Can’t get the DC appliances such as lights or DC fridge in the RV to work? Are the fuses in the converter popping?
Then you’ll have to look at the converter, it’s wiring, and what else is connected to it. A fault in any of these can cause the fuses to blow. This then affects the power supply to and from the converter powers the connected DC appliances when the RV is plugged into shore power and charges the house batteries too.
if you want to know why the fuses keep blowing then this post is for you. It explores the likely reasons why the converter may keep blowing fuses, shares tips on checks you can do to pinpoint the problem, and how you can DC power available again so that you can use all the appliances.
If your RV Converter is blowing fuses then it’s usually one of the following causes depending on whether the input fuse is or the reverse polarity fuses is blowing, a damaged converter, a faulty battery, damaged wiring, a faulty appliance, or a case of wrongly connected battery cables.
Here are a few checks you can do to narrow down the likely cause.
Reasons why your RV’s converter keeps blowing fuses? What Checks you can do
#1. Check if it is a faulty breaker or a fault with the converter or its connections.
First Connect the RV to a 120V source. Check if the breaker supplying the converter trips. If so, disconnect the converter, reset the breaker and check if it trips again with the converter disconnected.
If so then there’s likely a fault with the breaker. If it does not trip then there’s probably a fault with the converter or the circuits connected to it.
If the input fuse (15A or 20A) into the converter keeps blowing then it might be that:
#2. Check the Converter
The converter has an internal fault such as a short. To check for this, you can safely disconnect the battery cables and leads connecting to the fuse panel to which the DC appliances are connected. Replace the input fuse and then connect the converter to shore power.
Does it pop the fuse? If so, then there is likely a fault in the converter or the connected wires. Inspect the connected wires for any signs of damage or burnt marks. Replace any damaged cables.
If the cables are intact, then it is likely that the converter is faulty and needs to be replaced. Replace with another and check if the fuse pops or remains intact.
#3. Check the DC appliances and their wiring
to check if there is a fault in the DC circuit, Disconnect the converter from the 120V supply. Disconnect the converter positive output wire from the fuse panel leaving only the battery connected.
If the battery has a sufficient charge (~12.4V and above), switch on the DC appliances and check if the DC appliances work well. If so then the battery connections to the fuse panel and the appliance connections to the fuse panel are also O.K.
#4. The battery is faulty or deeply discharged
A faulty battery can cause the fuses to blow. A quick test you can do is after the converter has tested fine after step #1 above, with the DC fuse panel disconnected, connect the battery.
If the fuse blows then it’s likely that there is an internal battery fault or damaged battery wires. Inspect the battery wires for any signs of damage.
If you have a battery tester, use it to test the battery. Alternatively, you can have the battery tested at an Autozone.
Replace the battery if damaged. Deeply discharged batteries have also been known to trigger fuse blows as a result of the higher than usual initial current associated with a lower battery voltage.
The connected appliance(s) attempt to compensate for low voltage by drawing a higher current to meet their power requirements from the power formula, Power= Voltage x Current.
If the converter’s reverse polarity fuses blow then:
#5. The cables from the converter connecting to the battery have been interchanged. If the battery cables are interchanged then the reverse polarity fuse will blow. This can happen when a battery is being replaced.
Check the owner manual for the location of the reverse polarity fuses. Inspect them to check if any of the fuses have blown. Correct the wire connections and replace them with fuse(s) with ones that have the same rating and size.
Check if they blow again. If they do not blow then all should be good otherwise if they continue popping then the converter might be damaged and should be replaced.
Additionally, here are additional reasons why the fuses may blow and what checks you can do
If the converter keeps blowing fuses then it’s usually one of several faults, a damaged converter, a faulty battery, damaged wiring, or a faulty/shorting appliance. Also double-check that the battery cables have not been wrongly connected which can happen when replacing the battery.