The essentials in 30 seconds
- Rule of thumb: dockside charger at 30% of the raw lithium bank capacity. 200 Ah bank = 60 A charger minimum. 400 Ah bank = 120 A charger.
- Mandatory LFP profile. Never use lead-acid profile (overvoltage destructive). All Victron Blue Smart, Skylla-i, and MultiPlus chargers have LFP profile as standard in 2026.
- Brands stocked: Victron Blue Smart IP65 12V 25A (~ 350 € HT), 24V 13A (~ 215 € HT), Skylla-i 24V 100A (~ 1 200 €), Mastervolt ChargeMaster.
- MultiPlus combo inverter: 120–200 A charger + 3 000 W inverter in a single unit. Skysat standard for compact sailboat refits 40+ feet.
- 230 V port power: 60 A 12 V charger = 800 W AC side = 3.5 A at 230 V. Always below the 16 A standard marina power.
The dockside charger is the forgotten component of a lithium refit. After replacing the bank, the old lead-acid dockside charger is often kept — slowly destroying the new cells with an unsuitable charging profile. This article explains correct sizing and the brands stocked by Skysat.
For the lithium bank it powers, see how to size a sailboat lithium bank.
Sizing the charger for a lithium bank
Rule of thumb: 30% of raw bank capacity. Example:
- 100 Ah bank → 30 A charger minimum.
- 200 Ah bank → 60 A charger.
- 400 Ah bank → 120 A charger (prefer MultiPlus combo).
- 600+ Ah bank → 150–200 A charger (MultiPlus II).
Why 30%? A compromise between recharge speed (bank charged to 80% DoD in 3–4 h) and cell longevity (thermally acceptable rate, no stress). Going beyond (50%) speeds up recharge but reduces lifespan.
LFP profile — why it’s mandatory
The charger applies a specific charging profile depending on battery chemistry. For LiFePO4:
- Bulk: 14.4 V (12 V bank) or 28.8 V (24 V bank), maximum current.
- Absorption: 14.4 V for 30–60 min until full charge.
- Float: 13.5–13.8 V (never continuous 14.4 V = cell stress).
A lead-acid profile (14.7 V absorption + permanent 13.8 V float) on lithium destroys cells in 6–12 months. All modern Victron chargers have selectable LFP profile via VictronConnect.
Victron Blue Smart — entry and mid-range
- Blue Smart IP65 12V 25A: ~ 350 € HT. For 80–120 Ah lithium banks.
- Blue Smart IP65 24V 13A: ~ 215 € HT. For 24 V 50–100 Ah banks.
- Blue Smart IP67 12V 50A: ~ 480 € HT. For 150–200 Ah banks.
Smart = Bluetooth via VictronConnect for monitoring + LFP profile configuration. IP65/67 = acceptable waterproofing in damp lockers.
Victron MultiPlus — inverter combo
The MultiPlus combines a 50–200 A dockside charger + DC/AC inverter 800–5 000 W in one enclosure. Automatic transfer between shore power and battery in under 20 ms.
- MultiPlus 12/3000-120: 120 A charger + 3 000 W inverter. ~ 1 850 € HT.
- MultiPlus II 12/3000-120: new version, integrated monitoring. ~ 1 950 € HT.
- MultiPlus II 24/5000-120: 120 A 24 V + 5 000 W inverter. ~ 2 800 € HT. For 45+ foot yachts.
Benefit: saves space in the technical locker (1 unit instead of 2), intelligent management of marina power (limits input current if breaker trips).
Skylla-i and Mastervolt ChargeMaster — high-end
- Victron Skylla-i 24V/100A: ~ 1 200 € HT. Professional marine charger, IP21.
- Mastervolt ChargeMaster Plus 12/35-3: ~ 580 € HT. 3 independent outputs (house/start/3rd bank).
- Mastervolt ChargeMaster Plus 12/50-3: ~ 750 € HT.
- Mastervolt ChargeMaster Plus 24/20-3: ~ 680 € HT for 24 V yachts.
2026 model comparison chart
| Model | Voltage | Current | Outputs | Price HT |
|---|---|---|---|---|
| Blue Smart IP65 12V 25A | 12 V | 25 A | 1 | ~ 350 € |
| Blue Smart IP65 24V 13A | 24 V | 13 A | 1 | ~ 215 € |
| Blue Smart IP67 12V 50A | 12 V | 50 A | 1 | ~ 480 € |
| MultiPlus 12/3000-120 | 12 V | 120 A + 3 kW inverter | 2 | ~ 1 850 € |
| Mastervolt ChargeMaster Plus 12/35-3 | 12 V | 35 A | 3 outputs | ~ 580 € |
| Mastervolt ChargeMaster Plus 12/50-3 | 12 V | 50 A | 3 outputs | ~ 750 € |
| Skylla-i 24V/100A | 24 V | 100 A | 1 | ~ 1 200 € |
Installation and 230 V wiring
Workshop rules — dockside charger wiring
- 3-wire 230 V cable (live + neutral + earth): 1.5 mm² up to 16 A, 2.5 mm² above that.
- 30 mA RCD between marina socket and charger (ISO 13297 standard).
- Bonding earth link: mandatory between charger casing and boat ground.
- DC cable sized for max current + 30%: Blue Smart 50 A → 10 mm² minimum.
- Class T fuse on charger output: rated 1.5× nominal current.
- Program LFP profile via VictronConnect before commissioning.
FAQ — Using a dockside charger in practice
Can my old lead-acid charger charge lithium?
No, never. Lead-acid profile (14.7 V absorption + permanent 13.8 V float) destroys lithium cells in 6–12 months. Replacement mandatory for lithium conversion.
Is a charger too powerful for my bank?
Not dangerous but pointless. A 100 A charger on a 100 Ah bank charges in 1 h instead of 3 h, but adds thermal stress and current not absorbed (BMS limits). No technical or economic benefit. Stick to the 30% rule.
How long to recharge a 200 Ah bank?
With a 60 A charger: ~ 3 h Bulk + 1 h Absorption = 4 h to go from 20% to 100% SOC. One night at the marina is plenty.
Are multi-battery outputs essential?
Useful if you have multiple banks (house/start/3rd). The Mastervolt ChargeMaster Plus 3 outputs charge each bank intelligently. Otherwise, a single-output charger + Argofet (battery separator) at 80–120 € HT.
What marina power is available?
Standard French/European marina power: 16 A single-phase = 3 680 W max. Premium Mediterranean ports: 32 A = 7 360 W. Always below the marina breaker (and the boat’s).
Skysat stocks Victron Energy and Mastervolt. 2026 HT prices are indicative distributor rates.
