I have a 26S and have rewired the boat. I have gone from one battier, to a two battier system. I put a four way switch in, OFF, 1, 2, Both. I have a solor panel and a small charging system coming off my engine. Can someone with more knowlege then me (which is anyone)in wiring all of this together to get the best out of everything help me.
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Electrical Upgrade
You have a good start on your primary DC system. You are going to wire the batterys and the engine charger and the solar panel all together, yet control them seperately. You need a DC ground bus as well. A terminal strip to join all of your DC negative returns together will make this easier. You should have already selected wire gauge to match the current carrying needs of your systems. Wire a battery positve run from bat 1 to the Bat 1 terminal of the battery switch. Wire a positive run from bat 2 to the the Bat 2 terminal of the battery switch. The switch also has an output terminal that gives the positive output of the switch to your cicuit breaker panel or your fuse panel. You also need a negative run from the negative bus bar to the circuit breakers/fuse panel. Both DC battery negative leads go to the negative bus bar. The output from your outboard charging system can be wired to the battery switch output terminal. By selecting a battery switch position you can control the charging of your batterys. It is worth noting that you should not disconnect the batterys from the alternator once it has started charging, unless you have some kind of load on your circuit breaker panel or without the necessary jumper that can be installed to avoid damage to your charge system, or unless you have shut down the motor. The solar panel may be directly wired to the batterys, but only if it puts out a small current. If it is a significant panel, you will want a charge controller to prevent frying your batterys. With this set up you can use either batterys or both, charge either battery or both from the motor, and if fitting, the solar panel will keep up your batterys during storage. I would recommend Nigel Calders books on boat wiring. Good Luck John S
You have a good start on your primary DC system. You are going to wire the batterys and the engine charger and the solar panel all together, yet control them seperately. You need a DC ground bus as well. A terminal strip to join all of your DC negative returns together will make this easier. You should have already selected wire gauge to match the current carrying needs of your systems. Wire a battery positve run from bat 1 to the Bat 1 terminal of the battery switch. Wire a positive run from bat 2 to the the Bat 2 terminal of the battery switch. The switch also has an output terminal that gives the positive output of the switch to your cicuit breaker panel or your fuse panel. You also need a negative run from the negative bus bar to the circuit breakers/fuse panel. Both DC battery negative leads go to the negative bus bar. The output from your outboard charging system can be wired to the battery switch output terminal. By selecting a battery switch position you can control the charging of your batterys. It is worth noting that you should not disconnect the batterys from the alternator once it has started charging, unless you have some kind of load on your circuit breaker panel or without the necessary jumper that can be installed to avoid damage to your charge system, or unless you have shut down the motor. The solar panel may be directly wired to the batterys, but only if it puts out a small current. If it is a significant panel, you will want a charge controller to prevent frying your batterys. With this set up you can use either batterys or both, charge either battery or both from the motor, and if fitting, the solar panel will keep up your batterys during storage. I would recommend Nigel Calders books on boat wiring. Good Luck John S
Looks Good But....
Do you want to have the ability to charge your batterys individually from the engine? The reason I ask is that the motor charge system can be tricked into sensing the voltage of the higher battery and terminate charging, if the batterys have different charge status, or if you have two different types of batterys or even two batterys of different age. The current regs also want you to have current limiters at the positive cable for your solar and motor charging inputs. These limiters are more than the output values of the charge units, yet able to prevent fires from direct shorts, since you will have always hot cables running to your charging sources. Another good item to consider for your system is a digital voltmeter, which are getting really cheap now. You can see charge state, charging output, which might tell you to remove the solar panel or not charge the batterys from your motor. That is why I would put the motor charge at least on the other side of the battery switch. Good luck and send pictures
Do you want to have the ability to charge your batterys individually from the engine? The reason I ask is that the motor charge system can be tricked into sensing the voltage of the higher battery and terminate charging, if the batterys have different charge status, or if you have two different types of batterys or even two batterys of different age. The current regs also want you to have current limiters at the positive cable for your solar and motor charging inputs. These limiters are more than the output values of the charge units, yet able to prevent fires from direct shorts, since you will have always hot cables running to your charging sources. Another good item to consider for your system is a digital voltmeter, which are getting really cheap now. You can see charge state, charging output, which might tell you to remove the solar panel or not charge the batterys from your motor. That is why I would put the motor charge at least on the other side of the battery switch. Good luck and send pictures
Your diagramed system won't work, unless
YOu put diodes in the wires from the charging sources before each battery. As you have it drawn, the two batteries are in parrallel because of the leads from the charging sources. Since both are pretty low amp, diodes would make them very inefficient. I'd wire the sources to the common on the battery switch, that way you use and charge at the same time on the same battery. If you really wanted to charge one while using the other, you need another 1/2/all switch or two single pole switches.
