My Hunter Legend 37, launched in 1988 came with two 12 volt batteries located under the staircase. I purchased this boat a few months ago and noticed the following: 1. There are 4 golf cart batteries each 6 volt hooked up in series connected a Heart Inverter/ charger. These battteries power the fridge and the micro-wave only. Now the original two batteries under the stair case are now one 12 volt battery used to start the engine and run the balance of the on board systems, lights, water pressure etc. The second battery is missing. My question. I want to replace this single 12 volt battery with two 12 volt batteries linked up in parallel. There is currently a red battery switch with the regular isolated settings: off/1/All/2. This switch is currently hooked up to the positive and negative terminals of the single battery. If I hook this switche's positive lead to one battery and its negative lead to the second battery now hooked up in parallel will this switch isolate one battery from the other when its knob is turned from say position 1 to position number 2. I want to isolate one of these batteries as a engine starter battery only.The second one can run the secondary on board systems. Can I use one 12 volt starter battery hoked up to a 12 volt deep cycle battery for this application? All help is most appreciated. Thanks, Barrie
- Status
- Not open for further replies.
R
Rob Rich
Just went through this...
Barrie, Just went through this on my Catalina 27, so I feel your pain brother. I'm not an expert, but I think I know what you want to do. In short, the answer to your question about linking the batteries is no. You want to isolate those two batteries, and your proposal will link them. Also, I'm kind of worried about how your 12 Volt is hooked up to the switch. I guess it works, but it does not sound ideal. I would pick up the 12 Volt Bible from west marine, or similar book that explains parallel, series, and other battery setups. I heard Nigel Calders book is even better, but have no experience with it. I think what you are describing is a simple two battery setup that will allow you to switch from one battery (starter to start engine) to another (deep cell to run accessories while under sail). That is pretty easy (even a knucklehead like me can do it). You need to get the instructions for the type of battery switch you have, and wire the postitive battery terminals to the switch terminals accordingly. Be real careful to get it right though, or you could risk a fire. A solid knowledge of your particular schematic will save you time. Lack of said knowledge will invite bad things, like sparks and exploding batteries. Also, get a good idea of how you want to ground these guys. You may find things you didn't count on once you get into the wiring. I found quite a few... one of which was a fire hazard. Best of Luck! Rob
Barrie, Just went through this on my Catalina 27, so I feel your pain brother. I'm not an expert, but I think I know what you want to do. In short, the answer to your question about linking the batteries is no. You want to isolate those two batteries, and your proposal will link them. Also, I'm kind of worried about how your 12 Volt is hooked up to the switch. I guess it works, but it does not sound ideal. I would pick up the 12 Volt Bible from west marine, or similar book that explains parallel, series, and other battery setups. I heard Nigel Calders book is even better, but have no experience with it. I think what you are describing is a simple two battery setup that will allow you to switch from one battery (starter to start engine) to another (deep cell to run accessories while under sail). That is pretty easy (even a knucklehead like me can do it). You need to get the instructions for the type of battery switch you have, and wire the postitive battery terminals to the switch terminals accordingly. Be real careful to get it right though, or you could risk a fire. A solid knowledge of your particular schematic will save you time. Lack of said knowledge will invite bad things, like sparks and exploding batteries. Also, get a good idea of how you want to ground these guys. You may find things you didn't count on once you get into the wiring. I found quite a few... one of which was a fire hazard. Best of Luck! Rob
Check out the W/M battery diagram.
Barrie: There are a couple of different ways to do this but the ultimate is diagramed on the West Marine Site. They use ON/OFF switches so each circut can be switched off if needed. You will probalby also need a battery isolator too. The way the system is wired with the multiple ON/OFF switches is exactly what I have planned for this springs project.
Barrie: There are a couple of different ways to do this but the ultimate is diagramed on the West Marine Site. They use ON/OFF switches so each circut can be switched off if needed. You will probalby also need a battery isolator too. The way the system is wired with the multiple ON/OFF switches is exactly what I have planned for this springs project.
