Jump start

[pauleyman]

This isnt really dsm but generic but it could apply. Working on a volkswagen tdi today. Battery charger 200amp jump won't budge it. Jumper cables won't budge it. Battery is dead and won't charge. Bought a battery and it's fine.
On a jump start I guess you don't get the full amps from the donor?
I never really knew. I always thought even with a bad battery you could at least get it started and alternator takes over. Shows what I know. Comments?

 

[luv2rallye]

When jump starting, part of the current is going into the battery (depending on how low it is) and the rest to the starter so yes, you won't get to use the donor full amps to the starter. This along with voltage drop on the jumper cables and wires to the starter. All cable connections need to be clean and tight also.

 

[chrisman287]

When a battery is that shot you really need some good cables and I usually have the other car running. I’ll leave it connected for a bit before trying to turn the dead one over. 9 times out of 10 it’ll work

 

[evil_eagletalon]

Over the years as a sofa king ive seen a handful of batteries that wont even jump start. Its rare but it does happen. Its probably due to high resistance or open circuit.