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LiFePo battery?

Craig - interested data. Thanks for adding to this thread.

Two more data points to add to this thread (in keeping all the data in one convenient place for readers) ...

A few months ago, I left some of my panel on one weekend while working on the plan and forgot to shut it off. I ran my Shorai down well below the recommended level. I used an old laptop charger (15.6V 2.4A) connected directly to the LiFePO4 and checked it every couple hours until is was back up to about 14.5V. It took about 6 hours. It's been happy and healthy ever since. I've not tried a typical car charger. My aircraft electrical system is the stock alternator and wiring that Vans prescribes for a "basic" RV.

Recently, I left my plane sit in my hangar for 65 days (sad, I know). When I pulled it out, it started normally. I do not use any type of tender when the plane is in the hangar.
 
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I've used the Ballistic brand now for 80+ hrs. Slings the prop amazing and never an issue. I use the 3.1lb 325 cranking amp. I copied a MX2 driver on the field that uses the same for his IO540 beast. I've accidently fully discharged the battery and charged it back with a trickle charger about 40 hrs ago. No issues found.

I torture tested a 2lb 240 cranking amp ballistic before installing my current version.

I discharged the battery then charged it at 15.6 volts under "slow" on a snap-on professional grade charger. I could not detect any issues at this point (there might have been and just not visible yet)

I discharged the battery again and this time charged it back at 15.6volts and "rapid" charge on the snap-on charger. (skipped the medium setting) The battery was left charging for 12 hours (300% greater then planned flight times)

No fire or explosion (bummer :roll eyes:)

There was deforming and bulging however. The battery no longer held a charge after this stage.





I installed my 3.1lb battery after this test. I keep my charge system in the low 14volt range.

I do not support or advocate anyone using any battery type. Do what you as the builder and pilot in command determine to be safe. (I've had this information for awhile and just didn't post because I'm not an electrical engineer.) I fly jets and wrap airplanes in vinyl.

(sucks that we gotta worry about sharing information publicly)
 
I've used the Ballistic brand now for 80+ hrs. Slings the prop amazing and never an issue. I use the 3.1lb 325 cranking amp. I copied a MX2 driver on the field that uses the same for his IO540 beast. I've accidently fully discharged the battery and charged it back with a trickle charger about 40 hrs ago. No issues found.

I torture tested a 2lb 240 cranking amp ballistic before installing my current version.

I discharged the battery then charged it at 15.6 volts under "slow" on a snap-on professional grade charger. I could not detect any issues at this point (there might have been and just not visible yet)

I discharged the battery again and this time charged it back at 15.6volts and "rapid" charge on the snap-on charger. (skipped the medium setting) The battery was left charging for 12 hours (300% greater then planned flight times)

No fire or explosion (bummer :roll eyes:)

There was deforming and bulging however. The battery no longer held a charge after this stage.





I installed my 3.1lb battery after this test. I keep my charge system in the low 14volt range.

I do not support or advocate anyone using any battery type. Do what you as the builder and pilot in command determine to be safe. (I've had this information for awhile and just didn't post because I'm not an electrical engineer.) I fly jets and wrap airplanes in vinyl.

(sucks that we gotta worry about sharing information publicly)

do not use regular lead acid chargers with lifepo batteries. you need to use the chargers that are designed for lifepo. they are usually about $80-120.

contact Chip from Ballistic, he is a good guy and im sure he can provide more info
 
do not use regular lead acid chargers with lifepo batteries. you need to use the chargers that are designed for lifepo. they are usually about $80-120.

contact Chip from Ballistic, he is a good guy and im sure he can provide more info

I talked to him. Ballistic states that NO special charger required. Just keep the volts down was his comment.

I only charge my current battery at 14.3volts and 2-3amps using a normal $20 ace hardware charger for lawn mowers. I've had zero issues in 80+ hours.

If you read the post, I intentionally tried to fry the test battery. When you are flying, the altenator is not providing a "special" LiPro charging system.
 
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If you read the post, I intentionally tried to fry the test battery. When you are flying, the altenator is not providing a "special" LiPro charging system.

