1G battery/alternator question

[Dr DSM]

Heres what happened. i was driving home today and my radio kept shutting off and coming back on. i stopped at a store ran in and came out and the car would start. so i had my cousin give me a jump start and it started up right away. i got the car home and did a voltmeter test on the battery and it was at 10 volts so i went and got a new one. when i installed the new one i decided to test the alternator by starting the car and disconnecting the battery. when i did this the car stayed running until i opened the driver door and passenger door (which triggers the automatic seat belts). what do you guys think? do you think the alternator is draining the battery or if thats normal? my old battery was an optima red top that was completely fine just hours before

 

[sniver]

That's a bad test, and a good way to screw electronics up. A lack of a battery can cause voltage spikes that can fry ecus, ect.

If the battery is fully charged, connected, with high beams , blower on 5, rear defroster on, it should be charging at at least 13v.

If the alternators weak it will drop down under 12v and keep dropping.

 

[miguelmcv]

Your alternator is going off.

Test your alternator, maybe it barely keeps your car running and once there is an extra light or current draw, It stops working.

 

[Dr DSM]

Replaced the alternator and alt belt. All is good now thanks

 

[knewblewkorvett]

Good job!