Replaced loose battery terminal and alternator light is now on

Check the cables for correct tension. If the cables are too loose on the battery, the condition you describe can occur. Also, the battery cables can be fine, and the battery appear to have enough voltage, but can actually have a shorted cell which breaks down under starter load.
Check for corrosion on battery terminals (a white, crusty substance which feel slightly crunchy and greasy between the fingers); this corrosion can be harder to see on side-post battery terminals. Corrosion almost always happens as a result of too loose cables and alternator overcharging. Overcharging is as bad for a battery as undercharging.

Good luck.

hi yes this sounds like the battery is either, flat..low, or has come loose, check the terminals on the battery make sure they are good and tight and have grease on them ( stops corrosion) if everything is ok in that department, then try the battery itself, try getting a jump start from another vehicle, this will tell you if it is flat, then it will be a case of why has it gone flat..is the battery low on fluid, just top it up and charge, is the battery old, and just could be u/s, or it could be the battery is good, and the alternator is not charging it, check this out with a volt meter, jump start the vehicle, test on battery, if it reads 12.5 volts on idle, and 13.5 to 14 volts on 1000 rpm, its a good alternator, if it is lower than any of them, your alternator needs replacing, if it is over them voltages, your alternator is u/s as this is overcharging the battery which will kill it, so you will have to change both then...hope this is what you wanted, please vote and comment thanks

Maybe the PCM or Powertrain Control Module, this also controls the alternator by adjusting engine idle speed. In addition to proper alternator's internal regulator operation, also make sure the PCM is reading the alternator output properly.

Look for loose or dirty connections. Could be a poor ground connection or could be poor connections at the battery. Clean the battery terminal connections.

I had the same problem occur on an 86 model Nissan truck. It was determined that the alternator was overcharging the battery and caused it to get hot to the point it caught fire. Check the alternator to see if it is overcharging. Sorry to know that happened.

You may have a bad battery or alternator.
The battery terminals should read 12V+-.2V when the car is off, and it should read 13V-14V+-.2V when the car is running. If it's lower, then your alternator is not charging your battery properly and if it's over, then it's overcharging and damaging your battery.

You should also check to see if there's an issue with the alternator itself. It should read 13-14V +-.2V across the terminals with the car running and the alternator cranking.. If it's below 13, then it's undercharging your battery. If it's above 14V, then it's overcharging and damaging your battery

Other causes could be from the ECU which will also trigger the light to come on as the battery light doesn't mean just the battery / alternator, but any major electrical component

Never saw a charging system problem cause anyone to fail inspection. But, overcharging will cook the water out of your battery and can damage the computer system if not taken care of. Overcharge can be caused by either a grounded alternator field wire or a bad regulator. Since the condition appeared after replacing the alternator it too is suspect as an internal grounding can also cause that.

Check your battery ground connections. Make sure the vehicle chassis (and alternator) is properly grounded.
Check for any loose connections around the main high current 12V supply fuses.
Check the clicking in the steering column is not a loose supply wire arcing.

i think the alternator/regulator is overcharging the battery. this explains the cd player turning on and off and the headlight blowing. overcharging also will boil the battery fluid down and trap explosive gases in the battery. when it got really hot because of the lack of fluid, the battery shorted out and ignited the gases in the battery. replace the battery headlight and alternator, and check the output of the system at the battery while running it should be between 13.6 and 14.5.

Mike