1957 battery

[Jerry B.]

Is there any way to test the battery guage while it is still in the car. thanks

[Jerry B.]

Re: 1957 battery

Come on guys ,need a little help. I would like to take her for a spin but hesitade of running out of power. The guage does not register, remains on zero all the time. All electrical components have been restored. Yes, I polorize the regulator every time the battery is disconnected and the battery checks out at 13.4 volts. thanks

[Jim T.]

Re: 1957 battery

If you found 13.4 volts you must have just charged the battery. Check the battery voltage with the engine running, it should show on the multi-meter above 13.4 volts. If it does go for a drive. You could make up a couple wires to clip on the battery and run through the firewall connected to your multi-meter and have constant view of what the generator is doing while driving. My 1985 digital dash will show 14-14.5 volts when driving.

[Richard M.]

Re: 1957 battery

Jerry, Has the meter ever worked? How long have you owned the car? Was it working before and now not working?

A fully charged battery at rest with the engine off will read about 12.6 volts. Engine running and above idle, say 1200-1500 rpm or so will kick in the generator charging system, and you should read about 13.4 volts or near that.

If you see the higher voltage then your charging circuit appears functional. Turn on a load(lights, heater, etc), and you should see some deflection in the ammeter.

If no meter deflection, then either the meter is defective, or............possibly it has been bypassed by a prior owner. If you look at the back of the meter is it wired normally? A bypassed meter would have a wire or bar connected directly across the 2 terminal studs.

The entire electrical load of the car runs through the ammeter so if you move anything back there disconnect your battery first. The 2 terminal studs are isolated from the meter case with cardboard plates, both inside and outside. They can deteriorate with age.

Another test method for a "in car" test...........
Remove positive battery cable. Disconnect the harness ammeter wiring. Connect a low current(e.g. 5 amp or less) battery charger (+ lead) to the input stud of the meter. Wire a load to the output side of the meter, like a spare high beam headlight bulb, and connect the negative lead of the charger to the other terminal of the bulb. Turn the charger on then off and see if the meter deflects(it could go either way based on your polarity connection). If no deflection, bad meter.

Rich

[Jerry B.]

Re: 1957 battery

Thanks Jim and Richard for your replies. I have owned the "old girl" for seven years and spent the last two years on a frame up restoration. All the electrical components have been professional rebuilt and I installed a new wiring harness. I am not sure if the battery guage worked our not. Currently, it is wired black wires towards drivers and red wires towards pass. side. I decided to take her out, the battery voltage was 12.3 before I started and 12.6 while it was running. Still, no movement of the guage. Rich, tonight I am going to perform your "in car" suggestion using a low voltage charger. I will keep all posted.

[Richard M.]

Re: 1957 battery

Jerry, You have the ammeter wired correctly, and even if the wires were reversed it would still deflect, but in the wrong direction.

You should be reading around 13.4 volts with engine running at around 1200 RM and above. If you were at 1200+ rpm only getting 12.6v, then I think you may have a charging problem. 12.6v is the max you can get out of a fully charged battery at rest. i.e. 2.1v per cell x 6 cells.

Your ammeter may be fine. The non-charging(if so) may be misleading your troubleshooting. I'd investigate that further as you may be wasting time with the "in car" test as we haven't seen the right test results yet.

But........If you decide to do the "in car" test with the charger make sure it's low current, and if you'd feel safer you can put a 10 amp fuse in the + side of the test circuit.

Rich

[Richard M.]

Re: 1957 battery

Jerry, So thinking and re-reading your reply.......

Is this the first time running since restoration and rewiring?

Did you polarize the generator?

Are you certain all grounds are good, in particular between generator and regulator?

Rich

[Jerry B.]

Re: 1957 battery

Thanks Rich for all your time andsuggestions. In the middle of the night, I had an idea. What is the most current consuming component in a car. That would be the headlights and the lighter. With the battery connected and polarized engine not running, I turned on the lights and engaged the lighter. Bingo the ammeter showed a discharge. Sorry.another question. with the engine running and reguator polarized, is there an easy way to check voltabe output from the generator?

[Richard M.]

Re: 1957 battery

Jerry, A digital voltmeter is your friend. Connect meter to the battery with running engine at 1500 rpm and tell us what you're reading. If you don't have a meter Harbor Freight has them pretty cheap, or Radio Shack, etc.

Rich

[Jerry B.]

Re: 1957 battery

Hello Rich, here goes the latest readings with my new digtal volt meter. With all battery cables disconnected, there is a reading of 12.57 volt. After polarzing and 1750 rpm , the battery reads 12.39 volts, Then stopping engine disconnected the battery reads 12.47 volts. Yesterday I had the generator tested off the car and tested perfect. Is there a way to test and or adjust you voltage regulator? thanks much Rich

[Richard M.]

Re: 1957 battery

Okay, charging problem as suspected. Too bad you didn't bring the regulator too, they could test it at the shop too, if it was a auto electric shop that is. There are test procedures in the Chevrolet service manuals.

