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 a lead-acid profile (overvoltage is destructive). All Victron Blue Smart, Skylla-i, and MultiPlus chargers have LFP profile as standard in 2026.
- Distributed brands: Victron Blue Smart IP65 12V 25A (~ 350 € ex VAT), 24V 13A (~ 215 € ex VAT), 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+ ft.
- 230 V harbor power: 60 A 12 V charger = 800 W on AC side = 3.5 A at 230 V. Always below the standard 16 A harbor outlet.
The dockside charger is the forgotten component in a lithium refit. After replacing the bank, the old lead-acid dockside charger is often kept — slowly destroying the new cells with an unsuitable charge profile. This article explains correct sizing and the brands stocked at Skysat.
For the lithium bank it powers, see sizing 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 recharge but reduces lifespan.
LFP profile — why it is mandatory
The charger applies a specific charge 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 € ex VAT. For 80–120 Ah 12 V lithium banks.
- Blue Smart IP65 24V 13A: ~ 215 € ex VAT. For 24 V 50–100 Ah banks.
- Blue Smart IP67 12V 50A: ~ 480 € ex VAT. 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 a single 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 € ex VAT.
- MultiPlus II 12/3000-120: new version, integrated monitoring. ~ 1 950 € ex VAT.
- MultiPlus II 24/5000-120: 120 A 24 V + 5 000 W inverter. ~ 2 800 € ex VAT. For 45+ ft yachts.
Benefit: space saving in the technical locker (1 unit instead of 2), intelligent management of harbor power (limits input current if breaker trips).
Skylla-i and Mastervolt ChargeMaster — premium
- Victron Skylla-i 24V/100A: ~ 1 200 € ex VAT. Professional marine charger, IP21.
- Mastervolt ChargeMaster Plus 12/35-3: ~ 580 € ex VAT. 3 independent outputs (house/start/3rd bank).
- Mastervolt ChargeMaster Plus 12/50-3: ~ 750 € ex VAT.
- Mastervolt ChargeMaster Plus 24/20-3: ~ 680 € ex VAT for 24 V yachts.
2026 model comparison table
| Model | Voltage | Current | Outputs | Price ex VAT |
|---|---|---|---|---|
| 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
- 230 V 3-wire cable (live + neutral + earth): 1.5 mm² up to 16 A, 2.5 mm² above that.
- 30 mA RCD between harbor outlet and charger (ISO 13297 standard).
- Bonding earth link: mandatory between charger case 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.
- Set LFP profile via VictronConnect before commissioning.
FAQ — 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. Mandatory replacement for lithium conversion.
Is a charger too powerful for my bank?
Not dangerous but pointless. A 100 A charger on a 100 Ah bank will charge 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 many hours 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 in harbor is plenty.
Are multi-bank outputs essential?
Useful if you have multiple banks (house + start + 3rd bank). The Mastervolt ChargeMaster Plus 3 outputs charges each bank intelligently. Otherwise, a single-output charger + Argofet (battery separator) at 80–120 € ex VAT.
What harbor power is available?
Standard French/European harbor outlet: 16 A single-phase = 3 680 W max. Premium ports on the French Riviera: 32 A = 7 360 W. Always below the port and boat breakers.
Skysat distributes Victron Energy and Mastervolt. 2026 ex VAT prices are indicative distributor rates.
