The essentials in 30 seconds
- Rule of thumb: shore power 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 (destructive overvoltage). All Victron Blue Smart, Skylla-i, 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 inverter/charger combo: 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 rating.
The shore power charger is the forgotten component in a lithium refit. After replacing the bank, the old lead-acid shore charger is often kept — slowly destroying the new cells with an unsuitable charge 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. That is:
- 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’s mandatory
The charger applies a specific charge profile based 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 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 setup. IP65/67 = acceptable waterproofing in damp lockers.
Victron MultiPlus — inverter/charger combo
The MultiPlus combines a 50–200 A shore charger + 800–5,000 W DC/AC inverter in one enclosure. Automatic transfer between shore 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: saves space in the technical locker (one unit instead of two), intelligent management of harbor power (limits input current if breaker trips).
Skylla-i and Mastervolt ChargeMaster — high-end
- 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 — shore power charger wiring
- 230 V 3-wire cable (phase + neutral + ground): 1.5 mm² up to 16 A, 2.5 mm² above.
- 30 mA RCD between harbor outlet and charger (ISO 13297 standard).
- Bonding to boat ground: mandatory between charger case and boat ground.
- DC cable sized at 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 — Shore power chargers 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 is 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 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.
Is a multi-battery output essential?
Useful if you have multiple banks (house + start + 3rd). The ChargeMaster Plus 3-output Mastervolt charges each bank intelligently. Otherwise, a single-output charger + Argofet (battery separator) at $80–120 ex VAT works.
What harbor outlet power is available?
Standard French/European harbor outlet: 16 A single-phase = 3,680 W max. Premium Mediterranean ports: 32 A = 7,360 W. Always below the harbor breaker and the boat’s breaker.
Skysat distributes Victron Energy and Mastervolt. 2026 ex VAT prices are indicative distributor rates.
