BT Charge temperature inconsistent

Hi everyone, did anyone ever experience a big difference between the BT charge temperature for the same IBTS charge temperature?
If I normally charge at 473 F (IBTS) I’ll usually get a BT temperature of 320 F
But on one of my recent roast, the BT charge temperature was way higher! 472F (IBTS) 371 (BT)
It was a first batch too.

Interesting you mention this. I recently upgraded to RT 4 and while roasting yesterday I noticed my BT and IBTS temps were much closer to each other than usual. I usually roast 570 G charges but this time I had a 900 G batch and thought maybe that was the difference. I’ve never seen BT > IBTS before either.

1 Like

BT and IBTS will be closer in the roast if your batch is bigger.

My issue occurs before I put the beans into the roaster. The BT temperature was much higher than before for the same IBTS charge temp.

I’ve looked at your 473 preheats and they’re not always the same, but the last one was higher than the others. First, have you cleaned your IBTS recently? It might have gotten dirty and, being off, maybe goes on preheating a bit more. Other things to look at are the ambient temperature and preheat time. Was it hotter where you roast that day and also, something we can’t see, how many minutes did you run the preheat in all 473 preheats?


Thank you for your help! I think it was a combination of factors, including IBTS needing a wipe. I think this highlights the importance of pre-heat protocols as well as maintenance + accounting for environmental changes.

With my 1kg batches roasted to just before SC BT does cross IBTS. With my 1kg batches I find that after FC BT readings is more accurate due to bean mass. For me with 500g batches it doesn’t cross (and shouldn’t!)


That can happen in back-to-back roasts. Was that what you were doing in this case? The preceding roast will heat the face plate as the hot beans rub against it. When you preheat for the next roast, IBTS will hit the target pretty fast since everything is already heated- the Bullet just has to cool to meet criteria. If the IBTS hits charge criteria quickly you will have to wait for the BT to drop as the face plate is still cooling from the hot beans of the preceding roast.