As noted, several times, my battery has died after letting the car sit unstarted, for shorter and shorter intervals. Usually, after a jump and a nice drive later, all of the electrons were back in their proper place. This time, I wasn't so lucky, and after a few 30-minute drives home, the battery didn't hold a charge overnight. Something was wrong.
Did I have a parasitic drain on an otherwise good battery due to dodgy wiring in my Ford? Or, did my battery have one terminal in the grave? I found out, somewhat inclusively, but not before disabling my wipers.
Here's an electrical diagram of a car. Closing the Ignition Switch (via a key or maybe some other nefarious method) energizes the Car Stuff and vroom, vroom, off you go. An open ignition switch keeps the electrons from going anywhere, leaving them to congregate in your Battery, waiting for the next time you need to start the engine. When the ignition switch is closed, there's some activity in the Car Stuff block that charges the battery and otherwise supplies electricity to run the rest of the car.
What about that block in the middle, the one with the question mark? That's the electrical stuff running in the car independent of the ignition switch state: anti-theft system, maybe the radio, or that thing plugged into the cigarette lighter charging your phone. The question mark could also be a fault in the wiring causing a flow of electricity diminishing the battery's stored power between start-ups, causing that dreaded click followed by reaching for the jumper cables.
Once running, the engine generates enough power to both recharge the battery and power the rest of the system. The Freestyle battery wasn't holding enough of a charge to start the car, even after running it for 30-45 minutes on a long commute. It could be a bad battery, unable to store energy, or a leak in power due to a fault in the wiring.
Finding a wiring fault is accomplished by:
Here's a my electrical diagram modified to show what the system looks like with a meter installed. In the Freestyle, I removed the negative side of the battery and used a piece of plywood to insulate the terminal from the connector, so I didn't get a faulty read. I then attached a spare battery terminal to the battery to get a good place to attach the test leads.
Why did I use the negative terminal? It's much safer! There's a wire going from the negative side of the battery to the body of the car, and other points as well, essentially making the entire car the negative battery terminal. During my testing if I touched one of my testing probes to the metal of the car, I would be making a connection from one part of the negative terminal to the next, no real difference in voltage potential. But... if put the test terminals on the positive side and mistakenly touched something metal, ZAP, because I would effectively be connecting the positive and negative terminals directly, causing a short-circuit.
Back to doing the measuring because this is where things became interesting. When I initially connected the meter, the lights flashed and the meter showed about ~1.5 amps, this decreased to about 1 amp and the oscillated between 0 and 5 milli-amps. Naturally, I thought my free meter from HF was the culprit. Using my Craftsman meter, I saw the exact same results. The draw when the ignition switch was open (car off) was small not to be a significant load on the battery.
What was the use of pulling the fuses at this point? Not much, but I was still unsure if my measurement tools were working correctly, maybe the draw was really 1.5 amps consistently? Since the rear windshield wiper didn't work, I wondered if this was due to a wiring issue and that could be the problem? I pulled this fuse with no change in amps drawn. Going through the book, I tried some other likely culprits, one fuse at a time, with no success. Considering the glowing state of my ABS lights, maybe the ABS system was shorted somewhere? No dice.
It was getting late, so I decided to put things back together for the evening. The next day, the engine started weakly and needed a jump to leave the gym on my way to work, and again at the end of the work day from my HF sourced car jumping battery thing.
On drive to work, as it started to drizzle, and I was running even more late than usual, I found my wipers didn't work. Pulling over into a gas station, I opened the hood and checked the use for the wipers (since I pulled it, I remembered where it was). It looked OK. Hoping the rain didn't develop into a downpour (it didn't!), I headed to work. Putting the defroster on MAX and keep the windscreen clear of the light snow on the way home.
After dinner, I checked the fuse by using a continuity tester on my multi-meter: it worked. So I turned-on my wiper blades and when the fuse was 1/2 inserted, they wiped away. I used a bit of cleaning fluid and re-inserted the fuse, same result. After a little fiddling, I found inserting the fuse just the right way resulted in a good connection, and thus working wipers. Once working, I decided to not continue with testing other fuses, so that I didn't disable something more critical.
Thinking that I didn't really have a parasitic drain killing the battery, I wheeled on over to Advance Auto parts and had them install a battery for $120, about $20 more than one I would have purchased at Wal-Mart. Optimistically, I opted for the battery with the 3 year warranty. It's been more than a week with no problems, even though the temps have dipped into the single digits, so we'll call this fixed.
Did I have a parasitic drain on an otherwise good battery due to dodgy wiring in my Ford? Or, did my battery have one terminal in the grave? I found out, somewhat inclusively, but not before disabling my wipers.
| Hope this isn't too complicated! |
What about that block in the middle, the one with the question mark? That's the electrical stuff running in the car independent of the ignition switch state: anti-theft system, maybe the radio, or that thing plugged into the cigarette lighter charging your phone. The question mark could also be a fault in the wiring causing a flow of electricity diminishing the battery's stored power between start-ups, causing that dreaded click followed by reaching for the jumper cables.
Once running, the engine generates enough power to both recharge the battery and power the rest of the system. The Freestyle battery wasn't holding enough of a charge to start the car, even after running it for 30-45 minutes on a long commute. It could be a bad battery, unable to store energy, or a leak in power due to a fault in the wiring.
Finding a wiring fault is accomplished by:
- Adding a meter to detect the flow of electricity (amps, so an ammeter, just throw out that p)
- Isolating circuits, to find the rough starting point of the problem
| All metal in your car behaves as the negative side of the battery |
| Plywood insulates batter terminal so I don't get false positives |
Why did I use the negative terminal? It's much safer! There's a wire going from the negative side of the battery to the body of the car, and other points as well, essentially making the entire car the negative battery terminal. During my testing if I touched one of my testing probes to the metal of the car, I would be making a connection from one part of the negative terminal to the next, no real difference in voltage potential. But... if put the test terminals on the positive side and mistakenly touched something metal, ZAP, because I would effectively be connecting the positive and negative terminals directly, causing a short-circuit.
| Free HF Meter |
| Owner's manual to the rescue! |
It was getting late, so I decided to put things back together for the evening. The next day, the engine started weakly and needed a jump to leave the gym on my way to work, and again at the end of the work day from my HF sourced car jumping battery thing.
No Wipers
| Cleaning fluid didn't make a difference |
After dinner, I checked the fuse by using a continuity tester on my multi-meter: it worked. So I turned-on my wiper blades and when the fuse was 1/2 inserted, they wiped away. I used a bit of cleaning fluid and re-inserted the fuse, same result. After a little fiddling, I found inserting the fuse just the right way resulted in a good connection, and thus working wipers. Once working, I decided to not continue with testing other fuses, so that I didn't disable something more critical.
Thinking that I didn't really have a parasitic drain killing the battery, I wheeled on over to Advance Auto parts and had them install a battery for $120, about $20 more than one I would have purchased at Wal-Mart. Optimistically, I opted for the battery with the 3 year warranty. It's been more than a week with no problems, even though the temps have dipped into the single digits, so we'll call this fixed.
