Optima battery fully charged 12.80 volts.New one wire 100 amp alternator with 4 gage wire to starter.Battery in trunk with 2 gage wire to starter.With car at high idle get 14.70 amp at battery with both electric fans,fuel pump, MSD ,but as I drive the car it will suck all the juice from the battery.Did the MAD wire set up.do not see any more bad wire connections at the wire block at the fire wall.Had the battery load tested at auto zone-tested OK.Any thoughts? This really sucks.
battery getting drained while driving
- Thread starter ckdezert
- Start date
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KitCarlson
Well-Known Member
14.70 Amp at battery, is that in or out? Once the battery is charged, it takes little current, the alternator supplies the load. The running battery voltage should be about 13.8V.
TrailBeast
AKA Mopars4us on Youtube
14.7 volts at the battery I bet. (Not amps)
Yes 14.7 amps at battery.Had the battery load tested at auto zone. they ues a strange looking tool that has large coils on it that heat up as the test is run.It passed the test.I could take the new optama red top out off my jeep and try it,but had to be towed home after my last outing in the car.I am a little scared and down on cash for another tow charge.
KitCarlson
Well-Known Member
Amps or volts? If Amps in or out? If it is volts, you may cook the battery in the long run. With single wire alternator, not sure how that would provide overvoltage unless defective.
3406pk
Well-Known Member
How much amps are the cooling fans pulling. If they are pulling more than the alt can put out, then they would drain the battery.
67Dart273
Well-Known Member
RE--read your first post. This really does not make sense. I'd see if you can "rig" a voltmeter from the battery up to the front and monitor it for awhile as you drive. You don't need very large wire as a voltmeter draws a tiny bit of current.
Almost any wire you have lying around will work.......no18 or larger. I WOULD fuse it, any fuse you have lying around 1, 2, 5A fuse in case you 'zap' the wire.
Did you make your own cable ends or have them made? Maybe the cable ends are not making good connection?
Monitor battery voltage while cranking, and re-measure "up front" at the starter to read the difference.
Do the same thing with your charging wire............check charging voltage at the battery and at the alternator stud.
What else is in the circuit............solenoids, disconnects, etc?
Almost any wire you have lying around will work.......no18 or larger. I WOULD fuse it, any fuse you have lying around 1, 2, 5A fuse in case you 'zap' the wire.
Did you make your own cable ends or have them made? Maybe the cable ends are not making good connection?
Monitor battery voltage while cranking, and re-measure "up front" at the starter to read the difference.
Do the same thing with your charging wire............check charging voltage at the battery and at the alternator stud.
What else is in the circuit............solenoids, disconnects, etc?
jtkaaa07
BossMan
Sound's like the voltage regulator to me had the same problem on my mother inlaws duster last summer, loose wire from alternator to voltage regulator. Check the posts on the alternator, and make sure there tight first.
Inertia
Well-Known Member
Check your belt tension,, big amp alt needs tight belts..
nm9stheham
Well-Known Member
What is the ground (negative) cabling from your battery? How is that connected, through the chassis? And do you have a large cable from the chassis up front to the engine block?
What is the symptom that all the juice is being sucked from the battery? Does it fail to start after running for a while. Have you measured the battery voltage non-running when it does this?
It does not make sense that you have 14.7 volts at the battery when running at high idle but that the battery is being discharged. Are you measuring from battery + to battery -? Or are you measuring the 14.7 volts up at the starter?
What is the symptom that all the juice is being sucked from the battery? Does it fail to start after running for a while. Have you measured the battery voltage non-running when it does this?
It does not make sense that you have 14.7 volts at the battery when running at high idle but that the battery is being discharged. Are you measuring from battery + to battery -? Or are you measuring the 14.7 volts up at the starter?
TrailBeast
AKA Mopars4us on Youtube
How do we know if it's "sucking all the juice from the battery" or a case of starter heat soak?
Does the car die while driving it?
Do the lights go dim as it driving?
Is it hard to start after being driven?
Just a thought.
Does the car die while driving it?
Do the lights go dim as it driving?
Is it hard to start after being driven?
Just a thought.
KitCarlson
Well-Known Member
Now I wonder if "one wire" alternator means non isolated field, not GM style internal regulator. We all are only guessing. The use of a clamp on DC ammeter, and a voltmeter by a professional would sort the problem out in 5 minutes.
