Technical 6v battery dies in 5 seconds

Hey everyone, looking for some direction here...got a 53 Coronet w/Red Ram. OEM 6v wiring with generator. Car runs strong after sorting out all kinds of carb/timing issues.
Here's the newest issue: car will start right up with fully charged battery, but dies within 5 seconds. At that point, the battery is dead again.
I've checked/replaced the following since this issue started:
Battery - replaced (twice)
Battery cables - replaced w/1 ga.
Pos, Neg, Solenoid to starter
Voltage regulator - recently replaced (prior to this issue) cleaned contact points, etc.
Solenoid - replaced
Starter is strong, car starts right up
Generator torn down, reassembled yesterday, seems to work fine.

Started chasing with voltmeter last night, this is what I found:
Voltmeter = 6.4 at:
Battery neg to pos ground
Solenoid hot to battery pos ground
Solenoid hot to VR "FLD" and "ARM" terminals
VR "BAT" to "FLD" & BAT to "ARM" terminals
VR "BAT" terminal to generator armature bolt
NO READING ON VOLTMETER FROM VR "FLD" OR "ARM" TERMINALS TO GENERATOR ARMATURE BOLT, (but don't know if I should get a reading cuz I'm not connected to power source).

Generator "motors" when jumpers run from hot battery term to generator armature bolt, from hot side of solenoid to generator armature bolt and from VR "BAT" terminal to generator armature bolt. NOTHING HAPPENS WHEN JUMPING FROM FLD OR ARM TERMINALS ON VR TO GENERATOR ARMATURE BOLT.(again, not connected to power source, so probably makes sense?)

May be an oversimplification, but seems to me that there's an "open circuit" somewhere? Where is my battery juice going so quickly?

Thanks, sorry for the long post.


Sent from my SM-G975U using The H.A.M.B. mobile app

 

I wonder if your generator isn't polarized would it suck power? Or just not charge?

Sent from my LG-TP450 using The H.A.M.B. mobile app

 

P.S. try another battery?

Sent from my LG-TP450 using The H.A.M.B. mobile app

 

Odd that the batt would be dead in just a few minutes and no smoke escaped from the wireing, are these new batterys or something laying around in the shop, I would disconnect everything except the starting circut and then one by one hook them back up and see if you can determine which one is the problem, I want to lean towards the gen/regulator but it would seem to me that there would be some smoking wires or burnt regulator.

 

It doesn't pencil out, a fully charged battery has lots of juice. To drain it in 5 seconds isn't practical. Either it ain't charged, or it ain't dead, or some combination. Something would be on fire.

 

Agree with Truck64, IF the battery is really fully charged a short that would kill the battery in 5 seconds would produce tremendous heat, metal glowing red and burning away, sparks, wiring burning like a firecracker fuse etc. Are you checking the battery with a VOM before and after the event?

 

My charger shows full charge at 6.6 or 6.7, never above that. Where should a 6v battery be at full charge?

Sent from my SM-G975U using The H.A.M.B. mobile app

 

After car dies, I put charger on battery and it reads 6.1 or 6.2

Sent from my SM-G975U using The H.A.M.B. mobile app

 

Also, nothing burning, smoking, getting hot, etc. Makes no sense

Sent from my SM-G975U using The H.A.M.B. mobile app

 

Batteries both brand new

Sent from my SM-G975U using The H.A.M.B. mobile app

 

Maybe the generator/regulator has reversed polarity?

Charge the battery, then crank it with the generator disconnected and see what happens.

 

What kind of charger is this specifically?

I'd use a "dumb" charger, the kind Sears and Wards sold for about 50 years. Set it on 6 volts and leave it there for a day or so. Meanwhile, you need to test the generator itself. Can do this on the engine, which helps to prove out the wiring, or bench test it. What you want is the shop manual, or a good general old school manual. Make sure to use the right test hookups, Type "A" generators ground the field different than Type "B" (Ford). "Full fielding" is one test. This proves out the generator (mostly) and points toward the regulator as the problem.

They are tough systems that will handle abuse that would smoke a diode, but the mechanical voltage regulators are kind of touchy. The analog type voltmeter is what you want to use for most generator measurement work. And an ammeter capable of measuring at least 30 amps.

 

That doesn't mean they are charged. The last new battery I bought took 6 hours at 6 amps to come up to 100%

ALWAYS put a new battery on the charger, regardless of what the clerk says. Not trying to beat up on you. They are "supposed" to keep them topped off.

