Post by HONDAM on Apr 18, 2011 22:18:16 GMT -5
The electrical system is the nerve system of the boat and it is very important to keep that system in proper condition with sufficient capacity. The center of the electrical system is the battery and the following is a brief explanation of how a battery and charging system works and methods and equipment to keep it in proper condition.
Most of us use Lead Acid type batteries, these batteries consist of Lead, Sulfuric Acid, water, and a plastic shell. A 12 volt battery is actually 6 2.1 volt cells in series for a total of 12.6 volts. When at 12.6 volts a battery ideally consists purely of its base elements. As it is discharged the acid and the lead combines to form lead sulfate and as it is recharged the lead sulfate is separated back to its base elements of Lead and Sulfuric Acid while sacrificing some water.
As a battery is continually cycled not all of the lead sulfate is broke down all the way and the battery starts to diminish capacity. Also if the battery is discharged for any long period of time the Lead Sulfate will crystallize and cannot be broken down so it is very important to maintain your batteries at 80%+ capacity as much as possible.
So now that is how a battery works, now what about the electrical system of the boat. The battery has an amp-hour rating which indicates how long a battery will last before it is completely discharged. For example if a battery has a 125 amp-hour rating and there is a 20 amp load on the battery then the battery will last roughly 6.25 hours. Every piece of electrical equipment in the boat has some sort of amperage draw, if you add all of the equipment up in the boat then that will indicate your total load and compare that to your batteries capacity. If you have a charging system on the boat you can subtract that from the load of your electronic equipment and get a net load. This is why the charging system on a boat is key because if you start adding up the electric downriggers, GPS, Sonar, VHF, autopilot, stereo, lights, and anything else you have on it starts to add up and will suck your battery down quickly if there is not sufficient charging. The difference between 6 amps and 12 amps may not sound like much but if you take that same 20 amp load and decrease it by the 6 amp difference the time you have on that battery goes from 6.25 hours to almost 9 hours.
One of the most common ways to boost the capacity of the electrical system of a boat is with the addition of a second battery to obtain more amp-hours. There are many ways to do this which some of the most common include: a battery switch, battery isolator, and a voltage sensitive relay (VSR).
The most common and least expensive (~$30) is the battery switch. The battery switch can be hooked up in many different ways depending on how many engines are involved and the user?s personal preference. Its general limitations are that it is impossible to charge both batteries at the same time while having the batteries isolated. It likely one will drain one or both batteries with your onboard electronics. If you do not have a high demand for power in the boat this is often the way to go though because it is an easy and inexpensive method of adding a battery.
Another method is the installation of a battery isolator (~$70). This distributes your engines charge to both batteries and does not allow one battery to draw from the other. This is a good option especially when combines with a battery switch but still has a couple drawbacks. One it can be more complicated to install and is not always compatible with all charging systems. Two it uses about .5 volts so it will never be able to restore your batteries to a full charge.
The third method and probably the best is the VSR. What the VSR does is it senses the voltage of your starting battery for the engines and when it is fully charge it diverts the charging power of the engines to the electronics battery. This VSR will not consume power like the isolator and will work on all applications. It can cost more than the other two options though. With the right kit it can be very easy to install as well. I installed the Honda Battery Management System (~$150) on my last project boat and have used one on the cat for years; it?s definitely the way to go.
I hope this helps someone, with the holidays over and spring around the corner it is a relatively inexpensive and effective upgrade you may want to consider for the upcoming season.
Also if you haven?t, make sure you top off your batteries once a battery is over 80% discharge the Lead Sulfate reaches its max and can damage the battery and you don?t want it to crystallize either. 16 weeks of being in storage a battery without being topped off it starts significant loss of capacity.
Most of us use Lead Acid type batteries, these batteries consist of Lead, Sulfuric Acid, water, and a plastic shell. A 12 volt battery is actually 6 2.1 volt cells in series for a total of 12.6 volts. When at 12.6 volts a battery ideally consists purely of its base elements. As it is discharged the acid and the lead combines to form lead sulfate and as it is recharged the lead sulfate is separated back to its base elements of Lead and Sulfuric Acid while sacrificing some water.
As a battery is continually cycled not all of the lead sulfate is broke down all the way and the battery starts to diminish capacity. Also if the battery is discharged for any long period of time the Lead Sulfate will crystallize and cannot be broken down so it is very important to maintain your batteries at 80%+ capacity as much as possible.
So now that is how a battery works, now what about the electrical system of the boat. The battery has an amp-hour rating which indicates how long a battery will last before it is completely discharged. For example if a battery has a 125 amp-hour rating and there is a 20 amp load on the battery then the battery will last roughly 6.25 hours. Every piece of electrical equipment in the boat has some sort of amperage draw, if you add all of the equipment up in the boat then that will indicate your total load and compare that to your batteries capacity. If you have a charging system on the boat you can subtract that from the load of your electronic equipment and get a net load. This is why the charging system on a boat is key because if you start adding up the electric downriggers, GPS, Sonar, VHF, autopilot, stereo, lights, and anything else you have on it starts to add up and will suck your battery down quickly if there is not sufficient charging. The difference between 6 amps and 12 amps may not sound like much but if you take that same 20 amp load and decrease it by the 6 amp difference the time you have on that battery goes from 6.25 hours to almost 9 hours.
One of the most common ways to boost the capacity of the electrical system of a boat is with the addition of a second battery to obtain more amp-hours. There are many ways to do this which some of the most common include: a battery switch, battery isolator, and a voltage sensitive relay (VSR).
The most common and least expensive (~$30) is the battery switch. The battery switch can be hooked up in many different ways depending on how many engines are involved and the user?s personal preference. Its general limitations are that it is impossible to charge both batteries at the same time while having the batteries isolated. It likely one will drain one or both batteries with your onboard electronics. If you do not have a high demand for power in the boat this is often the way to go though because it is an easy and inexpensive method of adding a battery.
Another method is the installation of a battery isolator (~$70). This distributes your engines charge to both batteries and does not allow one battery to draw from the other. This is a good option especially when combines with a battery switch but still has a couple drawbacks. One it can be more complicated to install and is not always compatible with all charging systems. Two it uses about .5 volts so it will never be able to restore your batteries to a full charge.
The third method and probably the best is the VSR. What the VSR does is it senses the voltage of your starting battery for the engines and when it is fully charge it diverts the charging power of the engines to the electronics battery. This VSR will not consume power like the isolator and will work on all applications. It can cost more than the other two options though. With the right kit it can be very easy to install as well. I installed the Honda Battery Management System (~$150) on my last project boat and have used one on the cat for years; it?s definitely the way to go.
I hope this helps someone, with the holidays over and spring around the corner it is a relatively inexpensive and effective upgrade you may want to consider for the upcoming season.
Also if you haven?t, make sure you top off your batteries once a battery is over 80% discharge the Lead Sulfate reaches its max and can damage the battery and you don?t want it to crystallize either. 16 weeks of being in storage a battery without being topped off it starts significant loss of capacity.