Berk Main Fuse blows

[twirvin]

I have a 2014 Berk 390H and the main 175A fuse on the house batteries is blowing. I think the problem occurs when the house batteries get low and I start the generator using the coach batteries. This is just a guess for I cannot find a repeating pattern. Does anyone have any ideas on where to start troubleshooting? I tried enabling the automatic generator start when house batteries go below 10.5 v but that had no effect.

I would take it to the dealer but the problem is so random that I do not think they would help ... plus my dealer is less then great. The service department does not even have an answering machine (not kidding).

Any help would be appreciated.

[Batts-toy]

first of all I see this is your first post so welcome to the forum from mid California.

I suggest you start with not allowing your battery to go so low taking it to 10.5 will ruin the battery and seriously shorten it's usable life time. You should not let it get get below 50% charge which is (believe it or not) about 12 volts, if the fuse blowing is related to the low battery when starting the gen this may solve your problem.

Try turning off all the systems the battery and gen feed before starting the gen (when you have a very low battery). I am thinking the sudden rush of current could be what is causing the fuse to blow.

[twirvin]

I do not normally let the batteries drain that low, usually it is caused by user error. I will bump up the automatic generator start to 12v, like you suggest.

Thanks!

[twirvin]

Ok, after some testing here is what I found. Draining the house batteries will not cause a reverse flow from the coach batteries. Nothing I did with the house batteries drained would blow the 175a fuse.

I did find a scenario that would blow the fuse (sometimes). The fuse blowing culprit is the starting amps required for the 110v refrigerator combined with the slide out hydraulic pump amps. When the refrigerator first starts up (after being off) it requires significant 110v amps to get the compressor going. Those 110v amps cause the inverter to draw >165 amps at 12v. Combine that with the amps used by the slides and the fuse will blow(sometimes). The spec for the 175a fuse says it should be able to handle a pretty large surge so I am not sure why it blows ... maybe heat? Here is the fuse characteristics:

http://www.littelfuse.com/~/media/au..._datasheet.pdf

The lesson? After turning on the inverter give the RV 30-40 seconds before using the slides.

[Batts-toy]

Thanks for the feed back. Glad you sorted it out, the inverter will pull extra amps on initial start up as well so bringing one item on line at a time makes sense. Are you using the 32 volt rated fuse shown in the datasheet link? The reason I ask is the amp draw characteristics is different for 12v vs 32v