Brisvegas Posted June 11, 2017 Share Posted June 11, 2017 I'm just wondering whether forum members have any thoughts on jump starts. I'm specifically thinking about if there are any theories out there as to the possible dangers to electrical components in our cars, .... regardless as to whether your car is the "jumper" or the "jumpee." The Subaru manual sets out a procedure for Jump Starts, but makes no mention of any possible dangers. I'm just wondering if I should offer help in jump starting someone else's car, or if I should accept help to jump start mine. The following article is pretty clearly telling me not to do either. http://www.mynrma.com.au/get-involved/advocacy/news/why-you-shouldnt-jumpstart-a-modern-car.htm Link to comment Share on other sites More sharing options...
YeuEmMaiMai Posted June 11, 2017 Share Posted June 11, 2017 Personally I use a Rockford Booster pack as my jump starter. As long as you connect everything properly as instructed, there are minimal dangers. Link to comment Share on other sites More sharing options...
Yoda_One Posted June 11, 2017 Share Posted June 11, 2017 If concerned and you are not carring a personal lithium jump pack just call service or tow truck. Laughing at oneself and with others is good for the Soul! Laughing at Oneself and with Other is good for the Soul Link to comment Share on other sites More sharing options...
ehsnils Posted June 11, 2017 Share Posted June 11, 2017 The most radical problems that can occur is when you mix up positive and negative. But otherwise you shouldn't have much trouble doing a jump start. Best method is to connect the positive wires first, then negative wire from donor car battery and finally connect to a stable part of the engine on the receiving car far from the battery. Let the donor car idle and wait for a while so that the receiving car battery takes some charge then crank. Remove the wires in the opposite way starting with the ground on the engine. The reason to not put on the negative pole of the battery of the receiving car is that there's a risk of sparks that can ignite hydrogen gas at the battery. It's a small risk, but better be safe than sorry since sulfuric acid isn't fun. Here in Europe we also have to be careful with the voltage - trucks have 24V systems, cars 12V except for vintage cars that have 6V. Future trucks in North America will run 24V too, so in the future you should take care regarding voltage too. Link to comment Share on other sites More sharing options...
chowser51 Posted June 11, 2017 Share Posted June 11, 2017 Never used my car to start another one. I use a Kmashi portable jump starter. I've had to jump start my car once with it. I just used the Kmashi to jump start my police car yesterday (someone left everything inside on). Link to comment Share on other sites More sharing options...
larrya07 Posted June 12, 2017 Share Posted June 12, 2017 Problems that occur when jumping cars with battery cables fall under one or more of these three conditions. 1. most likely. allowing the jumper cables ends to touch after attaching or disconnecting to one of the batteries. This will most likely kill the diodes in the alternator. 2. as mentioned above connecting batteries of different voltages. 3 not likely unless one of the cars has a electrical issue. after the dead car starts not removing the jumper cables right away. Link to comment Share on other sites More sharing options...
MarK1D Posted June 18, 2017 Share Posted June 18, 2017 I read connecting battery to battery could potentially create a voltage spike damaging some Ecu parts? Sent from my iPad using Tapatalk Link to comment Share on other sites More sharing options...
Brisvegas Posted June 18, 2017 Author Share Posted June 18, 2017 I read connecting battery to battery could potentially create a voltage spike damaging some Ecu parts? I guess that's why I started this thread .... because I had read similar things. But it seems that the other forum members don't have too many concerns provided that the correct procedures are carried out. The Subaru manual has instructions on jump starts without mentioning any dangers, so I can only assume that means that it is safe to do it. I still admit to having some concerns, and will probably put jump starts into the "last resort" basket, and should the need arise, I will probably rely on roadside assist (which I pay a yearly subscription for). Link to comment Share on other sites More sharing options...
spect2k Posted June 18, 2017 Share Posted June 18, 2017 You can get "smart" jumper cables if you're not experienced and concerned. I got those for my wife's car. Absolutely idiot-proof! Not a bad idea for a knowledgeable person either... Link to comment Share on other sites More sharing options...
ammcinnis Posted June 18, 2017 Share Posted June 18, 2017 Not a bad idea for a knowledgeable person either... Agreed. Accidentally getting it wrong (e.g. polarity reversed) is easy to do and can be very expensive. "If you don't know where you're going, any road will take you there." ~ The Cheshire Cat (Alice in Wonderland) Link to comment Share on other sites More sharing options...
ehsnils Posted June 18, 2017 Share Posted June 18, 2017 I read connecting battery to battery could potentially create a voltage spike damaging some Ecu parts? Sent from my iPad using Tapatalk Only if you connect a 24V battery to a 12V battery. Or connect reverse. But the ECUs are specified to at least cope with overvoltage for a limited time. I have never seen anyone getting electrical failure due to jump starting an engine using proper technique so I file the claim that a jump start kills electronics more under urban myth. Link to comment Share on other sites More sharing options...
