I have a 92 Berreta GTZ.. I just bought a battery less than a year ago. The car will not start no matter how long I try to charge the battery. I can get power on the inside but cannot get the engine to start. This car has an after market ungo car alarm on it that I have disarmed sometime ago as it was going on randomly. Didn't know if the alarm was drawing on the battery or the alternator. How do you check if the alternator is bad. Again, I do get power on the inside but as soon as I try to start the car everything goes dead. Any ideas?

first item is the battery or battery cables.there are battery cable repair kits that replace battery clamp and about 6 inches of cable.

Make sure the battery has a full charge and battery connections all good. Engine cranking, the vehicle systems get battery voltage. Engine running, the vehicle systems get generator voltage, that can be several volt difference.
It seems like years ago I heard about removing spark plug on a vehicle that was hard to start, because of low battery. I tried it and it worked. Of course the engine was noisy as heck and it didn't run worth a darn, but, it started. In that example, I don't think it would matter which plug? I tried that about 50 years ago.
You can use digital multimeter across battery posts, everything off. The generic spec for a full charge is around 12.6 volts. Leave the meter leads touching battery posts, have helper turn key to crank, generic info says it shouldn't drop below 9.6 volts. If it drops way down, you need to get it checked out.
Also, if you have that spider fuel system, it is noted for problems.

If you can jump start it and disconnect the jumper cables then let it run for a minute or two at just a bit off-idle to try a little charge provided your belt is turning the alternator pulley, then disconnect the negative cable from the battery. If it continues to run just off idle the problem is a sulphated battery. If it dies the it's time for a new alternator.

i think there is problem on the electrical concern..bring the car to auto electrical and find out what is the main problem.

have a load test done on the battery as there is no guaranteed life for batteries
have the charge system check ed for correct charge operation

Take it to Auto Zone or O`riellys and they will test it for you at no charge.They can check your charging and starting system also.Hope this helps.Good luck.

The battery light comes on when there is an issue with the charging system. Most likley you have a bad alternator. With the engine running you should see a min. of 13.5 volts at the battery and better yet 14+ volts. If you have 12.5 or less than the alternator is not charging.

Once the vehicle is started the battery is no longer in play. The alternator is what keeps the power supply to the vehicle and recharges the battery for the next time you want to start the vehicle. Once battery voltage drops below 9 volts or so systems start to shut down. Eventually the battery will drain enough that the engine management system can no longer function and the vehicle will stall.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Yes Battery

all done

the hood should stell open no matter what un less the cable is broke i have the same car all that happens when the alarm is set off is the horn blows and the lights flash it doint stop the hood from oping