FJ5
Well-Known Member
reading this thread makes me realize what i don't know.
Trailbeast I'll be contacting you in the future with some questions regarding your HEI conversion.
Trailbeast I'll be contacting you in the future with some questions regarding your HEI conversion.
If I let the car fast idle with choke on get 14.7 volts at the battery and alternator.With car normal idle speed around 900-1000 rpm drops to 12.6. Both reading with both fans on that draw 48 amps for the pair.Nothing else in the circuit.no cut off switches ect.The belt is serpentine and is new and tight.wire from alt to starter has factory crimps. the crimp at starter to batt. is a crimp style that I did and may not be the best crimp.The battery cont. uses a factory crimp-so don't think that is problem.Will take new optima from Jeep Wednesday and swap it with the car and see what kind of charge Numbers I get with it.This is really frustrating. The car will die driving around.Last time died after long trip on freeway!Check the batt.-read 11.4 volts.Sure was lower,but the volts could have come up after the car sat for 2 hours.
thanks for all the input.
thanks for all the input.
67Dart273
Well-Known Member
That crossed my mind. Just for the record "I don't like" one wire alternators. A long run to the battery is one poor situation. What you need for them is a very oversize charging wire as short as possible to the battery
Having said that, I would not have thought that a no4 would cause trouble.
It's always possible the alternator is defective.
Having said that, I would not have thought that a no4 would cause trouble.
It's always possible the alternator is defective.
nm9stheham
Well-Known Member
Well, the 14.7 V reading says that the alternator is basically working OK, although that is a bit high. The drop to 12.6 V at lower idle is presumably due to the fan load at the lower RPM's.
I was going to ask about the belt; serpentines have been known to slip without a really tight tension, moreso than V's. Twice, I have had a similar problem with a V belts looking right and having tension but getting polished on the belts' contact surface and did not run the alternator at speed (each time, it was one of those stupid Top Cog types) and ran down the battery both times on a long interstate speed drives with a lot lower current draw. The battery ended up with a similar low voltage as your reading. When the belts get at speed, they can arc out in funny ways that they don't at idle speeds and fool you and slip, plus I assume they will stretch a bit when hot.
Is the smooth side of the belt on the alternator pulley or the grooved side? Howm much torque do you have to put on the tensioner pulley to make it move? If it is not a lot, then you probably do not have enough tension.
Next drive, rig the voltmeter onto the system and put it in the seat beside you and monitor the voltage directly.
I was going to ask about the belt; serpentines have been known to slip without a really tight tension, moreso than V's. Twice, I have had a similar problem with a V belts looking right and having tension but getting polished on the belts' contact surface and did not run the alternator at speed (each time, it was one of those stupid Top Cog types) and ran down the battery both times on a long interstate speed drives with a lot lower current draw. The battery ended up with a similar low voltage as your reading. When the belts get at speed, they can arc out in funny ways that they don't at idle speeds and fool you and slip, plus I assume they will stretch a bit when hot.
Is the smooth side of the belt on the alternator pulley or the grooved side? Howm much torque do you have to put on the tensioner pulley to make it move? If it is not a lot, then you probably do not have enough tension.
Next drive, rig the voltmeter onto the system and put it in the seat beside you and monitor the voltage directly.
belt system is March performance,so really cant change the pulley size,The belt tension is manual not idler.When the car is at reg. idling speed the alternator seems to stop charging. when I kick up the idle speed the alternator starts charging,but the charging rate is vary slow.I had heard that one wire alternators turn off at slow idle and kick back in when rpm pick back up,but did not think would pick up so slow.Is this normal?
Jez. You don't need 2 electric fans drawing 48 amps. I had a single 20 amp fan on my Rat motored tool truck hooked up with a relay and temp switch and it barely ran, even in 90+ temps pulling 16,000# load. You may need to rethink your combination. You mentioned you have a trunk mount battery. Is that when the problems started? Don't trust the battery in the trunk to be grounded well there. I would run a separate ground cable to the block and make sure the body is grounded well from there.
Batt grounded to sub frame .Have sub-frame connectors welded in.Alternator has ground to firewall,motor has two separate ground wires to sub frame and fire wall.You would not even think about telling some one living in the desert about not having enough cooling if you lived in the dez. was 103 two days ago.More fan more better.
More fan more better.[/QUOTE said:
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