Fire in Savanna

llamadave · 08-28-2023, 11:23 AM

On August 4, 2023, on our last day of a trip back from our daughter’s wedding in Oregon, we pulled over to put out a fire in the back under the bed or our Sprinter Sportsmobile Savanna. After removing the folding chairs and table from the back under the bed, I saw flames and used the fire extinguisher provided by SMB to quickly put it out. We had smelled a little smoke overnight in the campground, but figured it was a neighbor’s campfire. Then a few minutes of driving increased airflow and smoke set off the alarm above the sliding door.

Some of you may recall that Savanna’s layout, the same as our previous SMB Vanessa, has the back half of the bed covering a completely enclosed space with the Magnum MS2812 inverter/charger and associated wiring under there. I blame myself, after delivery in 2020, for reducing the few inches of clearance around the inverter/charger left by SMB when I pressed some of the wiring and the batteries up close tight against it. That was clearly a mistake.

After returning home and removing the two 300 AH Relion lithium batteries, I found that mainly some wood supports and plastic things had burned. The only wire that was damaged was a battery temperature sensor wire with its insulation partly burned. All other electrical things were operational and no fuses blew or breakers tripped. The cables had some melted plastic on them but all the insulation was intact. I see no evidence that a spark could have started the fire. Wood and plastic require a temperature over 400 F to ignite. How did it get that hot and why had this not happened in the past two years?

Previously in Oregon, 6 days earlier, we plugged into a campground and charged the batteries up from 50% SOC. Since then, we drove every day so our second alternator fully charged the batteries while driving and the inverter/charger had little to do. The night before the fire we were plugged in and ran the air conditioner for a while, again not involving the inverter/charger. The weather was hot, but not compared to 400 F. We had the back doors open for some time each night which would have somewhat cooled the enclosed space in the back.

I showed the damage to the local fire department asking about what caused it. Their only thought was that the temperature sensor wire that burned might have been shorted somewhere. But that wire, while grounded, would have had to come in contact with a wire with power and the wires near it had intact insulation.

So the mystery cause of the fire remains, but I think I have put things back together in a safe configuration. I repaired the damaged bed cushions and replaced the batteries leaving 4 inches of clearance around the inverter/charger. I placed a fire extinguisher accessible from the back doors. I purchased a couple of Google Nest smoke/CO detectors and placed one of them below the bed; it uses Wi-Fi through our always-on Savanna hotspot to report an alarm to my iPhone. I put a wireless thermometer under there and installed a 4 inch PVC ventilation tube above the inverter/charger exiting next to the mattress. Then I ran a test, charging the batteries from 25%. The temperature near the exit vent of the inverter/charger maxed out at 128 F and the battery monitor reported the temperature of the transformer inside the inverter/charger max 201 F and the FETs maxed at 174 F. I think these temperatures are nothing to be concerned about.

I hope our experience will help you be safer in your SMB.

David

larrie · 08-28-2023, 11:30 AM

Wow. That must have been scary. Am glad that you got the fire out before it did more damage and that you are both safe.

marret · 08-28-2023, 12:23 PM

Yeah, scary. Glad you caught it before any more damage and were able to repair without too much trouble. Great info for others. Thanks for posting.

1der · 08-28-2023, 12:42 PM

Glad your rig came through with minimal damage and. most importantly, you two were safe. Certainly a testament to working smoke detectors.

I think the mods made are a step in the right direction, but it still leaves unknowns and the mods may only mask/delay a repeat of the failure,.

While the Inverter/Charger features were not in use, the Transfer/Pass Through features of the Magnum were definitely in use. If the voltage coming in from shore power were to drop then resistance would increase creating heat and the
A/Con was running meaning there was a load. Why nothing in two years? I have had connections oxidize or anneal over time, both of which create resistance and high heat/ potential arcing.

I would consider replicating the scenario and having a heat sensing infrared gun in hand to check temps at every single wire connection and also possibly along wires. Any heavy duty cable that has a significant bend can create heat at the bend. Any crimped connector can have a bad contact surface inside.

Just my thoughts.

Twoxentrix · 08-28-2023, 12:53 PM

Seems you were very fortunate to catch the issue quickly. I have a considerable amount of electronics all stored under my gaucho bench, along with two amps. I’ve read enough ‘close’ encounters such as what you just experienced to leave me concerned. So couple years back I installed a Blaze Cut Fire Suppression tube over the electronics as a precaution. Is it the answer for absolute protection - no…but it’s proactive and makes me feel a little more confident something’s in place when I’m not around.

boywonder · 08-28-2023, 02:46 PM

My fire extinguisher has been laying around in the garage.....it's going back in the van ASAP.

**BroncoHauler** · 08-28-2023, 03:25 PM

Quote:

Originally Posted by boywonder

My fire extinguisher has been laying around in the garage.....it's going back in the van ASAP.

Check the manufature date and the state of charge before putting it back inthe van. An old or depleted extinguisher may not do you any good.

llamadave · 08-28-2023, 05:31 PM

Quote:

Originally Posted by 1der

I would consider replicating the scenario and having a heat sensing infrared gun in hand to check temps at every single wire connection and also possibly along wires. Any heavy duty cable that has a significant bend can create heat at the bend. Any crimped connector can have a bad contact surface inside.

1der: Good idea. I will do that!

Twoxentrix: First I heard about the Blaze Cut Fire Suppression tube. Looks perfect for my situation.

larrie and marret: Yes very scary. I lost only 2 camp chairs and a card table, and about a week of my time cleaning up and reorganizing the space.

86Scotty · 08-28-2023, 05:55 PM

Sorry to hear it Dave! Your vans are works of art. Glad you didn't have a total loss.

Twoxentrix · 08-28-2023, 06:06 PM

Quote:

Originally Posted by llamadave

Twoxentrix: First I heard about the Blaze Cut Fire Suppression tube. Looks perfect for my situation.

Let me add: the tubes are difficult to bend in tight spaces...not nearly as flexible as I anticipated - I purchased the T200 and routed it so it sits overhead the major components. If I were to do it again, I think it would be considerably easier to use two of the T100's.