Battery Location


Often overlooked, and not given too much thought, is the location of your batteries. I understand why though. The boat builder typically dictates the battery location, and we simply live with it. Most modern boat builders follow ABYC Standards and Guidelines, so the location is most likely adequate and safe.

Issues generally arise when you purchase an older boat. Older boats typically mean multiple owners. Multiple owners typically mean multiple modifications to the boat. Relocating batteries tends to be on that modification list.

So, this article will cover what I consider to be the three most important factors when it comes to the location of your batteries.

 Factor #1: A safe location. By far the most important factor. The location should be safe for the batteries, safe for your boat equipment, and most importantly… safe for everyone on board.

When it comes to a safe location for the batteries, it has mostly to do with what’s in the immediate area of the battery. Installing batteries directly next to the engines is less than ideal due to the heat generated from the engine, as well as all the mechanical movement taking place. Installing batteries where they may succumb to water, bilge debris, and various engine liquids… aka the bilge area, is also less than ideal. Batteries enjoy being clean and dry. Don’t create a safe location for your batteries just to then fill the area up with random boat essentials, tools, spare parts, etc. I have seen a great battery bank compartment naively turned into a toolbox. Loose wrenches, hammers, and jumper cables just hanging out right next to the batteries. Don’t worry though, that battery compartment became great again after conversing with the boat owner.


All boat equipment and parts should not be mounted directly above the battery due to the possibility of corrosive fumes venting from the battery caps/vents. Some examples of equipment/parts which should not be directly mounted above the battery are Battery Chargers, Inverters, battery combiners, and fuel system parts (lines, tanks, filters). In a perfect world, you wouldn’t have anything mounted directly above the batteries. When it comes to boats though, a perfect world doesn’t exist. If your boat does have equipment mounted above the battery, make sure it’s mounted as far up as possible and with an intervening barrier between the top of the battery and the equipment. You also don’t want to install a battery directly above the equipment either. Especially if you have Flooded Lead Acid Batteries. Spilled Electrolyte can and will ruin most boat equipment and parts. So, if your batteries are installed above the equipment, you must ensure there is an intervening barrier that can handle spilled electrolyte.

The location of your battery should not be a safety concern to you and your guests. Unfortunately, the more boats I step on, the more often I see someone choosing a battery location that puts them and their guests in a potentially dangerous situation. I have seen a flooded Lead Acid battery (an Everstart for lawn equipment to be exact) for the windless placed in a cabinet directly above the V-berth bed. This battery wasn’t even secured down, nor in any sort of battery tray or box. I have also seen lead acid batteries installed directly under bench seat cushions for bow thrusters. The only intervening barrier between the top of the batteries and your guest’s butt cheeks is some fiberglass and a cushion. I would not rely on that intervening barrier to provide adequate protection if one or both of those batteries decided to have a catastrophic failure. Not only should catastrophic failures be of concern, but also the potential of hydrogen gases being discharged (when charging) from lead acid batteries as well.

And for you sailors, take into consideration your battery location when it comes to the angle of your heeling. This is crucial for flooded lead acid batteries. Your battery should be installed port to starboard and not bow to stern. If the angle is great enough, there is a high probability you will leak electrolyte from the top caps and expose the top portion of the plates. When plates are exposed (not covered in the electrolyte) you will greatly dimmish the service life of your battery, especially when the battery is charging and discharging.

Here are the relevant ABYC Standards to the above factor:

E-10.7.5 Batteries shall not be installed directly above or below a fuel tank, fuel filter, or fitting in a fuel line without an intervening sole, floor, or deck. NOTE: This does not prohibit a battery from being installed directly above or below an uninterrupted fuel line.

E-10.7.7 Batteries shall not be installed, without an intervening barrier, directly below electrical equipment susceptible to attack from corrosive gasses.

A-31.6.6 To avoid corrosive fumes, battery chargers, inverters, and inverter/chargers shall not be installed directly over lead-acid batteries.

NOTE: Consideration should be given to:

  1. The type of battery installed (e.g., liquid electrolyte or immobilized electrolyte)
  2. The boat in which the battery is installed (e.g., angles of heel for sailboats and accelerations for powerboats


Factor #2: Distance from largest, primary load(s). The closer your battery is to its primary load(s), the better. Many perks come from having the battery close to the primary load(s). Less voltage drop (if wire/cable is sized correctly). Shorter wire/cable runs make it easier to properly route and secure. Also, the shorter the run, the less likely a fault will occur. But if one does occur, it will be far easier to troubleshoot.


Factor #3: Accessibility. This factor is short and simple. The easier it is to get to your batteries, the easier it is to provide them with maintenance and care. When it’s easy, you are more apt to do it. If you must become a contortionist and double jointed to get to your batteries, you may want to rethink that location as your batteries will most likely become neglected. A neglected battery will end up hating you and thus provide you with lousy service life.


CAVEAT: It’s all a give and take on a boat. You certainly “can’t have your cake and eat it too”. You may not be able to achieve all the above factors. And that’s ok. The only two factors I want you to achieve with every project and installation are Safety (meeting the ABYC Standards) and Reliability. Everything else is just a bonus.

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