Post by redcentinela on Jun 25, 2010 8:50:28 GMT -5
Hi everyone. I have a 1999 Montero Sport with a 6G72 engine. Every 2 or 3 days battery drains and cannot start it up. Voltage drops to 11.80v and when starting it drops to around 7-8 volts. Yesterday, the battery was fully charged. Alternator is delivering 14.5 volts, it is charging properly, apparently. When I use the digital voltmeter, you can see the voltage dropping very slowly like, lets say, you turn off the vehicule, the batterry has 13.78v, leave the test probes attached and you see the fourth digit decreasing one digit every 4-5 minutes. This is with the battery connected. Something is draining this battery. It doesn't happen if disconnected. Some people tell me that the alternator might be bad, leaking voltage, a bad diode in it, etc. Is there any way to test the alternator to find out if is is really leaking with a multimeter like I have?
By the way, battery is new, it is a 1000cca and 800ca battery bought on last may, 2010 in autozone. I had to buy a new battery because I thought it was the old batery it had.
Post by redcentinela on Jun 25, 2010 15:05:49 GMT -5
By the way, today I rode the monty for about 20 minutes, turned it off. I measured the voltage and it was 12.73V waited a couple of minutes and after 10 minutes current was on 12.66V. I took the positive terminal out and the voltage went up to 12.91V. I put the positive terminal back and after 15 minutes voltage remained at 12.91. As soon as I open the door, light goes on, shut the door and voltage goes down to 12.62 and keeps going down.
Post by redcentinela on Jun 25, 2010 19:36:45 GMT -5
Well, I did the current draw test. It draws around 63 mA. Some sources tell me this:
"60-90mA = Normal " "With key off most modern systems will not consume more than 96mA. "
Another source tell me this:
"0-14mA is normal" "15-29mA is above normal" "30mA or more is abnormal and battery will be dead within 24-48 hours."
I took all the fuses out and
Well, I would like to know what the normal range for a 1999 Montero Sport is. If I take fuse # 1 out which is the one that controls the dome and doors lights, it goes down to 52mA. When I replace this fuse, it went up to 57mA. The next step was to take the rest of the fuses with no difference, current draw remained at 57mA. Other thing I did was to take the red cable from the alternator and current draw went down to 46mA. With both (fuse and alternator cable) out current draw goes down to 34mA.
I really don't know if this is normal. any advise from you will be appreciated.
In my opinion I would accept 15-29mA draw seeing how your draw went down when you disconnected the Alternator I would suspect an issue in that circuit. usually when doing this test you would lock all doors and wait 10-15min to allow the systems to enter sleep mode. couple of questions. Do you have an alarm? Do you have a large audio system? also you might want to have the battery tested, and or the charging system. hope this helps.
Post by redcentinela on Jun 26, 2010 9:57:54 GMT -5
By the way, is there any c clamp multimeter sensitive enough to measure milliamps. I am asking because with this c clamp type multimeter I can measure the current draw without taking the battery cable out.
I also did the AC current testing. According with this info, you measure ac current instead of DC with the engine running. If it measure AC current, alternator is bad. I did this test but the AC readings are esporadic and erratic. First multimeter reads 140v, then 30v, then 90v anf finally goes to 0v and the cycle repeats again. What I don't have clear is that ac volts must be continue in order to know if alternator is bad or not. My readings are sporatic , not continue, the info found in internet doesn't specify if voltage must be continue or not.
AC volts reading will tell you nothing all the AC to DC converting happens inside the alternator if its outputting AC voltage you would have a lot of electrical problems going on. As far as the Amp clamp for millivolts I found one made by Fluke but its ridiculously expensive. if your meter has a min max button set your meter up and allow it to sit there for a while see what happens after 15-30 mins.
Post by redcentinela on Jun 28, 2010 19:15:39 GMT -5
Well, I finally found out that the alternator gets hotter even than the engine. It is an intermittent problem. When it does it, it drains 3.12 amps current draw. I took the alternator cable out and current drain dropped to 0.038 amps. Well I know I have to replace the alternator, but I actually don't have the money to buy it. Is there any specific part that can be replaced in the alternator in order to fix it. Thanks for your comments.
You probably have a bad diode in your diode tree inside the alternator, Not sure how to replace those, you may want to see if you can find a junk yard part and just replace it. if your super handy with a solder iron and know a bit about electronics then open up the alt and test the diodes find the bad one and replace it.