Hello, I have a used alternator. It is belived to be a motocraft. It is a high output 160 amp model. 12V The alternator has two posts for battery lugs. Positive and negative. It also has field and stator terminals. two spade terminals slightly recessed in housing and offset to each other. I have negative post grounded to engine. Positive Post has battery cable running to positive post on starter. Starter also has battery cable running to positve ground bar. Stator terminal is jumped to positive lug on alternator. Field is belived to be exciter. 12g wire run to ignition key Problem is that when I start engine alternator starts up and starts to put out amperage but after about 10 seconds wire running from stator terminal to positive lug on alternator destructs. Please help me out. I have pics of alternator, etc...

David,

The high output alternator you have puts out higher amps - not volts. 13.5 volts out is more than enough to keep your car battery charged. Excessive voltage will damage a battery.

If your car requires more amps than the original alternator was able to provide to (1) run the car and (2) all the electric accessories; then a higher output alternator is needed (the battery is only needed to start the engine, that's it - they are designed to provide a large amount of current (amps) for a short period of time as when starting). Otherwise, the battery would have to make up the difference between the what the alternator can provide and the actual amount of amps needed / used. Used this way, the battery lights would dim, engine slows and everything would just stop and go dark.

If you're running a powerful audio amplifier, the current it might need may be so much current that it may be too much for the alternator alone to provide - hence the high output style was installed. You can use one or more large value capacitors - or additional batteries to "fill" in whenever the amplifier briefly needs more current than the alternator can provide - without drawing on the main car battery.

Your alternator is probably just fine.

looks like it's a 12V power supply. You should be able to go to Radioshack and buy a 12V DC power supply (Us in the trade sometimes call them wall worts). Take the device in with you to make sure that the plug style is the same.

The first step is to check all of the battery cables and their connections. Insure that they are CLEAN and TIGHT (visual and physical inspection should ALWAYS be FIRST).

When you are satisfied that there are no problems with corrosion or loose connections, then you must use a battery load tester to load test the battery. On modern batteries, It is also recommended that you use a battery analyzer that can test the battery impednce. Sometimes a battery will show High impedence - even if it can pass a "load" test. Replace the battery if tests indicate it is necessary.

Please note that the rest of the charging system cannot be properly tested until the battery and the cables are all in good working condition.
Any attempts to check the alternator and its circuits with bad cables or battery are going to be, at the very best, inaccurate

Once the battery connections and battery are in good working order, then the alternator output must be tested. It should be tested for voltage output both at idle and at high RPM with a load applied. It should be tested for maximum amperage output to see if it coinsides with the alternator's amperage rating. It should also be tested for AC current or "ripple", indicating shorted diodes.

If the alternator fails any of the tests, then either the alternator should be replaced or the alternator control and output circuits must be diagnosed and repaired (it depends on WHICH test or tests it fails).

This sounds like a bad battery. Remove the battery and take to to your local auto parts store to have them check it.

Your alternator output normally should fall around 14 volts to deliver a charge to your car battery. Car batteries can easily adapt to 2V, 10V and 50V from a battery charger and likewise an upgrade from 12V to 14V output would not hurt anything.

Very short lesson on the charging system. Remember this, The higher the voltage the less the amps.in turn low voltage, high amps. When the Alternator is charging at or above 15v, It is virtually pure voltage and as a charging device is cooking your battery, not charging it. The alternator, though defective, is safe and your battery is in harms way. When an alt. is charging at or below13 volts, The charging amperage is approaching max output of the alternater, which, if maintained at that rate will overheat and cause alt, failure, The proper charging range is 13.6 to 14.2. Each end is the limit just short of maximum and eminent failure. Example: charging at 12v means the alternarer is at max output and is in danger of sling solder, litteraly. When you smell dulphur coming from the battery, The alt. is running wide open on the voltage and your batt ison death row. So, back to your problem. One more thing. All accessories that are designed to operate on 12v are art risk of being damaged from excess voltage. Some have a voltage limiter to protect against surges but not all. Oh, That is one heck of a hot alt at 140 amps. Is that original equipment? Well, I know I may have rambled a bit but I hope it helped you understand how it works so you can come to the conclusion I have. The Alternator has a bad regulator and is in whole or part defective. Good Luck, Ned

Is the problem much more noticeable when the car is at idle? Double check that Alternator output. 70 amps is not high output, and if the problem is especially noticeable at idle, it's probably due to the alternator putting out lower voltage( a common thing with alternators). Also, with that much draw from your sub amp, the wire from battery to alternator should be beefed up, as well as the ground wire from battery. You can make up your own cables by purchasing the wire to length and wire lugs at a local Welding shop, 4 gauge from alternator to battery is good. High output aftermarket Alternators shoot into the 200 amp range.