If you don't have one, see this website http://chevy.oldcarmanualproject.com/

...here's one. it's for '55 but test principles are very similar....

http://chevy.oldcarmanualproject.com/shop/1955truck2/55ctsm06y08.htm

Just make sure your ground is solid at the gen and reg. Many times paint prevents a good contact.

If it's not a original regulator and bad, you can get a replacement at many auto parts stores, like Napa.

Rich

[Jack H.]

Re: 1957 battery

The ammeter is actually a voltmeter that monitors voltage at different places in the electrical system. The IR drop between these two points is a known constant, therefore the voltage differential seen indicates both the direction and magnitude of current flowing from the battery (discharge) or to the battery from the generator (charging). Basically, the magnitude of 'swing' the ammeter is designed to monitor is in the +/- 2V range.

So, a basic go/no-go test for an ammeter is to remove it from the car (or simply disconnect the car's wiring to it) and MOMENTARILY connect a 1.5 V battery across the terminals. I capitalized 'momentarily' because you don't want the full power of the battery flowing through the ammeter for very long. So, it's a matter of just 'touching' the battery wires to the terminals of the ammeter to look for a needle deflection.

Now, reverse the polarity of your connecting wires and touch again to verify the pointer needle deflects in the opposite direction. If the ammeter passes this go/no-go test, you know it's basically functional. Whether or not its fully calibrated, is another issue.

Next, on older cars like your '57, the output of the generator runs in lock-step to engine RPM. There's little/no output at/near idle, so don't expect to see much, if any battery charging operation. When you climb above 1500 RPM, now you're just starting to get an appreciable degree of electrical output and when you're above, say 2200 RPM, you're now able to deliver a reasonable amount of charging current.

It's at these higher engine RPM levels, that the voltage regulator working with the generator through the car's wiring system ought to be 'clamping' the voltage measured across the battery to typical levels (13.6-14.2 VDC) associated with normal operation. So, you don't want to simply had REV the engine while monitoring the voltage across the battery. You want the engine to be operating for a reasonable time at elevated RPM levels when you measure/monitor the voltage across the battery.

Last, taking one charging component at a time down to the store for testing isn't the best way to diagnose. All FOUR key components should really be observed while they work together (generator, voltage regulator, battery AND the inter-connect wiring). When you take the key components in one at a time (generator, regulator, battery), you're leaving behind the 4th component (the inter-connect wiring).

Most decent auto electric shops (and some auto parts stores) have a test car on wheels that they can roll out to your car, connect and monitor the electrical system working in its native environment. THAT's what you want!!! Many will look at the car for free...

[John H.]

Re: 1957 battery

The ammeter is actually a voltmeter that monitors voltage at different places in the electrical system. The IR drop between these two points is a known constant, therefore the voltage differential seen indicates both the direction and magnitude of current flowing from the battery (discharge) or to the battery from the generator (charging). Basically, the magnitude of 'swing' the ammeter is designed to monitor is in the +/- 2V range.

Jack -

That's true for midyears, but not for C1's. The '57 uses a real ammeter, in series between the battery and all vehicle loads; the "battery gauge" that functions as you outlined started in '63.

[Richard M.]

Re: 1957 battery

Photos below show what can happen due to all of the load current going through a C1 ammeter when there's a bad connection. It must have been happening for a long time on this one in order to cook the metal meter case.

a little off topic but........
On C1's I've recently restored I've added a 30 amp inline fuse at the input side of the ammeter to protect wiring from a catastrophic overload and potential fire hazards. I use ring terminals on the fuse holder wiring and connect the 12 gauge Black from the battery to one end with a short flat head #10 machine screw, internal tooth lock washers and nut. Double insulated with shrink wrap and then vinyl tape. Output of the fuse to the ammeter input stud(driver's side of the ammeter). It can be removed for judging if necessary, or left in with a small point hit for the sake of safety. Personally, I'd leave it in during judging. As seen in the 3rd photo(white fuse holder orange wires), it's easily accessible. All you need to remember is to carry spare fuses.

I also add a 15 amp fuse to the lighter and the same for original clocks. The lighter fuse holder is the black one(yellow wires) beside the 30 Amp in photo. I simply make up mating terminals to the fuse holders so they can be removed for judging if desired.

The 30 amp fuse will likely not protect low current shorts like the infamous ignition wire shorting the distributor shielding, but could protect a majority of high current short circuits. A fuse could be added to the ignition circuit but would require a little more effort because it's wiring is directly at the ignition switch plug.

Rich

[Jerry B.]

Re: 1957 battery

First of all, I most thank all the folks that replied to my electrical problem. As suggested ,I removed the generator and voltage to be tested at a local generator repair shop. On the car, no charge to the battery. Removed units from the car and bench tested and every thing tested perfect. After several evolutions, worked on the bench not on the car. To make a long story short, the generator field was the problem. The tech stated in 42 years in the business, he has never had replace a generator fiield. Intesting!!!