Electrical mystery

[doog]

Okay I have two lithium 125 AH in parallel, wired to the inverter/charger DC studs. Works fine. The batteries are charge both by MPPT solar controller and 400 watts of panels and at times by a 3000 Watt generator.

The generator running the Renogy charger puts out a nice amperage for charging, and whats WEIRD is that the positive lead to the batteries does not get warm at all, but the ground lead does get quite warm.
There is no warmth at either terminal or at any splice or fitting, the entire negative wire gets noticably warm. Not dangerously or hot at all but just about 105 degrees and stays there during charging. The red which theoretically carries the exact same load does not get warm.

Okay this is Chinese wire from amazon and 10 ga. Could be bigger but its usually only under load from solar or the alternator output. Its just occuring to me this wire may have quality control issues and the black might have greater resistance than the red. Wouldnt be the first time bargain imports showed some lack of quality control. I will stick a meter on these leads and compare them...perhaps double up the ground lead.

[Tin Tin]

Is it easy to swap the red and black temporarily to test your theory assuming they are the same length.

[smac999]

You have 10awg wire to your inverter charger?????

[FlyingScot]

Use marine grade wire.
Use a 12V (or applicable voltage) wiring tables or App to determine wire size.
Use quality connectors and crimp properly.
Use proper terminology. The black wire in DC wiring is Negative. A ground wire is something completely different and usually green or green/yellow.

A bad connection will make the wire hot as well as the connection.

Please be careful and seek onsite help. The consequences of poor wiring are very serious.

[wholybee]

400W of panels is 30A at 13V. 10AWG wire will get warm with 30A.

[catsketcher]

Could you test the cables for resistance? The warm one should show a higher resistance than the cooler one. Maybe something in the quality control.

cheers

Phil