E
Eric Lorgus
No simple answer on this one
Barrie, To use a 1/2/both/off switch, you must run the pos & neg cables from each battery to the appropriate poles on the switch. Before going this route, you might want to consider using an isolater instead, which allows both batteries to be recharged simultaneously, but otherwise isolates them to avoid accidentally discharging your starting battery. Try visiting http://www.wellsmarinetech.com for more info on isolaters. The other consideration is the rule of thumb about mixing old and new batteries. You should avoid this, unless you plan on recharging them separately. This has to do with how batteries accept recharging. What you didn't mention was how the 6-volt batteries are being recharged. Are they connected to the same recharging system as the single house battery? Again, the advice about old & new batteries applies here. I agree with the recommendations about hitting the books on this one. Nigel Calder's "Boatowner's Mechanical and Electrical Manual" is excellent, and is available at the chandlery here. I think the key to a good battery setup is understanding how they will be typically be discharged and recharged. More power to you. Eric Lorgus
Barrie, To use a 1/2/both/off switch, you must run the pos & neg cables from each battery to the appropriate poles on the switch. Before going this route, you might want to consider using an isolater instead, which allows both batteries to be recharged simultaneously, but otherwise isolates them to avoid accidentally discharging your starting battery. Try visiting http://www.wellsmarinetech.com for more info on isolaters. The other consideration is the rule of thumb about mixing old and new batteries. You should avoid this, unless you plan on recharging them separately. This has to do with how batteries accept recharging. What you didn't mention was how the 6-volt batteries are being recharged. Are they connected to the same recharging system as the single house battery? Again, the advice about old & new batteries applies here. I agree with the recommendations about hitting the books on this one. Nigel Calder's "Boatowner's Mechanical and Electrical Manual" is excellent, and is available at the chandlery here. I think the key to a good battery setup is understanding how they will be typically be discharged and recharged. More power to you. Eric Lorgus
J
Jim O'Brien
Batt-Man
Barry, 1)Not to worry, you don't have that big a problem. Ok, first take out the single 12v and replace it with two identical 12v's in it's place. Must be 2 of the same amp hour rated batteries to charge and discharge with similar characteristics. Hook them up to the battery switch with the 2 negs together and the positives on the appropriate individual switch positions. This way you can choose one, two or both. Both would be parralell. (Same 12 volts, double the amp hours) This is a good thing! You can reserve one as a starting battery and use the other as additional house battery, and best of all you can recharge this set up by your alternator. 2)Don't mix and match different types of batteries on the same circuit. 3)The 4 golf cart batteries are hooked up to put out 24v's You can't charge them off your engine. Make sure these batteries never get wired up to your alternator this way. You would have to isolate them. This is a big pain and not the best way to go. Only charge these off your charger. Golf cart batteries make great house batteries because of their discharge characteristics. Never mix these together with the other types of batteries! 4) Inverters scare me. The power it takes for 12volts to make 120volts AC is way out of proportion. I would only do this for short periods of time and not rely on an inverter as a cure all! Microwave has to be rated at about 300 watts @ 120v AC, that's alot of power. You will probably run those 4 golf cart batteries dead in a few minutes of microwave useage, with the inverter. Best advise is not to run microw off batteries. If I can be of any other help, you can reach me direct at Oceanis370@aol.com Good luck and fair winds, Jim
Barry, 1)Not to worry, you don't have that big a problem. Ok, first take out the single 12v and replace it with two identical 12v's in it's place. Must be 2 of the same amp hour rated batteries to charge and discharge with similar characteristics. Hook them up to the battery switch with the 2 negs together and the positives on the appropriate individual switch positions. This way you can choose one, two or both. Both would be parralell. (Same 12 volts, double the amp hours) This is a good thing! You can reserve one as a starting battery and use the other as additional house battery, and best of all you can recharge this set up by your alternator. 2)Don't mix and match different types of batteries on the same circuit. 3)The 4 golf cart batteries are hooked up to put out 24v's You can't charge them off your engine. Make sure these batteries never get wired up to your alternator this way. You would have to isolate them. This is a big pain and not the best way to go. Only charge these off your charger. Golf cart batteries make great house batteries because of their discharge characteristics. Never mix these together with the other types of batteries! 4) Inverters scare me. The power it takes for 12volts to make 120volts AC is way out of proportion. I would only do this for short periods of time and not rely on an inverter as a cure all! Microwave has to be rated at about 300 watts @ 120v AC, that's alot of power. You will probably run those 4 golf cart batteries dead in a few minutes of microwave useage, with the inverter. Best advise is not to run microw off batteries. If I can be of any other help, you can reach me direct at Oceanis370@aol.com Good luck and fair winds, Jim
B
Barrie McDonald
Battery confusion Reply
Hi Jim O'Brien, Thanks for the reply re my battery questions. My golf cart batteries are charged by an old heart inverter/charger which is on the blink so I'm thinking of replacing it. My original charger is charging the single 12 volt under my stairs when on ac power, the engine charges this battery while under way. I was thinking of taking out this old 12 volt battery and installing a large 12 volt Trojan EVA 8 BATTERY, DEEP CYCLE WITH 216 AMPS. I did finally figure out that my 4 golf cart batteries are isolated from the single 12 volt one. My thinking is to keep the same setup and run my in house systems from the golf cart batteries but have the larger single volt deep cycle on reserve to start my engine and also to run my in house systems if the need arises. I also carry a portable jel pack battery as backup emergency starter battery if required. It has its own built in jumper cables and is most usesful as it also has a cigarette lighter adapter inlet. What do you think of this Jim? Does any of this make sense? Thanks, Barrie
Hi Jim O'Brien, Thanks for the reply re my battery questions. My golf cart batteries are charged by an old heart inverter/charger which is on the blink so I'm thinking of replacing it. My original charger is charging the single 12 volt under my stairs when on ac power, the engine charges this battery while under way. I was thinking of taking out this old 12 volt battery and installing a large 12 volt Trojan EVA 8 BATTERY, DEEP CYCLE WITH 216 AMPS. I did finally figure out that my 4 golf cart batteries are isolated from the single 12 volt one. My thinking is to keep the same setup and run my in house systems from the golf cart batteries but have the larger single volt deep cycle on reserve to start my engine and also to run my in house systems if the need arises. I also carry a portable jel pack battery as backup emergency starter battery if required. It has its own built in jumper cables and is most usesful as it also has a cigarette lighter adapter inlet. What do you think of this Jim? Does any of this make sense? Thanks, Barrie
