A reasonable estimate for a mid-size coach on shore power: 10 to 20A of continuous DC house load. Use your own measured or estimated values; these are illustrations, not specifications.
Add charge current:
Battle Born recommends .5C on the BB10012, which is 50A on a 100Ah bank. That is also the stated maximum. You want the converter to be able to deliver that to the battery 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 fall just short of delivering the full recommended charge current while running house loads simultaneously. It will still charge the battery; it will just do so more slowly because more of its output goes to house loads. A 60A or 70A converter covers the full recommended charge rate plus typical house loads with margin.
In practice, 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. If you run heavier loads simultaneously, or if you are 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 that 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 is only one dimension. The converter must also support the absorption voltage range the battery requires. The BB10012 needs 14.2 to 14.6V during bulk-to-absorption charging. Verify these three things on any converter you consider:
- Maximum DC output voltage reaches at least 14.2V.
- The lithium charging profile is either built in or selectable via a jumper or switch.
- The converter does not force a continuous high-voltage float above 13.8V.
Converters marketed as lithium-compatible from brands like Progressive Dynamics (PD9100L series) and WFCO (WF-8955-AD series) are designed with these targets in mind. Verify the specific model's spec sheet, not just the family name. The PD4600 series, for example, 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 they sense at startup.
Temperature and the BMS
The BB10012 manual states a charge temperature range of 25 degrees F to 135 degrees F (noting the internal discrepancy described above). Below the low-temperature threshold the BMS will not allow charging current. If a battery is not accepting a charge at a cold campsite, verify temperature before assuming a converter fault. Never attempt to bypass the BMS. It is 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)
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 differ.
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.