Why is this wire so hot?

[Sergio95050]

Perhaps there is a huge capacitance, what accumulated energy...

 

[AshleyL]

Say what? How is a closed breaker going to arc over?" Acr over to where? By your logic systems will be arcing and sparking everywhere every time a BMS disconnects for whatever reason.

Oh, actually it does happen every time when BMS disconnects under high current. It doesn't have to be in high voltage.

 

[SparkyJJO]

Oh, actually it does happen every time when BMS disconnects under high current. It doesn't have to be in high voltage.

Many BMS don't use a contactor. There's no arcing within the FETs (well, OK I guess they can, but they only do it once when they blow up).

 

[Texas-Mark]

Oh, actually it does happen every time when BMS disconnects under high current. It doesn't have to be in high voltage.

Totally different thing. Of course a contact "might" arc when opening. But in this case we are talking about a closed contact (the breaker) and the opening happening elsewhere (the BMS). The breaker is not going to arc when the BMS opens.

 

[AshleyL]

Many BMS don't use a contactor. There's no arcing within the FETs (well, OK I guess they can, but they only do it once when they blow up).

Depend if the gate-to-source voltage is high enough to arc across the gate dielectric.

The "contactor" might be the loose connection at the breaker terminal near the red wire.

Edit: To test it, just charge the battery at lower voltage 13.6 or 13.8v to prevent non stop BMS disconnect/reconnect due to OVP. If there is no heating.....then that is that. 3.4v or 3.45v per cell should be sufficient to get full charge for lifepo4

 

[Texas-Mark]

The "contactor" might be the loose connection at the breaker terminal near the red wire.

I already said the issue could be a bad crimp or a cheap breaker with resistance. However, it is still not going to magically arc across a closed breaker when the BMS opens upstream.

 

[Daddy Tanuki]

I already said the issue could be a bad crimp or a cheap breaker with resistance. However, it is still not going to magically arc across a closed breaker when the BMS opens upstream.

bet you crank 1000 amps at 100 VDC across that breaker it arcs....


pulling your leg