Problems getting temps. correct

I just completed my 9th all-grain batch and I seem to have my process to the point that I don’t have to curl up in the fetal position and cry myself to sleep every time I brew. I am on my 3rd. digital thermometer. I have a pen style that is accurate, but I would like something with a probe that I can leave in the mash so I can track the temp. without opening the lid. (I batch sparge). Any suggestions as to what you use?

I don’t worry about it. I get my temp at the beginning iof the mash, close the cooler and don’t open it for 60-90 min. The temps are always within 2-3F of where I started.

So at the risk of reinforcing the fact that I don’t know what I’m doing. Since you have your system dialed in do you try to over shoot your start temp by 2-3 degrees and shoot for the target as your final? Or do you Start at the target and let it drop?
Example: My 10.5 gallon rec. cooler 10 lb. grain bill. 3.25 gallons of 168f. Target 150f. I started at 152 and after 90 minutes it dropped to 147.2f. 1.5gallons of boiling water raised it to 164f. 10 minute rest. first runnings 3.2 gallons, Added 3.5 gallons of 168 degree f second runnings 3.5 gallons. OG target was 1.050 actual was 1.049. Which I’m pretty happy with.
My thought is I should slow down my first runnings to get every drop out of the first draw?
Recipe:
10 lbs koelsch malt
1 oz. Select Spalt 60 min.
Wyeast 2565.
Attempting a 100% koelsch

I start at the target temp and don’t worry about the small drop. But a few degrees is really not a big deal. In your example, you pretty much averaged 150 so I’d say you’re good.

I’m not sure how slowing down the first runnings would help you get all the wort out. If it’s a problem, just tip your cooler after the runnings stop.

Most of the work happens in the first 30 mins (this is a debatable subject) so depending on what you want to accomplish with the amount of beta/alpha amylase, temp will change.

The lower 150deg mash temp tells me that you want to have more beta amylase (more fermentable sugars). This will be accomplished at what you are doing or if you lower your starting value. This is because Beta Amylase works best at 148deg. However if you want to improve on your ability to repeat a certain recipe, the best thing to do is to keep everything constant.

What I would start with is fill up your cooler with a mash and let it sit for 60 mins and don’t mess with it. Then you can accurately get a measure of your temp drop over 60 mins. This should be relatively linear, and then you can come to a degree number you are receiving after 30 mins when most of the activity is done with. Then you can adjust different starting temps on what you want to accomplish with the different Amylase in your mash.

sounds like you just need to calibrate your system.
Maybe your cooler just soaks up that much at the beginning. If you start at 152 and are 147 after 10 min then it levels out, you just need to adjust your strike water temp and let it equilize.
Not every cooler acts the same.

Dropped 5 degrees on a 90 minute mash. I have learned to preheat my mash tun with a couple gallons of boiling water.

Listen to Denny - seriously, it’s gospel. Seek simplicity in homebrewing. I infusion mash, I eyeball strike water temp vs grain bill (and as a result get slightly variant grist viscosity - and yeah, experience plays in here) and when I hit my temp I keep the cooler shut for the duration (like Denny said). I run it an hour later, boil it, do the rest (with fundamentally sound technique but nothing crazy) and I make incredible beer. Batch after batch. Anyone can.

I’m amazed at how specific and complex homebrewers get. Perhaps some folks just geek out on measuring and seeing an exactly specific result. That’s cool. But if you just want to have fun and make incredible beer, it’s really so simple - don’t let the forest of this forum blind you from the trees.

This is what I came up with for monitoring mash temp: viewtopic.php?f=5&t=109024. I absolutely love it. Simple to use and accurate.

With respect to calculating strike water temp, this can easily be done in Beersmith. I’m still amazed that every time, if the temp doesn’t settle in on the money, it’s usually within a degree.