Midnite dc 100 amp din mount breaker runs hot

[Taos]

I recently upgraded my solar panels and noticed when I'm getting 70-80 amps flowing through my mnpv100 amp 150 volt dc breaker from charge controller ,it's running hot 45-55 degrees celcius or 115-131 Fahrenheit after several hours  is this normal ,this tells me the breaker contacts have resistance , i have done a voltage drop test on the circuit and im well within specs . I've also used a thermo imaging gun and the hottest spot is the breaker .I know Midnite solar dc breakers are rated for full amps rating compared to other brands that only allow 80% current rating .

[ClassicCrazy]

Maybe from your wire connections. Did you check those for tightness ?
What kind of wire goes to the breaker ?
I didn't know there was a din mount 100 amp breaker. When I go up that high in current I used the Midnite breakers that have studs on them and then use well crimped ring terminals.
You could try using some boot lace ferrels on the wires going to your breaker if you don't have those on the wires.
Larry

[Taos]

I've checked all screw torques all good ,used heat imaging gun , all good except the side of the breaker after 3-4 hours with heavy amps 50-70 amps , yes they make a din mount breaker it's two breakers sandwiched together with a y buss bar on Input and output with proper large screw for wires,100amp rating ,this is the largest they make in this style,I'm using t90 awg4  gauge wire thhn rated for 95 amps ,and did a voltage drop test while under heavy load aprox 70 amps all good . I've had solar for over 13 years and never checked heat with imaging gun,but my pv aray was aprox 20 percent compared to today. The reason I know is I was using the heat imaging gun to go over all my system to make sure there was no heat from a poor connection etc , last night I figured I better go to awg 2 wire with fine strand 620 for this gauge wire , it's all installed ,I will see in a few days what the results are ,unfortunately today it's a snowy day .      Thanks for your input !👍🏻

[ClassicCrazy]

If that doesn't work try a panel mount breaker if you can fit it in somehow. Sounds like the breaker you have isn't up to snuff.
I have been wanting to get a heat imaging camera for awhile but haven't gotten one  yet. I used to have one at work and it was very useful.
Larry

[FNG]

What charge controller are you using? A couple thoughts come to mind:
1- The breaker has resistance internally and as such will create some heat, this is not the contacts as such but just the internals that pass the 80-100A
2- Ripple, some mppts cause a lot of switching ripple that is actually current flowing in 2 directions so it semi cancels out but will also create a little more heat

[Taos]

I have several charge controllers but the two  that's on this system is Victron 250/85 and a Victron 150/85.  That would be reason why I don't have excessive voltage drop when measured.
Thanks for your input .