Scaling up batch volume and efficiency (batch)

[disney7]

I batch sparge and so far all of my recipes drain the tun once, refill, and drain again. So that's two batches.

When I do a high gravity beer, I still just do two batches, but my mash efficiency drops about 10%, which I understand is typical.

I want to make 10 gallons of an Oktoberfest and I've scaled my 5 gallon batch up with Beersmith. It calls for 3 batches and the grain bill will fill up my mash tun just like a high gravity beer.

Should I leave the efficiency alone since I'll be doing an extra batch sparge or should I treat it like a high gravity beer and drop the efficiency 10%?

I just don't want to wind up undershooting my OG.

Thanks

 

[disney7]

Surely someone has run into this issue...

 

[yogensha]

The additional batch sparge will likely increase your effeciency slightly. Check out this analysis for an idea of how much:

http://braukaiser.com/wiki/index.php?title=Batch_Sparging_Analysis