EarthX

[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.

[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.

[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.

[jrevens]

Check what your system charging voltage is. EarthX says it must be between 13.8 & 14.7v. You’re probably good to go, but if not it might be worthwhile looking at one of the new regulator/rectifiers from B&C… they have adjustable voltage capability.

[Slyfox]

I noticed today that mine is running right at 13.8. now if I did need one of these B and c regulators, what is the number needed for the Rotax 912uls, they don't show on the webpage specifically. thanks

[airlina]

I noticed today that mine is running right at 13.8. now if I did need one of these B and c regulators, what is the number needed for the Rotax 912uls, they don't show on the webpage specifically. thanks

Steve, I just went thru this when I just replaced my odyssey 680(with another odyssey). They list the charging voltage at 14.2V and my bus voltage was 13.9V . Found out from a recent kitplanes article that some voltage regulators are adjustable and in fact mine was, so I was able to bump up the voltage to 14.2v. So I would check to see if the one you are currently using can be adjusted before spending the bucks on a new one. Bruce N199CL

[Slyfox]

Steve, I just went thru this when I just replaced my odyssey 680(with another odyssey). They list the charging voltage at 14.2V and my bus voltage was 13.9V . Found out from a recent kitplanes article that some voltage regulators are adjustable and in fact mine was, so I was able to bump up the voltage to 14.2v. So I would check to see if the one you are currently using can be adjusted before spending the bucks on a new one. Bruce N199CL

I'm currently using the stock regulator (I think ducanti) It's the same one my original 912ul engine came with back in 1994. I have the new one that came with the 912uls engine back in 2008 looks the same. I put that one in my tool box in case this one blows, but it keeps on ticking. lol