10-4, I never understood the concept either. I use ballistic batteries in my race bikes and thought the same thing
 
I've installed one of the Shorai batteries in my -6A; pictures and descriptions of how I did so are here on VAF in this thread.

Short story: I love it!
 
Today, at the Seattle Motorcycle Show, I spoke with a couple Lithium Battery vendors. Here's what they had to say:

EarthX:
Their batteries have electronics built-in that balance the cells during charge & discharge, so no special chargers required. This is also supposed to prolong the life of the battery so that one cell doesn't become depleted before others, killing the battery early. The 36AH battery weighs 3.5lbs and costs $350.

Mirai:
These guys say their batteries don't need built-in electronics to balance the cells because they source matching cells for each battery. I'm a little skeptical that that would work. Their batteries are sized up to 27AH. Unfortunately, they are sized a little wider than the EarthX and Shorai batteries, so the 27AH size won't fit in my custom battery box. Weighs 3lbs and costs $250

I like the idea of the built-in balancing circuit, so am really leaning towards the EarthX batteries when my plane is closer to powering up in a year or so.
 
Charging

I've been following this thread for some time now and interested in the differing opinions. I have been using LiPo and LiFePo batteries in my R/C aircraft for some time now and have learned a lot of Does and Don'ts from my experiences. First off I truly dislike LiPo batteries because of there volatile nature, but I do like LiFePo batteries for there stable nature. They do need to be cared for however,and will not tolerate abuse. I have found over the years that batteries with internal balancers are the way to go, easier to maintain and longer life. LiFePo batteries do not like a trickle charge after they reach there full voltage and can be over charged if not controlled, this will affect the life expectancy significantly. My concern with a LiFePo in an aircraft would be how to properly charge it and with out a internal balancer the battery will ultimately be overcharged and could fail as a result. Besides from over charging, minimum voltage needs to be observed. Don't let the min voltage drop below 80% of fully charged voltage. If it happens bringing it back up could prove to be difficult.
With all that has been said, I am very interest in installing a LiFePo into my -8 project but it will defiantly have a balancer built in.
My 2c worth.:D
 
Charging part 2

I agree with Terry on this. I don't know if the battery in question has balance circuitry or not but really should have. I use LiFe packs in my competition RC sailplanes. They have balancing connectors as well as the regular charge plug. The charger I use is expensive but worth it for the features to keep the batteries perfect and most importantly, safe.

LiFe packs should not be continuously trickle charged. Think of it as a balloon being filled with air. It will only take so much!!!

I think some great stuff is coming in batteries in the next few years.
 
. First off I truly dislike LiPo batteries because of there volatile nature, but I do like LiFePo batteries .:D

Now I am confused. This means there are lithium polymer batteries that are NOT lithium iron polymer? LiPo batteries are just as bad as Lithium Ion? What?
 
I think this is the difference:
LiPo: Lithium Polymer
LiFePo: Lithium Iron Phosphate

Very different.
LiFePo: Lithium Iron Phosphate. Also, known as LiFePO4. And ditto on the differences. Do your research before writing them both off on the basis of the history of the LiPo types.
 
diode

Could you put a diode on the battery? Then charge it in the Hangar with a ballancer. If you wanted to you could put a relay with a timer that would charge off the alternator for 15 minutes of flight.
 
I've been following this discussion for some time and have seriously considered installing one. I feel comfortable that these are stable batteries under normal operating conditions, however I'm concerned about the following:

1) How well do these batteries operate back east in the summer when outside temps are 100+ degrees and the temps inside your cowling is considerably higher than that!

2) I have a 60A Alt. When at Osh2012, I let my battery drain down while working with a couple of my avionics vendors tweaking my settings and troubleshooting some issues. When it was time to depart, my voltage was low, however enough to start engine. My Alt kicked into overdrive charging my Odyssey batt with 50+ amp for a short time and trickling down to a more normal range within a few minutes. What would happen to one of these LiFePo batts under the same conditions? What is the max charging amps it can take and for how long before it's damaged? Under the same conditions, would I be forced to trickle charge my LiFePo batt in order to get the voltage up so that the Alt doesn't charge it too fast?
 
