Okay all you electro-heads out there, here is your chance to flex your expertise. The last two times I went sailing, my starting battery was nearly dead. It was not strong enough to turn the old Atomic 4, but it would power the radio and depth finder. A quick trace of the wiring indicated that it should be replaced. I eyeballed it for about 2 guage, but found out it was 6 guage. GASP! Anyway, this does not surprise me as the former owner made repairs only when something broke, and even then he rarely did it right (often pinching pennies wherever and whenever he could). Some info on the electrical: Standard two battery setup on a Catalina 27. Foreward battery is a dual purpose which has already been re-wired by yours truly with properly crimped and liquid-taped terminals. The aft battery is a 6-month-old marine-grade starting battery from WalMart, and is used soley as a starter. I use it to fire the engine and run out of the harbor. When the sails are raised, the engine is cut and the 4 position Guest battery switch (1,2,Both and Off)goes to the forward battery to power the radio and electronics. The starter battery is used once more when it is time to fire up the Atomic 4 and go home. Occasionally I set it to both to charge both batteries at once. The problem I found is that the ground for the cabin and navigation lights was (nearly invsibly) terminated on the negative battery cable at the battery post. It was my understanding that all grounds should be placed on the engine, which is where I moved the dislocated grounding wire. It worked fine. My questions are: Could this misplaced ground have caused the aft battery to run down even when the battery switch was off, or while using the forward battery? Why would someone wire a boat in this manner? And lastly, does anyone have any further recommendations? I will be replacing the battery cables and terminals this weekend. As always, I appreciate and value your help and advice. Best Regards, Rob Rich
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Ron
Multimeter test
Switch everything to your house battery. Now take the hot lead off the starting battery. Place the multimeter in between and check for current. If you get a reading, you have a short somewhere. Also maybe take the battery to a auto shop for load test. Maybe you have a cell going bad. You can also put a test light in between the positive cable and the battery. If any power is going out it will light up (even just barely). It's no fun looking for a short, but when you fix it you will sleep better at night.
Switch everything to your house battery. Now take the hot lead off the starting battery. Place the multimeter in between and check for current. If you get a reading, you have a short somewhere. Also maybe take the battery to a auto shop for load test. Maybe you have a cell going bad. You can also put a test light in between the positive cable and the battery. If any power is going out it will light up (even just barely). It's no fun looking for a short, but when you fix it you will sleep better at night.
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Al Budding
DC grounding
All ground wires should go to a dedicated negative ground bus. Only one ground wire should be attached to the engine. That wire should go from the starter case, or as close as you can get, to the negative ground bus. The second best choice would be grounding everything to the negative posts of the batteries, which is done by some boat builders. The best thing to do, if you intend to make modifications to your existing electrical system, is purchase one of the many excellent books on DC electrics from your local marine store and use it for guidance. A.B.
All ground wires should go to a dedicated negative ground bus. Only one ground wire should be attached to the engine. That wire should go from the starter case, or as close as you can get, to the negative ground bus. The second best choice would be grounding everything to the negative posts of the batteries, which is done by some boat builders. The best thing to do, if you intend to make modifications to your existing electrical system, is purchase one of the many excellent books on DC electrics from your local marine store and use it for guidance. A.B.
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R.W.Landau
Some things to check
Rob, I agree with Al and the grounding. Some place there you need to have a ground to the water. I agree with Al on the book, Nigel Calder would be a good one. Your batteries "full charged" voltage should be about 12.7+/- voltsfor a wet cell. A 50 % battery charge is just over 12 volts. Both of these voltages are measured about 2 to 4 hours after no battery use or charging. What I am saying is are you charging your batteries up to full capacity? Second, don't skimp on the wire you use. Use marine grade wire. If you can, coat all your connections with some thing to protect them from corrosion. WD40, silicone, even grease or vasoline if you can't find something specifically for that purpose. r.w.landau
Rob, I agree with Al and the grounding. Some place there you need to have a ground to the water. I agree with Al on the book, Nigel Calder would be a good one. Your batteries "full charged" voltage should be about 12.7+/- voltsfor a wet cell. A 50 % battery charge is just over 12 volts. Both of these voltages are measured about 2 to 4 hours after no battery use or charging. What I am saying is are you charging your batteries up to full capacity? Second, don't skimp on the wire you use. Use marine grade wire. If you can, coat all your connections with some thing to protect them from corrosion. WD40, silicone, even grease or vasoline if you can't find something specifically for that purpose. r.w.landau
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Thomas Ehmke
Proper Grounding-Rob