 

If it dies, and then you put your charger on it (before turning it on I assume) it reads 6.1 to 6.2 volts, then your battery is not dead. Will it not crank after it dies? check the Voltage again, and have some one crank it while you have a volt meter on the battery to see what it drops too. Problems like these are when I wish I still had my old Sun Vat 40 meter.

 

Maybe your FLAPS has a battery tester. No not the usual kind, but the kind that puts a load on the battery while checking the voltage. I've had batteries that would take a "surface charge" that would allow them to show normal voltage on a multi-meter.. However, using one of the testers that put a load on the battery, the voltage would immediately drop to 2 or 3.

I don't think this is your problem, but this kind of test would remove the batteries from the equation. More likely there is something funky in the connections.

I see "Nailhead Jason" beat me to it.

 

also where are these batteries coming from? it seriously sounds like you have batteries with shorted out cells in them that have just enough to hold together for one round of cranking and starting but then are to too dead to crank it again. and yes a battery can read full voltage, but when put under load to crank drop to 0 or so low it wont operate. Amperage is what cranks a motor over. if you have a volt meter that has an inductive pick up to read amps, you can see what the full load is when cranking off the battery cable while cranking the motor.

 

Maybe this?
Only change before problem?

 

6.1 volts is only 60% charged.

 

I hadn't thought of that, will do this afternoon.

 

Cheap(ish) charger from Harbor Freight Viking 6V/12V https://www.harborfreight.com/4-Amp...ntrolled-Battery-ChargerMaintainer-63350.html
I have the original shop manual for my car, I followed the instructions on "motoring" test where you hoot a jumper to the hot side of the solenoid and to the generator; doing so spins the pulley as it should.

 

Didn't know to do that, will keep that in mind. I've had this latest new one on the charger for 12 hours, still showing only 6.7/6.8...I thought I heard/read somewhere that a "fully charged" 6V battery would read above 7?

 

positive ground car ? just my 2 cent worth ...

 

Jason: After it dies, the car will crank, but not start, just assumed battery wasn't turning out enough juice.

 

Yes, positive ground

 

if it will crank, than the battery is most likely not the issue. When it cranks but wont start have you checked for spark? it almost sounds like the condenser or coil is getting hot and crapping out, then after it cools will work again. chased that exact problem on my friends model A over the summer. cheap condensers kept flaking out on it.

 

It can take a long time to charge a dead or deadish battery to 100% at a slow rate charge. Keep in mind a 6 or 12 volt battery won't reach a full charge at their battery post voltage. It takes about 2 volts above and beyond the resting open circuit voltage of any battery to approach a 100% charge, and that's at 77° F. In cold weather it is even more.

So for example, in a "12 volt" battery they aren't reaching a full charge till about 14.6 volts. They like to cook a while, too, at the charge. When the charge is removed and the battery sits for a while, or the surface charge is removed, it will measure 12.6 across the posts.

It could be your Harbor Fright charger is flaky or, the battery was really dead, and you're not reading it right. It won't be 100% charge till a bit over 8 volts on the charger. I wouldn't necessarily trust a digital voltage readout on a battery charger. Measure it right at the posts while charging. I have a Schumacher that simply displays "12" while it is charging, when it measures much, much higher. Scares the womenfolk and horses when they see the real numbers, probably saves on warranty returns.

The chargers start out with the amperage high, and voltage low. As the battery accepts the charge the amperage will taper off and the voltage will rise.

 

Is there another 6V car around that you can put your battery into as a test? The only battery I have ever seen dragged down to dead instantly had an internal short. Got an electrical schematic? Time to go over EVERY wire to make sure it isn't broken and connected correctly.

When was the starter last gone through? I would get it checked/rebuilt just to rule it out and it should not be expensive, getting stranded somewhere at night is expensive. Any old car I buy, I immediately change the starter, generator or alternator, water pump, fuel pump and master cylinder.

 

Since you tore down the generator , did it have a previous problem? You said it seemed fine after ? Electrical can be a pain. I think it is your generator. I had the same symptoms on a o/t and it was the alternator.

 

I did the old "pull a plug" spark test, and I am getting spark. Now I will do the same test after the car dies, before doing anything with the battery to see if I still have spark, good thought. Thanks

 

Great info, I will check voltage across the posts with the charger on it. Will also disconnect the generator and see if the car dies the same way without the genny. Have you had any experience with the whole reverse polarity thing on the VR or genny?