D
David Garrison
6 Volt in series & paralled?
Barrie, I wonder if your 6 volt batteries are wired in series and in parallel? What I mean is do you have one set of 2 6 volts wired in series (negative on one to positive on the other) plus the other 2 wired just the same and then the two sets wired in parallel (positive to positive)? If so, this is not an uncommon configuration and, as you may know, will give you double the amp hour capacity (assuming all batteries of same size) while maintaining a 12 volt bank. I would suggest leaving the 6 volts as your house bank and having just a single marine starting battery for starting the engine. You didn't say how many amp hours you've got with the golf cart batteries but I would guess somewhere around 440-480? If so, following the recommendation of not discharging your batteries below about 50% gives you about 220 or so useuable amp hours before recharging. I would consider NOT using the 12 volt to run any house loads but instead reserve that for starting only. If you can start your engine, you can at least recharge the house bank from it but if you can't start the engine because all your banks are dead...well, not so good. I think the design of having 3 separate on/off switches is a good one. #1 between starter and starting battery. #2 between house bank and house load (panel) and #3 to parallel the 2 switches in an emergency. Also, I would wire the alternator output directly to the house bank and use a battery combiner to allow charging of both the house and starting banks in the presence of a charge source (alternator, battery charger, etc). Having 3 switches eliminates the problem of having a 4 position switch, leaving the switch in the "all" position and draining both the starting and house banks. Good luck with your battery setup! David s/v Kindred Spirit
Barrie, I wonder if your 6 volt batteries are wired in series and in parallel? What I mean is do you have one set of 2 6 volts wired in series (negative on one to positive on the other) plus the other 2 wired just the same and then the two sets wired in parallel (positive to positive)? If so, this is not an uncommon configuration and, as you may know, will give you double the amp hour capacity (assuming all batteries of same size) while maintaining a 12 volt bank. I would suggest leaving the 6 volts as your house bank and having just a single marine starting battery for starting the engine. You didn't say how many amp hours you've got with the golf cart batteries but I would guess somewhere around 440-480? If so, following the recommendation of not discharging your batteries below about 50% gives you about 220 or so useuable amp hours before recharging. I would consider NOT using the 12 volt to run any house loads but instead reserve that for starting only. If you can start your engine, you can at least recharge the house bank from it but if you can't start the engine because all your banks are dead...well, not so good. I think the design of having 3 separate on/off switches is a good one. #1 between starter and starting battery. #2 between house bank and house load (panel) and #3 to parallel the 2 switches in an emergency. Also, I would wire the alternator output directly to the house bank and use a battery combiner to allow charging of both the house and starting banks in the presence of a charge source (alternator, battery charger, etc). Having 3 switches eliminates the problem of having a 4 position switch, leaving the switch in the "all" position and draining both the starting and house banks. Good luck with your battery setup! David s/v Kindred Spirit
M
Mickey McHugh
Inverter/Charger 24VDC
Guys, sounds like the inverter uses 24VDC which means the 4 golf cart 'house' batteries are in series and can only be recharged by the inverter/charger. Not a good setup for a sailboat as all other loads are 12VDC. Since you need the 120 VAC for the frig and you plan to replace the inverter (good idea), get one that uses 12VDC and make 2 banks out of the four 6 VDC batteries by hooking 2 in series and connecting to an AB switch. Make sure the charger portion of the inverter is sized for the battery banks its connected to. Now you have plenty of 12VDC 'House' power, just don't use the microwave unless the engine is running. BTW, I have never seen a battery switch that you have to wire the neg to it. ALL neg wires should terminate on the negative 'ground' buss bar. I think a separate 'conventional' starter battery for engine starting provide the proper starting amps and works just like in your car. If you rarely use the boat, a small solar panel or separate battery charger would work. A combiner or isolator is required to keep it for being used by the 'house'. We sail every weekend and using the engine to get out and back in the slip is enough to keep it charged so we don't need to charge the engine start battery (a group 24). How many cars have 'chargers'? The house batteries are another story - the bigger the charger, the better!
