Inverter fuse size; 300A vs 350A

[TJ&LadyDi]

A recent thread on this forum discussed a 300A fuse blowing in the inverter circuit and the need to carry a spare fuse. I finally got around to checking the value of the fuse in our all-electric 2018 MADP and found that it uses a 350A , not a 300A. Of course, I found that out after picking up a spare 300A fuse, but that's another story.

In looking around for JLLN-350A fuses, I found the OEM Littelfuse version selling new in the $80-$100 range. I also found a listing on Digi-Key (https://www.digikey.com/products/en?keywords=JLLN 350A) for a Riedon JLLN-350A selling new for $30. I checked all the specs and that fuse should be a very workable replacement for the Littelfuse version...and, at about 1/3 the price. So, I ordered up a pair of them at that price from Digital-Key (PN 696-1830-ND- $30.28 each + about $5 shipping for the pair).

They arrived today and I was anxious to compare them physically to the Littelfuse version. Imagine my surprise when I opened the shipping container and found a pair of...wait for it...Littelfuse JLLN-350A fuses that had been substituted in. Checking the Digi-Key website, I found that the Littelfuse JLLN-350A (PN F11994-ND) lists for $80.60 each. Now, I'm not complaining about the substitution, nor can I say that anyone else ordering the Riedon version might get the same substitution, but I was looking forward to seeing how the Riedon version compared physically to the Littelfuse. Next time, I guess.

TJ

 

[FLSteve]

@TJ&LadyDi … I also checked and have a 350 amp installed in my coach. So I will order one of these and see if I get the same "upgrade" as you.

FLSteve

 

[TJ&LadyDi]

Glad you checked! Everyone should check the fuse value BEFORE they buy a spare. I learned that the hard way!

It looks like the newer coaches (and especially the all-electric models) are now using the JLLN-350A fuse. BTW, JLLN is a spec for fast-blowing fuses and that's what we need in our coaches to prevent wiring damage from an overload.

The fuse holder on our coach (and, I think in many others) is on the side wall of the battery compartment. You will see large, red wires going underneath a snap-off plastic cover. There will actually be two sets of red wires (one set smaller than the other) running under plastic fuse covers. The 300A or 350A fuse is connected to the larger wire set.

I found it pretty easy to pop the plastic cover off and use my cell phone camera to take a close-up of the fuse. Then, you can view it at your convenience in a better location. The amperage value will be found on the white band circling the middle of the fuse body, as well as being stamped on the metal fuse body itself, adjacent to the white band.

Some of the 300A/350A fuses are unplated copper and others are silver-plated, I don't think it makes any difference as long as they are spec'd JLLN-350A Class T. The ones I got from Digi-Key were silver-plated.

TJ

 

[Neal]

Color me stupid, I just checked and my 2017 VTDP is a 350A as well. $50 out the car window again!

 

[Neal]

I personally would not have a problem using the 300A purchased if in a bind but I ordered 2 x correct ones mentioned above. Thanks TJ!!

 

[J&JD]

Mine is 350 also.

 

[Richpatty]

Placed my order too... They are going to think there is a run on them....

 

[TJ&LadyDi]

I personally would not have a problem using the 300A purchased if in a bind but I ordered 2 x correct ones mentioned above. Thanks TJ!!

Nor, would I...in a pinch. You just have to be careful with the loads on the inverter. I feel better having the correct size though.

With several people ordering them from Digit-Key, it will be interesting to see what shows up. I hope everyone is ordering the Riedon version at the lower cost. Even if you do get the Riedon JLLN 350A fuse, it will be fine; the specs are the same as the Littelfuse version.

TJ

 

[Just George]

Well perhaps it's my lucky day. Turns out my 2015 Ventana has the 300A version. Anyone with unwanted JLLN-300A care to make me a deal?

 

[Neal]

Anyone with unwanted JLLN-300A care to make me a deal?

@TJ&LadyDi should have first dibbs to offload his. If anyone wants mine let me know and I'll wheel and deal with you too, i.e. pay what I paid for it plus postage

 

[TJ&LadyDi]

I have a possible taker for mine. If he doesn't need it, I will make it available here.

TJ

 

[Neal]

Guess we can list it on the classifieds system too. I may do that with mine later.

 

[stang37]

Being a person who has had this fuse to blow. Understand nothing works in the coach. Even starting the generator does nothing for 120volt items as the inverter must have 12 volts to work. I had the coach for 1 month and was boom docking at a race when it blew. After 10 hours trying different suggestion from Newmar we finally figured out the fuse was blown thanks to the help from the inverter tech in California. She ask a simple question, what is the voltage at the inverter? "0" was the answer and she immediately said blown main fuse. Those fuses are hard to find any day of the week and really hard to find at 9 PM. My fuse blew due to loose bolts on the studs. Who didn't tighten the bolts who knows but it generated enough heat to start melting the mounting block before it blew. Had to install a temporary jumper for the night before finding a much smaller fuse to get power back. Newmar did find a mobile tech to come out and look. He had never seen a fuse that big. The best he could supply was a 175 amp fuse which we use for another 6 days. A new fuse and block was waiting at home when we returned. Just make sure your stud bolts are tight and it may never blow.

stang37
2016 Newmar Ventana
2020 Gladiator

 

[TJ&LadyDi]

Thanks for that insight, @stang37; good information to have. And, you are correct; those big fuses are not always readily available. Thus, the reason for carrying a spare or two. Thanks for possibly saving someone else from finding out the hard way.

TJ

 

[NWIP]

You all scarred me into purchasing a spare ? Thanks

 

[TJ&LadyDi]

You all scarred me into purchasing a spare ? Thanks

What are friends for, Bill?

TJ

 

[Webz]

Just ordered mine. I think, (hope) I have spares for most systems.

 

[Richpatty]

Mine is on it’s way too. I was thinking though...this fuse should rarely fail and I would be concerned if it did.

 

[TJ&LadyDi]

If we are all ordering from Digi-Key, the inventory control folks there must be wondering what the heck is going on. They probably haven't sold two a month until this past week.

I guess people have been stocking up on toilet paper for the coronavirus thing; why not 350A fuses?

TJ

 

[Neal]

There were 80+ when I ordered, now there are nearly half that left in inventory.