Hot, Hot, Hot!

[karl404]

Hi all,

I recently revamped the electrical system in my RV. I've got 680W of panels on the roof wired to a Victron 100|50 solar charger, 300 Ah of Battleborn lithium batteries, and a Victron Multi-plus 3000W inverter-charger. We took the RV on a monthlong trip in May and everything seemed to work well. I opened up the battery compartment the other day while doing some work in the coach and decided to crank up the A/C (with soft start). I don't plan on running the A/C for long periods with battery power but would like to be able to cool off the RV in the evening for 1/2 hour or so.

After the A/C had been running for a half hour, I noticed that the wires, distributor, and shunt all got very hot. I've got 4/0 ga wires running between my batteries and the inverter. The longest wires are less than 3 ft (running to the inverter). My BMS says i'm at about 140 A of current with the A/C compressor running and I measure about 0.05 V drop across each cable. This is about 10X what I calculate should happen for my cable length though I don't know what to expect for losses in the connectors.

Is this normal behavior or do I have a problem?

 

[MisterSandals]

This is about 10X what I calculate should happen for my cable length though I don't know what to expect for losses in the connectors.

I noticed that the wires, distributor, and shunt all got very hot.

What distributor, shunt and connectors?
Happen to have a pic of the wiring?
Is the area vented?
I will assume you've checked/cleaned the connections.

 

[time2roll]

Yes if 140 amps is getting 4/0 even warm there are connection or crimp issues. Mid wire should be cool until the heat moves along from where the issue is.

 

[karl404]

What distributor, shunt and connectors?
Happen to have a pic of the wiring?
Is the area vented?
I will assume you've checked/cleaned the connections.

Victron everything. I took pictures that show the connections. The area isn't vented generally, but open while I'm testing and getting these readings.

Today I ran the A/C on full for 30 minutes where it was drawing about 150 Amps and measured the temperature of the shunt at five minute intervals and also the main fuse when i realized it was the hottest point in the system

time(min) shunt(F) fuse(F)
0 87
5 90
10 90
15 94
20 95 148
25 97 152
30 98 155