I use a Ballistic 16 cell EVO2 on an IO-320 with Skytec starter and 122 tooth gear. From every aspect, except cold weather, I believe they perform better than any other lead acid I've used (properly rated cca, capacity, etc.). They have a great shelf charge life. Doesn't seem to drain with disuse (as fast as lead acid).

They do seem to like the heat (within limits). As far as cold, check this video before you commit to one if you fly with one in the Great White North.

http://www.youtube.com/watch?feature=player_embedded&v=OBfvR1EJJBk

As far as deep cycling, that's subjective. All I know is mine does as good as my previous lead acid for deep cycling on start. Few months ago I got into a 10-12 crank situation (bad hot start procedure). The Ballistic got me started and never really seemed to taper off in cranking effectiveness.
 
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I've put about 30 hours on my Shorai installation, including starts at single-digit temperatures which are common here on the planet Hoth (also known as Minnesota). I'm exceedingly happy with the performance of the battery.
 
At our recent EAA 326 chapter meeting, a member passed a Shorai LiFePo4 battery around. It was so light it almost seemed like an empty case!
About special charging; There is a special covered recepticle in the case between the main terminals. This is where the special charger connects to each individual cell to check and charge it, I'm told.
So the ship's charger will do just fine for every flight, plus the battery holds a charge for a very long time.
Additionally, if you use the specified charger, it will equalize all the cells and extend the battery life.
So I guess you don't need it, but should have one. Also, don't use a "smart charger" that has a pulse desuphating mode, that will damage a LiFePo4 battery.
Standard disclaimer, I don't have a LiFePo4 battery or special charger yet, just know what I've read while getting ready to buy one etc...
 
I've been following this discussion for some time and have seriously considered installing one. I feel comfortable that these are stable batteries under normal operating conditions, however I'm concerned about the following:

1) How well do these batteries operate back east in the summer when outside temps are 100+ degrees and the temps inside your cowling is considerably higher than that!

2) I have a 60A Alt. When at Osh2012, I let my battery drain down while working with a couple of my avionics vendors tweaking my settings and troubleshooting some issues. When it was time to depart, my voltage was low, however enough to start engine. My Alt kicked into overdrive charging my Odyssey batt with 50+ amp for a short time and trickling down to a more normal range within a few minutes. What would happen to one of these LiFePo batts under the same conditions? What is the max charging amps it can take and for how long before it's damaged? Under the same conditions, would I be forced to troule charge my LiFePo batt in order to get the voltage up so that the Alt doesn't charge it too fast?

Shoria recommends a max charge rate of 8 amps to our LFX18. We installed a Sterling product unit to limit charge to 3amps since this is our backup battery only. Reason we did this is to compile amp limmitter, reversed feed diode and over voltage protection all in one package. What are you guys experiencing on battery's wired direct into charging system? Is that something we should be concerned about or is the high rate of charge only short lived?
 
I Like It So Far!!!!

... I've put about 60 hours on my Shorai battery installation and am very happy so far. I used the largest one with the highest output they offer and still was able to save 23 lbs. over the Odissy 925 battery. The starting is great and it spins up better than ever. I noticed it doesn't like a continuous draw as with avionics on and engine off. The surface voltage declines rapidly in comparison to the lead acid battery. The manufacturer says that this is normal and you should size their battery at two times the amp hour rating of the one you are replacing. Even with this increase, the bad side is if you were to lose the alternator, your time on battery power is still somewhat limited as compared to the Odissy battery. At any rate, it is performing very well for what I do and have no bad things to say! Thanks, Allan...:D
 
Shoria recommends a max charge rate of 8 amps to our LFX18. We installed a Sterling product unit to limit charge to 3amps since this is our backup battery only. Reason we did this is to compile amp limmitter, reversed feed diode and over voltage protection all in one package. What are you guys experiencing on battery's wired direct into charging system? Is that something we should be concerned about or is the high rate of charge only short lived?
I'm curious about this too... What happens when my 60amp alternator dumps all the amperage the battery will take into it?
 
