The short answer. The battery swap is the easy part. Everything that charges it has to match lithium: the converter, the alternator path, the solar controller. Add a shunt monitor so you can see state of charge. Use the battery maker’s charge voltages and its cold-charge limit for every setting.
You’ll need
- Your new battery’s datasheet: charge voltage, float voltage, max charge current, lowest charging temperature
- Your converter’s manual, to check for a lithium mode
- A DC-DC charger for the alternator: Victron Orion-Tr Smart 12/12-30 isolated
- A solar controller with a lithium setting: Victron SmartSolar MPPT 100/30
- A shunt monitor: Victron SmartShunt 500A, or the RV battery monitor kit
- Cable and fuses sized for the new current: Wire gauge calculator
- A licensed electrician for any 120V work, like swapping the converter in the power center
The conversion, step by step
- Isolate the battery. Unplug shore power, turn off the generator and solar, then disconnect the battery negative.
- Get the battery maker’s numbers. Write them on one card.
- Set the converter’s lithium profile, or have a licensed electrician replace it (120V).
- Size cable first, then fuses, for any new charging path.
- Fit a DC-DC charger on the line from the alternator to the house battery.
- Switch the solar controller to its lithium profile.
- Fit a shunt monitor on the negative side and set it for lithium.
- Reconnect, then watch the first full charge on your phone.
You can do this. Take it one charging source at a time.
Start with the battery maker’s numbers
Every setting below comes back to this card. Here’s one maker’s example. Victron’s 12.8 V Smart lithium battery:
| Victron Lithium Battery Smart 12.8 V | Maker’s figure |
|---|---|
| Charge voltage | 14.0 to 14.4 V (14.2 V recommended) |
| Float voltage | 13.5 V |
| Charging temperature | +5°C to +50°C |
Victron’s manual is blunt about the cold. Charging below 5°C causes permanent cell damage. That’s the cold-charge limit, and in an RV parked in winter it matters.
Your battery may differ. Use your maker’s numbers, not these. For the bigger picture, see Lithium vs lead-acid batteries for boats, vans and RVs. Sizing the bank comes first: Battery bank size calculator.
Does my RV converter work with lithium?
Check your converter’s manual. Some have a lithium mode or a lithium version. Some charge only on a lead-acid profile.
One example with a printed spec: Progressive Dynamics’ PD9100L series is a lithium-only converter. Its manual says the 12V models give a nominal 14.6 V, at 30 to 80 A depending on model. It also says not to use it on lead-acid.
Now compare that 14.6 V to your battery card. Victron’s example range is 14.0 to 14.4 V. Your battery maker decides what’s right, not the converter.
If your converter has no lithium setting, you have two routes:
- Have a licensed electrician swap the converter for a lithium model. It sits on the 120V side of the power center.
- Add a shore charger with a Li-ion mode, like the Victron Blue Smart IP22 12/30 120V. Victron prints 14.2 V absorption in Li-ion mode. It plugs into a standard 120V outlet. More in Shore power charging: Blue Smart IP22 vs IP65.
Can the alternator charge lithium directly?
Don’t count on it. Victron’s lithium manual warns that lithium takes a much higher charge current than lead-acid, and that care is needed to avoid overloading the alternator.
The fix is a DC-DC charger. The Orion-Tr Smart 12/12-30 isolated charges at up to 30 A. Victron’s manual says controlled charging protects the alternator in lithium systems. It also detects when the engine is off and stops pulling from the start battery.
Set it up for lithium: – Pick a battery preset that matches your battery, or enter your maker’s numbers. – On lithium, the Orion’s absorption time is fixed, default 2 hours.
Wire it right. Victron calls for a 60 A fuse at each battery end, and cable from 6 to 16 mm² (AWG 6 max) depending on run length. Size each run in the Wire gauge calculator first, then fit the fuse. The boat version of this job is in Charging lithium from a boat alternator: Orion-Tr vs Cyrix vs combiner. For which Orion to buy, see Orion-Tr isolated vs non-isolated.
What about my solar controller?
Switch it to lithium. The SmartSolar MPPT 100/30 has a LiFePO4 preset with 14.2 V absorption on 12V. Victron’s default lithium absorption time is 2 hours, and you can adjust both.
Then deal with the cold. The MPPT has a low temperature cut-off. It’s off by default. Turn it on and the default is 5°C. It only works when the controller gets a battery temperature reading over Victron’s VE.Smart network, from a Battery Sense, or from a battery monitor fitted with a temperature sensor.
