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I'm having an issue with my car (It won't start) but it seems different from when my battery has been bad in the past.

Here's the general sequence of events:

  • Try to start car, it's completely dead (Even electronic unlocker doesn't work)
  • Connect car to jumper cables and immediately wipers turn on (So I know it's getting power)
  • After 5 minutes or so, try to start the car and it does the normal thing it does when the battery is almost dead
  • Wait another 10 minutes with the jumpers connected.
  • Try to start the car again. This time, the battery is completely dead. No lights, fans aren't working, and nothing from turning the ignition.

I tried the same thing again a few hours later with different cables and got the same result.

It doesn't seem like the battery, since the cables aren't providing any power. I thought maybe I blew a fuse or burnt out the jumpers but the whole sequence of events, with it getting minimal power at first but quickly dying completely happened a few hours later. Does anyone have any advice on how to figure out what's wrong with my car?

EDIT: It's 2005 Ford Escape

  • 2
    A good connection with quality jumper cables is often the difference between starting a car with a dead battery and not. Your car has a dead battery. Have you thought about replacing it? You've not given the make, model, or year of your vehicle. – cory Nov 30 '16 at 16:17
  • Edited with Year, Make and Model. If the battery is dead, why do I get this sequence of events: Gets a little charge from jumpers -> Gets no charge from jumpers -> wait a few hours -> Gets a little charge from jumpers -> Gets no charge from jumpers?? This is the part that is confusing me – popctrl Nov 30 '16 at 16:25
  • I imagine your intermittent "charge from jumpers" has to do with a dodgy connection. Often times, just wiggling them a little will be enough to change the quality of the connection. – cory Nov 30 '16 at 16:28
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In my experience with automotive electrical, it can be very tricky to figure out, but the first most important thing is ensuring that you have a fully charged, functioning, battery. There are a great many oddities that can be traced back to insufficient battery performance.

If you have not changed your battery in the past 11 years, it's probably time to replace it. If your battery is somewhat new (< 3 years) there's probably something wrong that is damaging it. Even a budget battery should last more than 3 years without critical failure. Personally, I'd probably throw a new battery in and see what happens.

If you have a couple tools, and really wanted to test what was happening, this is what I'd do:

  1. Test your battery. Simply disconnect it from your Escape's leads and check it with a voltmeter or multi-meter on the VDC setting. General rule of thumb (that I was taught with) is that it a battery falls below 10 VDC it's probably shot. If you have a good multi-meter you can also check the high/low readings over some hours. If your meter is constantly declining while the battery is not connected, then your battery is probably shot, especially if it's declining =< 11 VDC.
  2. Test with a proper battery. Either fully charge your battery (if it's healthy) using a battery charger, or get a new one to test with. Over a couple days, take readings 3 times a day (morning, noon and night). This will show if there are recharge issues from the alternator. Plus at this point you can do a lot of diagnostics on your system.
  3. Resolve the issue.

    a. If you discover that your test battery is losing voltage outside acceptable ranges, now you have to discover why. There are so many parts that could cause too much draw. Even a damaged alarm system (which I've run into in the past) can cause constant drain and cause you battery to be dead every morning after sitting all night. At this point, I'd probably recommend taking it in unless you're very comfortable and confident with automotive electrical systems. You could also come back here and update your post with new information and we can help diagnose it.

    b. If your battery is holding charge from 12VDC-14.5VDC you should be OK, although 12VDC should probably only be right after turning the motor and should go back up quickly.

You have to remember with electricity that many relays, capacitors, motors and such will only work within a specific window of power, but they all provide resistance to some degree. Even the wires, cables and conductors provide some resistance. If the voltage drops too low, the amps will not be able to make it to the needed devices in sufficient quantity to operate the device. This is why the starter is usually the first thing that stops working right - it takes huge amperage and if the voltage is too low, the resistance blocks the flow too much resulting is a weak turn, or no turn at all.

As for things that COULD (theoretically) cause your problem, there could be a relay that isn't functioning at ~10VDC but does function at ~12+ VDC which is causing a short. This would make it seem to work at or below 12 VDC, but stop working at or above 12 VDC. Of course once the battery becomes too drained (from shorting) it will release the relay and allow a new charge cycle to begin and the same symptoms to reoccur. That's a shot in the dark, but possible in theory (without knowing your car's system extensively I can't say for sure if that's possibly).

  • Well...My battery's running at 7.7 VDC so that must be the issue. Thanks for the guidance on how to test it, hopefully I'll mark this as the answer when I get back from the store :) – popctrl Dec 3 '16 at 15:50
  • That makes sense. I was leaning toward the battery as the issue. Good luck! :) – kyle_engineer Dec 3 '16 at 18:17
  • Awesome! Glad it all worked out. Keep an eye on it to ensure that nothing else is causing battery issues. – kyle_engineer Dec 5 '16 at 17:01
  • I'm fairly sure the issues with the battery stems from my aftermarket amplifier...But I'm not dishing out to fix that. – popctrl Dec 5 '16 at 17:04
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A bad or defective battery can play all kinds of games on you. What you have described is most likely a dead cell in the battery. It can act like it has power when it technically does not have enough to do all it is supposed to.

You have two choices.

  1. Disconnect the battery from the vehicle and completely charger it with a proper battery charger. If the same issue exists, replace it.
  2. Take the battery to be tested (it will need to be charged to properly test it).

If you can get it started and drive it to the auto parts store, many can diagnose it for you there (call first). Some will even replace the battery for you if you buy it from them.

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Did you check that the cable clamp connections are clean. They often have a build up of white/blue/green corrosion from the interaction of sulfuric acid with the lead or copper. If they are dirty, I tip hot water on them (from the jug) to get rid of the worst build up first. I have also found that some sand paper around the terminals on the battery, and inside the cable clamps, has been useful. Rinse everything off with hot water again after cleaning. Hot water will not hurt anything and it will dry quickly. It dilutes everything and washes it away without creating new chemical reactions. After drying, I apply high temperature bearing grease to the terminals and inside the clamps. If you get a sealed gel lead acid battery it will last longer and will be less likely to create corrosion on the terminals. All the best with it.

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