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I looked on the Shorai website and looked at the different batts to find one with the highest Max Charge Rate(A). The highest I could find was 18A. Many are way below that. Not all of their batts had the specs, but at least a good indicator.

I'm basically a novice at this, but I concerned that a 40A or 60A Alt could fry the Batt or the circuitry (smart charge batts) if you had low voltage, but were still able to start your engine (barely) and your Alt kicks in to charge the batt.

See my previous post on what happened to me at Osh2012. What would have happen to me if I had a Shorai or any other LiFePo batt, especially ones out there with the "smart charge circuitry" when my 60A Alt kicked into overdrive?
 
Thank you Mike (for the link) and Terry (for causing the question to form).
I was erroneously thinking that LiPo was poor shorthand for LiFePO4. I see now it is not. Thanks again.

Glad to help. LiPo and LiFePo are definitely different animals. LiFePo batteries are very stable and provide incredible power for there size. As for charging, a lithium based battery has a max charge rate in term of "C". The C rating of a specific battery is based on its output. So, if a battery is rated for 100 Amp hours and has a C rating of 10 it can be charged at a maximum of 10 amps. "C" , is a percentage of output capacity. If a LiFePo battery is not protected with internal manager/balancer it can be easily overcharged. LiFePo require constant current variable voltage charges. An alternator won't do it. They are constant voltage variable current. Not compatible in my book. :D
If you haven't noticed most of the LiFePo battery venders offer special chargers if there units are not internally managed. :cool:
 
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An alternator won't do it. They are constant voltage variable current. Not compatible in my book. :D
If you haven't noticed most of the LiFePo battery venders offer special chargers if there units are not internally managed. :cool:

This is incorrect, or at least only partially accurate given that even vendors with a BMC offer chargers.

While Shorai and others do sell balancing chargers, they specifically state that alternators will in fact charge the batteries. Shorai recommends doing so once per year; the condition inspection is a great time to do this. The rest of the time, the alternator keeps it charged just fine.

Empirically, I have 30+ hours on a Shorai LiFePo battery in my RV and it has yet to be attached to the balancing charger.
 
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I looked on the Shorai website and looked at the different batts to find one with the highest Max Charge Rate(A). The highest I could find was 18A. Many are way below that. Not all of their batts had the specs, but at least a good indicator.

I'm basically a novice at this, but I concerned that a 40A or 60A Alt could fry the Batt or the circuitry (smart charge batts) if you had low voltage, but were still able to start your engine (barely) and your Alt kicks in to charge the batt.

See my previous post on what happened to me at Osh2012. What would have happen to me if I had a Shorai or any other LiFePo batt, especially ones out there with the "smart charge circuitry" when my 60A Alt kicked into overdrive?

It would do some good to look at this site to learn about C rate for Li batteries. This is a basic standard rate for charge or discharge. A battery can operate at a higher C rate, but the base should be known to set some boundaries for charge limits. http://batteryuniversity.com/learn/article/what_is_the_c_rate

There is much more on that site about internal resistance too. PbA batteries have a higher internal resistance than LiXXX chemistries. That greatly helps the self discharge rate, and internal heating with high amps (charge or discharge)

Learning about new technologies is fun, as long as safety is maintained.
 
I have 100 hrs on my 3.1lbs Ballistic battery. I've only used a $30 charger from Ace Hardware made for riding lawn tractors. I only use the charger after long hangar times powered up. These batteries do not seem to trickle down like traditional Lead acid.

I have noticed that when the temp drops below 50F degrees volts read low initially (12.4ish). Normally it reads 12.8volts before start at all other higher temps. Regardless of Volt readings, starter engaged slings the prop just the same. (others have talked about these batteries need to warm/wake up at the lower temps by putting on elec loads)

100hrs and A LOT of start n stop operations with Young Eagle flights. The little 3.1lbs power source really slings the prop and hasn't let me down yet.

Hope that helps add to the data on this thread.
 
This is incorrect, or at least only partially accurate given that even vendors with a BMC offer chargers.

