Powerhouse Posted December 5, 2011 Report Posted December 5, 2011 I am not sure if this make sense so I am going to throw it out there. If a 60 amp alternator is put in a 12volt converted car, and the original 6v system 30 amp gauge is used. Will it still be calibrated for 30 amps or will it be off? I think it should still read the same...Amps is Amps right? Shouldn't effect the gauge if it's a 12 volt system now.... When I turn on my H4 halogen headlights, gauge cluster lights and 12v heater fan...the gauge shows a drain of almost 30 amps. Does that sound right? The rpms drop about 100 or so as well. There is a noticeable difference in exhaust sound too form the rpm drop. I am running a Langdon Hei setup. Thanks all. Quote
Oldguy48 Posted December 5, 2011 Report Posted December 5, 2011 Your amps gauge doesn't care whether your system is 6V or 12V. It just reads the amount of current flowing through it. What wattage are your headlamps? Divide the wattage rating by 12 to calculate the current each one draws. (ex. 55W divided by 12V equals 4.58A each). I'd guess the fan could pull at least 10A, plus whatever other loads are powered up. Add to that the amp gauge may not be very accurate. You could hook up another amp gauge in series with yours to verify the reading. Quote
Powerhouse Posted December 5, 2011 Author Report Posted December 5, 2011 Thanks. Good idea about wiring up a higher reading amp gauge. I might just do that. Quote
suntennis Posted December 5, 2011 Report Posted December 5, 2011 (edited) The cars amp gage is wired to show the current to the battery. If the battery is fully charged and the current demand is less than the output of the charging unit, this ammeter will only show a bit on the plus side. If the charging unit has failed, then the ammeter should show total current draw on the negative side. An ammeter could be put in series on a specific circuit such as the headlight main wire to measure current draw for just the headlights. I am not aware of amp gage being rated by voltage. Edited December 6, 2011 by suntennis Quote
Robert Horne Posted December 5, 2011 Report Posted December 5, 2011 My 38 Coupe has a 6 volt amp gauge, and I am running a 12 volt generator. The gauge always has a high reading to the plus side. I tried a 12 volt amp gauge, and it shows about half the reading of the 6 volt amp gauge. I put in a new battery this spring when I finally got the 38 on the road. With headlights, heater fan, etc. on, the 6 volt amp gauge still shows a positive reading. Quote
greg g Posted December 6, 2011 Report Posted December 6, 2011 when you changed to 12 V neg did you swap the wires on the terminals of the amp gauge?? If not that would be th reason for the negative reading rather than positive. 12V appliances, by following ohms laws draw less amps than similar 6V appliances. So 12V systems can use thinner wires, saving the manufacturers money on wires. so your 30 watt 6v Lights would draw 2x the amps of a 30 watt 12v lamp. Are you showing a charge (positive amps) with no accessories running?? Quote
YukonJack Posted December 6, 2011 Report Posted December 6, 2011 Thanks. Good idea about wiring up a higher reading amp gauge. I might just do that. I still use the stock amp gauge on 12 volts, but also hooked up a volt gauge under dash. Read somewhere volt gauges are supposed to be safer. Quote
Powerhouse Posted December 6, 2011 Author Report Posted December 6, 2011 I reversed the polarity on the amp gauge when I did the 12v neg ground conversion. On start up it will show a positive charge for a short time then go to 0. When I turn on the headlights it shows a drain of about 15...then when I turn on heater fan it goes to 30ish. Belt seems to be fine...just tight but can be moved about an inch. When I bought my alt it was sold to me as a 10SI 60AMP....but Know that I did some research I find it to be a 12SI for sure. But i have no idea about the amps. The place I got it form is no longer selling on line. Kansas select products. I want to just get a 98 amp stocker from napa for $100 and be safe. But thats $100. Quote
Adam H P15 D30 Posted December 7, 2011 Report Posted December 7, 2011 Do you have the guage wired correctly? I wired mine with the battery lead on one terminal and everything else on the other. Not sure if it's correct but seemed logical to me. Tells me if the current is going into the battery or out of the battery. Quote
Robert Horne Posted December 7, 2011 Report Posted December 7, 2011 I reversed the polarity on the amp gauge when I did the 12v neg ground conversion. On start up it will show a positive charge for a short time then go to 0. When I turn on the headlights it shows a drain of about 15...then when I turn on heater fan it goes to 30ish. Belt seems to be fine...just tight but can be moved about an inch. When I bought my alt it was sold to me as a 10SI 60AMP....but Know that I did some research I find it to be a 12SI for sure. But i have no idea about the amps. The place I got it form is no longer selling on line. Kansas select products. I want to just get a 98 amp stocker from napa for $100 and be safe. But thats $100. Sound like a diode went bad in the alt. My Mom's car did similar. The car would charge ok, Turn on the heater fan, small charge, Turn on lights,and heater fan,, discharge.. Turn on lights, heater fan, and wipers, big discharge I put on a rebuilt alt, no problems many years... Quote
Powerhouse Posted December 7, 2011 Author Report Posted December 7, 2011 Howdy folks. Yes, gauge is wired correctly as mentioned Adam. I am guessing something is wrong with the rebuild alt. I had to replace the brush holder thing since I saw it was cracked when I had the thing open to see how it worked. Other stuff looked kinda shabby. Only cost $60 rebuilt with no core charge...so it must have been a cheapy. Quote
