Picture this, you’re in the middle of your camping trip with friends and family and as you switch on the DC appliances in your RV, the inline battery fuse blows cutting off power flow to all of the connected DC appliances.
What causes this and how do you go about fixing it?
This post shares tips that can help you find out why the RV battery fuse keeps blowing and how you can fix the fault.
Quick Answer
Some of the possible reasons why the RV battery fuse may keep blowing are that the battery is faulty or the battery wires may be connected wrongly.
Read on for more reasons why it may blow, and what checks you can do to identify and fix the fault.
Reasons an RV Fuse may Keep Blowing
The inline battery fuse is sized to protect the battery cables from damage in case of a short circuit. If the fuse blows, check that:
#1. The Battery cables in the RV are connected the wrong way (reversed).
Confirm that the battery is connected the right way, and the wiring is not reversed, i.e. the ground wire connected to the positive battery post and the negative wire connected to the positive battery post.
You can confirm the ground wire for example using a digital multimeter set to read resistance (ohms).
Connect one probe of the meter to the ground terminal, or chassis of the RV. The second probe of the meter should be connected to the battery’s negative wire with the battery disconnected.
The multimeter should read zero ohms when the probe is connected to the negative wire of the battery otherwise it will read a value greater than zero in case it is connected to the positive cable.
#2. The battery is damaged with a shorted cell
If one or more cells of the battery is shorted then the battery will draw a high current from the charger blowing the fuse. Does the battery feel hot during the charging process?
You can test the battery using a good quality battery tester or get the batteries tested at an auto shop with reputable testing services.
#3. Damaged or shorting wiring leading to the fuse panel
A short in the wiring will also cause the fuses to blow. Inspect the wires from the battery to the converter and or to the fuse panel for any damage.
Are you able to connect the DC appliances directly to the DC appliances without connecting to the converter? If so, first disconnect all the appliances and then switch on one appliance at a time noting when the fuse blows.
If the fuse blows with a particular appliance connected, it may be its wiring or the appliance itself might be faulty.
Inspect and replace the wiring in case it is damaged. If an appliance is suspected to be faulty, replace it with another and check if the fuse blows.
#4. The Battery fuse is undersized
Is the inline fuse sized correctly? It should be able to handle at least the rated charge current from the battery charger or converter. If not, consult a qualified electrician to advise on this.
#5. The battery charger or converter is faulty and shorting. You may also be interested in this post: Why your RV converter keeps blowing fuses – and what to do
Related Questions
#1. Why a Battery Fuse May Blow when not RV is not connected to Shore Power or Generator Supply?
This may be a sign that the battery is damaged, the charger, or converter is faulty, or there is a fault in the wiring or DC appliance.
#2. Why a Battery Fuse blows when RV is Connected to a Generator?
If the inline battery fuse blows, double-check that the inline fuse is adequately sized. A high inrush current from the generator as it starts can blow the fuse it if is under sized. Consult a qualified electrician to advise on this.
Closing Thoughts
If the battery fuses keep blowing then it’s a sign that there’s a fault in the wiring, or fault with the battery, the appliances or you might even have an under-sized battery fuse.
If the RV is still under warranty, contact the dealer otherwise contact a qualified RV technician to support you if you do not have the skills to do it safely.
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