Lithium Battery for your Aircraft
Has anyone installed one at annual, or when a new battery was needed in any model Cessna?
I am intersted. I see nearly all benefits with no drawbacks. Lighter weight, hotter spark translating to better start, longer term reliability, extremely low dissipation of the charge when not utilized.
If someone has done so I'd like to hear about it. Thank you.
Comments
Hi stratus11,
No personal installation experience, but a few points about the current crop of Lithium batteries for you to consider...
Most on the market today are for experimental aircraft. Those that are "approved" for normally certificated aircraft seem to have TSO approval for the battery itself, but not for the installation unless there is a specific STC for make and model or through a field approval and form 337 on file with the FAA. Some have found it difficult to navigate this process. Yes, for larger aircraft installations the situation is better, but at a very significant cost.
Price wise, after a quick search, you are looking in the neighborhood of $400 at the low end to over $4000 at the high end; ballpark. In terms of capacity, they raise in price as capacity goes up. The capacity of my Concorde is 35 amp hours. I had a hard time finding an approved battery to match this capacity which is important as this parameter sets the amount of time you have to navigate and get the aircraft on the ground safely in the event of an alternator failure.
Depending on where the battery is mounted, the significant weight difference will most certainly require the weight and balance data for the aircraft to be updated.
No doubt, over the coming years, this situation will improve but not sure I would want to be an early adopter. By the way, although the lithium battery will give you good cranking power, I cannot see how it is going to give you "hotter spark" for better starting. The magneto may be turning faster but the energy in the spark is dependent on other factors, not the least of which is the supply voltage which remains the same.
Regards,
Mike
Thanks Mike. I’ve replaced one Mag with the Surefly electronic ignition. That is providing better ignition spark, based on the specifications of the equipment. I’m sure you’re right on the Mag capabilities. Cranking power is extremely important as you know. I expect better crank power to translate into longer lasting starter equipment.
Like most things in aviation I believe this technology is beyond mature. The 787 had lithium batteries in the late 2000s. Sure it had its issues but that’s another story. I’m all in. I’m looking forward to it. Once I install, I’ll let people know how it goes. If it blows up airborne and I crash, I guess you will all know.
This technology should’ve been certified across the light civilian aircraft spectrum many years ago. I blame the FAA approval process for this very good technology delay.
This enhancement would also save fuel with the weight savings and reduce the number of batteries we burn through. Just my humble opinion.
The EarthX battery is approved for some Cessnas, those where the battery is mounted in the tail cone.
They do not approve mounting the battery in the engine compartment, on the firewall. It cannot tolerate the high temps.
Note that for a C172 the difference in weight is 18 lb, or about 3 gallons of gas.
Also the approved model in only 15 amp-hr vs 24 for a Concorde RG25xc.
So, I see no advantage in using a Li-ion battery...
I have an Earth-X, and I love it. Particularly for the smaller Cessna’s, it’s genius! It’ll spin the prop so fast, you can nearly take off on that alone. Lighter, safer, long lasting -
I did hear the Earth-X seminar in Oshkosh. It’s very impressive the amount of engineering in that little battery.
If it’s available for your plane, it’s a worth serious consideration.
I have just installed an Earth-X Li-ion in an Express 2000 which is an experimental and the owner loves it. We installed it using the certified models instructions and found there is quite a bit of work to do. We had to re-design the battery hold down system as the battery is much smaller and lighter than the original Concord RG25XC. We also had to plumb a complete vent system and because the battery has a monitoring circuit we mounted an amber lamp and a test button for the lamp in the cockpit. The BMS is a great system depending on how the advisory lamp blinks ie solid, fast flashing or slow flashing tells you what the fault is with the battery. Each battery has a PCB and pigtail to connect to the advisory lamp. One last thing, you need to buy a special battery charger if you need to charge the battery as your regular charger wont do it. All in all not a cheap exercise.
robert,
So you paid the $925 for the ETX900 STC kit vs a $400 RG-25xc ?
Or did you just buy the battery and filled the extra space ?
No just re-designed the hold down section inside the original battery box and filled in the extra space with high density foam. BTW when the customer is sold on a new technology battery, he gets a new technology battery. Sometimes economics doesn't come into it.
For what it’s worth, I spoke to an engineer at EarthX about my T210M. He told me that the 210 is on the short list for approval and I could expect to hear something in 1Q25. The notion that their battery can’t handle the heat of being located forward of the firewall is false. The approval will include mounting the battery in the stock location. As such, I’m having my new panel designed with the EarthX BMS light integrated into the panel to future proof the system.
PCH,
Have you read the install and maint. doc ?
the battery is not approved for installations forward of the firewall.
https://earthxbatteries.com/list-of-stcs/
Just relaying what the engineer told me. Here is a portion of the email between myself and my installer from October 7th of this year. Take it for what it’s worth:
“Good news!
EarthX should have the STC done by 1Q25 and the verbiage that requires the battery to be mounted aft of the firewall removed from the STC soon thereafter. He said I was the 4th call this morning regarding this issue and was very curious as to where this info was coming from. He also mentioned that in the experimental world, 80% of their batteries are mounted firewall forward so there is no issue with the battery. It’s all (as per usual) just paperwork. So all that to say, let’s move forward with the battery light. “
I've been working with Reg, EarthX chief engineer, to provide them with 210 specific instalation information (box location and deminsions and such). The 210 is slightly different in that the battery box is totally enclosed with only 75% of it forward of the firewall. One difficulty is the vent port on the EarthX makes the battery too tall for the box. However, it can be installed on it's side which adds some space. They, EarthX, are also considering a battery version with a 90 dgree vent which will help as well.
note the battery environmental specs, 60 degC [ 140 degf ]. Most firewall air temps far exceed this. So, an enclosed battery box with a blast hose would be needed to cool the battery.
C. Using qualified personnel, i.e. such as an A&P, DER or informed AET, evaluate the airplane Model for EBS requirements.
ENVIRONMENT: Operating Temperature -30C to +60C (+65C, short term).
I found the environmental specs for a lead-acid battery, and the max. temp is 55 degC, or 131 degF. The comment on this is that the higher temps accelerate the chemical reaction, which reduces the life of the battery.
I've measured the temps in the firewall area on my Cessna, and they run about 185 degF .
So any battery mounted on the firewall should be in an enclosed box and air ducted to it for cooling.
My C175B has the battery in the tail cone...
It looks like either way the temp inside the engine compartment is too hot for a battery. Obviously that isn’t the case given where a lot of batteries are located. I don’t have access to my T210 or a pic but I would assume given the battery is enclosed in a battery box, and maybe some air that is directed towards the box, it’s not an issue. Furthermore, given the small size of a LiPO battery, it is installed with a (foam?) spacer in the same box. This would act as to further insulate the battery from excessive heat.
Patiently waiting for 1Q24. I should get my plane back from the avionics shop in the next month or so. On to the next controversial topic: what should I do to prep the engine for star? It will be almost 9 months since it’s ran.
Paul.