Litium battery question

[Jerrytex]

I am leaning towards going with a Shorai LFX18A1-BS12 battery. Super light and and plenty of CCA and can handle the 18 AMP rotax alternator, from what I found during my research.

My question is, all of you that are running the lithium batteries, are you keeping them on a charger when not flying?

Is the charger even necessary? It's $90! and looks flimsy.

My odyssey 625, I kept on a trickle/maintenance charger. But from what I read, the lithium batteries, don't bleed down unless something is left on.

Also, can you jump start a lithium battery? Like get to the airport, hook up jumper cables and crank......?

Might end up staying with ole faithful, oddesey 625, but gaining 10-12 pounds of useful load is appealing and it seems that the meltdowns of the lithiums are few and far between nowadays.

[desertdave]

I'm running an Earth-X (Forum Sponsor) for the last year or so. I do not keep it on a charger and the plane easily starts up every time.

[Shadowrider]

Earth x also. They have their own internal board that controls the charging, discharging, balancing, voltage. If volts get too low it will shutoff output to save the battery. I know earthx wants you to buy their fancy charger, but just send it 14v and it will charge and balance the cells. So, I just use my power supply and set it for 14v and couple amps. Another feature I like about the earth x if it detects a problem it will turn on a light, which can be tied into the Garmin g3x that gives me an earthx fault CAS if there is a problem. Mine has sat for a month and the battery was still showing 13.2 volt. (Earthx resting volts)

[DesertFox4]

EarthX with the fancy charger. Never needed to leave on the charger and by the rules at my airport, couldn’t leave it on any charger unattended. The Battery Management System works as advertised. The warning light will blink in the appropriate “ pattern” for any fault it might detect. Pushing two years now and still the cheapest weight reduction I employed on my build. Also the quickest starts I’ve experienced on a Rotax engine.

[jiott]

4+ years with EarthX battery. Never have left the charger on. If I rarely need to charge it (like if I do a bunch of avionics testing with the engine off) I just use an Aerovoltz lithium charger that I already had.

[buckchop]

How about in cold weather, say -10, -20, anyone been there yet with a cold start on the battery after u warm up motor if u have a 0235 lycoming in a KF5, The new battery i just put in her is 400cca, myB&C starter/alt paperwork says 300cca minimum, and im not impressed with off brand battery i bought at $125, should have got a better one. But could b the long run of cable from tail to motor, i want to remove it from the tail and move it closer to motor.

[Denalifox]

+1 for EarthX. Had one in my Cessna 120 and it sat for 5 months in the Alaskan winter. Fired right up in the spring. Also run one in my STi.

[PapuaPilot]

I'm also using an EarthX and don't charge it.

I would avoid other brands if you think you are trying to save money. The EarthX has dual BMS built into the battery. There are a lot of lithium batteries out there you could buy for less, but they probably don't have a built in BMS. That is what is going to save the battery from a thermal runaway, over discharge and over charge, etc. If you ever over discharge a lithium battery there is no way to recharge it, you just throw it away.

[Jerrytex]

Which model earthx battery? Rotax 912uls.

[DesertFox4]

ETX680


$379.00

or



ETX680C

$379.00


I installed the ETX680
with Kitfox Aircraft’s nice battery box for the
EarthX ETX680. I think the ETXC will fit in their battery box too.
29098

[Eric Page]

Note that the ETX680 and ETX900 share the same case size: "E". Either will fit in the same battery tray. If you have an electrically dependent engine and a single battery, you might consider using the 15.6Ah ETX900 instead of the 12.4Ah ETX680. Doing so will achieve longer alternator-out endurance, or the same endurance with less load shedding required. Weight difference is 0.8 lb.

Even without an electrically dependent engine, there are advantages to using the ETX900. It can supply higher starting current and tolerate higher recharge current. Those things, combined with its higher initial capacity mean it will likely last longer in the same environment than an ETX680.

Whether the longer lifespan will favorably amortize the $70 higher price is an open question...


Edited to add:

If you have a 912iS (and presumably a 915iS), neither of these batteries meet the minimum battery ampere-hour capacity listed in the Rotax installation manual, but the ETX900 is nearly big enough.


ATTENTION
The use of rechargeable batteries with lithium–ion technology should only be
used in combination with a suitable battery management system. If such an battery
is used, the responsibility is up to the aircraft manufacturer. The approval of
the relevant aeronautical authority may be necessary. For installation of lithium ion
batteries refer e.g. to FAA AC No: 20-184

ATTENTION
Observe the specifications of the battery.
The size of the battery needs to be adequate for essential flight equipment and has to
meet the airworthiness requirements of its place of operation.
When sizing the battery ensure that during each operating state and also during the transition
between two operation states a sufficient supply of the display is guaranteed (e. g.
during engine start). Furthermore, it must be ensured that at least 30 minutes after failure
of the primary power supply the display is supplied with sufficient energy, if it is necessary
for a safe operation of the aircraft.

