New alternator tests fine and battery, only putting out 11.5 volts checked across battery, and same terminal on back of alternator to negative bat post, dash info going crazy, bat light now on.

Bad connection, fusible link between the alternator and battery, bad new alternator .

Check grounds. Look at your cables. Could be corrosion.

Possibly the new alternator is bad or is not hooked up properly. Take it to any major auto parts store and they will do a free diagnosis of your charging system to help pinpoint the problem.

I don't know where you checked alternator out-put? I'd check at the alternator bat terminal and across battery posts, both, the reading should be close to the same.
It's possible when you took battery cable loose to install ammeter in series, a module may have shut off? Use a jumper wire to keep connection till you get the ammeter hooked up. Just my opinion.

there are three wires on the alternator.one of them is a feedback circuit to switch on the alternator.There is a fusible link which looks like regular wire,but it is like a fuse and is either 14 16 or 18 gauge .If the alternator was bad it could have blown that open.

Check for consumers staying on such as interior lights , radio etc.. To check for current draw, you need an AMP meter. remove the negative battery terminal. Connect one amp meter lead to the battery negative terminal and the other to the earth cable. Hold the cable against the battery negative cable, close all doors and press bonnet switch to closed position. Activate the alarm and wait for it to arm. Once it has armed itself, separate the earth cable from the battery terminal keeping the amp meter connected. read the current draw. Should be less then 100 milli amps. Usually +- 40ma. To check which circuit has current draw remove one fuse at a time and check if current draw drops. A drop in current draw will indicate that the problem is on that fuses circuit. Also check alternator charge rate. To check this hold a volt meter across the battery terminals. with engine off, should get battery voltage. Start the vehicle, battery voltage should rise to 13 -14v and maintain this voltage with the headlights on. The battery itself could be faulty, you would need to do a load test on the battery. Load tester needed to do this.

Check a conection cable between chassis and engine.Open and clean terminals.Put them back and check voltage.

How is the pigtail ground strap from engine block to body? Have you had engine diagnostic test done? Voltage rVOLTAGE DROP TEST
A voltage drop test is the only effective way to find excessive resistance in high amperage circuits. It's a quick and easy test that doesn't require any disassembly and will quickly show you whether or not you've got a good connection or a bad one.
To do a voltage drop test, you create a load in the circuit that's being tested. Then you use a digital volt meter (DVM) to measure the voltage drop across the live connection while it is under the load. Voltage always follows the path of least resistance, so if the circuit or connection being tested has too much resistance some of the voltage will flow through the DVM and create a voltage reading.


