I have two starting batteries(flooded) and I would like to replace one with a Deep Cycle house battery for cruising. I have the factory 1,2 or both switch and since my charger only has one line coming out, it is connected to the switch's 1 post and the only way to charge the #2 battery is by placing the switch to both. I don't know if this problem also exists with the engine alternator since I do most of my charging by A/C.(The engine will start on either 1 or 2 alone or both). My question is, can I replace one of the batteries with a deep cycle or will there be a problem when I place the switch on both for charging? I guess one will bleed into the other until they equalize when the A/C is off and the switch is on both. Will I be able to still operate on both when needed with different batteries?(Not different type but different designation, ie starting/deep cycle). Thanks. Lee
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Derek Rowell
Battery combiner
How about connecting a battery combiner such as West Marine #143268 right across your switch? You should never have to think about it again! The batteries will be connected in parallel for charging and disconnected in normal use. Derek
How about connecting a battery combiner such as West Marine #143268 right across your switch? You should never have to think about it again! The batteries will be connected in parallel for charging and disconnected in normal use. Derek
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Steve
Yes you can...as long as
Yes, you can replace one with a deep cycle, as long as they are both the same (wet, gel, etc.) The problems come in charging different types. They all have their own characteristics, and you can harm one at the expense of another. I think you have the right idea on how your charging systems works. It sounds like your switch has to be in the "BOTH" position for either your AC or your alternator to work. You might double check your AC charger though. Mine came with one line for charging from the factory, but it I removed the jumpers and ran my own lines, it could charge three banks seprately. Check in the West Marine catalog for a good explaination for the battery differences. It also gave a good explaination of the why each type likes to charge. Steve
Yes, you can replace one with a deep cycle, as long as they are both the same (wet, gel, etc.) The problems come in charging different types. They all have their own characteristics, and you can harm one at the expense of another. I think you have the right idea on how your charging systems works. It sounds like your switch has to be in the "BOTH" position for either your AC or your alternator to work. You might double check your AC charger though. Mine came with one line for charging from the factory, but it I removed the jumpers and ran my own lines, it could charge three banks seprately. Check in the West Marine catalog for a good explaination for the battery differences. It also gave a good explaination of the why each type likes to charge. Steve
All the above/below and.....
Lee: I would suggest that you use 2 deep cycle batteries. They have plenty of starting power and can be alternated for your house keeping. If you use one of the combiners as Derek recommended you will be able to leave your switch in either pos 1 or pos 2 for your housekeeping and starting and then the other battery is always in reserve.
Lee: I would suggest that you use 2 deep cycle batteries. They have plenty of starting power and can be alternated for your house keeping. If you use one of the combiners as Derek recommended you will be able to leave your switch in either pos 1 or pos 2 for your housekeeping and starting and then the other battery is always in reserve.
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Tom Ehmke
Lee, tweek it just a little more...
I have had a WM battery combiner on board for a few years, but had problems with batteries being constantly undercharged. The main reason for this was that I had chosen to break away from the shore power imbilical three years ago and was relying exclusively on the Mitubishi (stock) 35-amp alternator to charge the batteries. I found a solution in the WM catalog in one of the "West Advisors" It involves the use of a battery combiner, dedicated starting and house batteries, and a three-switch system. There is a switch for each battery and a parallel switch which (when left in the off position) prevents the batteries from draining if a cell fails in one of them. When turned on,the parallel switch permits a power boost or a transfer when (God Forbid) one of the batteries runs down. It worked well last season. Take a look at it on pages 562-563 in the 2001 WM catalog. One other comment. I was not in the habit of turning the off/1/all/2 battery switch off when I left the boat. If one of the batteries wasn't fully charged or (as happened twice) there was a faulty cell in one of them, both would be drawn down over a period of time and I would have to pull the car battery out and jump start the system... a pain in the a--. This solution solves both problems. It combines the batteries to maximize the charge in both batteries and isolates them through the parallel switch so that one cannot draw the other down. Not an expensive project. There is also a suggestion to upgrade the alternator in the advisory. I chose not to make that change and try what I have now for another season or two. Fair winds, Tom
I have had a WM battery combiner on board for a few years, but had problems with batteries being constantly undercharged. The main reason for this was that I had chosen to break away from the shore power imbilical three years ago and was relying exclusively on the Mitubishi (stock) 35-amp alternator to charge the batteries. I found a solution in the WM catalog in one of the "West Advisors" It involves the use of a battery combiner, dedicated starting and house batteries, and a three-switch system. There is a switch for each battery and a parallel switch which (when left in the off position) prevents the batteries from draining if a cell fails in one of them. When turned on,the parallel switch permits a power boost or a transfer when (God Forbid) one of the batteries runs down. It worked well last season. Take a look at it on pages 562-563 in the 2001 WM catalog. One other comment. I was not in the habit of turning the off/1/all/2 battery switch off when I left the boat. If one of the batteries wasn't fully charged or (as happened twice) there was a faulty cell in one of them, both would be drawn down over a period of time and I would have to pull the car battery out and jump start the system... a pain in the a--. This solution solves both problems. It combines the batteries to maximize the charge in both batteries and isolates them through the parallel switch so that one cannot draw the other down. Not an expensive project. There is also a suggestion to upgrade the alternator in the advisory. I chose not to make that change and try what I have now for another season or two. Fair winds, Tom
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Ron
Agree with Steve Dion
Since you should never discharge your battery below 50% and 50% is more than enough to start your engine, I would just get two deep cycle batteries and have plenty of house and starting power without all the worry and hassell...