Nominal voltage: 12 V
Internal resistance: maximal 10mΩ at -18 °C (-0.4 °F)
Cold Cranking Ampere (cca): At least 350 A at -18 °C (-0.4 °F) (SAE J537)
Capacity: At least 16 Ah

[DesertFox4]

Good info Eric. Battery choice IS dependent on engine installation and electrical load factors.

***My reply in post 10 is in response to Jerrytex’s question about what works for a Rotax 912uls installation specifically.
The EarthX ETX-680 or ETX-680C should also work well with a 912ul or 914.


For critical instrument battery backup, most go with TCW’s IBBS (Integrated Battery Backup System). Chose which battery backup system again depending on critical components needed for flight. https://www.tcwtech.com/product/integrated-battery-back-up-system-ibbs/?v=7516fd43adaa

[efwd]

EarthX is just so good to do business with to start. To address Jump starting, EarthX sells the Jump Pack which is multipurpose. I have one. It has the ability to charge cell phones etc etc, it is a flashlight as well. I keep it in the airplane since I won't just be able to pull up in my car when Im 100miles from home. As for the Charger, EarthX has some pretty nice units that act as a power supply for long power on needs. They didn't have the option for that when I needed it so I had to poney up for the power supply unit as well.

[dginok]

I'm using an Antigravity ATX20-RS, and loving it, especially combined with a John Deere-type regulator after the Ducati died. The plane starts better than ever, and I never keep it on a charger.

[Backpacker]

Earth x also. They have their own internal board that controls the charging, discharging, balancing, voltage.

At what voltage would it shut off the output to save the battery?...and would that voltage be the same for all the Earth X models?

[Shadowrider]

The BMS disconnects the battery from the load if it is drained to less than 5% remaining charge (an over-discharge condition). An over-discharged battery typically has a voltage less than 11.5V. If the BMS disconnects the battery, the voltage reading of the battery will be zero volts. Excessive cranking protection logic includes temperature monitoring to limit “high current use” (engine cranking) to 10 -30 seconds in any 60 second period. If the battery terminals are “shorted” (or a low impedance load is connected across terminals), which causes the battery volts to instantaneously drop to a very low level, the battery will disconnect from the load to protect the cells and BMS from damage (short circuit protection). If the BMS disconnects due to excessive cranking protection or short circuit protection, the BMS will automatically reconnect after a cooldown period (typically 1-3 minutes). The ETX series is designed for short circuit protection > 1000 Amps.
ETX Hundred Series

[littlecricket]

Earth-X sun n fun discount is 10% off and free shipping if anyone is interested.

[fastfred]

I have run both types and mostly the Lithium for the past few years. areovoltz is the one kitfox put in mine I think. It works fine if you don't run it down too far . They do have their own charger that is complicated to use. I also use a lithium maintainer / charger than works fine also. the answer to your question is no you do not need to keep a charger on it when there is no load.

On my Remos I recently traded the odyssey for An Antigravity lithium battery with more power and saved 12 lbs. They are much less than the earthx and it fit in my existing box. Google them.

[Backpacker]

I’m still building but purchased a Earth X and it has sat in the shipping box for a year aprox and the other day I checked it and was 13.1 V. Then I charged it with a Lithium Optimate charger which took aprox 45 min and then was at 13.6 V right after charging.

[Slyfox]

I just went through changing to the earthX. I put in the 680C. I have the 912uls engine. I also put in the B and C regulator, very nice unit. I made sure it was charging like 14.3 volts. I also got the led light for the panel, something that earthX sells to tell you if you have a problem. I don't put it on a charger and it cranks very fast no matter what the temp outside is. plane starts right up. I like it.

[FlyinFish N928M]

Hello guys, You are touching on a situation that is worth exploring. I have been test running my 912ULS, B&C AVC1 regulator with an Earth X 680, and my G3X is indicting after start up 13.4 volts with a high amperage. Examples are 3400 rpms at 13.5 Volts at 15amps, or 4000 rpms at 13.8 V at 18 amps. Called and talked to Earth X, they said this was normal with an avionics load at 6-7 amps, and roughly 11 amps leftover to charge the lithium battery. Only once did my system normalize to 14.4 volts at 6 and 7 amps. This did occur at the end of one of my run sessions, however I have yet to repeat this condition. Being that I'm on the ground testing while using my header tank as a main fuel tank, I run out of gas after about 20 mins. Thinking if I run longer than 20 mins my battery will normalize. As mentioned from Earth X, lithium batteries have a very low charge resistance, therefore they command as much amperage as they can get until the battery is back to full charge. Once charged the amps should come down, and voltage should go up. Again, Earth X tells me what I am experiencing is normal.

