Blowing 20 amp fuses on battery circuit

Wyarberry

New Member
Aug 10, 2016
9
I am new to the forum and have a 2013 Aliner Ranger 12 with a WFCO 8735 power plant. I keep blowing 20 am fuses. The main inline fuse outside the battery blows immediately and loudly when I hook up the battery. Battery is fully charged, and was replaced with a new on, and polarity is hooked up correctly. If I hook up Shore Power with the battery still hooked up, it blows the fourth fuse down in the Inverter, which is also 20 amps and is the main battery circuit. If I completely disconnect both wires from the battery terminals, I can hook up Shore Power without blowing the fuse in the Inverter. Making me crazy. Bad main ground, or bad Inverter? Any ideas would be welcomed.
 

romno

Member
Mar 22, 2015
25
Are you sure you have the battery wires connected correctly? What you describe (mainline fuse blowing immediately and loudly) sounds like a short to ground. Remember that on trailers, black wires are generally +12 V and white is ground...
 

Wyarberry

New Member
Aug 10, 2016
9
Polarity is correct, and further confirmed by the wire with the inline fuse going to positive. Was working for 3 months before, and nothing changed with setup, in fact wires are not long enough to switch.
 

romno

Member
Mar 22, 2015
25
I would think the next thing to check for is worn insulation where +12 V wiring may be exposed and contacting the frame. It's amazing what kind of wear can happen when things vibrate going down the road. Have you tried ohming-out the +12 V wiring with no battery attached? If you measure 0 (or close to 0) ohms, you know you've got a short. I apologize if I'm being to simplistic -- I don't know your level of expertise.
 

Wyarberry

New Member
Aug 10, 2016
9
You are not being too simplistic. All the wiring looked good to me, and was encased in a protective sleeve. Only thing was 6 to 8 gauge short ground wire to the trailer tongue was screwed into a single bus and screwed to the trailer. It looks like it could be a little corroded, and inline fuse holder had a little inside, which I cleaned with electrical contact cleaner. Would a bad ground cause this problem? Reason I ask, is that the Inverter fuse blows if Shore Power is hooked up with the battery hooked up.
 

romno

Member
Mar 22, 2015
25
A bad ground could be a potential cause of your problem. I still think it would be worthwhile to find a multi-meter and measure the resistance (ohms) between your power wire and ground.
 

romno

Member
Mar 22, 2015
25
Yes, measure at the terminal connectors with the battery disconnected and no Shore Power. If you measure anything below 10 ohms or so, you have a short. Otherwise, the reading should be in the range of several hundred ohms or more, depending on the specifics of your setup.
 

rabird

Howdy!
Mar 3, 2006
7,807
N. TX
report what ya find [;)]
report battery voltage
report voltage of the the disconnected wires @ the batt while plugged in with good fuses.
 

roybraddy

Super Active Member
Mar 23, 2016
2,393
King George, Virginia
My selfcheck for battery wiring is to find the words 'NEG' or the symbol '-' on the battery case and make sure this is the one going to the frame ground. I will even hand trace the negative terminal cable to frame ground to be sure...

Sometimes the manf will switch the terminals around on you for the same exact battery...

What you are describing sure sounds like those cables are reversed...

After I was sure everything was normal again I got RED tape and wrapped all of the POSITIVE cables at the terminals.

Roy Ken
 

Wyarberry

New Member
Aug 10, 2016
9
Definitely wired correctly with white to negative. Will try to find an ohmmeter and check readings at connectors.
 

Wyarberry

New Member
Aug 10, 2016
9
Here's the skinny. 1 positive and 2 grounds. When I test ohms on the + and ground that goes back to the converter, I get 24 ohms. When I test the + with the short ground to the tongue it flips all the way over to 0. Assume this means that the main ground to the trailer is faulty. That is where the corrosion appears. Bought a new bus lug and will clean up and re-connect and see if that works. On the right track?
 

roybraddy

Super Active Member
Mar 23, 2016
2,393
King George, Virginia
Definitely the two large gauge wiring is coming from the converter/charger 12VDC Power Distribution Panel.

Maybe one of the other wiring pairs has been reversed. My batteries have the converter/charger wires, the front tongue jack wires, and the Trailer Brake Breakaway wiring. I have added a couple of other direct battery connects...

Perhaps you can just have the the large size cables hooked up White to Ground and Black back to the 12VDc Power Distribution panel..

If that works normal it eliminates some of the problems...

Another problem I had to was replace my original FUSE Values when I added more batteries. Each battery in your battery bank will want to demand around 20AMPS of DC current when first being hit with the 14.4VDC Boost Charging Voltages. My mainline had 35AMP Fuses it originaly...

