North American Turbocoupe Organization



Electrical Issue
87Turbowisconsin Offline
Junior Member
#1
Just wondering if anyone has an idea why after a new battery is installed, the car starts but then drains to where it will not start 5 mins. later...Thanks for any help!
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turbotbirdguy79 Offline
Senior Member
#2
Check and see what your alt output is,I dont see a fully charged battery going dead after of only 5 minutes of running though.
1988 Tc,SC50(.63),Bosch BPV,Coolingmist methanol injection activated at 10 psi,FMS big valve 1.89/1.59 head,a234,ported E6,ported lower and upper intake,Gillis,3"downpipe,3"exaust,Kirbin AFPR,255 HP LPH pump,Racer Walsh adj cam pully 2* advanced*,K&N cone,MSD Blaster,autolite 103 plugs,T5 swap,3.73s,shifter,Centerforce stage 2 clutch,motorcraft tuneup.
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trashline Offline
Posting Freak
#3
yea sounds like the alt is toast. And it is pulling all the juice from the battery. Good time todo the 3G upgrade.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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Jeff K Offline
Administrator
#4
If the batt is good, 5 min of running, even with lights and heater blower on, should not drain the batt down that much even if the alternator is not charging at all. A good batt should power the basics on the car (EEC, brake lights, radio, etc) for half an hour min with no alt charging at all. that is what "reserve capacity" means that is stated on the batt.

If the alt were "pulling all the juice from the battery" to drain it down in 5 min, the alt would be melted down to slag.

Just because a batt is new doesnt mean it is good. Once years back I got a batt brand new that had little output, and would not hold any charge.
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Martin Offline
Senior Member
#5
I would have to agree with Jeff on this one. A new battery does not go flat in 5 minutes unless there is a massive drain. Having said that, have you done the quick and dirty test, pull the neg terminal off and quicly strike it, as you would a match, to see if it arcs. A big arc indicates a big drain. Jeffs take on it is probably correct! Batterys take what is termed a "surface charge" and for all appearances, seem fully charged, with a voltmeter it will read the right voltage, and will even start your car, once. The term surface simply means you have a full charge but very little amperage, so the battery will flatten out very quickly.
Martin
Stock 87, no mods, Black with the grey interior.
Boost High, Fly Low
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trashline Offline
Posting Freak
#6
that reminds me, when my truck alt went bad i was an hour away from home all the lights went dim. I turned everything off and cruised home pulled down my street and it died. this was atleast an hour. And a battery that was a year or two old.
Brian

www.BCPCustom.com

06 Cobalt SS
66 mustang 289 C4 handfully modded

Stingers IC install and tbird photos
http://community.webshots.com/user/trashline
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DonH Offline
Posting Freak
#7
Check the date code on the battery and see how old it is. It may have been sitting in the store for a year and lost its charge. In any case take it back and get another one.
1987 TC stock except ATR 2.5"
1983 Pontiac Transam T-top 5.7 T56 [email protected] top speed: 176mph
1978 Fairmont 2.3 4-spd Big-top S/W
1946 Willys CJ2A 134.2ci L4 No-top
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