I have some old vintage Sun gauges in my car. I currently have a Volts gauge in there, not connected. When I hook the Volts gauge across my battery it reads like 12 or 13 volts. The max that gauge can handle is 20 volts. I also have an old matching Amp gauge I could put in place of the volts gauge. What I want to do is hook a gauge to the alternator or voltage regulator so I can tell if the car is chargeing and how well while I'm driving down the road. Would I use the Volt or Amp gauge for this, and where would I connect it to on the alternator or voltage regulator? I've had problems with my old '74 not charging in the past. If it should happen again, it would be nice to know I've got a problem before I'm sitting on the side of the road with a dead battery.
Its easy to tell if its charging with a volt meter. Should read about 13.8 volts when at high idle. Reading amps tells you the alt is putting out but dosent say anything about the voltage regulator. A Volt meter is better also because you dont have to run heavy wire into your car. With an amp meter, all current must run through the meter to be acurate, except starter motor.
Amp gauges tell you in real time what your system is doing, but they are more complex and, frankly, dangerous than volts gauges. The volts gauge can give you a feel for what your charging system is doing too, but you have to feel the info out from what your volts are doing. I had an amp gauge catch my 75 on fire once. It shorted and burned the oil pressure gauge. Everything promptly caught fire and oil sprayed all over my interior from the melted oil gauge. Amp gauges run a lot more electricity through them than a volts gauge, and it is a volitile setup by nature IMO. I always remove amp gauges for volts gauges on my cars and equipment. Your volt gauge should read well over 12 volts if your system is up to snuff. Around 14-15 with the car running. This is read off the battery though, the voltage regulator will buffer the reading. Dave Edit: Ah the memories... I had forgot about the day I was going down Winchester (Memphis), and a relaxing drive turned into: Trying to get off the road, 6 lanes in traffic Spraying the fire extinguisher Getting sprayed with engine oil Gasping for clean air Shifting the toploader... All at the same time.
Can't stand outside the car and use a volt meter while it's going down the road. I know first hand about the amp gauges. My '74 had one on it when I got it. It shorted out and burned Terry at a car show and then not long after that it shorted out again and caught fire. That messed up blue spot in the carpet in the pic is where the rubber off the wire fell and melted into the carpet. So now that the amp gauge is ruled out, what about hooking the volt gauge to the battery directly and using a relay connected to a switch power source to turn it off and on? Probably connect it to the Radio power wire so that when you turn on the key the relay connects the volt gauge to the battery. I just want a way to keep an eye on what my electrical system is doing while I'm driving.
Is the way I mentioned an ok way to connect it though? I already have a wire comeing in from the battery cable post on my starter solenoid which keeps the memory in my radio when the car is off. Seems to me I can just run the gauge off that wire, through a relay and ground the negative side of the gauge to the body. The relay would be turned on by the ignition switch so that the gauge is only on when the ignition is. Ok or not? Seems to me if the gauge is connected at all times it would drain the battery if the car sits for a few days. But what do I know. Thanks for all the input.
I prefer volt gauges, mainly because they are far easier to install, and because I had a friend who's aftermarket amp gauge shorted and took out his whole electrical system...
Thanks guys. Now just to find the correct sender for the water temp gauge so I can get rid of that one laying on the transmission tunnel.
You dont need to put a relay on it. Just hook it up to any switched 12v line. Volts is common in a parallel circuit and cars are nothing but parallel circuits. In other words, you will get the same voltage reading wether you hook it up directly across the battery or across the tail lights.
I must have mis-directed the conversation. I thought the battery got extra voltage to charge up and the voltage regulator softened the voltage to the rest of the car. Now that I think about it, that doesn't make sense. Sorry. Dave
Betcha won't, unless you have some really large wire going to the taillights you'll have a voltage drop, especially when the lights are on. I think I just ran my voltmeter to the radio power wire.
Now now guys, to be accurate for battery charging, the voltmeter needs to be accross the battery posts and not even the cable ends. This even sees the condition of dirty cable connections. The charge current drops voltage accross the charge lead between the alternator and the battery post connections. This drop is seen in the rest of the car besides the other circuits adding their own drops from the currents they draw. But for practical use it is reasonable to just use a circut like the cigarette lighter socket as a monitor point. An LED monitor from Radio Shack will do as well as any other type installation as long as you can interpet the action of any type monitor that is used..
