What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Earthx Etx680 and semi-cold weather

lndwarrior

Well Known Member
3 year old battery. Have had hard starting issues after the plane sits for a few weeks.

Today i went to fly after 18 days in between flights. Nightime temps have been in the mid-thirties. Up to the 50s during the day.

On startup the battery was clearly straining. After about a 30 minutes of flying the battery was back up to full charge.

Im wondering if this is others experience? From what I've read this doesnt seem to be normal.
 
Did you put a load on the battery for a minute or so prior to cranking to warm it up? Keep in mind that regardless of the battery a cold engine is harder to turn over.
G
 
Do make sure you don't have a parasitic leak from the battery. I've seen a number of batteries replaced wrongly due to this.

Take off either lead on the battery and place a ammeter in between the battery and the lead. Use the mili-amp setting on the meter. You should have zero amps.

The biggest mistake I have seen causing this comes from the installation of the newer 406 MHZ ELT's. They require a connection to aircraft power, and since they are usually installed in the rear of the aircraft a conection is made directly to the battery due to it's proximity, such as in RV-8's and 10's.

The other cause is from internal cabin lighting that is wired directly to the battery. Those lights can get left ON and may not be bright enough to see that they are on. If left on, it can take several weeks to a month to completely discharge the battery, and if you are regularly flying, you won't notice it.

Vic
 
Self Discharge?

3 year old battery. Have had hard starting issues after the plane sits for a few weeks.

Today i went to fly after 18 days in between flights. Nightime temps have been in the mid-thirties. Up to the 50s during the day.

On startup the battery was clearly straining. After about a 30 minutes of flying the battery was back up to full charge.

Im wondering if this is others experience? From what I've read this doesnt seem to be normal.

This may have something to do with it.
https://batteryuniversity.com/learn/article/elevating_self_discharge

Battery-Discharge.jpg
 
odyssey

According to their website, the odyssey can be stored for about 24 months at 25C/77F, losing about 65% of its charge. Works out to about 2.7% per month...
 
Random thoughts...

The OP didn't mention if he was using a battery maintainer or not -- I suspect not...

Typically, the usage model for aircraft systems, (engines, batteries, etc.) is not the same as an Automobile, but we seem to expect the exact same behavior of these disparate systems.

If you had a car that just sat in the garage, our outside for weeks at a time you might expect it to start with a little sluggishness.

As for me, I've always used a battery maintainer/charger appropriate to the battery installed, because I know I'm not going to fly every day (I wish the opposite were true :) ) and I've never had an issue with a dead battery, sluggish start, etc.

YMMV

Cheers!
 
Just as a data point, EarthX is a LifePO4 (not on that chart).

LiFePO4 is also very resistant to self-discharge. Remember the old days when your NiCad batteries would go dead in a month or so just sitting on the shelf? That’s because they self discharge at rate of about 1% per day. LiFePO4 has a typical self discharge rate of 5% per month. In other words, it takes six months for a LiFePO4 battery to self discharge to the same level a conventional battery reaches in just thirty days.

Important! If you're going to use a battery maintainer be sure to take electronic ignition manufacturer guidelines into consideration.
 
Last edited:
thx

Do make sure you don't have a parasitic leak from the battery. I've seen a number of batteries replaced wrongly due to this.

Take off either lead on the battery and place a ammeter in between the battery and the lead. Use the mili-amp setting on the meter. You should have zero amps.

The biggest mistake I have seen causing this comes from the installation of the newer 406 MHZ ELT's. They require a connection to aircraft power, and since they are usually installed in the rear of the aircraft a conection is made directly to the battery due to it's proximity, such as in RV-8's and 10's.

The other cause is from internal cabin lighting that is wired directly to the battery. Those lights can get left ON and may not be bright enough to see that they are on. If left on, it can take several weeks to a month to completely discharge the battery, and if you are regularly flying, you won't notice it.

Vic

Great suggestions Vic. I will check these out. I appreciate you taking the time to respond.

My led panel lights are LED and on a rheostat, so this could be the problem. I know you can't see them during the day on anything but the highest setting.
 
Just as a data point, EarthX is a LifePO4 (not on that chart).

LiFePO4 is also very resistant to self-discharge. Remember the old days when your NiCad batteries would go dead in a month or so just sitting on the shelf? That?s because they self discharge at rate of about 1% per day. LiFePO4 has a typical self discharge rate of 5% per month. In other words, it takes six months for a LiFePO4 battery to self discharge to the same level a conventional battery reaches in just thirty days.

Important! If you're going to use a battery maintainer be sure to take electronic ignition manufacturer guidelines into consideration.

I assume you're referring to this note for P-Mag?


"OPERATING NOTES: Battery Chargers: Some styles of ground (110 volt) chargers will hammer the battery with charge pulses as part of their normal cycle. Such hammering is not a typical buss state and can cause problems for the ignition if it is powered ON during such a charge. So as a normal guideline, KEEP IGNITIONS POWERED OFF WHILE (GROUND) CHARGING."
 
I assume you're referring to this note for P-Mag?


"OPERATING NOTES: Battery Chargers: Some styles of ground (110 volt) chargers will hammer the battery with charge pulses as part of their normal cycle. Such hammering is not a typical buss state and can cause problems for the ignition if it is powered ON during such a charge. So as a normal guideline, KEEP IGNITIONS POWERED OFF WHILE (GROUND) CHARGING."

Yep, exactly ...
 
We are starting 360 CU-IN engines with tiny batteries (compared to your car).
Modern small light PM starters require large in-rush current vs wire wound.
Put 2 amp charger on it for 15-30 minutes wake battery up while you pre-flight.
Modern chargers will give you battery voltage and % charger.
Cold engine, cold battery, sitting for about 2.5 weeks sounds normal.
I'll never say anything critical about EarthX because triggers fans. :D
 
Last edited:
Just as a data point, EarthX is a LifePO4 (not on that chart).

LiFePO4 is also very resistant to self-discharge. Remember the old days when your NiCad batteries would go dead in a month or so just sitting on the shelf? That?s because they self discharge at rate of about 1% per day. LiFePO4 has a typical self discharge rate of 5% per month. In other words, it takes six months for a LiFePO4 battery to self discharge to the same level a conventional battery reaches in just thirty days.

I believe you are correct that LiPo batteries have higher self-discharge rates when compared to LiFePO4 chemistry. It would be good to see the data and how susceptible each is to temperature. I think they both suffer higher rates in the first 24 hours.
 
Cold

I don?t have one of these batteries but my understanding is that they work much better at higher temperatures. You might need to put a load on it for a few minutes (turn on the master switch) while doing your preflight. This will warm up the battery.

-Andy
 
I don?t remember the SureFly power drain, but was told it is very low - a few milliamps (hardwired to the battery with an inline fuse). However, after reading these posts, I?m wondering if anything bad is happening while the charger is connected. I wired mine according to the installation manual, but I?m considering putting a switch in that circuit.
 
SureFly ignition module draws less than 1 milliamp in standby mode. They recommend keeping a maintenance charger on the battery if the airplane is stored for one month or more. Apparently the charger doesn?t hurt anything in this case.
 
A data point on LiFePho4 cells

About 6.5 years ago, I bought a set of LiFePho4 cells to fix/upgrade an electric scooter of mine. Life happened and I didn't get back to the project or even look at the cells until last month. I tested the cells and found that they had all retained about 50% of nominal capacity. I'm not even sure they were shipped with a full charge. After cycling them, I found that they are delivering essentially 100% of rated capacity.

YMMV
 
Last edited:
Back
Top