Jump to content

Due to a hardware failure on the hosts systems, all posts and messages created between May 26th and Jan 13th have been lost. Additionally, if you joined the NPORA Forums community during that time, you'll need to re-register. -NPORA Mod Team *Updated: 05/19/2022 12:15AM PST

Charging Issue


maddmark1981
 Share

Recommended Posts

Ok so a few days ago I go to start the Pathfinder and theres just enough life in the battery to slow whirl once or twice. Everything was turned off. Lights stereo etc. So I take the battery inside and charge it overnight on my trickle charger. Next day I put it on and whammy it started. I remember I drove quite a bit that day making different stops and such then that night on my way home my headlights were awful dim so I shut them off and used the led to get home. Next morning I take my batt. Off the charger go to start and nothing ... Just a whirl or two on a thought to be charged battery. So I put the ol battery back in without charging it and boost it with my van. When I took the positive wire off while it was running the engine stopped!

Multi meter shows off the battery while running 13.5 after a engine rev.

Any ideas?

 

 

Sent from my LG-H812 using Tapatalk

Link to comment
Share on other sites

Your alternator is working or else you wouldn't have seen 13.5 volts. However, you should still see above battery voltage at idle. I would start by making sure the connections on the battery and back of the alternator are tight and clean. Check the belt and make sure it is tight so there is no slipping. Pop the top on the battery and check water level. Batteries generally only have a 5 to 7 year life span.

  • Like 1
Link to comment
Share on other sites

Your alternator is working or else you wouldn't have seen 13.5 volts. However, you should still see above battery voltage at idle. I would start by making sure the connections on the battery and back of the alternator are tight and clean. Check the belt and make sure it is tight so there is no slipping. Pop the top on the battery and check water level. Batteries generally only have a 5 to 7 year life span.

So even if it dies once I take the positive termanal off?

 

Sent from my LG-H812 using Tapatalk

Link to comment
Share on other sites

Pulling the battery terminal is not a good way to test the alty on a fuel injected rig. The battery does more than just hold power, it filters out the ripples and noise that the alternator makes. Think about it, the diodes in the alty chop 3-phase AC into DC, and the current going to the rotor inside has to pass through sliding brushes, which are always going to give you some noise (especially if they're worn/dirty). The output voltage will ripple and spike. Most computers are not built to deal with that. The Pathy is simple enough that you probably got lucky, but I wouldn't do it again--and I certainly wouldn't do it to a newer rig. Even on an older rig with points/condenser/carburetor, where there's not really anything to hurt, your voltmeter should tell you all you need to know. I've also read that you can fry the alternator diodes by unhooking the battery with it running--not certain how that works but another reason not to go there.

 

You shouldn't need to rev the engine to get the voltage up. If the engine is running, the battery voltage should be around 13-14V whether you rev it or not. This suggests that the alty isn't making enough juice to keep the battery charged. Could be a borked battery, but I'd be surprised if both your batteries were borked--and it's easy enough to check a battery. +1 for checking the connections and belt. If the connections are good, and the belt's not flapping in the breeze, my money's on the alternator.

Edited by Slartibartfast
  • Like 2
Link to comment
Share on other sites

FWIW my alternator puts out 14.1 at idle.

Generally alternators put out the same voltage, but vary the duty cycle to put out the amperage.

You can get the alt bench tested at like any autopart store for free.

 

Also the pull the positive when it's running trick doesn't work well on anything newer than like 67. Had to have a generator.

Edited by PathyAndTheJets
  • Like 2
Link to comment
Share on other sites

Yes, the only time you should see voltage swings is if the voltage regulator in the alternator was flakey. But usually they just die. Or if you have belt slippage so the alternator is not turning at rated speed. So at 700 RPM idle the alternator is only spinning at 300, which may not be fast enough to get up to voltage. Take the rpms to 2000, alternator is now spinning at 1000 so you are seeing it work at higher rpm, but it doesn't seem to work at lower rpm. I have seen this happen once, but there should be squealing, or massive belt glazing going on if this is happening.

