Ensuring a Safe Space for Batteries

As our hunger for amps increases, so too should our attention to ventilation of battery spaces.

By
Darrell Nicholson
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The battery space under a berth on this 45-foot catamaran is designed with an active ventilation system that sucks hot air out of the battery compartment and vents it overboard. A vent register allows ample airflow from the cabin into the space. A fire port with nearby extinguisher is accessible from the cockpit. Lithium batteries don’t vent gasses, but venting this space via a high temperature silicone hose reduces heat build up and offers an extra measure of smoke protection in case of fire. Containment in a stainless steel fireproof box is another option. Internal sensors on this 200AH LiFePO battery from CMPower, lets the crew monitor the status of each cell via a smart-phone app. Passive ventilation is sufficient for most battery spaces, including lead acid.

When charging, lead acid batteries generate hydrogen from the electrolysis of water, and some acid gases, the amount of which vary with the battery design, charging rate and state of charge. Hydrogen is explosive at concentrations above 4 percent and acid gases cause corrosion. This is why automobiles with batteries located under a seat or in the trunk are always vented outside through a vent tube. Some batteries designed for applications inside a vehicle are equipped with vent hose fittings, but most are not. Vehicle trunks are very poorly ventilated, and vehicle cabins are essentially unventilated when the vehicle is sitting still.

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Ensuring a Safe Space for Batteries
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Darrell Nicholson
Darrell Nicholson
Darrell Nicholson is Director of Belvoir Media Group's marine division and the editor of Practical Sailor. A lifelong thalassophile, he grew up sailing everything from El Toro dinghies to classic Morgans on Miami's Biscayne Bay. In the early 90s, he left a newspaper job to sail an old gaff-rigged ketch across the Pacific and has been writing about boats and the sea ever since. His weekly blog Inside Practical Sailor offers an inside look at current research and gear tests at Practical Sailor, while his award-winning column,"Rhumb Lines," tracks boating trends and reflects upon the sailing life. He sails a Sparkman & Stephens-designed Yankee 30 out of St. Petersburg, Florida. You can reach him at darrellnicholson.com.

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1 COMMENT

  1. Regarding the Quick-Fill wet cell battery fill system…I can recommend it without hesitation. Two years ago I was planning to replace all six of my 3+ year-old wet-cell batteries with AGM, but couldn’t overcome the $1,524 (+tax) total price delta and so I opted for new wet-cells and a $200 Flow-Rite Quick-Fill system (that Nigel Calder had highly recommended for significantly increasing the longevity of the batteries). As your article points out, the system allows me to remotely refill all battery cells to their recommended level without the time consuming hassle of removing all the boat’s mattresses, cushions and battery compartment access panels that [on my boat] have multiple screws. Moreover, no more removing each battery cap and dealing with ‘turkey baster bulb’ spills. Each month, I simply plug the system’s easily accessed filler hose into a bottle of distilled water and pump. The entire fill process for all the batteries now only takes <5 minutes rather than 60+ previously. One important note, according to FlowRite, the fill jug of distilled water must be located lower than the batteries when using the bulb pump…not sure why, but their tech support was adamant about this.