If a connection is good, you should find little or no voltage drop and see less than 0.4 volts for most connections, and ideally less than 0.1 volts. But if you find more than a few tenths of a voltage drop across a connection, it indicates excessive resistance and a need for cleaning or repair.
CHECKING THE STARTER CIRCUIT
To check the starter circuit for excessive resistance, you need to measure the voltage drop at the battery, battery cable connections and starter while the engine is being cranked.
The first check is "available battery voltage." For the starter to crank at normal speed, the battery must be at least 75% charged (12.4 volts or higher). Low battery voltage can not only affect the starter but every other electrical system in the vehicle.
A. Set your DVM to the 20 volt scale, then connect meter positive (+) lead to battery positive (+) post (not the clamp or cable), and the meter negative (-) lead to battery negative (-) post.
B. Disable the engine so it will not start when it is cranked. (Ground the ignition coil wire, or disable the ignition circuit or fuel pump relay.) Limit cranking time to 15 seconds or less.
C. While cranking the engine, record the volt reading on the DVM. D. Next, connect your meter positive (+) lead to the battery terminal stud on the starter, and the meter negative (-) lead to the starter housing.
E. While cranking the engine, record the volt reading.
F. Compare the two voltage readings. If both are the same, there are no excessive voltage drops on the positive feed side.
G. If available voltage at the starter is not within one (1) volt of battery voltage, there is excessive voltage drop in the circuit.
The next test is for voltage drop on the positive side of the starter circuit.
A. Make sure the battery is fully charged.
B. Disable ignition.
C. Set DVM on 2 volt scale.
D. Connect meter positive (+) lead to positive (+) battery post, and the meter negative (-) lead to the battery terminal stud on the starter. While cranking the engine, record the voltage reading.
The maximum allowable voltage drop including the solenoid or external relay in the starter circuit should be 0.6 volts or less.
If you find more than a 0.6 volt drop in the starter circuit, you can isolate the bad connection by using the following voltage drop tests.
* Check the positive battery post and cable connection by measuring the voltage drop between the two while cranking the engine. Connect the meter positive lead to the battery post and the meter negative lead to the cable clamp. A good post/cable connection should have zero voltage drop.
* Check the positive battery cable by measuring the voltage drop end to end while cranking the engine. Connect the meter positive lead to the clamp on the positive battery cable, and the meter negative lead to the end of the cable at the starter. Crank the engine and note the voltage reading. A good cable should have a voltage drop of 0.2 volts or less.
* To check the starter solenoid or relay connections, connect the meter positive lead to positive battery terminal on the solenoid or relay, and the meter negative lead to the starter motor terminal. Crank the engine and note the reading. A good connection should have a voltage drop of 0.2 volts or less.
Next, you need to check the negative side of the starter circuit. To check the entire circuit, connect the meter positive lead to a clean spot on the starter motor case and the meter negative lead to the negative battery post. Crank the engine and note the reading. The voltage drop on the negative side should be 0.3 volts or less.
If the voltage drop is too high, set your DVM to the 2 volt scale and start checking each connection on the negative side to find the bad connection or cable. Use the DVM leads to check across each connection while cranking the engine as before.
Check the negative battery post/ground cable connection (should be zero voltage drop).
Check the negative ground cable from the battery to the engine (should be 0.2 volts or less).
Check between the negative battery post and starter housing (should be 0.3 volts or less).
Check between the engine block and starter housing (should be 0.10 volts or less).
CHECKING THE CHARGING CIRCUIT
To check the alternator connections on the positive side for excessive resistance:
A. Set DVM on 2 volt DC scale.
B. Connect the meter positive lead to the alternator output stud (B+ terminal).
C. Connect the meter negative lead to the positive (+) battery post.
D. With the engine running at 1,800 to 2,000 rpm with all lights and accessories on (except the rear electric defroster), check the voltage drop reading. It should be 0.5 volts or less. If higher, the connections between the alternator output stud and battery need to be cleaned. Also, look for loose connections or undersized cables.
To check the alternator connections on the negative side for excessive resistance:
A. Set DVM on 2 volt DC scale.
B. Connect meter negative lead to alternator case.
C. Connect meter positive lead to battery negative (-) post.
D. With engine running at 1,800 to 2,000 rpm with all lights and accessories on (except rear defogger), check the voltage drop reading. On the negative side, it should be 0.2 volts or less. If excessive, the connections need cleaning or the negative cable needs to be replaced. Some alternators are mounted in rubber bushings and have a separate ground strap. If so equipped, be sure to check the voltage drop across this strap, too.

egulator checked with voltmeter?

check all battey connections and system grounds. Check that the battery has 12v and holds properly when load tested. To check charging system, don't disconnect any battery leads...put a volt meter across the battery. when running, you should have at least 12.9v and volts should not drop. (usual reading is generally at or near 13) at idle with all accessories on voltage should be close to that as well. voltage should not exceed 14.Also make sure that drive belt is not slipping.

clean battery terminals ,bring battery to be tested after charging, after reinstalling battery run car and test alternator output it should be a minimum of 13-14volts if it is under 13 replace alternator , use a voltmeter set on 12 volt 10 amp dc to check the wire to check is located on the back of the alternator covered with a rubber grommet of course hold negative wirw on volt meter to ground and touch red wire to big terminal on back of alternator while car is running should have 14 volts or at least 13 volts