HELP! Charging mystery
Thread Starter
Intermediate
Joined: Jun 2002
Posts: 36
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From: Redding ca
HELP! Charging mystery
'78 Vette. Everything was fine. 6 month old battery, 42 amp alternater. Intsalled flex-a-lite twin fans drawing 19.5 amps. After a couple of days the battery went dead. Bought a new 63 amp alternater. Every few days battery goes dead. Bought a new 960 cranking amp $130 battery. Every three days battery goes dead. Bought a new 110 amp $200 alternater, now the battery goes dead in 5 days. Fans run after the engine is shut off for anywhere from 30 seconds to 15 minutes, but that's not the problem. After that I can start the car but the battery is not re-charging all the way. Every day it gets a little weeker. If I charge it over night the volt meter shows 16 volts the first day, 15 the next then holds at 14 volts but gets harder to start then won't start. Not after the fans run, but after driving then turning off the car and trying to re-start. Isn't the voltage regulator in the alternater? Why isn't the alternater charging hard after I start the car? Helllp!!! :confused: :smash: :mad
Melting Slicks
Joined: Apr 2001
Posts: 2,280
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From: colorado springs CO
Re: HELP! Charging mystery (78MoneyPit)
why you got the fans hooked upto always on hot wire??
hook em upto an ignition on wire... so it dont run when engine is off!!!
ive got the dual flex alites also....
i should also note that the 100 amp or 1 million amp alternators dont provide that output at IDLE!! and that outputs at idle are probably pretty close for all 3 of those alternators..... but it should recover off idle a hell of a lot faster though...
sounds to me like you should hook it up ignition on instead of always on hot wire....
also bear in mind "alternator death" occurs when battery voltage drops below 12.7 volts!! oh the horror!!
hook em upto an ignition on wire... so it dont run when engine is off!!!
ive got the dual flex alites also....
i should also note that the 100 amp or 1 million amp alternators dont provide that output at IDLE!! and that outputs at idle are probably pretty close for all 3 of those alternators..... but it should recover off idle a hell of a lot faster though...
sounds to me like you should hook it up ignition on instead of always on hot wire....
also bear in mind "alternator death" occurs when battery voltage drops below 12.7 volts!! oh the horror!!
Thread Starter
Intermediate
Joined: Jun 2002
Posts: 36
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From: Redding ca
Re: HELP! Charging mystery (daily_driver)
First, I have it hooked to the hot wire on purpose. I often drive in 100 degrees for 5 mi. then stop for 10 min and drive 5 more etc. I need the engine to cool down during stops. That's why I hooked it up in the first place. But even if the battery drains, why won't it charge when I drive afterwards (at 2500 RPM) the volt meter doesn't show a good charge. But it does if the battery starts out charged.
Melting Slicks
Joined: Apr 2001
Posts: 2,280
Likes: 0
From: colorado springs CO
Re: HELP! Charging mystery (78MoneyPit)
hey, the trying to start after car is driven.....
could be starter heat soak!
i had bad starter heat soak with my stock exhuast manifolds....
went to dynomax ceramicoats and never looked back!!
:)
could be starter heat soak!
i had bad starter heat soak with my stock exhuast manifolds....
went to dynomax ceramicoats and never looked back!!
:)
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: HELP! Charging mystery (78MoneyPit)
Spending money on a large so called super duty battery is allmost useless for any car, a damn bike battery would work IF the electrical system is in good repair....and the first thing you need do is clean and check all connections, frame, engine grounds....and wiring harness....easily proven by use of DVM, without that sort of analysis, you are wasting your time....
also you need at minimum a 108 amp SI17 series alternator...they slightly larger type that is a direct plug in for your wimpy unit....with dual cooling fans and all the rest of the stuff, you need that sort of output....
in fact, if the cooling system is adequate, and tha't another topic entirely....a single 16" fan is fine....you don't need duals for anything but a BB engine....well unless i'ts something turbo'd or some such....
Leaving two fans on cooling an engine that is not running is a waste of battery power, your problem requires curing, not a bandaide.....
GENE
also you need at minimum a 108 amp SI17 series alternator...they slightly larger type that is a direct plug in for your wimpy unit....with dual cooling fans and all the rest of the stuff, you need that sort of output....
in fact, if the cooling system is adequate, and tha't another topic entirely....a single 16" fan is fine....you don't need duals for anything but a BB engine....well unless i'ts something turbo'd or some such....
Leaving two fans on cooling an engine that is not running is a waste of battery power, your problem requires curing, not a bandaide.....
GENE
Thread Starter
Intermediate
Joined: Jun 2002
Posts: 36
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From: Redding ca
Re: HELP! Charging mystery (daily_driver)
Starter not the problem (had that before) It starts fine when I get a jump start. I know the problem is that the battery is not charging enough while driving. What puzzles me is that if I charge it overnight the volt meter shows it charging at almost 17 volts while driving (I know the meter should show amps but it doesn't) but each day it goes down, gets harder to start then won't start at all. Also sometimes it starts after the fans have run for 15 minutes then won't start after driving at normal speed for 20 minutes. Not heat related or starter related because it will start with a jump.
