The second edition of my book is out.  Your RV is Broken is here on Amazon.

Roughing it smoothly.  Smoothly roughing it.  Wearing down the rough edges.  Designing (I won’t call it engineering) every day RVs, right to the rough edge…..

I saw a post in Facebook from someone with a similar melted fuse.  I responded with a comment and pointer to this upgrade/repair in facebook and found several other people that found themselves in the same “boat”.  A couple had the “melted” 400 amp fuse and the melted inverter switch.  One had his panel actually catch fire.  Fortunately, he was outside and saw it in time to get a fire extinquisher on it till the fire dept showed up.  His Insurance company fire investigator pointed to the inverter switch.  I had wondered if this problem was “just me” or because I upgraded my inverter (though all the parts claimed to be rated to be able to handle the load).  Now I see others are having the same problem with unmodified systems.  Spyder (not Lippert as I initially thought) SHOULD have some explaining to do as they are the source for these DC power panels.  

After posting this, and someone people wondering about their own RVs with this panel, I thought I should provide some pointers on how people can check for trouble and/or have their checked for proper connections. One way to check your panel would be to first make sure you are putting some current through the inverter switch.  Either be charging your batteries from a partially discharged state via generator/camp plugin or by drawing a significant load from your inverter that is using batteries (no generator or camp plugin).  If you are pushing lots of current through your battery wiring or a distribution panel such as this, and there is a poor connection heat will be the result.  Get a temperature gun and first take a temperature down in the lower right corner to get a reference.  Then measure the transfer switch and the area beneath the switch (Inverter fuse in this panel right below the left side of switch).  If the temperature is more than a couple of degrees warmer, you might have a resistive connection.  If it is 20, 30, 40 degrees warmer you have a serious problem.  This test has general applications too beyond just this RV. Start with your battery connections and measure the temperature of each and every one.  Then follow cables as much as possible to switches and other high current components.  None of them should be significantly warmer than the ambient temperature.  If you find a hot spot and aren’t comfortable working with high current components then hire someone to check.  The torque specs are on the back of this panel.  If you remove this panel without disconnecting the battery be extra careful. The panel is mounted in a steel frame and the main bus is very close to that frame.  Its best to disconnect first.

If you are the techie type, this might be your excuse to get an infrared camera.  But seriously, every RV should have a temperature gun.  For this purpose, checking brakes, looking for air leaks, checking AC output, refrigerator and freezer temperatures, checking the asphalt temperature in Death Valley, hot springs in Yellowstone and on and on.

The story:  I just completed a major upgrade on my Tiffen Open Road 32SA.  I’ll call it an upgrade, not a repair, because in one way, having to go down this road is the result of other work I’ve done.

Let’s go back to the beginning.  We picked up our motorhome, November 2018.  Headed right for Red Bay for some repair work.

Then headed out west.  We ended up in Quartzite for what turned out to be a couple of months – including for the big tent sale.  We had been experiencing some low voltage warnings on our 2000W MagnaSine inverter.  We had to be careful what appliances we were running, or we’d end up resetting the MagnaSine.  We went to the big tent show and found a good sale price on four 100 amp-hour BattleBorn lithium batteries.  We swapped four of them in and they helped.  Certainly, let us run the generator for shorter periods of time.  I sold the lead acid batteries for about half price which made me and the buyer happy.

Eventually, we upgraded the 2k MagnaSine to a 3k Victron Multiplus along with 800 watts of solar.  Now we were cooking with electrons.  And we were, often using an air fryer, a cook pot or induction cook top.  We hate the propane stove that came with the RV.  Till one day when the inverter just quit.

I pulled out a meter and followed the zero volts path back to find the big red inverter power switch had failed – and traced that to a fuse that heated up the power bus so hot it melted the back of the inverter switch.  The fuse never blew, it just got hot.  There is a long post on this fiasco here.

I bypassed the errant fuse with a short cable and in-line fuse and the next time we were near Red Bay, we had them replace the entire distribution panel.  This panel has three of those one-inch square fuses and four pushbutton circuit breakers AND a solenoid to connect the chassis and house batteries when driving.  The four breakers are held in place with one screw with the other side poking out through the panel.  A heavy wire hangs off each one – with no strain relief.  The tech and Red Bay broke one of these breakers re-installing the panel.  This is a terrible design.  I believe those breakers are designed to be held in place on three if not four sides.

Deja Vu

So, back on the road and a few months later:  same thing.  The inverter switch burns up.

We were on a 30 amp campsite.  Normally, I tell the Victron inverter to not allow more than 15 amps through and it supplements any more draw than that from the battery.  But I forgot to his time.  We had three appliances running, plus the air conditioner and popped the campground 30 amp breaker.  The Victron says “I”ve got this, hold my beer!”.  The Victron will actually provide up to 5600 watts for a short period of time.  In this case it was somewhere around 30 seconds before the inverter switch gave up the ghost, again.  This time I had all the parts, so quickly bypassed the failed components, again.

Engineering Dreams

All of the Tiffin/Syder supplied parts are rated to carry that load – but obviously, they really aren’t.  At no time did I ever blow the 400 amp fuses, either of them. So, I started dreaming about a new distribution system, built out of discrete components.  I gathered parts and we looked for a window when we could actually make it happen.  I had to be really sure of my design and parts because getting in the middle of nowhere and quitting wasn’t an option because no DC power means no Spyder controls, no inverter, no air conditioning etc.

Today turned out to be the day.  I laid out the whole system on a pair of boards that I had planned to install on the bottom of the battery bay and the front wall.

I made all the cables custom for the layout.  But a last-minute discussion with my wife led to the decision to skip the wood.  So, everything was mounted right to the storage bin wall: sheet metal – probably safer.  A lot harder, but I could use the same layout and all the cables were ready to go.

By using discrete components, I can measure temperatures to monitor how things are working and replace any part or connection that fails relatively easily.  On my someday list are more lithium batteries and more solar and this is a design I can be confident will stand up to the punishment and I won’t have to wait in line for parts from Tiffin or Spyder.

To the left is the new distribution system with labels for all the components.  On the

right is a partial block diagram of the power distribution in the 32SA.  The green boxes are AC breakers in the bedroom.  As usual, clicking on any image will bring up a new window with a larger version.