Replaced battery
 

Hey so I was having problems with what I thought was my battery. The first day this problem started it was 100 degrees out and my car had trouble starting. This continued for about a week, my car would start fine if it wasn't hot but would have trouble when it was hot from being i'n the sun. I assumed that this was my battery.

So I finally got around to switching today because I was busy with school and got a little sick.

But when I took out the old batter the green yellow black indicator which say if the battery doesn't have a charge or needs to be replaced. My old battery says that it's just not charged.

I also could not find a manufacture date on the battery but there is an 08 written i'n pen which I'm assuming is the date it was installed.

What I am really worried about is that my problem is not i'n fact my battery, but that it's not being charged.

If you guys could please help me diagnose this problem and make sure everything is fine with my car I would really appreciate it.

Thanks
Aron

What engine do you have ? when you say it wouldnt start do you mean the engine wouldnt turn over or turned over but wouldnt fire ?

I have a 3.0 and the engine would turn, it just wouldn't fire. It was definetly something with my battery. I'm just not sure of the batteries dead or it's just not getting charged anymore. Also since I replaced the battery, the 4x4 alert is on my daahboard

Is that 3.0l petrol ?

Yah 3.0l gas

Have yoy got a volt meter? if so put it across the battery with the engine off then again whilst its running, this will tell you if its charging or not. But you do say that it turns over but not start which would not indicate the battery i wouldnt of thought. Maybe a stupid question but have you tried another Key.

If the engine was turning over the battery was doing its job... it not firing off may be a different problem all together. I'd suspect fuel pressure bleeding down as a possibility as well as possibly a weak cam or crank sensor.

Well then I was wrong, it didn't turn at all. Eitherway the problem is definetly something to do with the battery. I just don't know whether that battery was dead or the car wasn't charging it.

Oh, so it didn't turn over? In post 3 you said it turned but didn't fire... Short trip city driving with AC on high can bring the charge level down over time. I see BMW's with all city miles go 2-3 years per battery while long rural/highway driving cars can go 4-5 years per battery... Speaking very generally of course.

I also have subs on a capacitor, which could kill the battery. But the meter on the battery was black which means it wasn't charged. Could the meter be wrong and the battery can't hold a charge?

The coloured indicator on the battery doesn't mean a thing. If the engine turned over as you said, then the battery wasn't the problem. If the engine didn't turn over because the battery had failed, then why would you trust the indicator on a broken battery?

If you want to know what the problem is, you should start with a voltmeter as was already suggested. Check battery voltage, with the engine running and not. Then get the battery load tested if necessary.

We

Well the point is I definetly kno it's something to do with the battery because I had trouble starting for a week and then I needed to be jumped and it didn't keep a charge after that.

Having had the car jump started could be the problem. If it was not done correctly it can cause all kinds of problems to the vehicle electronic systems.

We still need to know:

When you turn the key to start the car, does the engine turn over of not? If not then the battery may as you say be flat - in which case it needs charging.

If it does turn over, is it slow or a normal car cranking speed? If it's slow then again the battery may be the issue - it would help to know what the actual voltage on the battery terminals is. That would indicate whether it's a bad cell - in which case you need a replacement battery, or it's just flat.

If it turns over with no problem but the engine does not fire, then the problem is unlikely to be the battery. Never assume the 'Magic Eye' on the battery window is telling the truth - you need a volt meter.

We need the voltages with the engine off and running to see if the alternator is putting any charge out.

Let us know exactly what you are experiencing and we may be able to help further to narrow the issue down.

It should not be the capacitors on the sub as they do not pass DC, only AC - unless one is faulty.

Apart from the 4x4 warning light, are there any others showing?

If the battery is low on charge from driving with the AC on high and subs bumping for relatively short trips jump starting does NOT recharge the battery, but simply gives it a boost enough to start it that time. You would need to charge it properly with a battery charger to actually be recharged.

And the "magic eye" is only really good for a new battery as an indicator on whether it is good or needs to be charged etc. After years of service the bottom of the plastic "eye" gets coated in sulfur and it sinks rendering it useless...

The way to properly diagnose would be to fully charge the battery, then have a load test done (free at many auto parts stored) which will tell you the robustness of the battery under load and ability to bounce back from loads. Then a load test on the alternator will tell you the charging ability under loads etc. Yet again, free at many parts stores.

Just assuming you need a battery because you needed a jump start may not be addressing the cause of the issue, which could be anything from driving profile to draw etc.

The whole story goes as follows.

First day I noticed a problem it was 100 degrees out and the car didn't start as quick as normally, then again the same day it had trouble starting again and I had to step on the gas as I started it to help it start.

That whole week I had a little trouble starting especially when it was hot out.

Then i drove home from school about 35 miles and parked my car for the weekend.

When I came back to try and start the car 2 days later the battery it was completely dead and I needed a jump.

I jumped my car, properly and drove about an hour back to school.

Which I figured would charge the battery.

The car did not start the next day

And I changed the battery yesterday cuz I already had one because I assumed that was the problem. I'm just worried that it's the alternator and that the battery is gonna loss charge again.

How do I check if the alternator is charging the battery

Ok put a volt meter over the battery with the engine NOT running. Then start the engine and do the same again. You should see a difference in voltage as the alternator driven by the engine should put a slightly higher voltage back to the battery. If you do this then report back your findings i.e the voltage readings somebody should be able to help you. This as said before can be done free of charge at your local car spares shop if you dont have a meter.

Measure voltage on the battery terminals with the engine running. If your alternator is charging properly it should read 14V give or take 0.2V. There is an instrument cluster test mode that allows you to monitor the running voltage right on the OBD display. Do a search if you are interested.

The colored indicator dot on the battery is unreliable. I had bad cell in my battery and the indicator showed it just needed a charge. You need to get the battery load tested with a proper battery tester to know for sure (not just a volt meter).

So unless you post the results of either of the tests above I don't think anyone can help you any more than they already have.