Alternator performance, battery drain
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Alternator performance, battery drain
Hello Folks,<O
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I'm working on a recently purchased 1987 F150 4x4 with a 4.9 six that sat untouched for a year. The original owner stated the battery does not have a drain problem. Initially, the truck's battery had 5.5 volts. I assumed this low number was from no maintenance and not a battery drain. Once I got the truck up and running there is now a battery drain. I did the usual negative cable/post test light procedure, this gave a clearly visible dim light. After pulling the fuses I found there is nothing open in the electrical accessories. <O</O
Then I unplugged the connector at the upper alternator and the test light went off but strangely flashes a very, very dim illumination. It's flashing at about a normal turn signal interval. Before I unplugged/plugged back-in the alternator this drain would kill the battery in a few hours. <O</O
The alternator's performance would keep 12.6 volts at idle and 13.5 volts while driving. Any two accessories (lights plus heater) would bring this voltage down below 12.5 volts. To use the truck, I've been disconnecting the negative cable, however, this morning I drove the truck and the in-dash voltmeter was well above 14 volts with the lights, wipers and heater on (it's cold and rainy today in Michigan). When I got home I put a multi-meter between the negative cable and the negative post and set the meter to mA. The reading was 0.02 mA which is below the acceptable 300 milli-amps as I've read elsewhere. I put the test light back in series and its bulb is still very faintly flashing. Now I've permanently reconnected the negative cable to see if the problem is gone. If the battery doesn't die is it possible something in the alternator has reversed itself? Is it possible the alternator connector was not making a good contact and the unplugging and plugging back in is all it needed? <O</O
Thanks in advance for any replies! Greg Nicholson
</OI'm working on a recently purchased 1987 F150 4x4 with a 4.9 six that sat untouched for a year. The original owner stated the battery does not have a drain problem. Initially, the truck's battery had 5.5 volts. I assumed this low number was from no maintenance and not a battery drain. Once I got the truck up and running there is now a battery drain. I did the usual negative cable/post test light procedure, this gave a clearly visible dim light. After pulling the fuses I found there is nothing open in the electrical accessories. <O
</OThen I unplugged the connector at the upper alternator and the test light went off but strangely flashes a very, very dim illumination. It's flashing at about a normal turn signal interval. Before I unplugged/plugged back-in the alternator this drain would kill the battery in a few hours. <O
</OThe alternator's performance would keep 12.6 volts at idle and 13.5 volts while driving. Any two accessories (lights plus heater) would bring this voltage down below 12.5 volts. To use the truck, I've been disconnecting the negative cable, however, this morning I drove the truck and the in-dash voltmeter was well above 14 volts with the lights, wipers and heater on (it's cold and rainy today in Michigan). When I got home I put a multi-meter between the negative cable and the negative post and set the meter to mA. The reading was 0.02 mA which is below the acceptable 300 milli-amps as I've read elsewhere. I put the test light back in series and its bulb is still very faintly flashing. Now I've permanently reconnected the negative cable to see if the problem is gone. If the battery doesn't die is it possible something in the alternator has reversed itself? Is it possible the alternator connector was not making a good contact and the unplugging and plugging back in is all it needed? <O
</OThanks in advance for any replies! Greg Nicholson
