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 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 USD ex VAT), 24V 13A (~ $215 USD ex VAT), Skylla-i 24V 100A (~ $1,200 USD), Mastervolt ChargeMaster.
- MultiPlus combo inverter: 120–200 A charger + 3,000 W inverter in one unit. Skysat standard for compact sailboat refits 40+ ft.
- 230 V harbor power: 60 A 12 V charger = 800 W AC side = 3.5 A at 230 V. Always below the 16 A standard 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 your 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 balance 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’s 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 fully charged.
- 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 USD ex VAT. For 80–120 Ah 12 V lithium banks.
- Blue Smart IP65 24V 13A: ~ $215 USD ex VAT. For 24 V 50–100 Ah banks.
- Blue Smart IP67 12V 50A: ~ $480 USD ex VAT. For 150–200 Ah banks.
Smart = Bluetooth via VictronConnect for monitoring + LFP profile setup. 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 harbor power and battery in under 20 ms.
- MultiPlus 12/3000-120: 120 A charger + 3,000 W inverter. ~ $1,850 USD ex VAT.
- MultiPlus II 12/3000-120: new version, integrated monitoring. ~ $1,950 USD ex VAT.
- MultiPlus II 24/5000-120: 120 A 24 V + 5,000 W inverter. ~ $2,800 USD. For 45+ ft yachts.
Benefit: space saving in the technical locker (1 unit instead of 2), intelligent harbor power management (limits input current if port breaker trips).
Skylla-i and Mastervolt ChargeMaster — premium
- Victron Skylla-i 24V/100A: ~ $1,200 USD ex VAT. Professional marine charger, IP21.
- Mastervolt ChargeMaster Plus 12/35-3: ~ $580 USD ex VAT. 3 independent outputs (house/start/3rd bank).
- Mastervolt ChargeMaster Plus 12/50-3: ~ $750 USD ex VAT.
- Mastervolt ChargeMaster Plus 24/20-3: ~ $680 USD for 24 V yachts.
2026 model comparison chart
| Model | Voltage | Current | Outputs | Price ex VAT |
|---|---|---|---|---|
| Blue Smart IP65 12V 25A | 12 V | 25 A | 1 | ~ $350 USD |
| Blue Smart IP65 24V 13A | 24 V | 13 A | 1 | ~ $215 USD |
| Blue Smart IP67 12V 50A | 12 V | 50 A | 1 | ~ $480 USD |
| MultiPlus 12/3000-120 | 12 V | 120 A + 3 kW inverter | 2 | ~ $1,850 USD |
| Mastervolt ChargeMaster Plus 12/35-3 | 12 V | 35 A | 3 outputs | ~ $580 USD |
| Mastervolt ChargeMaster Plus 12/50-3 | 12 V | 50 A | 3 outputs | ~ $750 USD |
| Skylla-i 24V/100A | 24 V | 100 A | 1 | ~ $1,200 USD |
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.
- 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 recharges 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 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). Mastervolt ChargeMaster Plus 3 outputs charge each bank according to its needs. Otherwise, single-output charger + Argofet (battery separator) at $80–120 USD ex VAT.
What harbor power is available?
Standard 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 USD ex VAT prices are indicative distributor rates.