Pro
Joined: May 2002
Posts: 726
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From: Petaluma CA
Re: HELP! Charging mystery (78MoneyPit)
Things that make you go hmmm...I wish I had an answer for you, but it seems you have done what I would do. I have been to your home town and it was HOT :mad there... what about voltage reg? Other electrical oddities going on? Any other work done to the car, esp electricals? Do get back on this when you find out...thanks
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Race Director
Joined: Feb 2000
Posts: 12,431
Likes: 1
From: CT
Re: HELP! Charging mystery (Stevo)
the engine will not cool down with the fans running anyway. you have to have the water pump turning in order to cool the engine. the only thing you are cooling is the antifreeze inside the radiator. That is not going to help much. I think you should just wire it to run when the car is on. Get an electric water pump and you will be able to cool the motor when the engine is off.
Melting Slicks
Joined: Apr 2002
Posts: 2,103
Likes: 0
From: Tucson AZ
Re: HELP! Charging mystery (Stevo)
I mentioned battery cables earlier and not sure if they were checked. Corroded connections, degraded wires could cause a drain.
Check the tension of the alt belt. The alt may not be producing what it is capable of if te belt tension is off causing the belt to slip.
I agree that the battery and alternator choices are overkill. The problem does not seem to be one of the major components, but rather a loose link somewhere.
Check the tension of the alt belt. The alt may not be producing what it is capable of if te belt tension is off causing the belt to slip.
I agree that the battery and alternator choices are overkill. The problem does not seem to be one of the major components, but rather a loose link somewhere.
Pro
Joined: May 2000
Posts: 600
Likes: 0
From: Staten Island NY
Re: HELP! Charging mystery (78MoneyPit)
I think I can help. I had a similar problem on my 78. I did all the things you mentioned and was still scratching my head. I went deep into the wiring diagrams and found out that current flows through the generator warning light in the center guage cluster and then to the generator. Turns out I had a burnt out generator bulb. I put a new bulb in and walla...problem solved after spending alomost $200 in batteries and alternators.
Heres a scan from my electrical troubleshooting manual that explains this. Pay particular attention to the second paragraph.
I also have the entire electrical troubleshooting manual on my website at http://corvetteforum.net/c3/tunedport78/
If you have any other questions, feel free to email me
Hope this helps
Vic
Heres a scan from my electrical troubleshooting manual that explains this. Pay particular attention to the second paragraph.
I also have the entire electrical troubleshooting manual on my website at http://corvetteforum.net/c3/tunedport78/
If you have any other questions, feel free to email me
Hope this helps
Vic
Thread Starter
Intermediate
Joined: Jun 2002
Posts: 36
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From: Redding ca
Re: HELP! Charging mystery (tunedport78)
Are you talking about the warning light on the center cluster? For the rest of you guys this setup works great. Usually when I was driving around town in 100+ degree temps the engine runs at 200 and each time I used to get out of the car for ten or fifteen minutes and then back in it would start there and keep moving up. Now when I get back in the car and start it, as soon as the water from the radiator circulates the engine temp drops right back down to 180 or lower. Works very well. Should get a good test Monday or Tuesday, the temps suposed to be over 110.
Pro
Joined: May 2000
Posts: 600
Likes: 0
From: Staten Island NY
Re: HELP! Charging mystery (78MoneyPit)
Have you checked for any drains on the system? Disconnect the negative terminal from the battery and connect a test light or multimeter from the negative cable to the negative battery post. The test light should not come on. If it does, disconnect fuses one at a time until the light goes out. If that doesn't work start disconecting the alternator, wiper motor, starter and any other major electrical component one at a time until the light goes out. I had this problem also and it turned out that my wiper moter was the culprit.
Hope this helps
Vic
Hope this helps
Vic
Thread Starter
Intermediate
Joined: Jun 2002
Posts: 36
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From: Redding ca
Re: HELP! Charging mystery (tunedport78)
If that was the case you would expect it to not start after sitting overnight, but that's not the case. It seems to lose a little power over days. Even if the battery got low you would expect a 110 amp alternator to recharge it. The last time it died I had just finished driving 1/2 hour on the freeway, then it wouldn't start 20 minutes later.
Safety Car
Joined: Feb 1999
Posts: 3,631
Likes: 14
From: Fountain Hills AZ
Re: HELP! Charging mystery (78MoneyPit)
If the problem only began after installing the fans and hasn't been cured by replacing the battery and alternator, I suspect that something isn't right with the fan hookup. It might be worth your while to unplug the fans whenever you shut the engine down to confirm that they are or aren't the problem.
Pro
Joined: May 2000
Posts: 600
Likes: 0
From: Staten Island NY
Re: HELP! Charging mystery (Vetterodder)
I have to agree with vetterodder on the fans situation. If all else fails hit something with a really big hammer :)
Good luck and let us know how it turns out
Vic
:cheers:
Good luck and let us know how it turns out
Vic
:cheers:
Burning Brakes
Joined: Mar 2002
Posts: 803
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From: South San Francisco CA
Re: HELP! Charging mystery (78MoneyPit)
Connect your fans to a "non-always hot" wire and see what happens. It seems that everything was fine.....before you hooked up those fans.....doesn't it?