  • Like 1
Link to comment
Share on other sites

So today I put the charged batt in and drove 20km then shut off and it then started right back up, came back home same thing, its weird, there must be a bad connection.... I noticed my power windows wernt working there was a noise under the dash next to the passenger door then I hit it and they worked

Link to comment
Share on other sites

One of the guys here was having intermittent starting issues on a 3/4 ton Dodge. Him and I looked at it and found that it was a bad connection on the battery. He had sprayed terminal protection on it. Then he took the cables off to do some work, and when he put them back on they were in a different order. So the wire that had protection on top was now in the middle. The protection is a non conductive film, so the truck wouldn't start.

 

You may have something similar. Even if the connection is tight, there may be something on there preventing a good electrical path.

  • Like 1
Link to comment
Share on other sites

Ok so now it will last quite a while on a charge and even sometimes work properly so if the Alternator is doing its job why is it draining a charged battery at times? What could prevent it from keeping a charge?

 

Sent from my LG-H812 using Tapatalk

Link to comment
Share on other sites

How old is the battery? Does it have enough water in it? You can take both the battery and alternator in to an auto parts store and have them test it. They should have the ability to load test the battery.

 

Draining the battery while running, or when turned off?

You may have something staying on draining the battery. Turn the vehicle off and check to see how many amps are being drawn.

Link to comment
Share on other sites

A bad alternator diode can also cause a drain on the battery.

 

I've never messed with the power window system, but I'd check the service manual and see if maybe the power amp for the windows is in the part of the dash where you heard the noise.

  • Like 1
Link to comment
Share on other sites

Yes, the only time you should see voltage swings is if the voltage regulator in the alternator was flakey. But usually they just die. Or if you have belt slippage so the alternator is not turning at rated speed. So at 700 RPM idle the alternator is only spinning at 300, which may not be fast enough to get up to voltage. Take the rpms to 2000, alternator is now spinning at 1000 so you are seeing it work at higher rpm, but it doesn't seem to work at lower rpm. I have seen this happen once, but there should be squealing, or massive belt glazing going on if this is happening.

Ok cool Citron thanks.

My belts are a bit worn, there was some recent squeeling under the hood also. I noticed my belt going to the AC was good and snug but the other 2 seem tired. I had it running with the hood up at idle and the pully was spinning on the alt.

 

Sent from my LG-H812 using Tapatalk

Link to comment
Share on other sites

You can rebuild alternators. You can purchase a kit, that has bearings, brushes, regulator, etc or just replace the diode.

 

Usually, it is cheaper and easier to replace the alternator. It is pretty hard to track down rebuild kits anymore.

  • Like 1
Link to comment
Share on other sites

So yesterday I cleaned the terminal wires really good and tightned the belt on the alt. With a fresh charged batt. I was off, 20km then stopped for 2 hours. Started strong and went back 20km. Stopped for 3 hours. Started strong. Drove 35km. Stayed the night. Was a snowstorm and engine seemed quiet this morning. Prob full of snow. Then on my way home about 20km in started seeing power failure in my lights dimming. Sure enough just barley made it in my driveway and she died.

 

Sent from my LG-H812 using Tapatalk

Link to comment
Share on other sites

If you are replacing it, wouldn't hurt to look into upgrading to a 100 or 150 amp. Especially if you are going to run things like a winch. 70 amp seems awfully small. Of course these did not come with a lot of electronics stock.

Link to comment
Share on other sites

Like I said before... could be that the battery is well and truly borked, and the alt is struggling to keep up, or it could be that the alt is weak and won't charge unless it's spinning past a certain speed.

 

I would expect a parts place to be able to check the battery, and possibly the alt as well. I'd want to see which one was bad before putting money down.

 

My money's still on a bad diode in the alternator, though.

  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

Welcome to NPORA Forums

 

Please register to gain full access to the forum.

Make sure you read the Forum Guidelines and don't forget to post a new intro in the New People Start Here! section, to say hi too everyone.

 

-NPORA

×
×
  • Create New...