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Puzzler Battery Drain - what can it be?


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I could use some help, on an issue with my 65 Fastback.  This is probably a simple thing, but I just cannot figure it out.

Car is a Shelby Clone, and in the process I moved the battery to the trunK.  Positive cable to the engine, is a big, fat, welding cable, and Negative ground is short cable to rear frame rail.  Alternator, Battery, Starter Solenoid, Voltage Regulator are all new (each was replaced chasing this issue). Car is on a Battery Tender, and cranks over with ease and repeatedly when first attempting.  No issues driving, and Alternator pumping 14 volts back to battery while driving. However......when I cut off the car, even for 5 minutes, it barely, barely cranks over.  If I dont Fire It on 1st try, I need to jump it. Just like a car whose Lights have been left on.  Battery will still show 12+ volts - but the Amps must be way off???  Once I leave it back on the Battery Tender overnight - it cranks over with ease, and forever.  Could it be a heat issue?  Should I try battery #3? Could it be the starter?

All ideas appreciated. At this point I am limited to only short trips "around the block" for fear of it not starting back up.

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I could use some help, on an issue with my 65 Fastback.  This is probably a simple thing, but I just cannot figure it out.

Car is a Shelby Clone, and in the process I moved the battery to the trunK.  Positive cable to the engine, is a big, fat, welding cable, and Negative ground is short cable to rear frame rail.  Alternator, Battery, Starter Solenoid, Voltage Regulator are all new (each was replaced chasing this issue). Car is on a Battery Tender, and cranks over with ease and repeatedly when first attempting.  No issues driving, and Alternator pumping 14 volts back to battery while driving. However......when I cut off the car, even for 5 minutes, it barely, barely cranks over.  If I dont Fire It on 1st try, I need to jump it. Just like a car whose Lights have been left on.  Battery will still show 12+ volts - but the Amps must be way off???  Once I leave it back on the Battery Tender overnight - it cranks over with ease, and forever.  Could it be a heat issue?  Should I try battery #3? Could it be the starter?

All ideas appreciated. At this point I am limited to only short trips "around the block" for fear of it not starting back up.

 

The longer the positive cable, the more resistance. With more resistance the more amps needed to overcome the higher resistance. The same is true for charging. You mentioned that the amps go way down after driving the car. It possible that your alternator is not able to supply enough charge to the battery on the longer cable while supplying juice to everything else. More of an issue if you have added a modern stereo, subwoofer, amp etc.

 

A higher amp alternator might fix it.

1973 H Code Convertible - Medium Copper Metallic - June 8, 1973, Built Ford Marketing Sales Vehicle

DSC_0266xsm.jpg

satellite.png Proud Space Junk Award Winner!

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I could use some help, on an issue with my 65 Fastback.  This is probably a simple thing, but I just cannot figure it out.

Car is a Shelby Clone, and in the process I moved the battery to the trunK.  Positive cable to the engine, is a big, fat, welding cable, and Negative ground is short cable to rear frame rail.  Alternator, Battery, Starter Solenoid, Voltage Regulator are all new (each was replaced chasing this issue). Car is on a Battery Tender, and cranks over with ease and repeatedly when first attempting.  No issues driving, and Alternator pumping 14 volts back to battery while driving. However......when I cut off the car, even for 5 minutes, it barely, barely cranks over.  If I dont Fire It on 1st try, I need to jump it. Just like a car whose Lights have been left on.  Battery will still show 12+ volts - but the Amps must be way off???  Once I leave it back on the Battery Tender overnight - it cranks over with ease, and forever.  Could it be a heat issue?  Should I try battery #3? Could it be the starter?

All ideas appreciated. At this point I am limited to only short trips "around the block" for fear of it not starting back up.

 

ponysnake,

Just the fact that you stated that you replaced the voltage regulator tells me that you do not

have a modern charging system, capable of charging over 100 amps.

You will benefit greatly by having a permanent magnet gear reduction starter.

do you have headers ? , old school wound field coils don't care for too much heat, pmgr starters are not affected greatly by heat.

if your starter is taking huge amps and a small alternator only run time will replenish the battery.

by then you are into a heat soak issue on the old school starter.

what engine and compression ratio do you have ?

what ignition system and what kind of timing do you have @ cranking ?

Boilermaster

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Another thought. My newly built 428CJ would start strong when cold, but after getting it nice and hot, turning it off (to fill up at the pump for example), and then try starting it after a few minutes it would have difficulty turning over. Once in awhile, it would turn a little but could not fully turn over. If I waited instead till it cooled down, it would turn over no problem. Apparently, I needed a healthy fully charged battery to start the thing when she was hot and not so much when cold. How well does your engine turn over hot vs. cold without putting the battery back on the trickle charger?