Now I have a 60AMP DC output converter/charger and I I think I increased the Values to 80AMPS... The fuse next to the battery is there to protect the battery cable wiring ins case of of a direct short to ground farther down the zone. i.e. with a dead short these batteries can demand a good 200AMPS or more and this would fry the battery cable wiring and could very easily start a fire in the process...

If you have two 12VDC batteries in your bank they will want to demand 40AMPS of DC current when first connected for a few minutes if the Shore Power is connected feeding 120VAC to the converter/charger unit which might be rated at 45AMPS DC Output...

Another thought is those two wires that have been added going to screw taps might be BLACK and RED pairs. In this case Black might be Ground and Red would be Positive which is normal for Automotive wiring... My whole trailer uses the WHite and Black wires except for the JENSEN Car radio that is instaled. It has RED and BLACK cables so right away we see a BLACK wire on top of a WHITE wire in the junction box. Also then we see a Red wire on top of Black wire too haha... Makes the old timer's roll over in their graves...

When we hear about a battery change out and fuses get blown it is almost always the batteries got wired incorrectly... So don't blame all of us for asking haha...

You will figure it out sooner or later and get to slap your forehead when you do...

Roy Ken
 

roybraddy

Super Active Member
Mar 23, 2016
2,393
King George, Virginia
Most batteries only have ONE Frame Ground wire and many Positive HOT wires going to things...

Only have the one that physically goes to frame ground connected to the Negative battery terminal. Disconnect the second ground wire you found for the time being...
 

theseus

Living the Darkside...
Silver Supporting Member
Feb 6, 2007
3,494
Centerville, OH
Wyarberry said:
Reason I ask, is that the Inverter fuse blows if Shore Power is hooked up with the battery hooked up.


You said you had a WFCO converter. Those charge the battery when connected to Shore Power. So my 2 cents, is that, if you are connecting the battery up correctly (and you say you are) then there is a short between the converter and the battery. It is possible a wire has worked loose behind the converter and is shorting out or has damaged insulation around it.
 

Wyarberry

New Member
Aug 10, 2016
9
Ok friends and neighbors, drumroll please. Fuses are holding so far, so definitely appears to have been a corroded frame ground wire connection. Yaay.
 

fix_it

Active Member
Aug 29, 2010
595
Wyarberry said:
Ok friends and neighbors, drumroll please. Fuses are holding so far, so definitely appears to have been a corroded frame ground wire connection. Yaay.
A corroded ground will not cause the problem described. Either you accidentally fixed it, or its still there and will come back.

A bad ground will cause high resistance. High resistance causes less current to flow. Not more. It sure sounds fishy that you have two ground wires and one positive. Normally, I'd expect one ground that goes to the frame. Then there should be a positive for the converter, another for the breakaway switch, and possibly one more for the charge line to the pigtail (this might be spliced in elsewhere though).

If you have electric brakes, there should be a breakaway switch. If one of the wires from this switch goes to the battery, it goes on the positive side.

If one of the wires goes to the trailer pigtail, it probably goes on the positive.

With the battery unhooked, and Shore Power plugged in, measure voltage from one of the remaining wires to the trailer frame. If one has voltage, then it goes to the positive.

Any wires connected to the frame are negative.
 

Mickeyrv

Week day camping is great
Jul 22, 2012
830
Wyarberry said:
I am new to the forum and have a 2013 Aliner Ranger 12 with a WFCO 8735 power plant. I keep blowing 20 am fuses. The main inline fuse outside the battery blows immediately and loudly when I hook up the battery. Battery is fully charged, and was replaced with a new on, and polarity is hooked up correctly. If I hook up Shore Power with the battery still hooked up, it blows the fourth fuse down in the Inverter, which is also 20 amps and is the main battery circuit. If I completely disconnect both wires from the battery terminals, I can hook up Shore Power without blowing the fuse in the Inverter. Making me crazy. Bad main ground, or bad Inverter? Any ideas would be welcomed.


[PU] [TV] Check your Inverter manual maybe those should be 30 amp. fuses . 30 Amp fuses normally use a 12 gauge wire. Don't change fuses unless manual says they are supposed to be 30 amp units.
 

Wyarberry

New Member
Aug 10, 2016
9
Response to fix_it:
Sorry about the delay, have been traveling. Did the test you suggested, and appears that the other wire is indeed a ground wire. Other wire that was colored black did register voltage as expected. Think that the second ground wire in question goes all the way back to the Inverter, I suspect.
 




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