I recently bought 2 more BT-3100 —I already had 2 —— I’m testing hundreds of cells right now for a powerwall
The 2 I just purchased have fan issues —- The charger will stop and start in the Discharge option due to heat —- The older 3100 had a fan with a resistor to slow it down —the newer models have the replacement fan out of the 3400 —- I replaced the fans in the 2 newer 3100 with the 25 x 25 x 10 delta fan —no more problems
There is a whole other thread on this forum about the 3100— with all the fans issues and power supply problems
I also use a bigger 5amp power supply listed in that thread
The crazy part is my first Opus was a 3400 —— I never had any of these problems with it — here’s one of many threads