UKH

Partner and I are off to Patagonia (El Chalten, Frey, etc) this winter and wondering what sort of sleeping bag would be best i.e. fill weight? I've got a 850g down bag, is this too overkill?

What do you mean by 850g down bag?  I assume you mean 850 fill power.  What is the weight of the down?

I used an ME Firelite with about 400g of 900 fill power down for trekking in El Chalten and that was fine for me.  I tend to sleep quite warm though so can get away with a lighter sleeping bag. The comfort limit of the firelite is -8C.  

What are you going to do there? It’s a fairly open question. 
 

I’ve only been in December/January- imagine it is a little warmer in February. 

last time I went I took a cheap synthetic bag for valley camping, and a Rab bag with 350g of high quality goose down in it. 

A good mat is very important for sleeping on snow. 
 

For biving on routes I’d probably take one sleeping bag between too… with a home made ‘pizza slice’ to keep the drafts outs. And also a home sewn double bivi bag shelter. 
 

Nick your mums sewing machine, buy some Endurance pertex, and get creative. 

Which sleeping bag for Patagonia. Standards... tsk tsk. Slovenly grammar. Must stay behind after school 😡.

Hi Tom, probably should of been a bit more specific. My partner and I will be climbing in the Frey, Cochamo and El Chalten. Whilst in the later aiming for some of the Fitz peaks. Frey and Cochamo wise, it'll just be camping and not bivying. 

We're out there for a while so don't want to take more than 1 sleeping bag, bags are already quite heavy. We have either an Exped mat/Ridgerest and Alpkit Numo so both have good sleeping pads already. 

If I was going to take just one bag I’d probably take a bag with in the region of 400g of good quality goose down in it. I’d also make a ‘pizza slice’ so I could share it with my climbing partner on routes.

Though personally I’d rather have two sleeping bags and mats (one foam, one inflatable) on a trip like that, as it makes packing easier. As I can go to bed with a packed rucksack, and I don’t have to get up and frantically pack in the morning. 

From chilly experience the Numos aren't good for cold conditions. I've also had a few failures with them, although mine were the first generation ones. Long geeky post on the problems I had with my numos here https://lightfromthenorth.blogspot.com/2014/01/physics-you-can-sleep-on-des... 

I took a lightweight bag with me in February / March (I think it was a ME Helium 250) and I regretted it on the higher camps above El Chalten. Most nights were fine but the odd night it was colder and wetter I really suffered compared to my partner who had a very cozy Alpkit 800 something. 

For me a bad night sleep isn't the end of the world but after several it started to get me down a bit. If I went again I would definitely take the weight penalty for more sleep!