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Old 05-26-2023, 01:13 PM   #1
Join Date: Dec 2021
Posts: 10
Positive battery cable heat

When shore power is turned on the inverter/charger (RENOGY 3000w) will run my 120v system from shore power while charging my lithium battery. When I have shore power on the positive battery cable (2/0) is getting hot where it connects to the 300a fuse, no heat around the positive bus bar or positive battery terminal. New different style that has worked for me in the past is also experiencing the same thing. No loose connections, no obvious damage to any terminals, ground has a solid connection, also 2/0. The terminal connections are tight on the positive wire and the ground is not getting warm. Battery is testing normally when charging and when off the charger. There’s no large draw from the battery going to my 12v fuse box, the only thing it runs are some led lights.

Can anyone point me in a direction for further testing?

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Old 05-26-2023, 02:31 PM   #2
Bus Crazy
Join Date: Oct 2020
Location: Near Flagstaff AZ
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Year: 1974
Coachwork: Crown
Chassis: "Atomic"
Engine: DD 8V71
Heat means resistance. I would use a voltmeter and check the voltage at different points along that positive line, when it's under load. Connect the voltmeter negative (black) lead to a good ground, then touch the positive (red) lead to each terminal and each connector at each terminal. If you do this while there's a good load being pulled, then you may find a lower voltage at one point...and this will happen right "after" (downstream of) the resistance point.

Another, more sensitive, way to do this is to use both leads of the voltmeter from point-to-point on the positive cable terminals and connectors. In other words, touch one lead to a terminal's top and the other lead to the terminal's metal. If the connection is good between them, there should be almost 0 voltage reading. Resistance will show up as a voltage reading, meaning a differential in voltage between those two points. This test should also be done with the line under load.
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Old 05-26-2023, 02:31 PM   #3
Bus Crazy
Join Date: Apr 2020
Location: Northern California (Sacramento)
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Year: 1999
Coachwork: El Dorado Fiberglass
Chassis: Ford E450
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Seems like something is not hooked up right near the fuse-regardless of the tight connections.
-What is the brand of the fuse?
-Where is the 300A fuse in relation to the battery and inverter? Closer to the inverter or the battery? Juice runs in both directions, so the wire needs protection in both directions theoretically, if you follow the rule of putting the fuse as close to the source of juice as possible.
-How long is the 2/0 cable from the fuse to the battery? Hopefully less than 15 feet...
-And what is the state of charge of the battery when that wire gets warm? Is it getting warm only when charging at a high rate of amps?
-Is the inverter/charger configured correctly to charge your battery? A quick check indicates the max charge rate is configurable, so perhaps you can lower the max charge rate and see if that makes a difference (in which case something is clearly wrong because both the fuse and the wire should handle the likely max charge).
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Old 05-27-2023, 07:13 AM   #4
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Location: Andrews,Indiana
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Engine: 3116 Cat 250hp
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I make all of my own cables. I had one that was getting hot, no obvious problems, crimp looked and felt good. I made a new cable and problem solved. Just because a cable looks good doesn't mean that it is. I now regularly check all cables with a temp gun just to check.
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Old 05-29-2023, 11:11 AM   #5
Bus Crazy
Join Date: Oct 2020
Location: Near Flagstaff AZ
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Year: 1974
Coachwork: Crown
Chassis: "Atomic"
Engine: DD 8V71
Hey Albatross, be sure to (please) let us know what you try and what you find/found. It's helpful for anyone else who reads this thread. Thanks!
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Old 05-31-2023, 03:13 PM   #6
Join Date: Nov 2020
Location: Georgetown, TX
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Year: 2000
Coachwork: Thomas Built
Chassis: Safe-T-Liner
Engine: Cummins 24V
is it possible that it is CCA and not pure copper?
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battery, charging batteries, inverter, inverter/charger, lithium

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