Mounting Battery on Cool Side of FW and Where

RV4 and RV6 per plans was behind the fire wall, on the floor, center line between longitudinal "intercostals".

I am thinking of going AFT of the RV7 firewall to keep battery cool (especially Li-Ion). Access can be made to swing it down under panel. Another thought on the RV7 is many put access covers on the top between firewall and windshield. You could mount it below one of those?

The down side is if the battery decided to explode or melt down the fumes would be in cockpit.

Thoughts?

I'm going to be installing the EarthX ETX900-VNT and venting it overboard. If it explodes then I am out of luck

No way I would mount a LI-ION battery in the cockpit unless it was encased in a sealed metal box that was vented to the outside. I put two LI batteries on the hot side of my RV-9A firewall with blast tubes for cooling.

I'm putting the small EarthX battery in the right-hand cowl cheek, aft of the firewall. There's room but it's not exactly spacious. I needed to make an access door for it too.

Dave
RV-3B, working on the cowl

I put the EarthX ETX900-VNT (sealed metal box, vented outside, as referenced by 9GT) on the back side of my aft baggage compartment wall. It is vented through the bottom belly skin.

I have an EarthX 680c is mounted on the firewall with a blast tube. The former forward battery compartment is now a handy forward baggage area.

To clarify, the EarthX batteries use LiFePO4 chemistry not LiIon. There are multiple historical threads on the forum that refer to how (well) they handle thermal runaway and do not have the same risk of fire as LiIon. The threads also talk about the importance of venting if it is going to be mounted in the passenger or baggage compartment as well as having a monitoring circuit to detect any fault conditions.

From my experience of having bought an RV-10 with two EarthX ETX900 batteries mounted on the front of the firewall, some cooling via airflow helps manage temperatures in hot conditions.

As have been pointed out the batteries we use in aircraft is LiFePO4.
It will not explode or burn with open flames if overcharged but it will produce a lot of smoke. Plastic containment will partially melt.
I know this because my friend put an aircraft battery in the diesel generator we have in our hangar. There was something wrong with the voltage regulator and
the battery where toasted. I would not recommend placing a battery in the
passenger compartment.

Good luck

vas4vans said:

To clarify, the EarthX batteries use LiFePO4 chemistry not LiIon.

Click to expand...

Yes, they are lithium ion batteries. LiFePO4 batteries are a specific type of lithium iron chemistry battery, and what you are likely referring to with “LiIon” is lithium ion polymer chemistry batteries. Other types falling in the lithium ion category include lithium manganese oxide, and lithium cobalt oxide (used in the Boeing 787 Flameliner). There are more, each with various trade offs, but you get the idea.

I tested a non earthx LiFePO4 battery to destruction seven or eight years ago before installing one in my plane. It was hard to get to fail, actually - it took something like 15 minutes at 30v before the battery began to swell. No fire, but LOTS of smoke for several minutes. The mitigation strategy for that in the FMEA was to mount the battery external to the cockpit, which I did. No problems with that location after about 1300 hours.