Coolers & Lids...

I'm going to be starting my path on partial mashing here soon and I have been looking for a suitable cooler to use. I've found several 2 and 3 gallon coolers at the local stores around here pretty reasonable. Some of them, however, don't seem to have very thick lids in comparison to the side walls. My question is, will these particular coolers be able to hold temp very well or should I continue my search for a better cooler with a thicker lid? Thanks!

They should be fine. Mine has a fairly thin lid and the temp only drops by about 1.5 degrees in an hour.

If you wanted a little extra insulation, you could wrap a few towels around the top. I'm not sure how much heat it would keep in but it couldn't hurt.

The only 2 and 3 gal coolers I have seen have a uninsulated lid. Covering it with a blanket or towel should help.
The 5gal coolers usually have insulated lids however if you are using only a few pounds of grain then the heat loss will be similar due to the larger size. I have used my 5 gal cooler with a 4# mash without problem and it allows me to do decent AG batches also.
Craig

you could punch a couple of holes in the top and fill it with an insulation from a can, or try and pack it with some type of poly insulation.

Ping pong balls

https://www.homebrewtalk.com/showpost.php?p=198324&postcount=23

I just throw a towel over the top of my tun, and that do keep a lot of heat in.