FABLAB
+1y
When a battery is in perfect condition it is a load on the alternator, that is why adding a second battery sometimes (if not most of the time) only makes the problem worse. As the battery gets normal use it starts to be even more of a load on the alternator. My guess is your battery is at that point that it can still start your truck and maybe run your system or compressors for a few minutes but is weak. When you start your truck your alternator has to supply enough power to run whatever is on (usually compressors because we all seem to get a bit lazy when it comes to fixing leaks) PLUS it has to try to charge the battery. You also have to remember that your alternator isn't putting out all it can at idle. Alot of times when I see this at the shop it seems like it could be avoided by the customer changing their habbits, little things like sitting at the gas pump with their system and compressors running, or sitting ideling with system cranked in the mall parking lot lol. Hope this helps man, feel free to call me at the shop if you think a phone call would help. Jay 235-333-7274