1973 H Code Convertible - Medium Copper Metallic - June 8, 1973, Built Ford Marketing Sales Vehicle

DSC_0266xsm.jpg

satellite.png Proud Space Junk Award Winner!

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Another thought. My newly built 428CJ would start strong when cold, but after getting it nice and hot, turning it off (to fill up at the pump for example), and then try starting it after a few minutes it would have difficulty turning over. Once in awhile, it would turn a little but could not fully turn over. If I waited instead till it cooled down, it would turn over no problem. Apparently, I needed a healthy fully charged battery to start the thing when she was hot and not so much when cold. How well does your engine turn over hot vs. cold without putting the battery back on the trickle charger?

 

rackerm,

Exactly why I asked what starter and distributor, both of these items ease the starting of a hot nasty high compression engine.

That is why I switched to duraspark 2 over other so called BETTER ignition systems.

The duraspark blue modules have the ability to retard the timing 4-6 degrees when in the crank mode

(white wire)

pretty sure the msd 6, 6al have this capability as well.

Boilermaster

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You need to either lower the resistance in the starting circuit or use a battery with enough CCA to overcome it.

 

What gauge are the positive and negative cables?

 

What other grounds do you have other than the short cable to the rear of the car?

 

How many CCA is your battery?

 

Is the solenoid in the trunk or still on the firewall?

73 conv. 460, D0VE large valve heads, Performer RPM manifold, Voodoo 227/233 cam, Holley 950 HP carb, C6 trans, 3.25 trak-loc.

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I would ask Midlife harnesses for some guidance on this forum.  He is a master.

 

On my 71, I had a mystery power drain.  I diagnose a drain by putting a digital volt meter in line with the ground.  (Positive is on the terminal) use the leads of your DVM to make a connection between the neg cable and the battery post)  MAKE SURE EVERY SYSTEM IS TURNED OFF AND THE KEY IS OFF!   Do you have a current draw when measuring amps on the DVM?  Mine did and it ended up being a defective ignition switch.  Replaced that, and my problem went away.  Of course I pulled every fuse one by one before discovering that even with all the fuses out I still had a power draw.

 

kcmash

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I have battery in trunk as well. + and - wires going thru car to solenoid in engine bay.

I get almost 14 volts arriving at solenoid when it runs, 8+ volts at positive while cranking.

I run the largest 80amps battery I could find that fits the marine container i'm using. I now run EFI, so engine block is grounded as well, near alternator and from rear to firewall.

It was also grounded before, but added one and replaced the previous with a slightly wider one.

Both batt wires are cold and stay cold. Check if they are on yours. If not you have a resistance issue.

For the starter, I've got hot start issues so far as I can remember, no rotation or very slow RPM if engine was shut down when at operating temp for a while,

till I moved beginning of the year to a modern lightweight high torque one. While I have not tested it yet in driving conditions, in garage, hot or cold, doesn't make

any difference. It turns the healthy 351 like an asthmatic single cyl engine with no sparkplug :) Best part: $46 the piece on E-bay.

 

https://www.7173mustangs.com/thread-hi-torque-starter-landed?highlight=starter

73 modified Grande 351C. (Finally back on the road woohoo!) 

71 429CJ. ( In progress )

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I think you have a hot-start problem.

 

If you have the hot no-start and don't put it back on the battery tender does it start the next morning?

 

What is your battery voltage and amp readings during hot-start? Your battery could be good enough to start cold but not strong enough to do the job with all the extra resistance or your starter and cable situation isn't up to the task of hot crank.

Matt

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Thanks to ALL for the tips. I have a number of additional items to run down- based on these suggestion. The car has Shorty Headers, old/OEM style starter, MSD 6, and the replacement Alternator was probably OEM spec. I think I will Start, at the Starter - and go from there. Thanks Again. You all can imagine how it feels, to have a nice looking car - but are afraid of being embarrased to have it not start, when you take it out to show it off.

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Another thought. My newly built 428CJ would start strong when cold, but after getting it nice and hot, turning it off (to fill up at the pump for example), and then try starting it after a few minutes it would have difficulty turning over. Once in awhile, it would turn a little but could not fully turn over. If I waited instead till it cooled down, it would turn over no problem. Apparently, I needed a healthy fully charged battery to start the thing when she was hot and not so much when cold. How well does your engine turn over hot vs. cold without putting the battery back on the trickle charger?

 

Your situation sounds just like what I am experiencing.  Thanks for the tips. I have lots to Follow-Follow-up on.

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I'm with TommyK, check all the grounds, use multiple grounds, and make sure the starter to bell housing mating is metal to metal. Paint at a ground is not your friend nor are crimp connectors. Chuck

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