Since you should never discharge your battery below 50% and 50% is more than enough to start your engine, I would just get two deep cycle batteries and have plenty of house and starting power without all the worry and hassell...
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Lee Hadjiosif
Thanks to All
Thanks to all who have taken the time to reply to my battery question. I think I'll replace on starting with a deep cycle battery and try to keep them isolated with the existing switch. If this doesn't work, then I'll try the WM battery isolator. Lee S/V Calaloo
Thanks to all who have taken the time to reply to my battery question. I think I'll replace on starting with a deep cycle battery and try to keep them isolated with the existing switch. If this doesn't work, then I'll try the WM battery isolator. Lee S/V Calaloo
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Derek Rowell
Lee : Isolator or combiner?
Lee, A battery combiner is an entirely different animal from a battery isolator. An isolator is just a pair of high current diodes, while a combiner is an electro-mechanical relay. They work different ways... see the West Advisor.
Lee, A battery combiner is an entirely different animal from a battery isolator. An isolator is just a pair of high current diodes, while a combiner is an electro-mechanical relay. They work different ways... see the West Advisor.
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David R.
Mixed batteries on same circuit not good idea
Using a deep cycle battery and a starting battery on the same circuit is not a good idea, even if they are of the same physical type externally. The starter battery won't live long. When charging you will either severely overcharge the starting battery or undercharge the deep cycle. Either will shorten battery life, though overcharging is generally less harmful to wet cell batteries than undercharging. You just have to maintain the water levels as it gasses out. (gets converted to hydrogen
Using a deep cycle battery and a starting battery on the same circuit is not a good idea, even if they are of the same physical type externally. The starter battery won't live long. When charging you will either severely overcharge the starting battery or undercharge the deep cycle. Either will shorten battery life, though overcharging is generally less harmful to wet cell batteries than undercharging. You just have to maintain the water levels as it gasses out. (gets converted to hydrogen
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Les Murray
Lee, get an Echo Charger
Lee, You can do one of two things. First is you can replace the simple battery switch you have with a 1-all-2 switch, or you can get an Echo Charger. The Echo Charger is pretty neat and is perfect for charging a small starting battery. What it does is charge your starting battery from the other battery at a very low amp rate (~15 A). This way it is always topped off and ready in case you need it. This implies that you never use the starting battery except in emergencies. The nice thing is you can build up your house bank as large as you want of whatever technology (AGM, Gel, etc.) you want and not worry about frying your starting battery. You will probably still want to replace your existing battery switch with a three-way switch. This is because, with the echo charger, you want to avoid with this system is going to the ALL position (putting all batteries in parallel). This will cause the starting battery to try to equalize with your house bank and probably kill your starting battery. Remember, you are using your starting battery because your house bank is probably already dead. You may also want to consider getting a smart 3-stage regulator for your alternator to keep your house bank topped off. I am going through this right now. I am replacing my simple Group 24 house battery with two Group 31s and an echo charger for the starting battery. I am also getting a high output alternator and 3-stage regulator. You can never have too much battery capacity. Les Murray s/v Ceilidh '86 C-36 #560
Lee, You can do one of two things. First is you can replace the simple battery switch you have with a 1-all-2 switch, or you can get an Echo Charger. The Echo Charger is pretty neat and is perfect for charging a small starting battery. What it does is charge your starting battery from the other battery at a very low amp rate (~15 A). This way it is always topped off and ready in case you need it. This implies that you never use the starting battery except in emergencies. The nice thing is you can build up your house bank as large as you want of whatever technology (AGM, Gel, etc.) you want and not worry about frying your starting battery. You will probably still want to replace your existing battery switch with a three-way switch. This is because, with the echo charger, you want to avoid with this system is going to the ALL position (putting all batteries in parallel). This will cause the starting battery to try to equalize with your house bank and probably kill your starting battery. Remember, you are using your starting battery because your house bank is probably already dead. You may also want to consider getting a smart 3-stage regulator for your alternator to keep your house bank topped off. I am going through this right now. I am replacing my simple Group 24 house battery with two Group 31s and an echo charger for the starting battery. I am also getting a high output alternator and 3-stage regulator. You can never have too much battery capacity. Les Murray s/v Ceilidh '86 C-36 #560
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