You can try apps like Juice Defender to see if it improves your battery performance, but I believe there is something wrong with your phone. Losing 50% of battery overnight is impossible for me since I only lose 2-3% overnight (admittedly I am using a custom ROM with custom kernel, so battery performance can be better on mine). You may also want to install battery monitoring app to see if your battery drain is normal or not (for me it is around 10-50 mA on idle). If it is not, you should starting looking for rogue apps.
Lastly, I read somewhere that a factory reset is recommended when you update to ICS, so if you haven't done so, you can give it a try.

 

I too have noticed a battery drain since ICS update, not as much as 50%, but I would say at least 20%.

 

I get slightly less than I used to.

I did get more or less 48 hours and now I get around 30 hours (stock Vodafone ROM)

 

I had the same issue, but I did a factory reset, and since then the battery consumption seems to be better than before the ICS upgrade if anything.

 

Mine seems better after the update, but not much

 

My battery life seems to be getting worse by the day. In >Settings>Battery it's telling me that my screen has used 72% of my battery. I have the brightness set to almost close to the minimum and the screen turns off after 1 minute..so no idea why that is so heavily used..any help would be appreciated.
MJ

 

That seems pretty normal unless you've left the phone unused all day, today my phone has been on 9.5 hours, screen usage 74% and I've only used 27% of the battery power.

I always use the auto setting for the screen brightness.

 

KP
I changed my screen setting yesterday evening to the 'auto' setting and that seems to use less battery.
Its now been on battery for 7h50min and screen has used 21%, which seems more like normal.

 

Same here, maybe 10% overall at most.

 

sounds like something is wrong, buy an Anker battery from Amazon. They are bigger batteries and last longer than stock.

 

ive got a anker battery, for me its like an extra 4 hours, but after the ics update my battery drains alot faster sems like 2hours quicker

 

My battery life was really bad after ICS upgrade... it would last around 4 or 5 hours only.

Then I changed the wifi setting and my battery life return to normal as before the upgrade:

Settings>WiFi>Advanced>Keep Wi-Fi during Sleep -> changed to "ALWAYS"

I assume that when using the 4G it uses lot more battery than using WIFI.
With the ICS upgrade the default "Keep Wi-Fi on during sleep" setting changed to "Never" thus wifi turning off when the phone goes to sleep, then automatically the 4G kicked in draining all my battery.

Now since the WI-Fi is on even during sleep, the wifi keeps connected when available, the 4G is off, thus saving my battery life.

 

^^^ WiFi uses a *lot* less power than 4G. Stay connected to WiFi, when possible.

 

I have to say that, versus a comparable gingerbread useage, I am now finding that my battery life is better with ics. It does look like there are other factors at play regarding battery life than just ics alone.

 

I normally charge my phone over night so i don't have that issue, I how ever use GO Powermaster and have got the standard power savers and my own creation and I can now get a full day out of the phone on normal use.