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MBP sometimes won't charge. Problem with power or PRAM?

S

saminsocks

macrumors regular
Original poster
May 12, 2008
130
0
I've been having trouble for the past month with my MBP charging. I was at a coffee shop for several hours with the laptop plugged in and didn't have any trouble. I did a software update for the laptop and my iPhone, but I don't think it was anything pertinent to power. If I remember correctly, it was Safari and some other small update. Anyway, when I went home I plugged it in again later that evening, since I needed to charge my phone again. From what I can recall, it was charging, but when I woke up it had stopped charging and the battery had died. I tried cleaning the connection and also plugged it into a different outlet. Eventually it started charging again, but only long enough to give me 30 minutes of battery charge. It may have stopped charging when I plugged my phone in again, I didn't notice right away.

I tried resetting the PRAM and that didn't help. It was a week before I was able to take it to the Apple store. However, when I took it in, it charged without a problem. We also tested my adapter and that worked fine in my machine and in one at the store. There also didn't seem to be a problem with my iPhone, that they could tell.

I took it home and was able to charge it again. However, a couple days ago I went back to the coffee shop and as soon as I plugged it in it stopped charging. I had things to do, so I just let the battery die. When I got back home I tried charging it again and it worked.

I haven't plugged in my phone since the problem started, or anything else, so it's not a problem with USB. My battery has had "service" status for several months, but when we went to the Apple store they checked it and it was at 80%, so it's low but not very low. Every time the battery dies the PRAM settings are reset. The only thing that has been consistent in the instances when it stops charging (other than the first time) is that I changed the date/time settings back to automatically detect (I don't have Internet access at home so I have been setting it manually until I go online). If that's the case, it sounds like a problem with the PRAM, but I don't know if that's just a coincidence. So far I haven't put it back to automatic and I haven't had any trouble with being able to charge, and it's been a couple days. However, I don't want to spend $40 on a new PRAM battery if it's really a power problem.

Any advice on what it could be or other tests I can do?



Intel Core 2 Duo
2.2 GHz processor
Snow Leopard 10.6.7
 
PRAM/NVRAM has nothing to do with power/charging/battery issues. Resetting it will not help. Try resetting the SMC, instructions for which are in the following link under CHARGING.
This should answer most, if not all, of your battery questions:
 
I forgot to mention that I did that each time. It sometimes worked, sometimes did not.

Is there a way to replace the SMC? I was under the impression that PRAM controls it, which is why I am wondering if it would be beneficial to replace that.
 
I had this problem with my new 2011 MBP and it just turned out to be a faulty power adapter. Got a replacement at the Apple Store a few weeks ago and it always charges now.
 
saminsocks said:
I forgot to mention that I did that each time. It sometimes worked, sometimes did not.

Is there a way to replace the SMC?
Click to expand...
No, you don't need to replace the SMC, only reset it. There are 3 primary components to your Mac's charging system: the MagSafe power adapter, the battery and your logic board. If your battery is not damaged or defective or worn out, and if you reset the SMC and troubleshoot the adapter (link to which is right above the SMC link in the FAQ), then the only culprit that remains is the logic board.
saminsocks said:
I was under the impression that PRAM controls it, which is why I am wondering if it would be beneficial to replace that.
Click to expand...
No, PRAM/NVRAM has nothing to do with it:
 
Thanks. I've been a primary Mac owner for years but have never really had to troubleshoot them, so I don't understand completely how everything works.

Are there tests I can do to check to see which component is the problem? The Apple store only did a very basic quick check. Since the problem is intermittent I may just take it apart and make sure everything is plugged in properly. I don't really have money to get a battery or logic board if that's not the problem.

amroc, how did they test your adapter? They plugged mine into another machine and it worked fine, so we ruled that out, but if it's intermittent that's not a very reliable test. Unfortunately I don't have another adapter to try when I'm not able to charge my laptop.
 
Heya saminsocks, Yeah the prob was intermittent with mine too, it would fail to charge maybe only 10-20% of the time.

I managed to plug the charger into a friends macbook, and I was lucky enough to see it not charge straight away (although after a bit of messing, it started to charge again, just like it did on mine). After trying out their charger for a bit on my macbook, and not seeing the problem, I was confident enough to just ask for an exchange.

It's not happened once now in the last 2 weeks since getting the new charger, and it used to happen daily before (I use my macbook a lot). So, I'm pretty sure now it was the charger at fault.

The didn't even check the charger at the Apple Store, they just gave me a new one. Might be worth you just going back and exchanging it? I'd say after my experience there's a decent chance that might be the problem.

Good luck.
 
My MBP is 4 years old, so it's no longer covered under Applecare :( I do freelance work from time to time at a hotel near here, though, and the AV staff I work with have a box full of unclaimed power adapters in lost and found, so I may be able to snag a new one from them. Or at least borrow one long enough to see if it will charge my laptop when my original one doesn't.

Hopefully that's all that it is. That's the easiest thing to fix. If it's a logic board issue I may have to see if my friend is still willing to give me her old MBP for parts. I was going to use it to replace my keyboard, her logic board may still be good as well.
 
amroc said:
I had this problem with my new 2011 MBP and it just turned out to be a faulty power adapter. Got a replacement at the Apple Store a few weeks ago and it always charges now.
Click to expand...

Exactly the same happened to me.
 
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