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  #11  
Old 01-19-2020, 09:06 AM
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bkervaski bkervaski is offline
 
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Location: Birmingham, Alabama
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Quote:
Originally Posted by bjdecker View Post
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 ...
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  #12  
Old 01-19-2020, 09:10 AM
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gmcjetpilot gmcjetpilot is offline
 
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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.
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Last edited by gmcjetpilot : 01-19-2020 at 09:13 AM.
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  #13  
Old 01-19-2020, 09:31 AM
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MiserBird MiserBird is offline
 
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Default SureFly ignition drain

Anyone know what the standby drain is for a SureFly mag ?
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  #14  
Old 01-19-2020, 10:00 AM
Northernliving Northernliving is offline
 
Join Date: May 2005
Location: Boston, MA
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Quote:
Originally Posted by bkervaski View Post
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.
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  #15  
Old 01-19-2020, 10:29 AM
simpkinsona simpkinsona is offline
 
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Location: Vacaville, CA
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Default 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
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  #16  
Old 01-19-2020, 10:54 AM
Scott Hersha Scott Hersha is offline
 
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Location: Cincinnati, OH
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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.
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RV6/2001 built/sold 2005
RV8 Fastback/2008 built/sold 2015
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Cincinnati, OH/KHAO
JAN2020
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  #17  
Old 01-19-2020, 11:25 AM
Scott Hersha Scott Hersha is offline
 
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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.
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RV6/2001 built/sold 2005
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RV4/bought 2016/sold/2017
RV8/2018 built/Sold(sadly)
RV4/bought 2019 Flying
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JAN2020
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  #18  
Old 01-19-2020, 12:28 PM
kcameron kcameron is offline
 
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Posts: 210
Default 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
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Last edited by kcameron : 01-19-2020 at 12:31 PM. Reason: grammar
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