Choose a smart charger sized to roughly 10–20% of your battery bank's amp-hours, with the right charge profile for your battery type. A 200Ah bank wants a ~20–40A charger; lithium needs a lithium-specific profile or it won't fully or safely charge. This guide covers sizing the charger, why the charge profile matters, and how a charger, a converter, and an inverter/charger differ.
Step 1 — Size the charger to your bank
Charge current is usually sized at about 10–20% of bank capacity (C/5 to C/10): a 200Ah bank pairs well with a 20–40A charger. Bigger chargers refill faster but draw more shore power; lithium can accept higher rates than lead-acid.
| Battery bank | Charger size (typical) |
|---|---|
| 100Ah | 10–20A |
| 200Ah | 20–40A |
| 300–400Ah | 40–60A+ |
Step 2 — Match the charge profile
This is the part people miss. A charger set for lead-acid/AGM won't correctly charge lithium — you need a lithium (LiFePO4) profile or a selectable multi-chemistry smart charger. Smart chargers also multi-stage (bulk/absorption/float) to protect the battery and top it fully.
Step 3 — Charger vs converter vs inverter/charger
- Battery charger: dedicated smart charger from shore/AC — best for precise, healthy charging (e.g. Victron Blue Smart).
- Converter/charger: the RV's built-in 120V→12V unit; older ones lack a lithium profile and may need upgrading.
- Inverter/charger: combines charging + inverting + transfer switching (e.g. MultiPlus) — one box for a full power system.
Building a system? See how to choose an RV inverter and battery buying guide. For charging while driving, add a DC-DC charger.
Features to look for
- Selectable lithium/AGM/gel profiles
- IP-rated/water-resistant housing for RV environments
- Bluetooth monitoring and multi-stage charging
- Multiple outputs if charging a start + house battery
Our picks by use-case
- Simple shore charging: a smart charger ~20A with a lithium profile (e.g. Victron Blue Smart) — shop smart battery chargers.
- Full power system: an inverter/charger for charging + AC in one.
- Charge on the move: add a DC-DC charger alongside shore charging.
FAQ
What size battery charger do I need?
About 10–20% of your bank's amp-hours — a 200Ah bank pairs with a 20–40A charger. Lithium tolerates higher rates than lead-acid.
Can I charge lithium with my existing RV converter?
Only if it has a lithium profile. Many older converters are lead-acid-only and should be upgraded to a lithium-capable smart charger.
Charger or inverter/charger — which should I buy?
A standalone smart charger is simplest for shore charging; an inverter/charger adds inverting and transfer switching if you want a full system.
Do I still need a DC-DC charger?
Yes if you want to charge from the alternator while driving — a shore charger only works when plugged in.
Charge it right: Shop RV battery chargers — in stock, ships from Upland, CA.