Brisvegas Posted June 19, 2017 Author Share Posted June 19, 2017 But the ECUs are specified to at least cope with overvoltage for a limited time. I have never seen anyone getting electrical failure due to jump starting an engine using proper technique so I file the claim that a jump start kills electronics more under urban myth. Thank you and to the others who have replied to the thread. I have just come across an online article that suggests that not starting the engine on the donor vehicle is an added safeguard to prevent voltage spikes and so I will add that to my "jump start procedures" " ... Avoiding voltage spikes When you connect jumper cables from a running vehicle to a dead battery, the alternator in the running vehicle instantly puts out maximum charging voltage. That can create a voltage spike of up to 15.5 volts in both vehicles. And it's that voltage spike that can fry computers and digital devices. One way to eliminate the voltage spike is to leave the engine off in the donor car. That will prevent frying computers in the donor car. But if the car won't start right up, don't grind away to the point that you end up with dead batteries in both cars! Jump-starting with a jumper pack (also called a booster pack or a juice pack) is a better alternative. The battery inside the jumper pack provides the boost to the dead battery at a safe voltage. When used properly, it's the safest way to protect the electronics in the dead vehicle while providing enough boost to get the engine running. ..." I will also look into investing in a jumper pack (as suggested also by Rowlette) ...... I may sound like I am overthinking this whole jump start thing, but with young kids to consider I want to make sure that lithium-ion batteries are safe to store in a car on long hot trips as referenced by the following article ... """ .. If They Can't Stand the Heat… All of the jump starters we tested had a maximum recommended operating/storage temperature, ranging from 120 degrees Fahrenheit for the Pilot InstaBoost up to 185 degrees for the Bolt Power D28. While some manufacturers cautioned only against operation at high temperatures (with reduced performance as a consequence), others specifically warned not to store the units at high temperatures--and that included the Pilot InstaBoost with its 120-degree rating. That's a major concern: According to the National Highway Traffic Safety Administration (NHTSA), the temperature inside of a car parked in direct sunlight can reach between 131 and 172 degrees Fahrenheit when the temperature outside is between 80 and 100 degrees. In hot desert areas, the inside temperature can rise even higher. Unfortunately, the device manufacturers were guarded on the potential consequences of storing these units at high temperatures. Complicating matters, it's the fact that most of the units list their temperature ranges (operating or storage) in the instructions, but not on the product packaging. The takeaway: Read the instructions carefully and check the fine print. During the hot summer months, consider storing the unit in a cool location and only taking it with you on long trips. If you are storing the unit in the car, choose a location out of direct sunlight, such as the glovebox or the trunk. Link to comment Share on other sites More sharing options...
ehsnils Posted June 19, 2017 Share Posted June 19, 2017 The 15.5 volt spike is something that car electronics shall cope with, it's not abnormal. A normal requirement is to have an upper limit of 18V for 2 hours and 24V for 2 minutes on the ECUs in a car, but for plug-in chargers for your phone and other devices it's a different matter. As long as the donor vehicle is idling the alternator is also not running at maximum power and you will be safe. As for LiIon batteries - as long as they are body temperature and below they are OK, but if exposed for higher temp then they are in the danger zone. Link to comment Share on other sites More sharing options...
Bolt Posted June 21, 2017 Share Posted June 21, 2017 I'm just wondering whether forum members have any thoughts on jump starts. I'm specifically thinking about if there are any theories out there as to the possible dangers to electrical components in our cars, .... regardless as to whether your car is the "jumper" or the "jumpee." Jumping your car won't damage any OEM components. However some aftermarket components are built to very shitty standards, especially cheap alarm systems and LED lights. These can be damaged by a slight breeze let alone load dumps and voltage spikes from jump starts. Link to comment Share on other sites More sharing options...
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