YOu put diodes in the wires from the charging sources before each battery. As you have it drawn, the two batteries are in parrallel because of the leads from the charging sources. Since both are pretty low amp, diodes would make them very inefficient. I'd wire the sources to the common on the battery switch, that way you use and charge at the same time on the same battery. If you really wanted to charge one while using the other, you need another 1/2/all switch or two single pole switches.
won't work
The switch won't do anything in this config unless you do something like Mr Cassel suggests. The batteries are tied together thru the charging circuit. Try these suggestions:
The switch won't do anything in this config unless you do something like Mr Cassel suggests. The batteries are tied together thru the charging circuit. Try these suggestions:
One battery bank or two?
Also keep in mind that batteries only have two terminals. Im curious why you need two seperate batteries on a boat like a 26S? Seems to me that if you MUST have some sort of battery to run/start the motor, then you might need to have dedicated starting battery but on a 26C (or most sailboats this size and under), you can always just pull start the outboard. Ive got one battery bank (composed of two batteries tied plus to plus , minus to minus) and saw no reason to change to anything else????
Also keep in mind that batteries only have two terminals. Im curious why you need two seperate batteries on a boat like a 26S? Seems to me that if you MUST have some sort of battery to run/start the motor, then you might need to have dedicated starting battery but on a 26C (or most sailboats this size and under), you can always just pull start the outboard. Ive got one battery bank (composed of two batteries tied plus to plus , minus to minus) and saw no reason to change to anything else????
Walts point is well proven in these posts...
In an effort to "problem solve" sometimes the bigger picture is overlooked. Lets set aside the main reason I often hear for two batteries - that of not being left without power. As this thread illustrates dual batteries are not just a PIA (as you now have two to monitor and two to individually charge and two to evenly discharge) - but also require RIGOR as you must keep on top of this constant manual process. I reality, many end up with over charged (and more importantly from a battery longevity perspective) over discharged batteries. You have to consider the "manual" aspect of any system - and it is usually the manual/procedural aspect that fails first. Chris
In an effort to "problem solve" sometimes the bigger picture is overlooked. Lets set aside the main reason I often hear for two batteries - that of not being left without power. As this thread illustrates dual batteries are not just a PIA (as you now have two to monitor and two to individually charge and two to evenly discharge) - but also require RIGOR as you must keep on top of this constant manual process. I reality, many end up with over charged (and more importantly from a battery longevity perspective) over discharged batteries. You have to consider the "manual" aspect of any system - and it is usually the manual/procedural aspect that fails first. Chris
How a single battery system can work
This is almost a "part 2" to my previous post. Lets consider how a single battery system can meet the "don't want to be left without power" desire. First off, install a high capacity battery. Without getting into the argument of what amp/hr means suffice to say that a 125 amp/hr battery will run things longer than a 75 amp/hr unit. Generally about 50% more usable capacity. Two 6 volt "golf cart" batteries in series are an excellent way to accomplish this (I heard they are closer to true deep cycle than the typical marine deep cycle/starting battery). Second, use a charge controller with your solar panel to remove the issue of overcharging or having to switch the panel in and out of the system. On the subject of solar - go for a 30 watt monocrystalline unit. Lots of power for a 26S and these are smaller than the previous gen ration 15 watt units. The one I use is only 11 X 26 inches and fits on the aft rail - with space for the swim ladder, BBQ and getting at the outboard. Third - the BIGGY. Use some of the cash you save from not buying that second battery, battery isolator, battery switch and buy a decent battery monitor! You can purchase units that monitor inflow and outflow and give a