No DC Power after shutting down Generator

[acoleman43]

I talked with a tech at WFCO regarding this issue. He is 99% sure that the 20A inline fuse is to small. He recommends installing and testing a 50A in its place. The 8 awg wire is rated for 60A and goes from the battery to the Power Dist. Panel/55A converter. Can anybody with a 2022 Grand Design Momentum G classc or older check and confirm there DC fuse size and report back please ? Thanks

That depends on your distribution center. in my 21G we had a WFCO WF-8955PEC. Rated at 55 amps, and had (2) 40a fuses. See pic below. Looks like it's the same as your unit.

I had no fuse between my batteries and distribution panel, but I didn't have the fancy energy management system either.

If that fuse is between battery(s) and distribution panel, and is for the distribution panel, you shouldn't need it....in my opinion. The distribution panel has it's own protection (as you can see in the picture below) which would make that fuse redundant/unnecessary. But I don't know if that fuse is necessary for the energy management system. If it is, it doesn't make much sense as your distribution panel may require much more than 20a (up to 55a).

Problem is, if it's a standard blade fuse, they only make them up to 40a. Anything "larger" needs to be a different fuse type.

8awg wire sounds about right from battery to distribution panel. 8 awg is typically rated at 55a.

[Jlawles2]

I can see both sides of the coin. Instead of fusing it, you might opt for a self resetting circuit breaker like most campers use. https://www.amazon.com/Amp-Automatic.../dp/B006PJI1YW is a 50 amp, but they do make larger ones.

[acoleman43]

I can see both sides of the coin. Instead of fusing it, you might opt for a self resetting circuit breaker like most campers use. https://www.amazon.com/Amp-Automatic.../dp/B006PJI1YW is a 50 amp, but they do make larger ones.

Do you think the fuse is even necessary? My ignorance of the new energy management system is the only thing keeping me from saying just remove the fuse.

[Jlawles2]

Do you think the fuse is even necessary? My ignorance of the new energy management system is the only thing keeping me from saying just remove the fuse.

If they put one there, it probably has a reason. Either way, short protection on any power circuit is not a bad thing.

[bpep]

Thanks for all the helpful feedback. Sorry for not replying sooner but ive been out camping. I talked with GD Production side and he says the wiring diagram does not show that 20A inline fuse for DC. Also the 8 awg wire that supplies dc power has a 30A resettable circuit breaker close to the battery. And with amp clamp attached to dc wire 30 seconds after gen start up i get a reading of 32A and the 20A fuse is still intact. Crazy!

[bpep]

In-line 20A Fuse was removed and replaced with a butt connector. The dealer with advice from GD performed the work under warranty. This 20A online fuse was a mistake at the factory. Scott Moronde and Theresa Wallace so far so good.

[Jlawles2]

I guess someone grabbed the wrong wire for the fuse. Wonder if there is something else in there that is supposed to be on a 20 amp fuse?

So what's the wire nut with the blue tape for?

[Thorvald]

In-line 20A Fuse was removed and replaced with a butt connector. The dealer with advice from GD performed the work under warranty. This 20A online fuse was a mistake at the factory. Scott Moronde and Theresa Wallace so far so good.

Do you have any more information on this being a mistake? I swear on my 2022 25G I have that same fuse inside the storage compartment but never blown it. I’ll check this weekend and trace it out to where it goes.

If it’s a mistake I wish they would issue a bulletin on this (not a recall, just an advisory).

Cheers
Tim

[howson]

Thorvald -- please track down what this fuse is connected to (on both ends). If you have the time, here's a few other questions that may clarify the purpose for the fuse:

What stops working when the fuse is pulled?

What gauge is the wire the 20A fuse protecting?

Can you estimate the length of the wire the 20A fuse is protecting?

If you have a clamp meter, when does the wire (that has the fuse on it) have an amperage reading? (What's running?)

Howard

[Thorvald]

Will do, sure enough I have it:



I’ll do some tests tomorrow.

[Thorvald]

Did some work this weekend to try to trace it back. Appears to be the 8 AWG that comes from the battery disconnect in the Wet Bay. I’ll have to disconnect both ends and tone it out to be 100% sure which I’ll do next.

Mine has a 30 Amp fuse in it but still well under the dual 40 Amp that he Power Center has.

I checked the power Center and it does have two 8 AWG red wires to its positive input and I see two 8 AWG feeding out the back. I’ll trace those as well (though I am pretty sure one is from the 30 Amp fuse and Battery disconnect. As you can see from the photos, they’ve spliced and marret’d that cable, a ridiculous amount of times.

[bpep]

Do you have any more information on this being a mistake? I swear on my 2022 25G I have that same fuse inside the storage compartment but never blown it. I’ll check this weekend and trace it out to where it goes.

If it’s a mistake I wish they would issue a bulletin on this (not a recall, just an advisory).

Cheers
Tim

Thorvald, mine was a 20A fuse not a 30A like your setup. Mine blew twice in a short time. If your system seems to be working for you I would leave it as is IMO. You can still follow up with GD and WFCO just to be sure. I was told the 20A fuse slowed the battery charging time due to the resistance. Also I have the 12V DC Refrigerator which consistently draws 3-5A. After 3 days of dry camping (Fridge,TV,Lights,Inverter) and not enough Generator or Solar the Lifepo4 100ah batteries would go below 12V. Upon generator start up the amps would surge and blow the fuse. I did recently install the Victron BMV-712 Battery Monitor which shows battery charge percentage as well as draw etc. This helps a lot.

[TucsonJim]

I was told the 20A fuse slowed the battery charging time due to the resistance.

LOL. Do you remember who told you that? A 20 amp fuse will only have about 5mΩ. It will not slow charging time.

Jim

[Jlawles2]

20 Amp may have prevented charging due to infinite resistance in the air gap it created when it gave up.

I agree with Jim. As long as the fuse is not blown, it should not slow the charging.

[acoleman43]

Simplicity is always better. Why place an inline fuse hidden in a mess of wires that has no known purpose?

Does anybody know what this fuse is used for?