I am trying to figure what why I had to get a jump start with a new battery after it ran fine for 5 days then sat for 2 days?
I have an 86 Cutlass Supreme Brougham with a V8 305. I'm wondering if I can
check for an alternator issue by disconnecting 1 side of battery post while running?
It's a new battery since having it parked in storage for 3 months and had no
problems starting for 5 days. I checked to see if any lights etc were left on but found
nothing obvious. However after 2 nights of not being moved I had to get it jump
started and had instant success starting the 1st turn. I'm confused and also a girl lol.
NNNOOO don't ever disconnect the battery with the engine running, you cause voltage surges that can wipe out your vehicles electronics. Do this: Turn everything off, disconnect a battery cable, put a test light between the cable end and the battery post, if the light turns on you have a battery draw that will kill a battery overnight, then you need to find it, the first thing is to electrically disconnect the alternator, if the light goes out the alternator is your problem, if the light stays on then you have something on, like a glove box light or a trunk light, if you have verified that nothing is still on then you need to start removing the fuses one at a time noting what fuse went where until the test light goes out, when it does that circuit is the culprit, then you need to find out what componets are on that circuit and eliminate them one at a time until the light goes out, when it does repair or replace that system. Then start putting it back together while watching the light making sure it does not come back on. Now a note on parasitic draws, if at the end of all this you notice a faint glow on the test light, that is normal, it is called a parasitic draw, it is caused by memory chips in the cars electronics. Hope this helped.
Check your belts and make sure the pulley on the alt. is spinning about the same rate as the rest. My brother had the same problem on his cutlass and he spent weeks looking for what was drawing voltage while the car was sitting, took 5 minutes of looking at it running to realize the belt was slipping :-) As for disconnecting the battery, unless you have a mechanical voltage regulator this will not work. You'll likely end up spending money out of pocket to replace some fried electronics.