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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,077
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Question for the electrical engineers and gurus
Which Batt if any in a two batt system like on a diesel pickup (two batt in parallel )
Should be used to jump a single batt vehicle? I say it does not matter. Others say it does. I can not find a technical write up anywhere. I have jumped many vehicles and never payed any atn, to which i hooked up to. Your thoughts?
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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03-10-2015, 06:28 PM
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Registered
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Doesn't matter.......either one will provide 12 volts.
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Pete 79 911SC RoW "Tornadoes come out of frikkin nowhere. One minute everything is all sunshine and puppies the next thing you know you've got flying cows".- Stomachmonkey |
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03-10-2015, 06:34 PM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,077
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I understand that.
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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03-10-2015, 06:36 PM
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Parrothead member
Join Date: Jul 2003
Location: Monmouth county, NJ USA
Posts: 13,827
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Doesn't make a difference.
.
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Vinny Red '86 944, 05 Ford Super Duty Dually '02 Ram 3500 Diesel 4x4 Dually, '07Jeep Wrangler '62 Mercury Meteor '90 Harley 1200 XL "Live your Life in such a way that the Westboro Baptist Church will want to picket your funeral." |
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03-10-2015, 06:54 PM
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Band.
Join Date: Dec 2003
Location: Denver, CO
Posts: 13,314
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The one that's closer will provide .000000000000000001% better performance.
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1983 SC Coupe 1963 BMW R60/2 1972 Triumph Tiger 1995 Triumph Daytona SuperIII |
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03-10-2015, 07:06 PM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
Posts: 14,077
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I guess the stupid in the argument is that the alt wire is on one side, not both.
I think the answer is there is no correct answer, which is what i thought.
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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03-10-2015, 07:09 PM
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Band.
Join Date: Dec 2003
Location: Denver, CO
Posts: 13,314
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You could totally calculate the voltage/current drop in the length of cable that is farther away from the alternator, if you knew the properties of the cable used in the construction of the vehicle.
 I just did a quick mental calculation based on the knowledge I acquired from my Bachelors of Music.
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1983 SC Coupe 1963 BMW R60/2 1972 Triumph Tiger 1995 Triumph Daytona SuperIII |
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03-10-2015, 07:14 PM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
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It cant be worth the effort....LOL
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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03-10-2015, 07:16 PM
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canna change law physics
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If they are truly in parallel, there should be no difference. They are both are used to turn the starter and should be balanced, or one will die before the other. The same is true for charging.
Besides, with a diesel truck, the alternator is usually an extra heavy duty. I doubt you will be pulling current from anything except the alternator. Most battery cables should be used to CHARGE a battery, not try to start a car.
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James The pessimist complains about the wind; the optimist expects it to change; the engineer adjusts the sails.- William Arthur Ward (1921-1994) Red-beard for President, 2020 |
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03-10-2015, 08:14 PM
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Registered
Join Date: Jun 2001
Location: Sweden
Posts: 5,910
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Doesn't matter...the battery that is further away from jump cables will provide slightly less amperage due to miniscule voltage drop across the cables that is connecting it to another battery...that's all.
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Thank you for your time, |
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03-10-2015, 11:29 PM
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Bandwidth AbUser
Join Date: Nov 2001
Location: SoCal
Posts: 29,522
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Doesn't matter.
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Jim R. |
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03-11-2015, 03:58 AM
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You do not have permissi
Join Date: Aug 2001
Location: midwest
Posts: 39,828
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Voltage= Amperage x Resistance: https://en.wikipedia.org/wiki/Ohm%27s_law
Batteries in parallel stay 12V but the amps available double(assuming both are same). If one drops it gets refilled by the other. Considering that most of the resistance is in the discharged battery and it has a much smaller mass and electrical potential than the two in the truck, any resistance in the cables/connection should be negligible. The limitations are in how fast the dead battery will accept new electrons. Resistance does play a larger role at higher voltages, but this is only 12V. |
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03-11-2015, 05:03 AM
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non-whiner
Join Date: Aug 2012
Location: Slightly right of center
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Doesn't matter, but I'm real curious as to the reasons given by those who say it does.
What reasons do they give so we can laugh at them?
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"Too much is just enough." |
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03-11-2015, 05:09 AM
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Air Medal or two
Join Date: Jul 2003
Location: cross roads
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Quote:
Its a elementary thought as thats not how the systems charge anyway (unless your name is Lucus ) LOL
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D troop 3/5 Air Cav,( Bastard CAV) and 162 Assult Helicopter Co- (Vultures) South of Saigon, U Minh Forest, Delta, and all parts in between |
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03-11-2015, 07:11 AM
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Professional Bull5hiter
Join Date: Mar 2008
Location: Alice Springs, Australia
Posts: 8,889
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It's all about how the smoke fills the batteries. The one closest to the alternator fills first, then when it's full it spills over into the next battery, and so on. You won't be able to use the battery connected via the jumper cables to start anything unless it is full of smoke first.
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Jeff 83 944 Guards Red 23 718 GT Silver |
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03-11-2015, 07:30 AM
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non-whiner
Join Date: Aug 2012
Location: Slightly right of center
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This should help:
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"Too much is just enough." |
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03-11-2015, 07:58 AM
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1979 Porsche 911SC
1970/1982 Porsche 914-6/911SC 2.7 RS