Powerhouse Posted December 7, 2011 Author Report Posted December 7, 2011 from a website: http://www.expeditionlandrover.info/Delco_Alternators.html The 30 amp ammeter can easily burn out with a 60 amp or higher alternator. You will need a 60 amp gauge for the up to 60 AMP alternators. Remove the ammeter, connect the + and - wires together and install an automotive voltmeter between switched 12V and ground. An ammeter will tell you if the vehicle is getting its load from the alternator/generator or battery, how much the current draw is but not much else. A voltmeter will tell you if your alternator is putting out enough voltage for the load and still charging the battery. Does this sound right? Why would an ammeter blow out? Quote
martybose Posted December 8, 2011 Report Posted December 8, 2011 from a website: http://www.expeditionlandrover.info/Delco_Alternators.html The 30 amp ammeter can easily burn out with a 60 amp or higher alternator. You will need a 60 amp gauge for the up to 60 AMP alternators. Remove the ammeter, connect the + and - wires together and install an automotive voltmeter between switched 12V and ground. An ammeter will tell you if the vehicle is getting its load from the alternator/generator or battery, how much the current draw is but not much else. A voltmeter will tell you if your alternator is putting out enough voltage for the load and still charging the battery. Does this sound right? Why would an ammeter blow out? Sounds like an ammeter salesman. My alternator is rated at 80 amps. Once in a great while it will peg on the charge side for a second or two after starting, then immediately drops to less than 20 amps.. I don't think it is that big a problem. Marty Quote
Adam H P15 D30 Posted December 8, 2011 Report Posted December 8, 2011 I have a 60 amp alternator and occasionally mine will also peg on start up. It really depends on the guage of the shunt inside the ammeter. I don't know the size but if it is large it can handle a lot more amps then the guage face is calibrated to show. Remember the guage is inductive. Maybe someone can post the size of the shunt inside the guage, that will determine the amps it can handle. The visable part of the guage only shows the measured visable range. Quote
Powerhouse Posted December 9, 2011 Author Report Posted December 9, 2011 (edited) OK. So I just put in a new 12SI alternator thinking it would fix my Amp discharge problem. Same old issue. Still show discharge...and the new alt is a higher amp version than the previous one. Please tell me if this wire outing is correct. From Terminal 1 (excite) - to Ignition post on ignition switch. This is the yellow wire that used to have a diode. So electricity will only flow one way...to the alternator. NOTE: Have removed diode since this post. It is unecessary with multiposition ig switch.) From Terminal 2 (voltage sensing)- Just a Jumper to the Power output post From Power output post (red) - to ammeter Edited December 12, 2011 by Powerhouse Quote
Robert Horne Posted December 9, 2011 Report Posted December 9, 2011 (edited) The red post on the alt should have wire going to the amp gauge, and then from amp gauge to battery. I have my wire on the battery side of the starter relay/solenoid......Bob... Edited December 9, 2011 by Robert Horne Quote
Powerhouse Posted December 9, 2011 Author Report Posted December 9, 2011 this is how it's routed. Is this wrong? Quote
Robert Horne Posted December 10, 2011 Report Posted December 10, 2011 Maybe this wiring diagram will help. On this diagram, black wire, "10BK", going to amp gauge one side. From the second side of the amp gauge is a red wire "10RE", going to the starter relay, battery side. Your wires may be different colors, as long as they are right gauge is fine. Quote
Powerhouse Posted December 12, 2011 Author Report Posted December 12, 2011 Thanks for the chart. Seems to be a similar set up. I checked my setup many times. I even replaced the in line diode. No change in charging. I made a new bracket to get more tension on the belt...not that it needed any, but worth a try. Still no change. I read that the in line diode in unnecessary when using a newer ignition switch with accessory post. So I took the diode out, but no change. And the engine did turn off properly with ignition switch. I just don't get why it isn't charging. I tested the alternator with multimeter and it doesn't get any higher than 12.5, and revved up quite a bit. As I have it wired the charge comes from alt to amp gauge(which also has a link to ignition switch AM terminal)...then goes through amp gauge back to positive post on floor starter(directly to battery for charging it). When running, "charge" goes to ammeter and all electrics via the link to AM terminal which, when running, flows to accessory terminal on ignition switch. This way electric is used by various items before going through gauge and the draw is then shown on the amp gauge. This has got to be the correct way of wiring it. But the old and new alternators just won't charge! What the heck! Quote
Powerhouse Posted December 14, 2011 Author Report Posted December 14, 2011 OK folks. One of the most important things I've learned about working on cars. Change the cheapest part in the system first genious. It turned out to be...the v belt. Looked fine but was worn down and not gripping enough. SO atfer buying a new alternator, fabbing a new bracket to get more tension, messing around with wiring and diodes and whatnot...it was only the dang old belt. Brain farts are so ANNOYING! Well, now I can put all those 12 volt accessories in (just kidding, as if I could afford anything else). Maybe even a radio. hahaha Quote
Robert Horne Posted December 14, 2011 Report Posted December 14, 2011 Often it is one little simple repair. My old Chevy van gave me a challenge in that it would charge sometimes, and not charge sometimes. After much trial and error, turned out to be the wire connecter plug on the alt. Quote
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