Question: Modern Automobiles & Discharged Battery

[Woussko]

Why should you never just jump start a modern automobile or light truck and let the engine run to recharge a severally discharged battery? Why must you disconnect it (battery) and recharge it with a battery charger to no less than 90% of full charge before reconnecting it and trying to start the engine. This is for real and failure to do the above will result in costly repairs being needed. My question is why is this so. What's changed from the older times where the charging system could deal with a discharged battery?

One hint: Many cars can't deal with having high beam headlights on, and the blower set to high when you have the wipers on. You'll get away with if for a short time but not for long. Try it and you will soon have :eek: :eek: and :eek: and then *&^%$# it anyway.

This isn't maybe for ALL brands and models but it is for far too many of them currently made.

[BHD]

my guess is your referring to the voltage regulators in the new alternatives can not take it, and the electronics can not take the over voltage of the charging,

since I do not have "new" cars, and mostly I have the good old stuff, that you can run with out a battery if one wants if your alternator is working, and are nearly bullet proof,

Keeping the top of ones battery clean can help greatly in keeping a battery from discharging,

Also If your having alternator problems fix it, or batteries going fix it, or the bad one will take the other one out very soon,

Many times if your battery is nearing the end of the "months it was designed for" 60 month" or a "24 month", some times there is more there, but usaly the manufacture has the plates fairly close in there life, so you start to suspect some problems, if your battery is past it guaranteed life, consider it suspect of the problem. use a load meter and see if can still supply a charge under a starting load, besides being hard on the alternator, it will over heat the starter as well do the voltage drop.