Ok you electronic wizards help me out Please!! I'm in the process of replacing my stock 51 amp alternator with one that puts out 105 amps. I noticed that the original wire that was hooked up to the positive output of the alternator is grounded when the ignition switch is off. It becomes positive when the ignition switch is on. Can anyone tell me if this normal behavior and if so can you explain to me why this is so. I've been told it has to do with the ammeter but I need more convincing. I'm also adding a new additional starting battery and I wanted to hook up a positive line straight to the positive output on the alternator to the positive post of the starting battery. Then hook up the original positive output wire, the same one which I'm asking why it goes ground to positive with a flick of the ignition switch, to same positive post on the alternator. Is this possible??? I've also installed a Balmar ARS-4 smart regulator and conected the original house batteries in parallel and ran them to # 1 on the Perko switch and the starting battery to #2. Thanks for any input.
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Doesn't Sound Right
Will, A couple of things sound funny. First, you should not have an ammeter in your circuit. Much has been written about changing the wiring harness in the C30, 34, and 36. Eliminate the ammeter and long wiring run up to the engine panel, probable corrosion points, increase the charging voltage, and decrease charging time. Call Seaward Products for the info and parts. Easy to do. I've never heard of an ignition switch grounding out an alternator. Sounds like a great way to fry the alternator if the switch shorts out (moisture, etc.) The ignition switch usually supplies power to the field terminal of the alternator. A 105 amp alternator is more than the M25 or M25XP was designed to handle. You might not have any problems, but every factory rep I've talked to has said that about 90 amps is max for that engine. Check out the C36 website for an alternator upgrade article by Rodd Collins. A number of people (including myself) have done it with no mounting or other problems. As has been said many other times, Nigel Calder's book is an outstanding source of electrical info. Page 521 of the 2003 WM catalog gives you a primer on elec systems, but read Nigel's book. Rather than having your alternator output go directly to the starting battery, which hardly gets used at all, have the output go directly to the house bank, and charge the starting battery with an echo charger or similar. Wiring for the whole system, especially a larger charging system, should be upgraded. Stock wiring was not designed to handle today's bigger electrical loads. Another item you might want to think about is a battery monitor. The Link 10 goes for about $200, and you'll always know what's going on with the system. Just my opinions. Tom Soko Julandra C36 #659
Will, A couple of things sound funny. First, you should not have an ammeter in your circuit. Much has been written about changing the wiring harness in the C30, 34, and 36. Eliminate the ammeter and long wiring run up to the engine panel, probable corrosion points, increase the charging voltage, and decrease charging time. Call Seaward Products for the info and parts. Easy to do. I've never heard of an ignition switch grounding out an alternator. Sounds like a great way to fry the alternator if the switch shorts out (moisture, etc.) The ignition switch usually supplies power to the field terminal of the alternator. A 105 amp alternator is more than the M25 or M25XP was designed to handle. You might not have any problems, but every factory rep I've talked to has said that about 90 amps is max for that engine. Check out the C36 website for an alternator upgrade article by Rodd Collins. A number of people (including myself) have done it with no mounting or other problems. As has been said many other times, Nigel Calder's book is an outstanding source of electrical info. Page 521 of the 2003 WM catalog gives you a primer on elec systems, but read Nigel's book. Rather than having your alternator output go directly to the starting battery, which hardly gets used at all, have the output go directly to the house bank, and charge the starting battery with an echo charger or similar. Wiring for the whole system, especially a larger charging system, should be upgraded. Stock wiring was not designed to handle today's bigger electrical loads. Another item you might want to think about is a battery monitor. The Link 10 goes for about $200, and you'll always know what's going on with the system. Just my opinions. Tom Soko Julandra C36 #659
Education !!!
Tom Thank you for putting into one paragraph what's taken me years to put into perspective for some of the "research ridden denizens" of this "site. Stu PS ...and without using the word "research"
Tom Thank you for putting into one paragraph what's taken me years to put into perspective for some of the "research ridden denizens" of this "site. Stu PS ...and without using the word "research"
Thanks Tom
Hey Tom thanks for all the info. The more ideas the better. I did upgrade the wiring and I was considering bypassing the ammeter. I even decided that it would be better to charge the house batteries rather than than the starter battery. You see Stu I have been doing my research. In fact that what the forum is all about isn't it. So Tom I guess we are kind of on the same page on this. I actually did all this because someone else had already done it and it was a big success. He did use a 90 amp alternator but the alternator shop said the 105 was an upgrade. 105 is the actual max output but at the rpm I will be running it will produce 90amps give or take a couple amps. Thanks again. See ya on the water.
Hey Tom thanks for all the info. The more ideas the better. I did upgrade the wiring and I was considering bypassing the ammeter. I even decided that it would be better to charge the house batteries rather than than the starter battery. You see Stu I have been doing my research. In fact that what the forum is all about isn't it. So Tom I guess we are kind of on the same page on this. I actually did all this because someone else had already done it and it was a big success. He did use a 90 amp alternator but the alternator shop said the 105 was an upgrade. 105 is the actual max output but at the rpm I will be running it will produce 90amps give or take a couple amps. Thanks again. See ya on the water.
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