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  #131  
Old 02-25-2014, 04:29 PM
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grayforge grayforge is offline
 
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Welcome Kathy! I'm glad you made it through the aviation questions. It's smooth sailing from here. :-)
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  #132  
Old 02-25-2014, 04:37 PM
BillL BillL is online now
 
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Quote:
Originally Posted by EarthX Lithium View Post
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!
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  #133  
Old 02-26-2014, 09:51 AM
EarthX Lithium EarthX Lithium is offline
 
Join Date: Feb 2014
Location: Windsor, CO
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Default 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.
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  #134  
Old 02-26-2014, 11:32 AM
nucleus nucleus is offline
 
Join Date: Sep 2006
Location: Bozeman, Montana
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Talking 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.
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  #135  
Old 02-26-2014, 12:03 PM
EarthX Lithium EarthX Lithium is offline
 
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Location: Windsor, CO
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Default 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.
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  #136  
Old 02-26-2014, 02:06 PM
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CharlieWaffles CharlieWaffles is offline
 
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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?
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  #137  
Old 02-26-2014, 02:51 PM
EarthX Lithium EarthX Lithium is offline
 
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Location: Windsor, CO
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Default 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.
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  #138  
Old 02-26-2014, 03:11 PM
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TangoPapa TangoPapa is offline
 
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Location: Ponte Vedra, FL
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Default 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.
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  #139  
Old 02-26-2014, 03:58 PM
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grayforge grayforge is offline
 
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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
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  #140  
Old 02-26-2014, 04:49 PM
EarthX Lithium EarthX Lithium is offline
 
Join Date: Feb 2014
Location: Windsor, CO
Posts: 257
Default 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.
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