Failed Car Alternator Work Around




Introduction: Failed Car Alternator Work Around

There are some things you should just never, never, do...

Failed Car Alternator Quick Work Around

So you car's alternator has failed and you have no time to get it fixed... Your battery under the hood may even be dead from running your car without a functioning alternator. You need to drive your car NOW!.... What to do?

My solution was to add a second battery in the passenger compartment that could be easily charged or swapped out to keep the car going and get you to your destination. You don't have to wait to charge the dead battery and you don't have to swap out the battery under the hood.

Add a second battery on the passenger floorboard. You get twice the capacity with both batteries charged. Remember your car electrical system is running only on battery and is not being recharged by the alternator -- ultimately the batter(ies) will be exhausted and your car will not drive, so having more battery capacity is a good thing.

This quick 'fix' gets you up and driving as fast as possible with minimal work on the car.

CAUTION / DISCLAIMER: Although I have used the method described to drive a car with a broken alternator, I do not recommend it. This Instructable is mainly for entertainment purposes. There are many hazards that can be introduced and many that may be unforeseen. So don't do it. If you do, you are responsible for your actions and not me. In other words, I don't want to hear from your lawyer! Be safe and smart.

Step 1: Materials


1. Second Automotive Battery (Fully Charged - You keep it charged all the time just in case, don't you?)

2. Long Heavy Duty Jumper Cables

3. The All Important Duct Tape

Step 2: Position Your 'Secondary' Battery on the Passenger Floorboard

Place the second battery on the passenger floorboard, making sure it is level and stable. You don't want it falling over and spilling electrolyte (sulfuric acid).

Step 3: Run the Jumper Cables Through the Window

Open the passenger's window and run the jumper cables through the window.

Make sure the jumper cables are not shorted together. You can do this by clamping one of the jaws onto the insulated cable so they don't touch. Only do this if the teeth on the jaw will not damage the insulation on the cables.

Step 4: Open the Hood and Run the Jumper Cables to the Battery

Snake your jumper cables across the engine compartment to the existing car battery. Make sure that the jumper cables will not get caught in any moving parts, especially belts or fans. Make sure the cable insulation will not contact hot parts and melt. Make sure the cables will not bounce around and get caught in moving parts or contact hot parts. You might have to use some duct tape here.

Step 5: Connect the Jumper Cables to the Car Battery

Connect the jumper cables coming from the passenger compartment battery (not connected) to the car's battery under the hood. Position the jumper cable clamps/jaws to that they can lay as flat as possible so that the hood could be closed. Make sure that the clamps don't short against each other or the opposite battery post or to the car frame or other metal.

Step 6: Gently Close the Car Hood Until the Safety Catch Engages

With the jumper cables positioned as near to the front of the hood as possible, gently close the car hood making sure that nothing shorts out and nothing gets pinched. You won't be able to close the hood all the way because of the jumper cables leaving the engine compartment. But gently close the hood until the Hood Safely Catch Latches onto the hood.

Reposition the jumper cables if necessary to get the hood to close enough to engage the Safety Catch. This catch keeps the hood from flying off in case it was not closed properly or the main latch fails. In this case the Hood Safety Catch keeps the hood closed while driving.

If you're Hood Safety Catch is not there, is damaged, or doesn't function properly don't use this Instructable.

Step 7: Tape Down the Jumper Cables

Duct Tape the Jumper Cables in place from the engine compartment back the the passenger compartment.

Carefully roll up the passenger window so that the window is as closed as it can be without pinching the jumper cables too much.

Step 8: Connect the Interior Battery

Connect the Jumper Cables to the passenger compartment battery.

Your are good to drive off to your destination!




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    11 Discussions

    What is practical and actually, not that humorous is, may increase the efficiency of the vehicle is like how this is performed though maybe no on the floorboard with a non SLA/AGM battery.

    Say a hypothetical situation being experienced in the instructable is you don't have time to charge the battery, the trolling motor battery is charged, you have jumper cables, you need to get to work or somewhere one time. This will work.

    To perform the energy efficiency method, you can mount the battery in a more secure location with a safer battery and run the wires to be most efficient. Then create some sort of charger system so when you are at a location where you can charge, you can charge the battery. Then you have the added advantage of not using the alternator to cause more drag on the drive train.

    Seems I read about someone in their truck doing this years ago to max out efficiency of their V8 or diesel. I forget. They decided to not use the alternator.

    Next would be not using the fan and going with an electric fan system... though many newer makes and models do this already. I was looking at a Dodge Viper fan or Lincoln I forget which model fan for my Dodge Ram 360 V8 at one time and doing a "selectable" alternator option similar to the A/C electric clutch that I never moved forward on as I have other projects. I was thinking I could use a bearing on the shaft with back plate and a pin also as a manual get out and do it method to.

    2 replies

    One final note is I just realized this may actually lower the signals noise on my Dodge Ram I'm modifying out to a radio direction finding (RDF) patrol camper rig. Like this design though with a long bed and not extended cab:

    I'm going to have to investigate doing this again. I am already have two more deep cycle batteries to add with a backup switch to be able to start if the starting battery fails as well as DC and AC chargers. I was going to mount the solar cells permanently though was reading there is more AM noise from the solar cells or at least that is what Toyota noted with the Prius solar roof panel design to charge the main battery.

    I meant to say above "...need to get to work or somewhere ON time."

    Neat instructable also. Something I didn't expect to see on here. Thanks for sharing!

    Good suggestion for short period, with extra Battery it will encourage the repair of alternator.


    5 replies

    Valid Point - As I said:

    "CAUTION / DISCLAIMER: Although I have used the method described to drive a car with a broken alternator, I do not recommend it. This Instructable is mainly for entertainment purposes. There are many hazards that can be introduced and many that may be unforeseen. So don't do it. If you do, you are responsible for your actions and not me. In other words, I don't want to hear from your lawyer! Be safe and smart."

    The dead battery serves no purpose, its smarter to swap out the dead with a charged one. if you have 2 charged batteries, id keep one in the trunk and swap accordingly. Also your setup is running in parralel, not series that would actually benefit you.

    Thanks for the comment. My intent was to avoid doing any work on the car. Getting a battery out of the engine compartment can be a bit time consuming particularly if the battery clamp is rusted.

    I am not sure I understand your comment to connect the batteries in series - my car would not like 24V ! :-)

    Even a rusted clamp can't be more time consuming than rigging cables to a second battery inside the car. Also, most people don't just have a second battery lying around. If a person isn't comfortable enough to remove a serpentine belt and unbolt an alternator, they're probably not going to be comfortable running jumper cables inside the passenger compartment to a completely unsecured battery on the floor.

    series would double the voltage, that's not a good idea.

    I have done something similar when my alternator went out on a Wednesday and I wouldn't have time to change it until Saturday. I bought a cheap trickle charger at Walmart and mounted it under the hood, connected the leads to the battery terminals, and ran the plug a short way out from the front grill. Charged the battery overnight and would have a full charge for the morning drive to work. Carry along an extension cord and charge it at work so I could get home. Worked great for a few days and didn't kill the battery. I also didn't use any "extra" electrical i.e. Lights, ac, fans, radio, etc so I could get the most life out of the charge for those few days.