CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Battery Boost Damage

I have been told by some friends who are engineers that giving someone a battery boost could damage my car’s electrical system if I own a fairly new car. I have tried searching online everywhere and posting on blogs, but I seem to get conflicting answers and no hard evidence. Is this true? Your help would be greatly appreciated.

If the booster cables are connected and disconnected correctly–on both cars–there is no likelihood of damage. That being said, you might be surprised to see how many posts we get in this forum from people who did not connect the cables correctly, and who suffered electrical system damage as a result.

Human error is always a factor, and if someone is stressed by a vehicle breakdown, they are more prone to error. Even if you, as the donor, are careful, there is a real chance of the “donee” (is that a word?) screwing things up with your car.

Post some of the answers you have already recieved and post the engineers rational for what they profess,they must back up their ideas also.

For what it is worth BMW provides a “jump point” under the hood of all their vehicles,if jumping a car could damage it you would think a purpose built jump point would not be designed in the car.

Maybe we should go back to the old days and the emergency hand crank. My Dad’s 1939 Chevrolet had an emergency crank and I saw him “twist her tail” on several occasions to start the engine when the battery was dead. When he traded the Chevrolet for a 1947 Dodge that didn’t have the emergency hand crank provision, I worried about how he would start the car if the battery was low. Today, you can’t even push start a car with a dead battery. Jump starting is the only answer. My 2006 Chevrolet Uplander has a jump start point under the hood and instructions in the owner’s manual with the procedure to jump start the car.

When I was in high school, I worked for a farmer that had a Farmall F-12 tractor that had magneto ignition and started with a hand crank. I regarded anyone who used a tractor with a battery starter as a wimp. Today, even push lawnmowers and roto-tillers have available battery electric starting. As difficult as my two cycle Earthquake roto-tiller is to start, I’m beginning to wish that I would have swallowed my pride, become a wimp and bought the model with the optional electric start.

It’s the reverse voltage polarity that damages cars’ electronics and electrical systems which occurs where the jumper cables are connected wrong.
Walmart, and other stores, have jumper cables available which have a polarity safety device built into the cables. Use those for the greatest safety. They CAN’T be connected wrong.
As far as greater forward voltage obtained with correctly connected jumper cables, the voltage won’t be more than 15 volts from the donor car, which is well within the safe operating range of the electronics.