watermellon
Member
- Joined
- August 15, 2010
- Messages
- 48
- Reaction score
- 0
- City, State
- Saskatoon, Saskatchewan
- Year, Model & Trim Level
- white 1989 ranger, 2.3l
"Solved"
I had a parasitic drain of 3.9 amps on my 89 ranger. I had just installed an aftermarket stereo. Tried it out and it worked fine. Didn't drive my truck for about a week and when I decided to take it for a run it wouldn't start. The battery was dead. I boosted it, did some driving around town, parked it at home and about 8 hours later tried starting it again. It wouldn't start, just a clicking sound when I turned the key. The following morning I charged the battery for 4 hours, started the truck, went to work and at home time the battery was dead again. Checked out the Forum and realized I had a battery drain somewheres.
Here's how I checked for a battery drain. Firstly, I made sure the little switch that comes on when the door is opened was pushed in and secured. Secondly I made sure the key was not in the ignition because the drain happens when the truck is parked and not running.
Then I disconnected the (-) negative battery cable and hooked up my multimeter between it and the (-) battery post. I had set the multimeter to the 10 amp DC setting and attached the black multimeter probe to the post and the red probe to the cable. I got a reading of 3.9 amps. That is very high, in fact it really surprised me. *
I then started searching for the parasitic drain by removing fuses one at a time. I did this by first disconnecting the black multimeter probe from the (-) battery post. I then removed one fuse from the fuse box, reconnected the black probe to the (-) battery post and checked the multimeter reading. The reading was again 3.9 amps. I disconnected the black probe again repeated the process for each and every fuse until all the ciruits were tested. Nothing changed. I then visually checked all the fuses in the fuse box next to the battery... everything was good. I couldn't figure out what was causing the drain.
I went back on the computer and somewhere read that a bad alternator can drain your battery even if the car isn't running. So I disconnected the alternator by unplugging the 2 connectors on it. I took a multimeter reading the same way I had done with the fuses and it read ZERO. I plugged the connectors back in and took another reading... 3.9 amps. I removed the alternator and had it tested. It was shot. I installed a new alternator, took a multimeter reading with the 2 connectors plugged in ... ZERO. I started my truck and drove it around and then parked it. In the morning I tried starting it AND it started. I was extremely happy! I have now been driving my truck for a week and have had no problem with it starting. As for the new stereo it works fine and it wasn't the cause of the battery's parasitic drain.
Remember if your truck is experiencing a parasitic battery drain check for a drain at the under the dash fuse panel by removing fuses one at a time and by noting the multimeter reading. If the problem persists then try testing the alternator.
* a normal battery drain for a newer vehicle with a computer and other accessories that stay "ON" all the time would be between 25 and 50 mA (milliamps) or .025 and .05 Amps. An older vehicle like my 1989 Ranger which doesn't have any "ON" items should be ZERO or very close to zero. The 3.9 Amp loss I was getting was equivalent to 3900 mA. To calculate Amps to milliamps just multiply the amps by 1000... 1 amp X 1000=1000mA
I had a parasitic drain of 3.9 amps on my 89 ranger. I had just installed an aftermarket stereo. Tried it out and it worked fine. Didn't drive my truck for about a week and when I decided to take it for a run it wouldn't start. The battery was dead. I boosted it, did some driving around town, parked it at home and about 8 hours later tried starting it again. It wouldn't start, just a clicking sound when I turned the key. The following morning I charged the battery for 4 hours, started the truck, went to work and at home time the battery was dead again. Checked out the Forum and realized I had a battery drain somewheres.
Here's how I checked for a battery drain. Firstly, I made sure the little switch that comes on when the door is opened was pushed in and secured. Secondly I made sure the key was not in the ignition because the drain happens when the truck is parked and not running.
Then I disconnected the (-) negative battery cable and hooked up my multimeter between it and the (-) battery post. I had set the multimeter to the 10 amp DC setting and attached the black multimeter probe to the post and the red probe to the cable. I got a reading of 3.9 amps. That is very high, in fact it really surprised me. *
I then started searching for the parasitic drain by removing fuses one at a time. I did this by first disconnecting the black multimeter probe from the (-) battery post. I then removed one fuse from the fuse box, reconnected the black probe to the (-) battery post and checked the multimeter reading. The reading was again 3.9 amps. I disconnected the black probe again repeated the process for each and every fuse until all the ciruits were tested. Nothing changed. I then visually checked all the fuses in the fuse box next to the battery... everything was good. I couldn't figure out what was causing the drain.
I went back on the computer and somewhere read that a bad alternator can drain your battery even if the car isn't running. So I disconnected the alternator by unplugging the 2 connectors on it. I took a multimeter reading the same way I had done with the fuses and it read ZERO. I plugged the connectors back in and took another reading... 3.9 amps. I removed the alternator and had it tested. It was shot. I installed a new alternator, took a multimeter reading with the 2 connectors plugged in ... ZERO. I started my truck and drove it around and then parked it. In the morning I tried starting it AND it started. I was extremely happy! I have now been driving my truck for a week and have had no problem with it starting. As for the new stereo it works fine and it wasn't the cause of the battery's parasitic drain.
Remember if your truck is experiencing a parasitic battery drain check for a drain at the under the dash fuse panel by removing fuses one at a time and by noting the multimeter reading. If the problem persists then try testing the alternator.
* a normal battery drain for a newer vehicle with a computer and other accessories that stay "ON" all the time would be between 25 and 50 mA (milliamps) or .025 and .05 Amps. An older vehicle like my 1989 Ranger which doesn't have any "ON" items should be ZERO or very close to zero. The 3.9 Amp loss I was getting was equivalent to 3900 mA. To calculate Amps to milliamps just multiply the amps by 1000... 1 amp X 1000=1000mA