Victron adds two notes. Some batteries block cold charging on their own, so the setting isn’t needed for those. And check the lithium supplier’s figure before you rely on 5°C.
Victron’s manual gives a 35 to 40 A battery fuse for the 100/30.
Why add a battery monitor?
Voltage tells you little on lithium. Victron’s lithium manual says the battery doesn’t calculate its own state of charge, and points you to a BMV or SmartShunt.
The Victron SmartShunt 500A goes on the negative side. Its defaults are for lead-acid, so change them. For a 12V lithium bank, Victron’s manual gives 13.9 V as the charged voltage. Set it just below your charger’s absorption voltage. Full settings are in SmartShunt setup for lithium: the settings that matter.
The SmartShunt can also share battery voltage, current and, with its optional temperature sensor fitted, temperature with Victron chargers over VE.Smart. That’s how the solar controller gets the temperature reading it needs for the cold cut-off. The RV battery monitor kit puts the shunt and its parts in one box.
Does this guide fit your RV?
This applies if: – Your RV has a 12V house bank on lead-acid, and you’re moving to a 12V lithium (LiFePO4) battery. – You charge from a converter, the engine alternator, solar, or any mix.
This doesn’t apply if: – Your RV runs a 24V or 48V house bank. The steps hold, but the parts above are 12V. – Your lithium battery came as part of a full system from the RV maker. Follow their manual. – The job touches the 120V panel, shore inlet or generator wiring. That needs a licensed electrician.
Products used in this guide
| Product | Why it’s here |
|---|---|
| Victron Orion-Tr Smart 12/12-30 isolated | 30 A DC-DC charger between the alternator and the house battery. |
| Victron SmartSolar MPPT 100/30 | Solar controller with a LiFePO4 preset and a cold cut-off. |
| Victron SmartShunt 500A | State of charge on your phone and, with its temperature sensor, a temperature feed for the chargers. |
| Victron Blue Smart IP22 12/30 120V | 30 A shore charger with a Li-ion mode, if your converter has none. |
Prices show live from the store.
Quick answers
Do I need a new converter for lithium batteries in my RV? Only if yours has no lithium setting that matches your battery maker’s voltages. Check the manual. If it doesn’t, swap it (licensed electrician) or add a shore charger with a Li-ion mode.
Can I charge RV lithium from the engine alternator? Yes, through a DC-DC charger. Victron says controlled charging protects the alternator, because lithium can pull far more current than lead-acid.
Can I charge lithium in freezing weather? Not below your battery maker’s limit. Victron’s limit is 5°C, and charging colder causes permanent damage. Use a battery that blocks cold charging, or a cold cut-off on the charger with a temperature sensor.
Do my 12V lights and appliances need to change? Not for the battery swap itself. The changes are in the charging sources and the monitor.
Is a battery monitor really needed? Victron says its lithium battery doesn’t work out state of charge itself and recommends a BMV or SmartShunt. Without one, you’re guessing.
Sources
- Victron 12.8 & 25.6 V Lithium-Iron-Phosphate Batteries Smart datasheet: https://www.victronenergy.com/upload/documents/Datasheet-12,8-&-25,6-Volt-lithium-iron-phosphate-batteries-Smart-EN.pdf
- Victron Lithium Battery Smart manual: https://www.victronenergy.com/upload/documents/Lithium_Battery_Smart/15958-Manual_Lithium_Smart_Battery-pdf-en.pdf
- Progressive Dynamics PD9100L Series owner’s manual: https://www.progressivedyn.com/wp-content/uploads/2017/05/110621A-English.pdf
- Victron Orion-Tr Smart DC-DC Charger Isolated manual: https://www.victronenergy.com/upload/documents/Orion-Tr_Smart_DC-DC_Charger_-_Isolated/34439-Orion-Tr_Smart_DC-DC_Charger-pdf-en.pdf
- Victron MPPT solar charger manual (SmartSolar MPPT 100/30 & 100/50): https://www.victronenergy.com/upload/documents/Manual_SmartSolar_MPPT_100-30__100-50/29694-MPPT_solar_charger_manual-pdf-en.pdf
- Victron SmartShunt manual: https://www.victronenergy.com/upload/documents/SmartShunt/9172-Manual_BMV_and_SmartShunt-pdf-en.pdf
- Victron Blue Smart IP22 Charger 120 VAC datasheet: https://www.victronenergy.com/upload/documents/Datasheet-Blue-Smart-IP22-Charger-120-VAC-EN-.pdf
