Battery Load Test vs. Specific Gravity Readings
- Thread starter Colonel Biggs
- Start date
Mitch//pa
BANNED
Are you starting it with the advance lever up or down?
Does it crank good with the key off? ( this removes the ignition system from the equation)Could be a timing issue
Starter bolts to long?
Does it turn easy with the hand crank?
Clean and ohm test all 4 cable connections
Do a cell and load test
Is there a draw with the key off overnight? Ck with a testlight
How many amps is the starter drawing with the key off and cranking?
Do all your testing with a fully charged battery
Do not try and test anything with basic jumper cables or a battery charger alone..
Does it crank good with the key off? ( this removes the ignition system from the equation)Could be a timing issue
Starter bolts to long?
Does it turn easy with the hand crank?
Clean and ohm test all 4 cable connections
Do a cell and load test
Is there a draw with the key off overnight? Ck with a testlight
How many amps is the starter drawing with the key off and cranking?
Do all your testing with a fully charged battery
Do not try and test anything with basic jumper cables or a battery charger alone..
Last edited:
Tom Wesenberg
Well-known member
Yes, that's why I like to use a voltmeter on the battery and lay an inductive ammeter on the starter cable while cranking the engine. My good working starter draws just over 100 amps cranking a stock engine.
If you see 200 or more amps, the starter may be shorted or dragging. The drive end bushing is the one that carries the load and wears. If you remove the armature you can see wear marks on the iron core if it's dragging on the pole shoes. I almost never have to replace the front end bushing.
Luckily it's the two ground brushes that wear about twice as fast as the harder to replace brushes off the field windings. I worked on a bad starter once where someone had undercut the commutator, and copper was shorting the segments. Starters shouldn't be undercut, because the strong springs and metal brushes will keep the insulation worn down for good contact.
Yes SG readings can look good but a load test will tell you if a battery has the capicity to hold amps over a given period of time, the little crome 75 amp load testers are barely enough to test a batt a 200 amp tester is bay far better,what these do is put a 200 amp laod on a 600 amp hour battery if the batt cannot handle that load for several seconds it will drop off,the 75 amp testers do not put enough load on for a decent test.
A batt can have what I would call a top charge it would show correct voltage and a SG reading but would not hold a load test,charge battery on a real charger on low overnight and re test if it still does not hold a load test batt is junk.
A batt can have what I would call a top charge it would show correct voltage and a SG reading but would not hold a load test,charge battery on a real charger on low overnight and re test if it still does not hold a load test batt is junk.
Dollar Bill
Well-known member
SG readings could be reflecting a surface charge if battery has been recently charged. Load test will give you a better indication of battery condition.
mshmodela
Well-known member
I have the same battery... Had similar issues... What I did was to ensure the cell were full and to charge it twice over two days ~12hrs at 6V at 6A... That was last October and have yet to stick any charger on the battery... 3 weeks without a starting in Jan. And it worked fine.... I assume you have a battery disconnect switch.. So to ensure it's not getting slowly drained somehow by the car.
The cause: likely me using a battery tender that I suspect slowly drained the battery.
tbirdtbird
BANNED
"The engine cranked for about 20-30 seconds in total before quitting altogether."
Why so long? An A should fire off after about 2 full revolutions.
Good idea about an auxillary ground cable but move it even closer to the starter....to a bell housing bolt. What gauge is the auxillary cable?
In a starter circuit, because the amp draws are so high, ALL terminals have to be very very clean and tight....both battery posts and the grounding point and the cable end on the starter switch.
If you are using a battery kill switch these have been known to be a source of poor connections.
Armatures do not just slowly deteriorate. I am not yet convinced from what you have said that there is anything wrong with the starter.
When you bench test the starter with 6 volts, how are you grounding the case?
You should put heavy vice-grips very firmly on one of the mounting tabs and then clamp your jumper to the vice grip. Starters need A BUNCH of electricity. Using 12 volts will easily overcome any potential poor connections, which is part of the reason that everyone went to 12 volt systems in 1956. The other reason was that they could save on the cost of the very heavy copper cables that 6V requires
Why so long? An A should fire off after about 2 full revolutions.
Good idea about an auxillary ground cable but move it even closer to the starter....to a bell housing bolt. What gauge is the auxillary cable?
In a starter circuit, because the amp draws are so high, ALL terminals have to be very very clean and tight....both battery posts and the grounding point and the cable end on the starter switch.
If you are using a battery kill switch these have been known to be a source of poor connections.
Armatures do not just slowly deteriorate. I am not yet convinced from what you have said that there is anything wrong with the starter.
