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EarthX ETX900 in RV-14(A)?

CF86301

Active Member
Has anyone installed an EarthX ETX900 in an RV-14(A) and flown it? If so, I'd be interested in hearing about battery box and charging system implications.

The EarthX batteries got a good writeup in Kitplanes. And because I'm installing a YIO-390-EXP119 with an accessory case and standby alternator, and a Hartzell aluminum constant speed prop, it would be nice to offset the extra weight.
 
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I have had it in both of my 14A with great experience. The batter will fit the standard box, you just need to put some of the provided foam spacer on the sides of it as it is not as wide as the odyssey battery.
 
First off, what's the amperage output from your alternator? If you're using a 60 amp alternator, you'll be OK with the ETX680 (but the ETX900 is fine). If you're using a stronger alternator like a 70 amp, you need the ETX900.

A basic rule of thumb for the ETX series: The first two digits on the battery model should be larger than the alternator's amperage.

Examples:
For a 60 amp alternator, use the ETX68(0).
For a 70 amp alternator, use the ETX90(0).
 
First off, what's the amperage output from your alternator? If you're using a 60 amp alternator, you'll be OK with the ETX680 (but the ETX900 is fine). If you're using a stronger alternator like a 70 amp, you need the ETX900.

A basic rule of thumb for the ETX series: The first two digits on the battery model should be larger than the alternator's amperage.

Examples:
For a 60 amp alternator, use the ETX68(0).
For a 70 amp alternator, use the ETX90(0).
I am curious to understand the logic of this. Would this imply that if you have a 70 or 80A alternator, you can not use a 650?
Or if you have a 40A alternator, you can not use a 900?

I do understand that using a 900 with a 40A alternator may demand more load than the alternator can provide but that shouldn't cause any problems, only taking longer to charge.
Do I understand this correctly or there are some other things in play?
 
The logic behind max charging current is in the EarthX specs

I am curious to understand the logic of this. Would this imply that if you have a 70 or 80A alternator, you can not use a 650?
Or if you have a 40A alternator, you can not use a 900?

I do understand that using a 900 with a 40A alternator may demand more load than the alternator can provide but that shouldn't cause any problems, only taking longer to charge.
Do I understand this correctly or there are some other things in play?

First, thanks for your feedback on the battery box adjustment (foam inserts).

Regarding the alternator, the EarthX ETX680 product specification sheet states that the maximum charging current for the ETX680 is 60 Amps. The ETX900 product spec sheet states that the maximum charging current is 80 Amps.

Someone else commented in another thread that the lithium iron phosphate batteries will try to recharge themselves at the maximum alternator output as soon as the alternator comes on line. This person had an 80A alternator with a 60A circuit breaker in series, trying to charge an ETX900, if I recall correctly, and the breaker would pop whenever the RPM was high enough for the alternator to put out its full rated current.

I submitted a question to B&C tech support about using an alternator with a lower capacity than the battery max charging current. They have no reservations regarding using an LX60 alternator and LR3D regulator with the ETX900. They say under certain situations (high RPM, cold temps), the charging current might reach 65A. They recommend a 60A ANL current limiter installed firewall forward.
 
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Someone else commented in another thread that the lithium iron phosphate batteries will try to recharge themselves at the maximum alternator output as soon as the alternator comes on line. This person had an 80A alternator with a 60A circuit breaker in series, trying to charge an ETX900, if I recall correctly, and the breaker would pop whenever the RPM was high enough for the alternator to put out its full rated current.

The comment about Lithium batteries pulling as many amps available to charge themselves is correct. If my battery is somewhat low in Amps, I do see a much higher amp usage (30-40) at the start up which may take 5-10 minutes into flight before the amps come back to a normal*draw for my plane.
In regards to the user with a 60A CB on a 80A alternator, he clearly sized that wrong and ought to replace it.* The recommended guideline*is about 5-10A above the rated alternator output.* I have a 70A CB on my 60A alternator as they can generate a bit more than their rated Amperage.* This ensures against nuisance*CB tripping.
 
Thread where CB tripping was reported

In regards to the user with a 60A CB on a 80A alternator, he clearly sized that wrong and ought to replace it.* The recommended guideline*is about 5-10A above the rated alternator output.* I have a 70A CB on my 60A alternator as they can generate a bit more than their rated Amperage.* This ensures against nuisance*CB tripping.

Perhaps you remember this thread: https://vansairforce.net/community/showthread.php?t=210240
 
To clarify one point in the thread. There is no minimum sized alternator when using a EarthX. There is a maximum that has been pointed out in other posts. That maximum is based on your alternator output to avoid overcharging the battery and I assume causing damage or an overheat. We run a 900 off a 40 amp alternator with no issues.
 
ETX900's

Been running 2 of these for almost 3 years. Check ampacity every 6 months and still 95% +. Never had any issues. Check out the insulated battery boxes from Earth X.
 
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EarthX ETX 900 in RV14

I put an ETX 900 in my RV14A about 2 months ago. The PC 680 just would not start the new engine on a cold day. As mentioned earlier, it fits in the stock battery mount with some adjustment.

I mounted a large 2 inch scat tube to direct cooling air to it - probably overkill. Works Great - highly recommended. Its expensive but its worth every penny.

I pop open the oil door after shutdown which is when the battery is probably exposed to the highest heat levels.
 
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