While Shorai and others do sell balancing chargers, they specifically state that alternators will in fact charge the batteries. Shorai recommends doing so once per year; the condition inspection is a great time to do this. The rest of the time, the alternator keeps it charged just fine.

Don't get me wrong. I'm not saying it can't be done. Charging straight from the alternator is not optimal and has some risk. Excess charge is dissipated from the battery as heat. If two LiFePo batteries were put in a side by side test, one with a BMS and one without. My money is on the one with the BMS. It will live longer and provide better service.
I like the stats on this battery.
http://earthxmotorsports.com/our-batteries/
 
Going to try and answer questions from the horses mouth

Thank you all who have purchased the EarthX lithium batteries for your airplanes and as many of you have asked us to go on this forum, I am going to attempt to be a resource here. Thank you Russ for helping out with the registration questions!! I am not an expert by any means on aircraft and our main focus and expertise has been of starter batteries for the power sport industry, but that being said, the aircraft market found us and will make us an expert in this field as well. I thank you all in advance! I am an expert on batteries though and if I can be of assistance, I will do my best to answer your questions. We are not a certified aircraft battery and should be only used in experimental aircraft (see, I am catching on already to the aircraft world...). I look forward to your questions. Kathy
 
Welcome to VAF!

Kathy, welcome to VAF------the best site on the planet for things RVish:D

Good to have the support of another vendor.
 
Thank you all who have purchased the EarthX lithium batteries for your airplanes and as many of you have asked us to go on this forum, I am going to attempt to be a resource here. Thank you Russ for helping out with the registration questions!! I am not an expert by any means on aircraft and our main focus and expertise has been of starter batteries for the power sport industry, but that being said, the aircraft market found us and will make us an expert in this field as well. I thank you all in advance! I am an expert on batteries though and if I can be of assistance, I will do my best to answer your questions. We are not a certified aircraft battery and should be only used in experimental aircraft (see, I am catching on already to the aircraft world...). I look forward to your questions. Kathy

Hi Kathy, welcome to the fray. I think one of the questions is around the scenario where the owner rolls up to the airshow, forgets to turn off something and comes back to find the battery low. They get a "jump" start to get the engine running.

What would the the amperage draw for low states of charge (SOC) down to 25%. Since the charging system will attempt to maintain the 14v buss voltage, what is the battery draw? A nice chart (graph) showing the amperage draw vs SOC with with fixed 14 volt across the battery would be very good information for this crowd. ( assume 80F ambient temp) And, what is the recommended procedure for the discharged battery and eager-to-go situation.

Thanks in advance for your participation!
 
Great question Bill!

I better clarify my abilities, I am the sales director at EarthX and not an engineer so for the really technical questions, I will have to try and get our engineering department to help out with graphs and data but we are introducing new products all the time and this task is difficult to say the least!

I can answer your question about what would happen if you left something on while "parked" and came back to find a battery that will not turn your engine over. You can do a couple of things, you can jump the battery from another like sized battery the same as always; you could put it on a charger if one was available; you can use a jump pack to boost it. It is always best to let the engine run for a least 5 minutes after doing this to bring the charge back up before you hit the run way. With our EarthX battery, we do have a low voltage cut off so you do not destroy the battery. If the voltage reads 0V, that means the cut off has been triggered and to "wake" it up, all the above will work unless you have a smart charger that reads a 0V and determines the battery is dead (as a lead acid would be if it read 0V) then it will not send out a current to reconnect the loop. It only takes a millisecond to do this but you have to have a current go through the battery to reconnect and start the charging process.
 
LiFePO4

The Lithium Iron Phosphate chemistry does not discharge at all when stored.

That said there different sub chemistries so to speak. The China Aviation Lithium Battery company (CALB) has a LiFePO4 chemistry that can do 12C discharge with very little voltage sag compared to the cobalt-aluminum chemistry that Tesla and (most cordless drills) use at 3C.

Top balancing your cells is probably an exercise in futility, bottom balancing makes all kinds of sense, but not likely needed.

Seems like a lot of "Battery Management Systems" try to constantly monitor voltage of each cell end up creating uneven parasitic loads that create the need to "balance" -Self-fulfilling prophecy.