decent idea of capacity. They can warn you of reaching certain power levels and some can even take the batter offline until it once again reaches a certain charge level. Yes, you can do this with a voltmeter or a simple bar led monitor - but that old "manual" work creeps back in. If you want to be assured of having power - automate the monitoring process. Another advantage is that you get a true idea of your power demands and remaining capacity - and can plan power usage accordingly. When would I use multiple batteries? On a larger boat with higher power demands for sure! Then we're talking more than two batteries and a solar/outboard charge method. We make every weekend in the summer a 3 day affair plus several times for a week or two straight (can you tell I'm not retired - sigh). We have never run out of power - and we run the usual "trailerable" load of depth, VHF, GPS, Autopilot (usually when the OB is running), pressure water (low current draw system) and a reasonable amount of lighting in the evening (mostly LED). In my opinion it's all about simplicity and automated monitoring. One final bit to pass on. I have seen this for electric start outboards. Use the smallest motorcycle/lawn tractor starting battery for engine starting. Locate it as close to the outboard as you can - like in the aft locker on a 26S. As most outboards charge through the starting battery connections you'll need a charge isolator to ensure the outboard keeps it topped up while not allowing the outboard starter to draw from your house battery. Lots of ways to skin the cat - and this is just one persons opinion... Chris
This is almost a "part 2" to my previous post. Lets consider how a single battery system can meet the "don't want to be left without power" desire. First off, install a high capacity battery. Without getting into the argument of what amp/hr means suffice to say that a 125 amp/hr battery will run things longer than a 75 amp/hr unit. Generally about 50% more usable capacity. Two 6 volt "golf cart" batteries in series are an excellent way to accomplish this (I heard they are closer to true deep cycle than the typical marine deep cycle/starting battery). Second, use a charge controller with your solar panel to remove the issue of overcharging or having to switch the panel in and out of the system. On the subject of solar - go for a 30 watt monocrystalline unit. Lots of power for a 26S and these are smaller than the previous gen ration 15 watt units. The one I use is only 11 X 26 inches and fits on the aft rail - with space for the swim ladder, BBQ and getting at the outboard. Third - the BIGGY. Use some of the cash you save from not buying that second battery, battery isolator, battery switch and buy a decent battery monitor! You can purchase units that monitor inflow and outflow and give a decent idea of capacity. They can warn you of reaching certain power levels and some can even take the batter offline until it once again reaches a certain charge level. Yes, you can do this with a voltmeter or a simple bar led monitor - but that old "manual" work creeps back in. If you want to be assured of having power - automate the monitoring process. Another advantage is that you get a true idea of your power demands and remaining capacity - and can plan power usage accordingly. When would I use multiple batteries? On a larger boat with higher power demands for sure! Then we're talking more than two batteries and a solar/outboard charge method. We make every weekend in the summer a 3 day affair plus several times for a week or two straight (can you tell I'm not retired - sigh). We have never run out of power - and we run the usual "trailerable" load of depth, VHF, GPS, Autopilot (usually when the OB is running), pressure water (low current draw system) and a reasonable amount of lighting in the evening (mostly LED). In my opinion it's all about simplicity and automated monitoring. One final bit to pass on. I have seen this for electric start outboards. Use the smallest motorcycle/lawn tractor starting battery for engine starting. Locate it as close to the outboard as you can - like in the aft locker on a 26S. As most outboards charge through the starting battery connections you'll need a charge isolator to ensure the outboard keeps it topped up while not allowing the outboard starter to draw from your house battery. Lots of ways to skin the cat - and this is just one persons opinion... Chris
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