EarthX

[Slyfox]

I'm seriously considering this battery in my kitfox. I currently have the pc680. My question is: there is the ETX680 and the ETX680c, they claim that there is only a size difference but I want to know from people that have bought this battery what they would buy. I want the best of course. I also want to know if the charger is really needed. I fly a lot, at least 3 times a week. I have the 912uls in my model 4. thanks

[efwd]

I have the 680c which is starting my 912is beautifully. As for the charger, I have not used it since the first top off 3 years ago. I also fly regularly. I have a power source to operate the electronics during maintenance. I believe they have a charger now that can be utilized as a power supply. I will admit, I haven't really needed the power source either. Updating my Garmin stuff only takes about 40 min for the two EFIS. My battery doesn't have any problem running that stuff for 40 min.

[Slyfox]

doesn't the battery come fully charged? I don't have an efis so I'm good, all steam. I know old school, works for me.

[PapuaPilot]

I upgraded to the EarthX 680C from the Odyssey 680 years ago and love it. You don't really need a charger if you fly a lot. This battery holds its charge for a long time.

I did my first ever no preheat start a couple days ago at about 35 degrees for a spur of the moment flight. I hadn't flown the plane for about a month and had not charged the battery. It took at least 10 times cranking before I found the right amount of priming to keep it running. Even after cranking 10 times the starter was cranking great.

[Slyfox]

I did my first ever no preheat start a couple days ago at about 35 degrees for a spur of the moment flight. I hadn't flown the plane for about a month and had not charged the battery. It took at least 10 times cranking before I found the right amount of priming to keep it running. Even after cranking 10 times the starter was cranking great.

This is the main reason I want to upgrade. Even with preheat I have a hard time getting the starting power needed to start my engine in colder weather.

[Eric Page]

doesn't the battery come fully charged?

Lithium chemistry cells are often shipped with a "storage charge" in them, which is around 40-50% of capacity. At that level, self-discharge is very minimal.

EDIT: In response to Eddie's post #8 below, I should emphasize that my comment above refers to cells, not complete batteries. Addition of the active circuitry inherent in a battery management system will create a drain that must be offset over long storage periods.

[PapuaPilot]

For my upgrade I removed the battery from the tail and put the EarthX up front with only 3' of cable from the battery to the starter. The difference was amazing due to shorter cables, higher battery voltage (13.5 vs. 12.5) and minimal self discharge. Totally recommend it.

[efwd]

I do believe Kitfox stopped shipping the EarthX batteries with their FWF kits on account of batteries failing by the time they get installed. That is what happened to me. My battery self discharged below what could be recovered. The EarthX customer service was terrific. I wish I could recall her name but she usually answers the phone and she is extremely knowledgeable about their products. They ended up shipping me a new battery no questions. I believe the document inside the battery box tells you not to allow it to sit for so long. Unfortunately I never opened the box to read that until it had already sat for 2 years. They new I had neglected it and still stood by it and replaced it.

[Eric Page]

For those considering EarthX, you might want to look at the electrical section of your engine's installation manual, particularly for electrically dependent models like the Rotax "iS" engines. In the current 912iS manual, the battery specification requires a capacity of "at least 16 Ah."

Looking at the EarthX spec sheet, the ETX-680 and -680C are rated at 12.4 Ah, at a 1C discharge rate. That means you'll only get that capacity from a brand new battery if you discharge it at no more than 12.4 amps. An aged battery, or a battery discharged at a higher rate, will result in lower capacity.

This makes little difference in how it spins the engine starter, but it's very important if both of the alternator/regulator systems fail. That leaves the battery to carry the ECU, fuel pumps, ignition system and airframe buses until you reach a safe landing spot. This is why Rotax specifies a 16 Ah battery, and is one of the drawbacks of lithium chemistries compared to lead-acid in the same dimensional footprint.

If your ship is a day-VFR-only machine, and you don't fly in remote areas or over hostile terrain, then you might be OK with a shorter battery-only endurance. Just be sure that you've done the load analysis so you know your plane's electrical demands and can choose a battery -- and test/maintain it in a way -- that matches your risk tolerance.

As an aside... The Odyssey PC680 is a 16 Ah battery. The EarthX ETX-900 has the same case size as their ETX-680 but offers 15.6 Ah capacity; compared to the -680, it's +$70 and +13 oz. It's still not 16 Ah, but it's darn close. Makes you wonder why EarthX uses the "680" designation for a battery that isn't equivalent to the PC680.

[Slyfox]

For those considering EarthX, you might want to look at the electrical section of your engine's installation manual, particularly for electrically dependent models like the Rotax "iS" engines. In the current 912iS manual, the battery specification requires a capacity of "at least 16 Ah."

Looking at the EarthX spec sheet, the ETX-680 and -680C are rated at 12.4 Ah, at a 1C discharge rate. That means you'll only get that capacity from a brand new battery if you discharge it at no more than 12.4 amps. An aged battery, or a battery discharged at a higher rate, will result in lower capacity.

This makes little difference in how it spins the engine starter, but it's very important if both of the alternator/regulator systems fail. That leaves the battery to carry the ECU, fuel pumps, ignition system and airframe buses until you reach a safe landing spot. This is why Rotax specifies a 16 Ah battery, and is one of the drawbacks of lithium chemistries compared to lead-acid in the same dimensional footprint.

If your ship is a day-VFR-only machine, and you don't fly in remote areas or over hostile terrain, then you might be OK with a shorter battery-only endurance. Just be sure that you've done the load analysis so you know your plane's electrical demands and can choose a battery -- and test/maintain it in a way -- that matches your risk tolerance.

As an aside... The Odyssey PC680 is a 16 Ah battery. The EarthX ETX-900 has the same case size as their ETX-680 but offers 15.6 Ah capacity; compared to the -680, it's +$70 and +13 oz. It's still not 16 Ah, but it's darn close. Makes you wonder why EarthX uses the "680" designation for a battery that isn't equivalent to the PC680.

I guess I can say it doesn't matter to me. My plane does not have: efis, efi, transponder of any kind, don't use lights day vfr. so I guess it doesn't matter. But I do go into the back country. When I throw my master switch everything is off to the battery. no memory devices. I have a radio on line and a com (dynon) run a fuel pump (if the mechanical poops) IVO electric prop. outside of that nothing.