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so this car won't start from a jump starter pack. I also tried leaving the pack in place for an hour to charge up the battery for longer before starting.

I am thinking of disconnecting one cable from the battery while jump starting the car so none of the current flows through the battery. If that's a worthwhile idea, I wonder about what to do once the car has started:

Thank you for your help!

Pᴀᴜʟsᴛᴇʀ2
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allstar
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  • It would help if you described what happens when you try to start the engine using the booster pack. Does anything happen? Does the starter turn too slowly? Does the engine fire at all? – HandyHowie May 26 '20 at 08:57
  • I don't hear any sound at all from the engine. Regarding the closing of this question, I think the second part of the question is not covered in the link. It's clear from comments below that driving around with the battery disconnected risks damage to electronic components, but what about re-attaching the cable as soon as possible after starting? – allstar May 29 '20 at 05:06
  • Those moderators who closed this question made a bad decision. The second bullet point of this question could be a valuable last resort, but it has not been answered yet. – RayLuo Oct 29 '21 at 05:05

3 Answers3

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The battery acts as a sort of buffer for the alternator. It can reduce the surges from the alternator that can potentially damage electrical components. The alternator will run the vehicle without the battery but is not recommended. If the alternator is good, and it doesn't jump, it may be because the installed battery is so discharged it impedes the jumpstart. If that's the case the battery should be brought to good condition before starting. If you run a car with a battery in that bad of condition it tolls heavily on the alternator.

HandyHowie
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Jupiter
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Disconnecting the battery is a bad idea. All current flows through the battery, if you disconnect it your car may not run right after you take the starter pack off as it is an important part of the electrical system. Starter packs do not charge your battery, they provide a short burst of energy to get your car started, once it is running your car's alternator will provide electricity to run the car and charge the battery.

If the car won't start despite the starter pack then you make have been using it wrong, or something else is wrong with your car. Try charging the pack up and going through the manual to make sure you understand how to use it, I had one which had been badly translated from Chinese to English and it took a bit of head scratching to figure it out.

GdD
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  • My understanding is that the alternator and battery are connected in parallel, so once the car is started the alternator would provide the electrical power to run the car. – allstar May 25 '20 at 23:32
  • @allstar they are in parallel, but power can come from either which is why, during winter use, some cars end up with a flat battery as the alternator does not provide enough power and trips may be short... – Solar Mike May 26 '20 at 04:55
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In the "good ole days" of 6 V batteries, I would generally disconnect the battery . Otherwise some of the jumper batterys' power is wasted going into the weak battery. This was important because normally the problem showed up in cold weather ( like 0 to 20F) and you needed all the power you could get.After it jump started ,it was no problem to hook up the old battery, the generator provided power to the ignition,etc. Things are so easy today with 12v and alternators ,now I generally don't bother to disconnect the old battery. My brother did manage to blow the side out of a 6 V battery when jump starting ( hydrogen can build up during fast discharge ) however he went on to become a college professor so understandably had limited mechanical skills. One car I had, I welded up a steel frame to hold a second 6V battery under the hood. In cold weather I would jump with both batteries in series ( 12 V).

blacksmith37
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