For anyone still having activesync or battery problems I have a potential fix:
I've had two issues lately.
First, my battery life was draining at an insane rate. iPhone5 lasted about 3-4 hours before absolutely dead from a full charge. LTE disabled, WiFi disabled, icloud turned off...about as power efficient as I could make it, and I was hardly using it at all. I was losing 1% batt every 2-4 minutes.
I solved this problem by removing my work account (Exchange Activesync) from my mail accounts. Obviously I couldn't stay like that for very long, so after confirming it stemmed the battery issue, I tried to add it back. Did a bunch of different methods and tests, and what ended up working for me was:
- Remove ALL accounts (Had Exchange, gmail, icloud)
- hard reset the phone.
- After it came back up, I reset the Network Settings just for good measure.
- In Mail control panel, make sure "Default Account" doesn't have an old mail account listed (option may be not even present if you've removed all accounts, but I was having issues earlier where even though I'd removed accounts, it kept listing them in the Default Account/Calendar sections
- Add the Account
- Open Mail
- It actually took a min or two to start populating data, I didn't think it had worked, so give it a few minutes.
My battery life issue seems to be fixed, and my ActiveSync account works again. I've been off the charge for about 4h 40m now, and battery is at 90%, and that's with moderate usage on LTE.
Hopefully this helps out anyone having similar issues. For what it's worth, I removed/readded my Exchange account several times and it never worked until I had removed all accounts (my iCloud account was the last one to be removed), so if possible, just remove everything.
I have NOT added my iCloud account back yet, but will be doing this now to see if any issues reappear.