My 1999 Hunter 420 has a house-bank of 2 batteries (wired together), and a separate starter battery. The batteries have a "1, 2, BOTH" switch. I do not have a generator. I leave the switch on "BOTH" all the time. This is true when I sail, motor, or anchor, and also when I am back at the dock and hooked into shore power. In the four years I have had the boat, I have had no battery problems. A recent article in “Ask the Experts” in Sail Magazine (March, 2005), said "To avoid discharging all the batteries [same set up in the magazine’s example as mine], remember to switch [using the 1, 2, BOTH switch] to the house bank when you shut the engine down." Is my practice of leaving the switch on BOTH all the time a bad one? If so, what should I be doing and why? Secondly, I have a solar generating system. When I bought the boat, I was advised not to use it (by taking out the fuse on its line) as it tends to "fry" the batteries. Does the solar tend to do that? When should I use the solar system?
- Status
Battery Switch
Jim, you essentially have one bank with three batteries with the switch on "both" all the time. This is especially not good if your starter battery is a different size and rating than your house batteries. The reason to use the switch is to isolate the two systems in case of a problem. Your solar panels should feed a regulator (the better ones prevent overcharging) which should feed your batteries. I have seen a on/off switch installed to prevent overcharging also. Nigel Calder's book "Boatowner's Mechanical & Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems" covers this in much more detail than I can here.
Jim, you essentially have one bank with three batteries with the switch on "both" all the time. This is especially not good if your starter battery is a different size and rating than your house batteries. The reason to use the switch is to isolate the two systems in case of a problem. Your solar panels should feed a regulator (the better ones prevent overcharging) which should feed your batteries. I have seen a on/off switch installed to prevent overcharging also. Nigel Calder's book "Boatowner's Mechanical & Electrical Manual: How to Maintain, Repair, and Improve Your Boat's Essential Systems" covers this in much more detail than I can here.
Yes and maybe
If you have two banks (house and start) running through a single 1-2-both-off switch then it is indeed a bad idea to leave the switch on both at engine shut down. Basically you're combining the house and start batteries into one bank that you could run down to the point of having no ability to crank the diesel (assuming you are away from shore power.) Don't ask me how I know this. With your current set up you should combine the banks when charging (motoring or when on the shore charger) and isolate the starting battery when there is no charging happening. Having said this I'd highly recommend ditching your current switch routing and replace with a dedicated on-off switch for each bank and a combiner between the two. The advisor in the West Marine catalogue outlines the details nicely. We did this 4 years ago and it was one of the best upgrades we ever did. Both banks stay on all the time, no switching necessary. The combiner makes the routing of charging current automatic. I think the 1-2-both-off switch is the biggest disservice ever perpetrated on the boating universe. I don't know why manufacturers continue to use them. They unnecessarily invite trouble. As to the solar question, well, it depends. If you've got a big enough panel and a battery bank without a load on it then yes, you could over-charge. With any load at all and a big enough bank it's not likely with a small panel. A regulator isn't a bad idea but I'd just install an on-off switch (or pull the fuse) at the dock because you don't need it there anyway. Overcharge on the hook? Not a chance. I'd have to have some numbers to answer your question more accurately. Jerry's suggestion of educating yourself with Calder's book is a good one.
If you have two banks (house and start) running through a single 1-2-both-off switch then it is indeed a bad idea to leave the switch on both at engine shut down. Basically you're combining the house and start batteries into one bank that you could run down to the point of having no ability to crank the diesel (assuming you are away from shore power.) Don't ask me how I know this. With your current set up you should combine the banks when charging (motoring or when on the shore charger) and isolate the starting battery when there is no charging happening. Having said this I'd highly recommend ditching your current switch routing and replace with a dedicated on-off switch for each bank and a combiner between the two. The advisor in the West Marine catalogue outlines the details nicely. We did this 4 years ago and it was one of the best upgrades we ever did. Both banks stay on all the time, no switching necessary. The combiner makes the routing of charging current automatic. I think the 1-2-both-off switch is the biggest disservice ever perpetrated on the boating universe. I don't know why manufacturers continue to use them. They unnecessarily invite trouble. As to the solar question, well, it depends. If you've got a big enough panel and a battery bank without a load on it then yes, you could over-charge. With any load at all and a big enough bank it's not likely with a small panel. A regulator isn't a bad idea but I'd just install an on-off switch (or pull the fuse) at the dock because you don't need it there anyway. Overcharge on the hook? Not a chance. I'd have to have some numbers to answer your question more accurately. Jerry's suggestion of educating yourself with Calder's book is a good one.
Jim
What he others have said is correct. To put it simply, IF the system works with no failures, then running in "Both" will never be a problem. HOWEVER, IF anything goes wrong with any battery in the system, the entire circuit will be discharged. The point of having a dedicated 'Starter Battery' is to be sure that your engine will start regardless of the condition of the house batteries.
What he others have said is correct. To put it simply, IF the system works with no failures, then running in "Both" will never be a problem. HOWEVER, IF anything goes wrong with any battery in the system, the entire circuit will be discharged. The point of having a dedicated 'Starter Battery' is to be sure that your engine will start regardless of the condition of the house batteries.
Battery combiner and separate
"on Off" switch for the cranking battery I added was the way I went to solve problem with my 2 house batteries, especially while cranking the engine with the nav gear (radar/chartplotter) on. If needed, I can use all three and don't have to worry about switch positions.
"on Off" switch for the cranking battery I added was the way I went to solve problem with my 2 house batteries, especially while cranking the engine with the nav gear (radar/chartplotter) on. If needed, I can use all three and don't have to worry about switch positions.
what I did
I wired the two house batteries so that they by pass the battery switch, ie they are always connected to the house, the DC switch panel. Thus the battery switch simply determines which battery is connected for starting. I still have the option of 1 (starting battery) or 2 (house batteries) or both, to start the engine. I also installed a coupler/isolator to charge both battery banks when the engine is running. The AC battery charger has two outputs and charges both batteries when connected to shore power (or the Honda generator).
I wired the two house batteries so that they by pass the battery switch, ie they are always connected to the house, the DC switch panel. Thus the battery switch simply determines which battery is connected for starting. I still have the option of 1 (starting battery) or 2 (house batteries) or both, to start the engine. I also installed a coupler/isolator to charge both battery banks when the engine is running. The AC battery charger has two outputs and charges both batteries when connected to shore power (or the Honda generator).
Even
My sailing mentor advised me long ago to simply do this... if it's an odd numbered day, simply switch battery selector to "1", if even numbered day, "2". Works pretty good for me... Good sailing! Ted
My sailing mentor advised me long ago to simply do this... if it's an odd numbered day, simply switch battery selector to "1", if even numbered day, "2". Works pretty good for me... Good sailing! Ted
- Status