If you just bottom balance them, hook them up in series, they will not drift apart in the least.
 
LifePo4

The lithium iron phosphate chemistry does have a very small discharge rate, average is 1-2% a month compared to a lead acid battery that is closer to 30% a month. Hence why even if the lead acid battery is just sitting on a shelf, you will need to charge it. Now a lithium battery can sit on a shelf for a year and you do not have to do a thing to it. But once you put it inside a vehicle, the vehicle will draw upon the battery to run the clocks, GPS, security system etc.

As far as balancing, this is a needed requirement for lithium cells that are used in series as they are individual cells that will charge and discharge at different rates if you do not have a balancing circuit to keep them uniform. It is ONLY in the power sport industry that companies are selling these type batteries without this feature built in. Your cordless drill battery, your computer battery, your cell phone battery, or even a hearing aid battery has a balancing circuit built in to perform this feature.
 
Kathy, when I look at your product website, say for the ETX36D (http://earthxmotorsports.com/shop/etx36d/) it shows in the specs Max Charge Amps: 10A. Is this indicating that the battery can only accept up to 10A for recharging? What happens in our planes (or a vehicle) with an alternator putting out above that amperage value? Is there any damage to the battery having this higher charge going to the battery?
 
Charging limits

That has been the million dollar question we have received all week! The warning on the top of the battery is for using a charger, not your alternator output. Most power sport chargers are 5 amps or less and this warning is to try and prevent someone from using a car charger that can go up to 80+amps or even higher. When your alternator is charging up the battery, it is also running all of the instrumentation as well and the full amount doesn't go into the battery, therefore, it will not harm your battery if the battery is correctly sized. Our ETX36D is designed to take a lot more amps than say our baby one, an ETX6A. Hope that answers your question.
 
BMS Technology

Glad to see the vender get involved. Thank you. As for my question, your battery is equipped with a battery management system, does that limit or regulate the amp draw when charging.
 
Hi Kathy,

Another question I have relates to how different vendors' batteries relate in capacity. IE, does your ETX36D have the same capacity as the Shorai LFX36A3-BS12, etc. Another way to state the question is, are the ratings across different manufacturers standardized?

Thanks!
Russ
 
AMP draw limiting

As of this moment, no, we do not limit the charging current but the engineers are working on testing and developing this feature. But if you have the correct battery, for the correct application, you will not exceed the limits.
 
Standardized rating

Hi Kathy,

Another question I have relates to how different vendors' batteries relate in capacity. IE, does your ETX36D have the same capacity as the Shorai LFX36A3-BS12, etc. Another way to state the question is, are the ratings across different manufacturers standardized?

Thanks!
Russ

Hi Russ,

Great question and the answer is "no".

In the lead acid world, manufacturers use standardized tests so you can compare apples to apples and being that the industry is over 170 years old, and a multi billion dollar industry, it is regulated and reputations and branding has occurred. Now the lithium iron phosphate market is very new at the consumer level (it has been used by the military since the 70's but it is just now affordable to the consumer market) and the market is being filled with new brands. As it is such a small player in the world of batteries at this point in time, nobody is regulating what the capacity, CCA's, and other "marketing" terms are being used. We do not compare ourselves to other lithium's as their is no one regulating their claims but we do compare and use the same tests that the lead acid batteries use so you can compare apples to apples. A perfect example of this is the CCA rating. This is a standardized test that was developed by The Society of Automotive Engineers (SAE) and is very defined with a mathematical test and result. The test is to be performed at 0 deg F and a measurement of the cranking amps that the battery can put out over a period of 30 seconds. To the best of our testing and knowledge, we are the only manufacturer that tests to this standard in the lithium market which is why there is so much talk about cold starts. A correctly rated battery does not have cold start issues.
 
2 ext36c in parallel ?

Hi
Could i expect to put 2 ext36c in parallel to have something that look like my odyssey pc925 ? ( the battery i have in my RV-10) Less weight would really help my CG.
 
What size?

It appears that all of the suggested batteries are larger (3.4" vs. 3.0")
across the smallest dimension than the odyssey pc680 that many of us are using.

