Guest tom48ply Posted March 16, 2013 Share Posted March 16, 2013 I have 1948 Plymouth at idle the amp gauge reads 1+ then I turn on headlights it jumps up to 6+ is this normal. thanks Link to comment Share on other sites More sharing options...
nickelroadster Posted March 17, 2013 Share Posted March 17, 2013 What does it do if you blip the throttle? Does it move in a positive direction? I would almost wonder if the ammeter is hooked up in the right direction. Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 17, 2013 Share Posted March 17, 2013 no does not go up when I hit gas just when I use electrical like headlights and radio. just watched some youtube videos and some of the 48 Plymouth on there did the same thing Link to comment Share on other sites More sharing options...
misterc9 Posted March 17, 2013 Share Posted March 17, 2013 It's possible the battery is hooked up backwards. Old generator cars will still run and charge with the reversed polarity except the ammeter reads backwards. I think these Plymouths had positive ground when new. Or it could be like nickelroadster said. Link to comment Share on other sites More sharing options...
Curti Posted March 17, 2013 Share Posted March 17, 2013 I think the wires on the amp gage are reversed and the generator in not putting out any current. Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 17, 2013 Share Posted March 17, 2013 thanks guys I will look at wires as soon as old man winter leaves minnesota Link to comment Share on other sites More sharing options...
DonMicheletti Posted March 17, 2013 Share Posted March 17, 2013 The '48 Plymouth is positive ground. It is most likely that the battery terminals are reversed. Reversing the leads to the ammeter isnt easy to do under the dash and is unlikely. Having actually reversed the battery terminals myself in error, I know that the generator will work that way too.There is always the high tech generator check - get the engine on high idle and pull one of the battery cables. If the engine continues to run the generator is working - if the engine dies, it is not Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 17, 2013 Share Posted March 17, 2013 last summer I had battery terminals on the backwards meaning pos on pos neg on neg and the amp gauge read -1 at idle and -6 when I turned on headlights or radio so I switched to the way it should be. pos gound.thats when it went to +1 at idle and +6 on I turn headlights and I will try that high tech generator check thanks Link to comment Share on other sites More sharing options...
Guest Bob Call Posted March 17, 2013 Share Posted March 17, 2013 last summer I had battery terminals on the backwards meaning pos on pos neg on neg and the amp gauge read -1 at idle and -6 when I turned on headlights or radio so I switched to the way it should be. pos gound.thats when it went to +1 at idle and +6 on I turn headlights and I will try that high tech generator check thanksTom this statement does not make sense to me. The cables are not positive or negative, the battery terminals are positive or negative. The larger diameter terminal post, sometimes painted red, is positive. The cable from this terminal should be grounded to the the engine block and in turn the engine block to the car body. The smaller diameter terminal post, sometimes painted black or green, is negative. The cable from this terminal should go directly to the starter solenoid. With the battery connected in this manner the amp meter will read minus when the car is at idle and lights or radio is turned on. If you have had the battery connected backwards, negative ground, you should polarize the regulator when you correct the battery connections. Google "regulator polarize" and you will find instructions on how the short two terminals on the regulator to polarize. Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 17, 2013 Share Posted March 17, 2013 sorry for poor explanation yes my negative battery terminal goes to my starter solenoid and my positive terminal on battery goes to engine block as ground and I polarized after doing this. that's when the amp gauge started reading in +'s. I'm assuming the amp gauge should not read in the +'s then. and it should be reading in the minus. don't know much about positive ground. is it possible that the person who had It before me switched it to negative ground. and how could I tell if it was thanks again Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 18, 2013 Share Posted March 18, 2013 I still don't know what my amp meter should read. should it be in minus or plus with positive gound Link to comment Share on other sites More sharing options...
nickelroadster Posted March 18, 2013 Share Posted March 18, 2013 What your ammeter reads does not depend on whether or not it reads positive or negative. A positive reading means that it is charging and a negative one means that it is discharging whether or not you have positive or negative grounding. My earlier suggestion that the ammeter may be hooked up backwards had more to do with your description of it's behavior. Turning on the headlights at idle can very well result in a slight discharge. The reason that autos changed to alternators was the weak charging of a generator equipped cars at low rpms. For your car to increase it's charging rate when you turn on the headlights at idle is sort of the opposite of what might be expected. Generators normally don't have a very high output until they are run at a little higher rpm. To me it would be fairly normal for your battery to run down if you left your headlights on and ran the car at idle for an extended period of time. What do you know of the history of your car? How long have you had it and have you had any charging issues with it before. Check your system carefully and don't get hung up on the semantics of positive and negative. I hope we are not getting you more confused. Link to comment Share on other sites More sharing options...
Curti Posted March 18, 2013 Share Posted March 18, 2013 If the generator is putting out current ( amps) Don's high tech test above. Lets assume the car continues to run. The current runs from the generator to the regulator through the amp gage and on into the battery to charge it .All the amp gage is doing is measuring current flow one way or the other. The key thing is, as nickel roadester says: if no accessories are on you then rev the car up a bit the amp gage should deflect one way ot the other. ( preferably to the + side)If it deflects to the minus side then turn the lights on and the needle comes back more tward the center the wires on the back of the amp meter are connected backward. If you then switch the wires around, start the car, the amp gage will register on the + side and come down a bit when an accessory is turned on.If you are up under the dash switching the wires around I suggest disconnecting the battery + ground. Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 18, 2013 Share Posted March 18, 2013 I got the car 1 year ago. drove the car one day a week to local car show and had to charge the battery after each show. I drove the first half of summer with battery cables hooked up wrong. I returned it to positive ground it started to read plus 1 on amp gauge. but still had to charge battery. so don't know if burnt anything out. so bought a new battery upgrading ground cable to thicker ones put new brushes in generator just trying to get kinks out before summer car shows start we will see thanks for the help Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 18, 2013 Share Posted March 18, 2013 If the battery was hooked up wrong, or if the battery was out of the car over the winter or if you took the generator apart, it may be necessary to polarize the generator for it to work. This is not hard to do, it will be covered in your repair manual or you can do a search.Ammeter should show 0 when you turn on the key. Negative when the starter is turning. Slight positive when the engine is running, up to a couple of amps at idle, slowly dropping as the battery charges up. Higher when you turn on the lights. Link to comment Share on other sites More sharing options...
Guest tom48ply Posted March 18, 2013 Share Posted March 18, 2013 that's exactly what it's doing. so that's normal. maybe battery just went bad and won't take charge. o yeah i did polarized the regulator thanks again guys u have been very helpful Link to comment Share on other sites More sharing options...
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