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CAUTION! LiFePO4 Battery Capacity!
I've had a couple of different topics recently on the Aerovoltz/Ballistic LiFePO4 batteries and also on alternator wiring connectors overheating. I just got some information from EarthX that is very interesting.
What I've found out is this: While the 12-cell Aerovoltz/Ballistic (same battery - different brand names) is easily capable of starting my Jabiru 3300, it only has a capacity of maybe 3 amps. Therefore, the battery gets pulled down quickly by the starter, and the Jabiru does not produce charging current until it hits 1900 rpm. That means all the electrical systems during taxi, run-up, etc. are running on battery only. (The Jab has dual magnetos so it doesn't depend on the battery once started.) During take-off and revving the engine beyond 1900 rpm, there is a sudden in-rush of alternator current to replenish the battery. Lithium batteries naturally have low internal resistance and allow the in-rush of current. I've been told the "20 amp" alternator might actually be putting out as much as 32 amps!
Technical support at EarthX said my 12-cell Ballistic was seriously under-sized in terms of capacity. He said my previous Odyssey PC680 had about 12.8 amps capacity. An EarthX ETX36D has 12 amps of capacity and was what he recommended. It's roughly the same size as the PC680, so it'll fit my battery box, and only weighs 3.5 lbs - 1 lb more than the 12-cell Ballistic. He assured me this would work well in my application and eliminate the in-rush of current from the alternator.
An added plus is that the EarthX has an on-board battery management system to balance charge the cells, prevent over and under charge, and protect the battery from excessive charging current.
So ... lesson learned - consider the capacity of the battery when choosing one for your application!
BTW, EarthX has great customer service and technical support - they quickly got me information I needed!
(Looks like the Ballistic moves to my '84 Honda Nighthawk!)
John
N750A
Replies to This Discussion
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Permalink Reply by Louis W. Ott on
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Hi John,
I bought a Shorai LFX18L1-BS12 battery and the special charger for it. Significant $$$ spent. I was ready to install it in place of my present Odyssey PC680 when the recent discussion of the LiFePO4 batteries came up here. Although the Shorai should have been adequate for starting the engine I hadn't thought about the max charging rate. That is only 8 amps. Probably not enough. I did some more research and checked on the EarthX web site for their specs. I agree that their ETX36 series should make a good replacement for the PC680 and will give about equal amp/hr rating of the PC680 with more cranking amps too. The 60 amp max recharge rate won't be exceeded by my charging system either. I feel a lot better about using this EarthX battery than the Shorai. The Shorai isn't all a waste as it will go in my Triumph Bonneville. The EarthX customer service was pleasant to deal with as you mentioned. I'll save about 11.5 lbs weight over the PC680 and that is important in my Miss Piggy 601XL-B.
Thanks for the info.
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Permalink Reply by John Austin on
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I just installed the ETX36D today. It's a smidge thicker than the PC680, slightly less wide and slightly less tall, but close. It fit in the battery tray I had originally built for the PC680 without a problem. Too windy to fly comfortably today! My Ballistic is going to my Honda Nighthawk, but I wish I had a Bonneville to put it in! ;>)
John
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Permalink Reply by Mark Maltais on
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Just looking over these EarthX batteries. I was looking into a Aerovoltz type but these are interesting. If I'm reading the specs right they don't need a balance charger since the BMS circuit is built right in! That would be a lot more convenient.
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You're correct, Mark - no external balance charger required. They also have built-in protection from over-discharging (such as leaving the master on, which can kill a lithium battery!) and protection from being charged at too high a voltage. There's nothing wrong with the Aerovoltz/Ballistic, but apparently it would take a 24-cell (which I don't think they make!) to match my previous Odyssey's PC680 capacity. I don't think the balance charging is such a chore - you only need to do it a few times a year and I was going to do it at oil changes - but I just decided "to heck with it" and give the much more expensive EarthX a try - believe me, you'll hear if it doesn't go well! Ha!
John
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Update -
I've now got a few hours on the EarthX ETX36D and it has been trouble-free! The alternator connections look good with no signs of overheating and my 20 amp alternator breaker quit tripping. Apparently the increased capacity of the ETX36D has stopped the in-rush of alternator charging current and that has solved my problems - I'll certainly let you know if otherwise!
John
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Permalink Reply by Walt Snyder on
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Thanks, John, I'll look for those signs of a problem with the Pulse and post if there are any issues.
Walt Snyder
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That's good to hear! I just ordered the 36C last week. Should be getting it in a few days! :)
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I finished replacing my PC 680 battery with an EarthX 36D. I took some pictures during the install which may help if you are considering this. The EarthX people were very helpful answering any question I had. My aircraft is a 601XL B.
This is a post EarthX made on another forum with more information on their batteries. EarthX is the only LiFePo4 manufacturer that appears to be going after the experimental aircraft market.
"Just thought I would put some links in here so you can easily review what the manufacturer's manuals are putting out there for technical data. We are working with Bob Nuckolls among other professionals to provide the information that is geared toward aircraft as well as power sports so you can make an educated choice in which battery is best for you.
This is for Shorai: http://shoraipower.com/installation-guides
This is for Ballistic's: they don't have a manual that I could find after searching their website, this is the most technical piece of data they have: http://www.ballisticparts.com/tech/charging.php
This is for EarthX:http://earthxmotorsports.com/wp-cont...l_111017_G.pdf
We also have on the Experimental aircraft page, a direct comparison of the Odyssey battery and the EarthX battery so you can see for yourself the differences and what would be the best fit for your use. Sometimes we are better, and sometimes we are not, depending on the model and we list them all so you know what you are gaining or losing. Here is that link: http://earthxmotorsports.com/product...ntal-aircraft/
And I do realize we are a competitor of Shorai, but I can't help but point out they specifically point out in their warranty that use in aircraft is not covered.
Here's that link: http://shoraipower.com/Customer-Service.html
And this is a total plug for our batteries, I apologize in advance, but we are only patent pending technology battery in this market that has over discharge, over charge and cell balancing built into our battery. You do not need a special charger in order to balance the charge/discharge of the cells and this also ensures that while your charging system is charging the battery, it is doing so evenly. And if you read ALL of our competitor's warranties, if you over discharge or over charge their battery it is not covered. Other than cost, the other down fall of a lithium battery is they are much less tolerant to being over discharged or overcharged than a lead acid and doing it one time, you can kill the battery. This type of protection and safety built into our batteries was not an option in our opinion, but a requirement.
Kathy (EarthX)"
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I had to make very minimal modifications to fit the ETX36D where the PC680 used to go. About all I had to do was remove a foam strip on the battery retaining strap to accommodate the slightly thicker ETX36D and I also used some of the supplied self-adhesive foam pads to elevate the battery slightly so it would clear the upturned lip of the battery support. Here's a pic:
John
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I joined the club! :)
Here's a good size comparison with my old battery!
Hoping to crank her over on the weekend for first time!!! :D
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I went the way of the Full Spectrum Pulse 3, and I'll post how it goes. Aircraft Spruce carries them, and it supposedly can handle the Rotax 912 no problem, so we'll see. It's amazing how small and light they are. The have a pretty good website for questions.
Walt Snyder
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Permalink Reply by Randy Boykin on
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I was looking at the manual for these batteries and was wondering what the difference in the 36 C,D & E are besides the size. Does anyone know?
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