Is there a LiFePo battery that will fit inside the footprint of the pc680 in all three dimensions? And have adequate capacity?
 
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speaking of capacity...

For the factory rep,

I'd love to see figures on the actual energy density of these batteries. Those of us with electrically dependent planes (meaning not just the panel instruments, but the engine, as well) need to know how long the battery can continue to provide power at various lower current discharge rates. Say, at 5A, 10A, & 15A continuous loads.

Any info available?

Thanks,

Charlie
 
It appears that all of the suggested batteries are larger (3.4" vs. 3.0")
across the smallest dimension than the odyssey pc680 that many of us are using.

Is there a LiFePo battery that will fit inside the footprint of the pc680 in all three dimensions? And have adequate capacity?

Check out this thread. I've been using it in the frozen land of MN since December; I have about 30 hours on it now without any issues whatsoever.
 
I ended up buying some .032 4130 SHEET and fabricated another box.
6.55w x 3.4d x 5.0t

DSC00571.JPG
 
Replacement of the PC925

Hi
Could i expect to put 2 ext36c in parallel to have something that look like my odyssey pc925 ? ( the battery i have in my RV-10) Less weight would really help my CG.

Yes, you could put 2 ETX36C's in parallel which would give you the power of the Odyssey PC925 and weigh in at less than 7 pounds.
 
It appears that all of the suggested batteries are larger (3.4" vs. 3.0")
across the smallest dimension than the odyssey pc680 that many of us are using.

Is there a LiFePo battery that will fit inside the footprint of the pc680 in all three dimensions? And have adequate capacity?

You are absolutely right, our battery is .4" wider than the PC680 and to be honest, up until just now, no one has pointed that out as a problem. Our cases are designed for the power sport industry, for example, the ETX36D is an exact case size of the YTX20L-BS or the YTX20HL-BS as this is a very popular OEM size in our market. At this moment, that is our expertise and what our product is developed towards, a starter battery for the power sport market. As the aircraft market has found us and we have sold 100's of these batteries now to this market, that is not to say we will not become an expertise in this market and start design and development geared towards aircraft specifically.

That being said, if we were to have a case designed just for your planes, what size would you want it to be? We can either copy the PC680 for example, or we can design a case to the exact dimensions you want. Also, if you could have the capacity you wanted, what would that be? The aircraft lead acid market uses batteries that are designed for 80% depth of discharge. The Odyssey PC680 is a 16 amp hour battery and at 80% DOD, you have 12.8 amp hours to use. Our lithium batteries in the ETX36 batteries are an actual 12 ah and you can use 100% of it's capacity, which is less capacity than the PC680 by .8amps. But the cost of a lithium battery goes up with the amount of amp hours, so keep that in mind with your "wish" list on what you would like for your planes but anything can be done! But we listen to what you all say and work on developing a battery designed 100% towards aircraft use but at this moment in time, it is not a perfect replacement.
 
Y(snip)
That being said, if we were to have a case designed just for your planes, what size would you want it to be? We can either copy the PC680 for example, or we can design a case to the exact dimensions you want. Also, if you could have the capacity you wanted, what would that be? (snip)

Given that there are at least hundreds if not thousands of the PC 680 batteries in service, the form factor has become as much of a "standard" as we get in experimental aviation. I would suggest an exact copy of the case, including the terminals. This would make the battery a "drop-in" replacement for most.

As far as capacity, there are two major goals: engine starting and the ability to operate critical electronics reliably for an extended time.

Our starting loads are probably higher (peak current) than most of your current "motorsports" market. The ability to perform multiple start attempts, even in cold weather, without damaging or depleting the battery is important.
The low "self-discharge" rate of the LiFePo is a big plus.

As for the electronics, i think most would like to see the battery able to supply 8-10 amps at 11 volts or better very reliably for more than an hour, even towards the end of its service life.
 
James hit the nail on the head.

A PC680 sized battery would be perfect. You then might offer a couple different capacities in that size: ETX36 and maybe an ETX48 with 33% more capacity if it would fit.

Thanks!
Russ
 
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