If the belt is 3 yrs old or older, change it. If it has oil or anti-freeze or grease on it, change it. If new, add more tension to the belt.

Before, you buy a new Alternator or Battery... Check the Battery with a DC-Volt meter. It should read 12.5 volts or more with the key off. If the Battery reads less then 12.5 volts, have it charged free at Autozone or O'Reiley's auto. If the voltage is 12.5 volts or more, start your engine. With the engine running check the battery voltage again. It should read 13.5 to 15.5 volts. IF YES, Your charging system is work fine.

**IF NOT, and your Battery voltage 12.5 or less, You DO have a charging problem. It must be 13.5 to 15.5 volts!!! 1 - The first thing you want to check is the Battery cables and Battery post contacts. Remove the Negative cables FIRST!!!! Then the Positive, Clean the battery posts and cables with a wire brush!!! There are (3) Large Black cables on the Positive post of the battery, one goes to the starter, one goes to the relays & fues on the fire wall, and one goes to the back of the Alternator Battery output terminal.

Remove and clean the cable, nut & terminal of the Alternator with a wire brush. Then, reconect it tight to the Alternator output terminal. Now, there is (1) Large Black cable & (2) small wires on the Negative post of the Battery. The Large one goes to the Engine Block Ground. The small ones go to the front fender screw on the passenger side car body. Clean them with a wire brush. The most IMPORTANT GROUND is the Large Black cable from the Negative of the Battery going to the ENGINE BLOCK!!! To Remove & wire brush them clean, fallow the Large Black cable going to the Engine Block under the side coil assembly. Remove (3) NUTS & a triangle metal shild. clean all (3) wires & the Bolt & NUTS. Re-assemble very tight!!!

When completed, Reconect the Positive Battery cables firt! Then, the Negative Cables. Make sure they are all making good contact and are nice & tight. Now, check your battery voltage again with the car off! It should be 12.5 volts or more. Re-start the car, Check the battery voltage for 13.5 to 15.5 volts. IF - YES....IT'S FIXED! IF - NOT.... Turn the car OFF & look for a small black conector that plugs into the side or under the Alternator. It will have only (1) small RED wire going to it.
Very carefully, stick a straight-pin in the red wire & let the pin come out the other side. Don't let it touch any metal !

Start the car & let it run. Now put the (black) lead of your DC-Volt-Meter on the Negative of the Battery. Then, put the ((red) lead of your meter on the straight pin. It MUST have 8.0 to 12.0 DC-volts there !
IF - YES... The regulator inside the Alternator in BAD. (REPLACE) the Alternator. IF - THERE IS NO VOLTAGE there... Then, the red wire is bad... or the (P C M section) inside the ENGINE CONTROL MODULE is BAD!

The Alternator is about $100.00, The red wire is about $2.00, But the ENGINE CONTROL MODULE is about $400.00 plus from a dealer. Only, about $170.00 from autozone and about $125.00 from a wrecking yard.

**** NOTE **** If your Engine Control Module is bad, Look for my INFORMATION on FIX-YA, "HOW TO REPLACE THE ECM on a 94 BUICK" Thanks and GOOD LUCK !!!

Hi,

Based on your post/description, I would suggest that:
1. There is no need to install a diode from the boat motor alternator since most current design used electronic regulators with built-in diodes. The output of the alternator therefore could go straight to the battery or a switch (*selecting battery 1 or 2);
2. It would probably be safer that you would install a diode after a portable generator since some design do not need/use internal rectification but are connected straight to the windings/coil;
3. There is no need to install diode after each solar panel.

To my understanding the Plasmatronics have built-in in-line diodes to its inputs/outputs (unless otherwise required such as with the "Catch Diode protection" across the load). Additionally, unlike in some other system, a PL-20 would require that the negatives not be tied to a common ground. The PL-20 is relatively a straight forward connection (it's the programming that is a challenge).

Hope this be of help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

Tight lines.