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Posted By Discussion Topic: Over charging condition on '36 V8? -- page: 1 2     Flatbob 04-19-2010 @ 7:40 PM reply profile send p.m. Member Posts: 437 Joined: Oct 2009 Am wondering if Optima batteries are more prone to damage than wet cell batteries with an over charge condition. I'm on my 3rd Optima in less than 2 years, tried to get a reading across battery posts while engine was at idle but got very erratic readings, some as high as 12 plus volts, this doesn't seem like it would be possible. Superreal stated that a generator over charging could damage electrical components; my car is running rough (radio no longer works & fuel gauge needle rises as RPM increases.) Will take battery to get checked as I'm constantly recharging but doesn't hold charge. TomO 04-20-2010 @ 7:00 AM reply profile send p.m. Senior Posts: 7257 Joined: Oct 2009 Any battery will fail to deliver long life if overcharged, the Optima is sensitive to fast charging. The erratic voltage readings could be due to using a digital meter that is not rated for automotive use. The transient spikes from the generator brushes bouncing will cause these erratic readings. Try using an analog meter to check the generator voltage. You should be able to set your generator's 3rd brush by using the ammeter. Set the brush so that the ammeter reads 0 amps with the headlights on and the engine running at about 1500 RPM or 30MPH. You could also install the solid state voltage regulator to replace your cutout. This would be my recommendation. Tom Flatbob 04-20-2010 @ 7:18 AM reply profile send p.m. Member Posts: 437 Joined: Oct 2009 TomO, analog meter, is this available at an auto parts store? Thanks, Bob supereal 04-20-2010 @ 8:47 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Cheap analog (needle type) meters are available at Walmart, Radio Shack, and other outlets. As TomO says, digital meters are often too sensitive, particularly on inputs that are not steady state. The output of a generator is quite "dirty". That is, it is full of spikes and valleys, usually due to bad brushes or worn commutator. The "damping" of the meter needle will help get a better idea of the circuit voltage. When there is a wide variance in voltage, the meter reads the "RMS" (root mean square) to provide an average. Optimas, and other brands of glass mat batteries are damaged by high or inconsistent charging. My Optimas have lasted more than six year, and still hold a charge. I suggest you be sure that your generator and engine is well grounded. If you can't read an almost steady 7-7.5 volts across the battery when at a fast idle, the generator and/or the cutout probably needs repair or replacement. Also, be sure all connections between the cutout, ammeter, and the battery are clean and tight. Any poor connection will produce your problem, with consequent battery failure. Flatbob 04-20-2010 @ 4:08 PM reply profile send p.m. Member Posts: 437 Joined: Oct 2009 TomO, Supereal, got an analog meter and shows 8.5V across the battery terminals at fast idle; this is too high correct? Will adjust brushes to read 7.5V at fast idle correct? Thanks, Bob ford38v8 04-20-2010 @ 6:58 PM reply profile send p.m. Senior Posts: 2769 Joined: Oct 2009 Flatbob, I believe Super and Tom will agree that 8.5V is too high, but also, that when you have a fully charged battery, your cutout should do its job and reduce the input down to 6.5V to 7V. This is also when you will see your ammeter show Zero+. After using the starter to fire up your engine, normally it will take 5-10 miles of normal driving to recharge the battery. A fast idle should do it in 15 minutes. Alan TomO 04-21-2010 @ 7:57 AM reply profile send p.m. Senior Posts: 7257 Joined: Oct 2009 Alan, My understanding of a cutout is that it is a common relay designed to close the points when 6.5 volts is applied to the coil. It will hold those points closed until the voltage drops below the pick voltage. It does not care about the state of charge of the battery, you need a voltage regulator to take the state of the battery charge into consideration. Tom supereal 04-21-2010 @ 10:06 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Yes, 8.5 volts is too high, and will cook your battery. Adjust the system voltage to no more than 7.5 volts at a fast idle. The purpose of the cutout is to disconnect the generator when the engine is shut down so the battery isn't drained. It isn't a voltage regulator of any kind with the three brush generator. We set those with a voltmeter, as most ammeters are not accurate enough to be reliable. Some high charging rates are due to a partially shorted battery, either sulfated or with a bad cell, causing a high resistance. A loose or otherwise batter cable can also raise system resistance. Voltage is the product of current multiplied by resistance. Flatbob 04-21-2010 @ 4:49 PM reply profile send p.m. Member Posts: 437 Joined: Oct 2009 After brush adjustment my meter now shows slightly over 7 volts at fast idle & with headlights on amp. gauge shows zero charge. supereal 04-22-2010 @ 7:36 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 I'd run it there, as you are very close. Most old car dashboard ammeters don't move much, and are not reliable enough to set the charging rate. If we need to check system current, we use a clamp-on ammeter, as most VOM meters can't handle the load. That's why the voltmeter technique is helpful.

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