JK-BMS B2A8S20P (11.2 version) temperature 86.3°C (187.34°F) too high ?

[HRTKD]

Change the way you connect the cable to the BMS. Instead of allowing the cable to come in at a ~45° angle, change it to be perpendicular to the BMS. By allowing it to be 45°, you're reducing the surface contact area. More surface contact area means less resistance. It isn't a huge difference in contact area, but at those amps, you need all the contact surface area you can get.

Two 7 awg cables in parallel is effectively a single 4 awg. Using 4' as the round trip distance, my wire gauge calculator says you should be using a single 2 awg, or two 5 awg cables.

How hot are your cables getting?

 

[RCinFLA]

Appoximate prediction based on 25 deg C ambient air environment. MOSFET's will be much higher temp than outside case. There is only one overtemp sensor on one of the four strings of MOSFET's.

Measure voltage drop across BMS. If you have some blown MOSFET's, solder joint fractures, or current shunt resistors failures the voltage drop will be greater than chart for given current and the BMS will get even hotter for given current.

 

[Berseker]

Same experience, my 150amps jk bms mosfet overtemp warning comes on when charging at 60amps AC

 

[LydMekk]

My 200A versions stay under 30c during charging.
Consider passive cooling for your battery box.
See my battery build thread in my signature.

 

[Berseker]

My 200A versions stay under 30c during charging.
Consider passive cooling for your battery box.
See my battery build thread in my signature.

The cell temps stay a cool 32 deg C.hence why i suspect the issue may have to do with how i extended the P cable .
I only added a 7inch extension using 35mm cable to the P cable and nothing to the B cable. Could this be an issue?

 

[HRTKD]

The cell temps stay a cool 32 deg C.hence why i suspect the issue may have to do with how i extended the P cable .
I only added a 7inch extension using 35mm cable to the P cable and nothing to the B cable. Could this be an issue?

If it's a poor connection with the extension, then that could be the problem. I would expect the wires to be hot too.

 

[LydMekk]

As he said only a problem if it is a bad crimp or you are using alu cable...