When you bench test the starter with 6 volts, how are you grounding the case?
You should put heavy vice-grips very firmly on one of the mounting tabs and then clamp your jumper to the vice grip. Starters need A BUNCH of electricity. Using 12 volts will easily overcome any potential poor connections, which is part of the reason that everyone went to 12 volt systems in 1956. The other reason was that they could save on the cost of the very heavy copper cables that 6V requires
Colonel Biggs
Senior Member
My apologies for the delay in my response to all of your helpful thoughts. I have been traveling of late - partly related to the starter issue. But, I have read, and re-read, all of your comments in attempting to come to grips with this issue.
Interstate ran a load test on the battery for me, and they stated that it passed with more than flying colors. My next move was to travel to Baytown, TX where Houston Club member Bill McCree lives, and where he rebuilds starters and generators. Some of you have no doubt seen his books, carried by the "A" vendors, on the rebuilding of starters and generators.
He placed my starter on his testing machine (either 200 or 300 amps), and it spun like a bandit. That really threw me. With the cover band off, he showed me where the sparks were jumping, because of an undercut armature from some previous restoration. He said that will wear down the brushes over time, but that the armature was still serviceable, if one didn't mind replacing the brushes from time to time. Lastly, he told me to use a spacer on the mounting bolts (starter still out of the car), and to observe their penetration into the flywheel housing to ensure that none were making contact with the flywheel. That was the only thing that he could think of to explain the slow rotation of the armature with the starter in the car. I told him that I didn't think that could be a problem, because I was using original starter bolts. "Just make sure," says he.
Last night, I did as he said, and darned if the bolt at 9 pm was making full contact, and the one at 6 pm was making light to moderate contact. Shows you what I know. How could this be, using original hardware? And, why hadn't this problem cropped up long before this? Ground down two of the bolts and mounted the starter. It spun, just like he said it would. I'm not going to ask whether the flywheel is moving on me; I'll save that for another day.
I want to thank you all for your posts. I have saved them for the next starter problem. The issue that I have now, which I may place in a separate post, is that I'm not getting fuel to the cylinders, despite a nicely spinning starter. I have spark at each or the plugs, and I have used two good carburetors, but there is no firing. And the engine ran like a charm before all of this occurred. When it rains, it pours...
Interstate ran a load test on the battery for me, and they stated that it passed with more than flying colors. My next move was to travel to Baytown, TX where Houston Club member Bill McCree lives, and where he rebuilds starters and generators. Some of you have no doubt seen his books, carried by the "A" vendors, on the rebuilding of starters and generators.
He placed my starter on his testing machine (either 200 or 300 amps), and it spun like a bandit. That really threw me. With the cover band off, he showed me where the sparks were jumping, because of an undercut armature from some previous restoration. He said that will wear down the brushes over time, but that the armature was still serviceable, if one didn't mind replacing the brushes from time to time. Lastly, he told me to use a spacer on the mounting bolts (starter still out of the car), and to observe their penetration into the flywheel housing to ensure that none were making contact with the flywheel. That was the only thing that he could think of to explain the slow rotation of the armature with the starter in the car. I told him that I didn't think that could be a problem, because I was using original starter bolts. "Just make sure," says he.
Last night, I did as he said, and darned if the bolt at 9 pm was making full contact, and the one at 6 pm was making light to moderate contact. Shows you what I know. How could this be, using original hardware? And, why hadn't this problem cropped up long before this? Ground down two of the bolts and mounted the starter. It spun, just like he said it would. I'm not going to ask whether the flywheel is moving on me; I'll save that for another day.
I want to thank you all for your posts. I have saved them for the next starter problem. The issue that I have now, which I may place in a separate post, is that I'm not getting fuel to the cylinders, despite a nicely spinning starter. I have spark at each or the plugs, and I have used two good carburetors, but there is no firing. And the engine ran like a charm before all of this occurred. When it rains, it pours...
Tom Wesenberg
Well-known member
Screw A-20904 is 3/8-16 x 1" long according to my July 1, 1931 Parts Price List.
Notice how Ford calls a bolt, without a nut, a screw.
Notice how Ford calls a bolt, without a nut, a screw.
Colonel Biggs
Senior Member
The bolt head is also thick, if I remember correctly, which is why I knew that this bolt/screw could not be the problem.. I had to grind about 3/16" off of the bolt at 9 pm, and an 1/8" off of the one at 6 pm. So much for original hardware...
Colonel Biggs
Senior Member
Good point, Benson. Bill McCree asked me that question, too. But, even the lock washers I use for the starter are original. When driving down the road, you can sense if there is a lock washer missing at the starter....