Why every boat needs a modern battery charger
Flat batteries can leave your cruising plans tied to the dock, but the wrong charger can do more harm than good. Emrhys Barrell tests 10 portable units costing from £39 to £252.
If your boat is not fitted with a battery charger, a small portable unit is a useful and versatile addition: compact, relatively cheap and it can be used on your car as well as your boat. Even if your boat has a fixed battery charger, a portable one can give individual batteries a full charge at the end of the season. You can leave most of them permanently connected over the winter, keeping a bank of batteries in tip-top condition, or recharge a fully discharged battery.
If your boat relies on the engine alternator alone to keep the batteries charged, the portable charger can really come into its own. First, diesels don't like running unloaded, and second, the alternator regulator probably only ever allows the batteries to reach around 80% charge. A good portable charger keeps them at their maximum capacity.