Earthx under seat mounting?

[John Bickham]

I am starting the wiring and panel phase finally! Only five years behind schedule.

I'm considering the Earthx and mounting it under the right seat (da wife`s). Chose this location for several reasons: O-540 forward CG, avoid heat limits of engine compartment, and ease of access. I've read the installation manual and found Jared's Kitplane article. I'm not finding any details on "in cabin" mounting. There is as vented option. Just not sure if that is really necessary?

As with any new technology, there were growing pains and bad press. I'm having trouble seeing through the fog of internet opinion.

Some of ya'll have done this and curious on mounting specifics.

[jaredyates]

John, if I were in your shoes today I would install the battery under the seat and use the vented box, even with the 360. Using the lithium battery makes the cg issue insignificant. Getting the battery away from the engine compartment will make it last longer, avoiding the high temp exposure. If you are out in the field and need a jump start, the under seat position makes this possible/much safer also. In my case the benefits of moving the battery do not offset the costs of changing the wiring, but for a new install that's what I would do.

[BravoGolf]

I have an EarthX in my RV on the firewall and had to install a blast tube to keep it cool. The temperature around the battery runs about 115 in cruise. Having it away from the engine compartment is a good idea.

[Bdflies]

Hi John!

I have an Earth X under the pilot seat (mine!). Every time I push the start button I am amazed at how that itty bitty thing spins the motor! Sorry I can’t speak to the technical or safety issues.

Hey John; It’s CRAWFISH SEASON!

Bill

[John Bickham]

Good shrimp, crawfish and sausage are missed since we moved. Just curious, is your battery installation sealed and vented?

Thanks

[Bdflies]

Mine is the Experimental version that’s not self vented and it’s not in a sealed / vented case. Just sitting under my seat, for all the world to see. I’m not suggesting that my installation is a model to copy. Just how I did it.

I bet y’all are enjoying the great Southwestern food!!

[svyolo]

Mine is going on the firewall, I just haven't decided which side yet. If it is on the engine side it will be in a nearly sealed box, with a very small blast tube. The blast tube isn't to cool the battery, just to apply a slight overpressure to keep hot air out of the battery box.

I want to CG to be as forward as possible, and keep the heavy wires as short and light as possible. Battery - 2 inches to master relay - 2 inches to starter relay - straight forward a couple of feet to the starter. I might even get away with making the wire a gauge smaller in size.

[jaredyates]

If the EarthX does manage to fail in a thermal runaway, it can produce a lot of smoke as the liquid inside is heated. This failure mode is very rare and unlikely if you install it per their instructions, but having the vented box is the final link the chain to ensure that the smoke is passed out of the cabin.

[alaskabearhawk]

I know Matt Schumacher planned on using the lightweight battery cables in his project. It’s copper-clad fine strand aluminum. Anyone else tried this?

https://quartermax.com/ultra-lightweight-2-gauge-battery-cable/

https://www.amazon.com/XS-Power-RK2GA-1-Light-Weight-Battery/dp/B00QKTVYL4

Not the only manufacturer, but seems to be popular with those into racing and wanting to count the ounces.

[BravoGolf]

My problem of heat was not battery heat but the heat of the engine compartment. The EarthX has a warning light built into the BMS that flashes based on charging conditions but also on heat conditions. I was getting that light activated during climb conditions so I put the carb heat sensor (Dynon system) on the firewall to monitor heat in the surrounding area. After I put a blast tube in that area the temp runs in the 115 during cruise and 131 in climb conditions. The EarthX warning light is worth the time to install it

[Battson]

I put my EarthX under the dashboard, away from the firewall so it doesn't get the conducted heat. Keeping it cool was the major consideration.
Two reasons why I put it under the dash.
1. I didn't want it under the passenger seat in case of fire, a remote chance but not impossible.
2. Keep weight forward on the IO-540, to get the best CG range, although the weight is minor, but it all helps.

Lightweight battery cables sounds like a risky idea, for starting and battery life. You need a certain conductivity of the metal and cross-sectional area to get enough power to the starter motor without really straining the battery. Unless there has been a technology breakthrough, I am not aware of any free lunch when it comes to increasing power conduction at room temperature. The lightest option is probably solid copper at a SWAG, unless you want to spend big money on exotic metals. Copper and aluminium conductors have well understood properties, and cross sectional area is king.

