Possible problem with electrical system.

[Hzd Skizzy 27]

My brother's car (2002 Nissan Xterra 3.3L v6) all stock electrical seems to be having a couple issues regarding its electrical system.

For starters, if left sitting for more than 2 days the car has very much trouble starting. It will crank very slowly 1 or 2 times then stop. Then of course starts immediately when cabled to another car. I put a DMM on the battery which rests at around 12.8, pretty normal. Then 14.2 when the car is turned on, also normal. After say 15 minutes...it seems as though the alternator stops giving 14.2 and goes down to 12.6 (under battery resting voltage). That I noticed was an immediate issue. Then I turned the car off and the dmm read 11.4. If this has been happening all the time, I guess that explains the trouble starting when it sits. Turn the car back on immediately, it then goes to 12.6, no more 14.2v.We suppose there is an issue with the alternator, and we are prepared to replace it. But if that could not be the actual issue, it would be a waste of money and time. I'm here to have some reinforcement on my decision of replacing the alternator or being told to check a few other things out first to see if that could remedy the problem. Thanks!

[jonbearsmt 919]

sound like the battery has a bad cell to me... take to the local parts house and have it load tested.....

if you take the truck down there.. they can load test the battery.. and the alternator. while its installed in the truck!.

[An-i-no 86]

Does the charging stud have plastic around it? Check and see if that's damaged.

I recently had a problem with my alt not charging once it got hot. What ended up being the problem was the weld on the charging stud had come slightly loose and when the plastic around it got hot it ballooned and the connection got very very weak. Once the car/engine had sat and cooled off it charged fine.

I was baffled in the beginning though.

[Jason Witt 65]

I had a similar issue, ended up being a stuck brush in my alternator.

[altoncustomtech 773]

sound like the battery has a bad cell to me... take to the local parts house and have it load tested.....

if you take the truck down there.. they can load test the battery.. and the alternator. while its installed in the truck!.

I agree with Jon 100%

I've been through many issues exactly like the one you're describing and every time it was a bad cell in the battery. That's not to say that there could be other problems as well such as with the alternator, but having a load test done on the battery and the alternator will determine whether it's just one or both. As I said tho, if I were a betting man my money is on the battery.

[David William 0]

nothing else its the battery which is causing this problem.. you can check the connecting wire wheather it properly connected to that battery or not...

me too facing prolem with this wires or battery...

Even i am facing similar kind of problems in car mitsubishi..

In my car mitsubishi pajero , the dash lights remain on, I have checked batteries ok. new alternator fitted. ok for 3weeks, same problem, replacement alternator fitted, 2weeks same problem. had to jump start to garage and they are stuck. bafelled even where in the sticks and need help. It was giving 14v or there about but now dropped to 12 or less......

do anybody has got idea regarding this???????????

Edited November 5, 2012 by David William

[shizzzon 461]

Sounds like the regulator is damaged OR better yet, the Bridge Rectifier is on it's last leg and can only put out 33 or 67% of it's rating.

Either way.. let's assume the alt is going to be replaced.

Next step, your battery must be put on a charger, no alternator and do it NOW!