iPhone 4 that won't charge easily. What else to try?

[clay]

I recently acquired a used, ATT iPhone 4. It was reported by the previous owner to have trouble charging. It arrived dead, but plugged it in to a port on my Mac Mini overnight, and in the morning, it was about half charged. Started it up, did a full erase and started fresh in iOS 6.1.3. Jailbroke it, used it basically as an iPod Touch around the house for about a day, then started noticing that whenever I plugged it in, while the icon indicated charging, it was not actually charging. So, thinking that it might be Jailbreak related, I wiped again, this time installing iOS 7. Same deal.

I was able to get it to charge if I just left it overnight plugged in to a USB charger that I have. Looking at the specs, it looks very similar in terms of power to the official iPhone charger. I also tried using one of the larger iPad charging bricks, same deal. Says it's charging, but charge level actually goes down slowly, like it would if it were just sitting there.

So, I think at this point, I can get it to charge if I turn it off and plug it in. I'm now testing having it plugged into a USB port on my Macbook Pro, to see if that is somehow different.

I started from scratch in terms of software on this. Did a full factory erase and then set it up as a new iPhone. Did not restore from a backup in iTunes, and haven't really added apps yet.

Is this a symptom of a bad battery? I'd be happy to drop the $15 to buy a good quality battery and replace it myself. But if there's something else up in the charging circuitry, maybe I should just try and get $100 out of it, and find something else.

What do you folks think?

[beagledave]

I would just get a battery. I automatically got one when I purchased a used iPhone4 a few months ago.

Only seven bucks. Shipped.

[clay]

I'll give that a try, thanks.

If anyone else has other suggestions, feel free to share.

[kj4btkljv]

Check for dust/crud build up in the dock port on the phone itself. Use a magnifying glass, maybe there's gunk in there blocking the dock cable from inserting all the way, and therefore not charging like normal.

I say this because I cleaned my boss's phone of this stuff. It's pocket lint, and over time it can build up in the socket and cause all kinds of wonkiness.

Edit: Oops, forgot to mention what I cleaned it out with. Air can with the blower tube/nozzle, fine point tweezers, paper clip tip, and a tooth pick.

Jeff

[rz]

I'll ditto the toothpick in the port suggestion. My iPhone 5, after only a few months, was having problems charging. I shot compressed air in the port, but that didn't help. I finally got a wooden toothpick and scraped out a big piece of pocket lint that had probably gotten compressed pretty well when I plugged the charging cable in. That fixed the problem.

[fauch]

Replace the battery, plain and simple, it was the BEST thing I have ever done for my iPhone 4. Cost almost NOTHING and the results were dramatic....

Why Apple doesn't make these batteries User serviceable, I really don't know. The ONLY tricky thing in the replacement (if you don't have the crazy proprietary screws) is prying the glue off the old battery and the antenna ground clip which surely could have been put elsewhere in order to allow an easy battery swap.... Makes no sense, even by Apple standards.... That said, I had a shop do it, still cost me like 15 bucks total and I never looked back...

[clay]

thanks, folks. I'll pick up a spare battery.