The million dollar question is, does anyone know the max continuous time for AC generator at full capacity? My fear is that this situation may over heat, or overtax my copper windings around the magnets and cause a total failure. On take off, I will be running at max power, then to 5500 rpms for an extended time. Should I be concerned? I do not know enough about the rotax electrical system or Earth X batteries to know any better.

Any other thoughts from other Rotax 912 pilots using the AVC1 and Earth X Battery?

Thank you for your comments!

Mike

[jiott]

I'm going to give a reply that is admittedly not very expert, but I believe the Rotax generator is good for about 21 amps with no problems. The problem is much more likely to be the Ducati voltage regulator. I have heard that much over about 13 amps for a prolonged (whatever that means) period of time can overheat and damage or reduce the life of the regulator. If I were you, I would figure out a way to limit the charging amps to less than the 18 you mentioned. My 912uls system with the EarthX 680C never draws more than 10-11 amps charging and my regulator lasts a long time. Just my 2 cents.

[Shadowrider]

Mike I have never read or seen a max alternator output time limit. 18 amps output on a good day and full power is what the stock will put out. It takes about 30 min into the flight before I will normalize my battery volts at 14.1. Edge Performance has a graph I remember seeing for the stock versus the aftermarket one they sell. I will see if I can find it. But based on your description I would have to agree that everything seems normal. You wont see 18 amps until your fully power. Just FYI I know a couple that will never see normalized voltage unless they turn off all the lights. (So they are running the alternator at max entire flight)

30252

[Delta Whisky]

Mike - here's a link to my go to page on the Rotax alternator. HTH. http://contrails.free.fr/elec_alt_rotax_en.php

[Eric Page]

Alternators are limited by the physics inherent in their magnetics. They are incapable of putting out more current than their design limit. If more is demanded of them, their output voltage will drop, limiting current. Unless Rotax under-specified the copper wire diameter in their alternator design, it's not a worry.

[FlyinFish N928M]

Appreciate the feed back from everyone!

All of your information here has been excellent!!

The research in the Contrails article is good, most of it is above me, however the caption that talks about the tortures of the stator windings on the bench, "running at full power for weeks and the insulation still in perfect condition" gives me a lot confidence that I am in the clear that the AC power will not fail and melt down under hard operations.

The learning curve is steep until you start communicating with other folks that have been there already. I have alot of confidence B&C has done their homework before releasing the AVC1. The lithium batteries adds a new twist to the electrical plan and it is just a matter of time before you understand what normal operations should look like. I want the first flight and beyond to be perfect, and knowing what to be look out for is essential.

I will be doing more electrical testing this weekend with an inductance amp meter and comparing indicted volts/amps on the G3X and GEA24 engine module, to actual measurements behind the panel to ensure everything is reading correctly. Will attempt to add an extra reserve to my fuel so that I may get into that 30min recharge window and hopefully see my electrical system normalize.

If anyone else has added input/research on this subject please share for the common wealth of knowledge!

Thank you all!

Mike

Contrails caption below:

Reassuring values

We can rest assured, knowing that each time, the assumptions taken are very conservative.
The heat will be better rejected by conduction through the housing of the ROTAX than by the running of our test bench, ambient air temperature might very well be below 80°C, and the insulation of the winding is not necessarily poor quality.
NB : we observe that despite the "tortures" undergone at full power for weeks, the winding insulation still in perfect condition (Cf. fontispice).

[Jerrytex]

So a quick question to the others running the earthX or other lithium batteries.....How long can you leave on the master switch, and avionics before the battery is depleted or the BMS turns it off?

For example, if you turn on your master and avionics switches which turns on......Solenoid, 10" EFIS, 4" EFIS, Garmin 327, Garmin GTR 200 Radio, ADSB Echo, and IFLY GPS, all very low amperage items, how long before the BMS shuts off the Battery? I know there is a formula to figure out amp draw, but I am curious what others have experienced as far as minutes before the batt quits.

[PapuaPilot]

I would never do this intentionally and haven't done it accidentally. I would use the formula to see what it theoretically could do.

I estimate I can go approximately 2 hours on the EarthX 680 battery after loosing my charging system running one G3X 10" screen, com radio, transponder and a few other circuits. Lights and trim are part of my essential bus, but are intermittent loads aren't included, but are available. I bypassed my master solenoid, so the coil is not part of the load. I believe my load is between 5-6 amps when I go to my essential bus.