Rob, I read the other responses to your problem and ask you to consider a couple of other possibilities.. Some of the symptoms sound very familiar. I have had problems for the last two seasons with batteries and this season (hopefully) they will be under control. How do you charge the batteries, by alternator only, or do you have an AC battery charger for dockside charging? If the alternator is your only method of charging, it's possible that the output isn't sufficient to charge both batteries, especially if you set the battery switch at the "both" setting, or neglect to set the switch to charge the starting battery fully. The output of the Mitsubishi alternator on my Westerbeke 10-2 is 30 amps. If that amperage isn't carefully managed, one or both of the batteries can be undercharged. Another possibility is a defective cell in one of the batteries. If that were the case and the switch were left in the "both" position, the batteries would be in parallel and the stronger would charge the weaker and continue to lose its charge to the weaker battery until both were discharged. That doesn't sound like your problem as you said that it was the starting battery only that was discharged. Another possibility is that the automotive battery you use for starting is already defective. Starting batteries benefit from use and suffer from lack of same. On a boat that is not used as frequently as an auto, the battery doesn't seem to have as long a life, sometimes even drastically shorter. I didn't start having chronic battery problems until I took a slip w/o shore power. The AC battery charger masked some of the problems I had with incorrect use of the battery switch and insufficient charging from the alternator. I've made the first steps to correct the situation. The next step may be to purchase a high capacity alternator. Tom
Rob, I read the other responses to your problem and ask you to consider a couple of other possibilities.. Some of the symptoms sound very familiar. I have had problems for the last two seasons with batteries and this season (hopefully) they will be under control. How do you charge the batteries, by alternator only, or do you have an AC battery charger for dockside charging? If the alternator is your only method of charging, it's possible that the output isn't sufficient to charge both batteries, especially if you set the battery switch at the "both" setting, or neglect to set the switch to charge the starting battery fully. The output of the Mitsubishi alternator on my Westerbeke 10-2 is 30 amps. If that amperage isn't carefully managed, one or both of the batteries can be undercharged. Another possibility is a defective cell in one of the batteries. If that were the case and the switch were left in the "both" position, the batteries would be in parallel and the stronger would charge the weaker and continue to lose its charge to the weaker battery until both were discharged. That doesn't sound like your problem as you said that it was the starting battery only that was discharged. Another possibility is that the automotive battery you use for starting is already defective. Starting batteries benefit from use and suffer from lack of same. On a boat that is not used as frequently as an auto, the battery doesn't seem to have as long a life, sometimes even drastically shorter. I didn't start having chronic battery problems until I took a slip w/o shore power. The AC battery charger masked some of the problems I had with incorrect use of the battery switch and insufficient charging from the alternator. I've made the first steps to correct the situation. The next step may be to purchase a high capacity alternator. Tom
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Rob Rich
Thanks Guys...
Only 60 today here and cloudy, so I spent the day on the docks. I went to West Marine in the morning and got two 6 foot lengths of 2 guage wire, selected four terminals and crimped them myself at West's crimping bench. That's one reason I love that store - they let you use their equipment for cables and wiring (of course liability factors in there too). Took the cables out to the boat, double coated the ends with liquid electrical tape, ran them and installed, this time propery gounding both the lighting and battery cables to the Atomic 4 (at separate locations). I do have shore power, and a nice little battery charger with settings for deep cycle, regular, 15A and 2A trickle (plus 100A starter). I left the battery charging last night (auto shutoff protection), and it was maintaining the charge 2 hours later. Multimeter showed it was around 12 3/4 volts. Boat fired up right away with the new cables. Cabin lights seemed to burn brighter. 4 hours after installation, starter turned very quickly again (faster than forward dual-purpose). Will go check on it tomorrow and see how she is, but if you don't see another post, the it's fixed. No more worrying when I turn the key! Thanks! Rob
Only 60 today here and cloudy, so I spent the day on the docks. I went to West Marine in the morning and got two 6 foot lengths of 2 guage wire, selected four terminals and crimped them myself at West's crimping bench. That's one reason I love that store - they let you use their equipment for cables and wiring (of course liability factors in there too). Took the cables out to the boat, double coated the ends with liquid electrical tape, ran them and installed, this time propery gounding both the lighting and battery cables to the Atomic 4 (at separate locations). I do have shore power, and a nice little battery charger with settings for deep cycle, regular, 15A and 2A trickle (plus 100A starter). I left the battery charging last night (auto shutoff protection), and it was maintaining the charge 2 hours later. Multimeter showed it was around 12 3/4 volts. Boat fired up right away with the new cables. Cabin lights seemed to burn brighter. 4 hours after installation, starter turned very quickly again (faster than forward dual-purpose). Will go check on it tomorrow and see how she is, but if you don't see another post, the it's fixed. No more worrying when I turn the key! Thanks! Rob
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