Guys, sounds like the inverter uses 24VDC which means the 4 golf cart 'house' batteries are in series and can only be recharged by the inverter/charger. Not a good setup for a sailboat as all other loads are 12VDC. Since you need the 120 VAC for the frig and you plan to replace the inverter (good idea), get one that uses 12VDC and make 2 banks out of the four 6 VDC batteries by hooking 2 in series and connecting to an AB switch. Make sure the charger portion of the inverter is sized for the battery banks its connected to. Now you have plenty of 12VDC 'House' power, just don't use the microwave unless the engine is running. BTW, I have never seen a battery switch that you have to wire the neg to it. ALL neg wires should terminate on the negative 'ground' buss bar. I think a separate 'conventional' starter battery for engine starting provide the proper starting amps and works just like in your car. If you rarely use the boat, a small solar panel or separate battery charger would work. A combiner or isolator is required to keep it for being used by the 'house'. We sail every weekend and using the engine to get out and back in the slip is enough to keep it charged so we don't need to charge the engine start battery (a group 24). How many cars have 'chargers'? The house batteries are another story - the bigger the charger, the better!
J
Jim O'Brien
Batt-Man2
Barrie, think about your situation by breaking down your scenario into 2 seperate items, and approach one at a time. 1) Take out the single 12v, replace with 2 marine deep cycle batteries. Group24 if you can fit them. They have around 550 to 625 cranking amps depending upon how much you spend for them. 2) Golf cart batteries are good, if you use them correctly. I agree with David, 24volts not the first choice. There is nothing wrong with pairing the golf cart batts to 2 12volt pairs. You take two 6volts put them in series and you have 12volts. (pos to neg - and the other side is neg to pos + and voulet! 12volts. You can do that twice, so all 4 golf cart batts are now 2 pairs of 12volts each. Then you could charge one pair of golf batts with a regular charger because the charger thinks it's charging a 12volt batt. (Shhhhh, don't tell it!) Then you can put the 2 sets of paired batts on another switch to isolate them and have a reserve house battery situation also. Although I am a certified auto mechanic, I went to college for electrical engineering. So trust me on this. Simple rule. Series doubles the voltage, parallel doubles the amps but keeps the volts the same.When it comes to batteries supplying power to an object, always think in terms of 12 volts. I hope this helps. Jim O'Brien Beneteau 36
Barrie, think about your situation by breaking down your scenario into 2 seperate items, and approach one at a time. 1) Take out the single 12v, replace with 2 marine deep cycle batteries. Group24 if you can fit them. They have around 550 to 625 cranking amps depending upon how much you spend for them. 2) Golf cart batteries are good, if you use them correctly. I agree with David, 24volts not the first choice. There is nothing wrong with pairing the golf cart batts to 2 12volt pairs. You take two 6volts put them in series and you have 12volts. (pos to neg - and the other side is neg to pos + and voulet! 12volts. You can do that twice, so all 4 golf cart batts are now 2 pairs of 12volts each. Then you could charge one pair of golf batts with a regular charger because the charger thinks it's charging a 12volt batt. (Shhhhh, don't tell it!) Then you can put the 2 sets of paired batts on another switch to isolate them and have a reserve house battery situation also. Although I am a certified auto mechanic, I went to college for electrical engineering. So trust me on this. Simple rule. Series doubles the voltage, parallel doubles the amps but keeps the volts the same.When it comes to batteries supplying power to an object, always think in terms of 12 volts. I hope this helps. Jim O'Brien Beneteau 36
B
Barrie McDonald
Batt-Man2 Reply
Hi Jim, Thanks for your fine advice. These group 24 batteries you recommend, are they the ones I see on the Trojan Deep cycle list, Their deep cycle 12 volts , battery types 24 TMS, 24 TM and 24TMX. My 6 volt golf cart batteries are hooked up in series to provide 12 volts as my old Heart Inverter used 12 volts dc not 24. Can you send me a drawing as to how the other switch is hooked up to isolate the golf cart batteries. Thanks, my e-mail is "bmcdonald@dccnet.com" Thanks again Jim, Barrie
Hi Jim, Thanks for your fine advice. These group 24 batteries you recommend, are they the ones I see on the Trojan Deep cycle list, Their deep cycle 12 volts , battery types 24 TMS, 24 TM and 24TMX. My 6 volt golf cart batteries are hooked up in series to provide 12 volts as my old Heart Inverter used 12 volts dc not 24. Can you send me a drawing as to how the other switch is hooked up to isolate the golf cart batteries. Thanks, my e-mail is "bmcdonald@dccnet.com" Thanks again Jim, Barrie
- Status
- Not open for further replies.