I experimented with lightweight battery cables (not the variety linked above), and ended up re-wiring the starting loom with the normal heavy gauge stuff. The rest of the wire I left as is, because the current flow is much less so the wire need not be so large.

[Bcone1381]

If the EarthX does manage to fail in a thermal runaway, it can produce a lot of smoke as the liquid inside is heated. This failure mode is very rare and unlikely if you install it per their instructions, but having the vented box is the final link the chain to ensure that the smoke is passed out of the cabin.

I agree with Jared. EarthX instructions demand that an electrical system has an over voltage protection device installed. This is commonly done with a "crow bar over voltage protection circuit" according to the Aeroelectic connection book. Voltage regulators fail...sometimes with too high of voltage output....like +30 Volts.

If an electrical system does not have an O.V. protection device, and the alternator's voltage regulator fails to control the voltage output, your 12V alternator could put out +30V. Its especially risky for the EarthX battery installation.

So, make sure your system has a Crow Bar over voltage protection circuit. If one installs an internally regulated alternator be suspicious and do some research. If your shopping, I like B & C specialty products for alternators and regulators.

[svyolo]

EarthX has built in BMS (Battery Management System) that would shut off the battery in case of over voltage. Actually every lithium installation, even the cheapest 30 dollar mobile phone, has one built in. Protects against overcharging/voltage, over discharge (just as bad), and temperature.

That is the good news. The bad news is that your battery just got disconnected if one of those parameters are met.

I helped a buddy of mine burn his Jeep CJ to the ground about 30 years ago. It wouldn't start, so he kept cranking while I was troubleshooting. I noticed an orange glow reflecting off the concrete below. It was the wire going from the Starter relay to the starter.

I doubt a mini battery we put in a plane would crank the engine long enough to do the same, but I would hate to be the first one to do it.

[jaredyates]

I'm not sure that all, or even most of the lithium cranking batteries have a bms, be sure to investigate if you are counting on it. The earthx bms uses mosfets to disconnect the battery in overvoltage events. The mosfets can fail if the voltage climbs high enough, which is why they require a crowbar overvoltage also. These systems, like many that we use, can be more complicated than meets the eye. Definitely a case where we need to follow the directions.

[whee]

I’ve had the displeasure of experiencing a thermal runaway of a lithium-ion battery. I was working on the plane using my 18v lithium-ion battery powered drill when the drill suddenly quite. I thought it odd since it was a fairly fresh battery and when I when to eject it the battery was hot. I quickly removed the battery and set it in the garage floor. I stepped back and watched as it let the magic smoke out. It would have been even less fun in a small cockpit, perhaps even incapacitating.

So, if you install one inside the cabin I suggest you put it in a sealed box vented to the outside.

For battery cables Aero electric suggest the possible use of welding cable. That’s what we used. The size calculation indicated we needed fairly small wire, 4 or 6 AWG I can’t remember which.

[PaulSA]

I have an ETX1200 fitted to my RV10. It gives amazing cranking amps - enough (so the story goes) to move the aircraft on level concrete. So, I wouldn't use lightweight cables!

Concerning the thermal runaway, it's pretty much been said. It is a REQUIREMENT that you both connect up the warning light and have an over-voltage protection on your alternator. You then have several levels of protection in the event of over-voltage. Firstly, the ALT should drop off-line. Secondly, the battery electronics shut off the charge. Thirdly, the warning light comes on and you manually shut off the ALT field.

[jaredyates]

I’ve had the displeasure of experiencing a thermal runaway of a lithium-ion battery.

This is one of the reasons why we don't use that type of cell (most likely a lithium cobalt) in this application. The lithium iron phosphate that we see inthe earthx has a much higher threshold for runaway (500 degrees vs 300) and a much more benign failure mode .

We still have plenty of lithium cobalt batteries in most cockpits though, including cell phones, ipads, maybe flashlights, etc.

[whee]

This is one of the reasons why we don't use that type of cell (most likely a lithium cobalt) in this application. The lithium iron phosphate that we see inthe earthx has a much higher threshold for runaway (500 degrees vs 300) and a much more benign failure mode .

We still have plenty of lithium cobalt batteries in most cockpits though, including cell phones, ipads, maybe flashlights, etc.

After I had this experience I tried to look up the battery chemistry but was unsuccessful. I did find several sources that stated lithium manganese oxide is the primary chemistry used in power tool batteries.

Regardless, thermal runaway is possible for all lithium batteries so I think it would be wise to vent the battery box to the exterior.