The settings
Most solar controllers, DC-DC chargers and inverter-chargers have a lithium or LiFePO4 preset. If yours asks for numbers, these are from the makers' manuals:
| Setting | 12V battery (Battle Born) | 48V rack battery (EG4 LifePower4) |
|---|---|---|
| Bulk / absorption | 14.2–14.6 V | 56.8 V |
| Float | 13.4–13.8 V, or off | follow the inverter's battery profile |
| Equalization | off | off |
| Temperature compensation | off | off |
| Charge current | up to 0.5C (50 A per 100Ah) | set by the battery over its communication cable |
Two settings do the most damage when left on from a lead-acid profile: equalization and temperature compensation. Both push the voltage around in ways lithium doesn't want.
Where the charge comes from
- Solar: an MPPT controller set to lithium. What size panel for a 100Ah battery.
- The alternator, while driving: a DC-DC charger, which also limits the current so the alternator doesn't overheat. What size DC-DC charger.
- Shore power or a generator: the charger in an inverter-charger. What size generator.
- On the bench: a LiFePO4 battery charger.
Temperature
Don't charge below 32°F (0°C). EG4's rack battery refuses on its own; for any battery, check the manual. In a cold van or shed, a self-heating battery or an indoor spot solves it. More: lithium batteries in cold weather.
Before connecting batteries together
Bring every battery to the same state of charge first (Battle Born's manual says this in capitals). Charge each one full on its own, then connect them in parallel.
If it stops charging
Work through solar not charging your battery? Check these 7 things. If the battery shut itself off after running flat, see the last question below.
Questions people ask
What voltage do you charge a 12V LiFePO4 battery at?
Battle Born's manual gives 14.2–14.6 V for bulk and absorption and 13.4–13.8 V for float, with equalization and temperature compensation off. A 24V battery doubles those numbers; EG4's 48V LifePower4 charges at 56.8 V.
Can I charge a LiFePO4 battery with a regular lead-acid charger?
Only if it has a lithium setting, or lets you set those voltages and turn off equalization and desulfation modes. Those modes push the voltage higher than a lithium battery wants.
Can you charge LiFePO4 below freezing?
No. Battle Born lists a charge range of 32–131°F for its standard battery, and EG4's LifePower4 stops charging at 32°F on its own. Self-heating batteries warm themselves first; otherwise warm the battery before charging.
Do I need to fully charge a LiFePO4 battery every time?
No. Charging part way is fine. Let it reach full now and then so the battery's management system can balance the cells; Battle Born notes that a battery left out of balance can cut off early at high voltage.
My lithium battery shut off and won't charge. What now?
It's probably in low-voltage disconnect. Battle Born's battery still accepts a charge in that state, but if a charger can't see it, the manual says to jump it with a 12V source to wake it up, within 24 hours of the shutdown.
Sources
- Battle Born 100Ah 12V battery manual (charging voltages, temperatures, low-voltage disconnect) Battle Born Batteries
- Battle Born BB10012 datasheet (0.5C recommended, 50 A max charge) Battle Born Batteries
- EG4 LifePower4 48V V2 troubleshooting and maintenance guide (56.8 V charge, 32°F charge cut-off) EG4 Electronics
Every number on this page comes from these sources. Spotted something out of date? Tell me.
Get the exact setup
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