Smart Battery Chargers


Although not entirely essential for starter batteries that get regular use, a smart charger to take care of leisure batteries is absolutely essential.

If you have arrived here from the link on my 'batteries' page, you will already be aware of how deep cycle batteries behave, and how they are able to survive for many years if looked after properly. This is where the smart charger comes in its own.

As with so many things, smart chargers come in many shapes and sizes. We are going to concentrate on simple mains operated smart chargers that are going to care of our battery banks. When we are on the move we'll leave the alternator to do the work.

If your needs are more complex I would suggest direct professional advice for your own individual circumstances and set up.

Before you buy any type of charger you should consider how much work it's going to have to do and where it's going to be sited. The standard recommendation for charger amperage is that it should be at least 10% of battery capacity. However, if like me, your boat normally has mains power and your alternator provides sufficient power for your leisure needs whilst your travelling, you can do the job more cheaply by purchasing a lower amperage unit and still take care of your leisure bank.

We mentioned siting of your smart charger earlier. Clearly it needs to be in reasonable proximity to your batteries, but not directly above them. Additionally there is the question of humidity. My Victron in in the canvas canopied wheelhouse. This place is not directly affected by rain, but it can get quite hot in summer and does suffer from a level of condensation in colder weather. As live aboards all year round we're generating warm moist air that does rise up into the wheelhouse. This can and does generate condensation. It is with this in mind that I made my buying choice. I'd like to introduce you to the 'IP' descriptor commonly displayed in the equipment's description.

'IP' or 'Ingress Protection' is your guide to the level of protection a piece of equipment has against ingress of both dust and moisture. My own Victron has a rating of IP67. The first number designates resistance to dust. The range is from 0 to 6, where '0' offers no protection and '6' is totally dust proof. On this basis my Victron is completely dust proof. The second digit in the IP67 rating refers to protection against ingress of moisture. In this case the range is 0 to 8, where '0' is no protection and 8 is waterproof under one metre of water. Here is the full description.

Where a number is replaced with an 'x' it means that the item has not been rated for that property

You can see that with an IP67 rating, my Victron charger is pretty waterproof and so should deal easily with any airborn condensation. To deal with summer heat I've placed the unit under my chart table. It has free air flow around it and is always shaded from the sun.

Bear in mind that not everyone needs such a high IP rating. Victron do a similar charger to mine with a rating of IP22. This is not a bad thing because this unit is fan cooled where mine is solid state. As such, air flows through it when the fan is running If you check the ratings below you'll see why the rating appears low, but you'll also understand that in the right position this is not an issue. I needed a high level of protection against damp, but sincerely hope I never get to see the unit's submersion performance!

Here's an International link to Victron chargers, smart types and others. Works in USA, Australia, United Kingdom and Canada. Be sure to check for the correct mains voltage as I have noticed 115 volts available in the UK. Don't forget that if you can't see exactly what you want, you can use the 'search' function on any ebay page you are seeing. On this occasion I'm not using visual links, as the text links are producing better results.

IP Ratings - See what they mean.

IP Rated Enclosures - quick find chart

First Digit (intrusion protection)

0 - No special protection
1 - Protection from a large part of the body such as a hand (but no protection from deliberate access); from solid objects greater than 50mm in diameter.
2 - Protection against fingers or other object not greater than 80mm in length and 12mm in diameter.
3 - Protection from entry by tools, wires etc, with a diameter of 2.5 mm or more.
4 - Protection against solid bodies larger than 1mm (eg fine tools/small etc).
5 - Protected against dust that may harm equipment.
6 - Totally dust tight.

Second Digit (moisture protection)

0 - No protection. 1 Protection against condensation.
2 - Protection against water droplets deflected up to 15° from vertical
3 - Protected against spray up to 60° from vertical.
4 - Protected against water spray from all directions.
5 - Protection against low pressure water jets (all directions)
6 - Protection against string water jets and waves.
7 - Protected against temporary immersion.
8 - Protected against prolonged effects of immersion under pressure.

IP 67 Enclosures - IP rated as "dust tight" and protected against temporary immersion. This is my smart charger rating