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05-18-2015, 04:32 PM
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Join Date: Feb 2014
Location: Windsor, CO
Posts: 257
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Vans Forum, we want your input!
First off, thank you all who have been supporting us over the years and adding your valuable input. We are now officially working with 11 OEM aircraft manufacturers and are endorsed and trusted by their own independent R & D testing departments! Thank you!
As this market is relatively new, there is some gray areas that we want your input with.
We would like to ask all of your for your input about the specs for a lithium iron phosphate battery. It can replace a lead acid battery, but it is not the same. To date, we have tried to write up the spec's in a comparison type language but maybe it's time to revolutionize this area.
A lead acid battery open circuit voltage (OCV) is technically 12.6V. (definition of an OCV is: Open circuit voltage (or potential) is voltage which is not connected to any load in a circuit) but we call it a 12V.
A lithium iron phosphate battery OCV is technically a 13.2V but the industry calls it a 12V so that people know they can use it as a replacement.
We are considering changing how the industry labels the batteries, or at least our batteries, and want to call the voltage 13.2V but we are afraid consumers will think they can not use it as a replacement for a 12v battery. Any thoughts?
Second question, any input on how to label the amp hours? This is an area that is all over the charts from battery manufacturer to battery manufacturer. (and marketing material as well) We want to state exactly how much amperage you have in the event you are using the battery as a deep cycle application such as when your alternator fails. We list both now, what type of equivalent amperage a lead acid battery would have for the amount of cranking power and the usable amp hour. We want to go to listing only the usable amperage but the numbers of what a lead acid might say will look much more in comparison even though it might be less as very few will list the true usable amperage. As an example, if we list the ETX680 as 12.4ah, and the PC680 list theirs as 16, but only have 12.3 usable for an hour) it is confusing. And if you compared another lead acid manufacturer, their listed 18 amp hour might only be 10 usable by design.
Look forward to hearing your input and thank you in advance!
Kathy
www.earthxmotorsports.com
Thanks Vans Forum users
__________________
Fly Lightly,
Kathy
Last edited by EarthX Lithium : 05-21-2015 at 09:56 AM.
Reason: incorrect amp hour and better explanation
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05-18-2015, 05:29 PM
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Join Date: Feb 2008
Location: Los Angeles, CA
Posts: 146
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L.A.E or L.A.Q?
How about labeling the batteries and your marketing material with a "Lead Acid Equivalent" marking something like (L.A.E 12v - 18ah) or L.A.Q might be catchier.

__________________
RV-x Planning stage
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05-18-2015, 06:11 PM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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Hi Kathy,
First, thank you for your continued efforts to provide 'apples to apples' comparisons; that's what we really need.
But...Statements like the one in your post, that a PC680 is rated at 18AH but only has 12AH usable, makes it look like y'all don't understand battery tech, at least lead-acid battery tech (though most batteries exhibit discharge curves that are similar in nature).
Lead-acid batteries typically have an ampere-hour rating that is based on a "20 hour rate". This means: how many amps the battery can supply, if the discharge is accomplished at a steady rate over a 20 hour window. Any shorter discharge window (higher discharge rate) will *always* result in a lower total AH availability from the battery. In other words, if you can get 20 AH by drawing 1 amp continuously for 20 hours, you will never be able to get 20 AH if you draw at a 20 Amp rate (you'll do good to get 45 minutes at that rate).
Here's a link to the actual specs of a PC680
http://www.odysseybatteries.com/batt...680_series.htm
And here's a link to a pdf of Odessey's performance data sheets (I think I've posted it before).
http://www.odysseybattery.com/docume...M-002_1214.pdf
Page 6 shows the discharge curve for a PC680. Note from the 1st link that the AH rating of a PC680 is 16AH; not 18AH. Looking at page 6 in the 2nd link, a 0.8 Amp continuous discharge can continue for 20 hours. 20*0.8=16AH. But if you discharge at a continuous 143 Amps, you can only do it for 2 minutes. 2/60*143=4.76AH. Your 12.8 AH usable figure apparently comes (approximately) from the line that shows a 12.3 Amp draw will last for 1 hour.
The chart and the graph give the same info, in different formats
So, if you want to provide comparable data, pick one of your battery models (the 12 AH model?). Determine the discharge rate in amps that will take your battery to the point where it (or its controller) will no longer supply usable power to the load at the end of a 20 hour window. (Odessey specifies 10.02 Volts as fully discharged.) That amp number, times 20, becomes the AH rating of the battery. Then do the same test to determine the current available over a 10 hour window. Etc, etc down (up?) to a 2 minute window. Write up a chart of the numbers, graph it, and publish it. Done.
I see no technical advantage to labeling your battery as 13.x vs 12 volts; but you might sell an extra battery or two to someone who doesn't understand the technical details, if that's a goal you'd want to embrace (I hope it isn't).
Hope that's useful info for you; it's at least what I'm looking for.
Thanks again for your efforts,
Charlie
Last edited by rv7charlie : 05-18-2015 at 09:19 PM.
Reason: clarity
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05-18-2015, 06:39 PM
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Join Date: Nov 2006
Location: Savannah, GA
Posts: 1,029
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Quote:
Originally Posted by EarthX Lithium
First off, thank you all who have been supporting us over the years and adding your valuable input. We are now officially working with 11 OEM aircraft manufacturers and are endorsed and trusted by their own independent R & D testing departments! Thank you!
As this market is relatively new, there is some gray areas that we want your input with.
We would like to ask all of your for your input about the specs for a lithium iron phosphate battery. It can replace a lead acid battery, but it is not the same. To date, we have tried to write up the spec's in a comparison type language but maybe it's time to revolutionize this area.
A lead acid battery open circuit voltage (OCV) is technically 12.6V. (definition of an OCV is: Open circuit voltage (or potential) is voltage which is not connected to any load in a circuit) but we call it a 12V.
A lithium iron phosphate battery OCV is technically a 13.2V but the industry calls it a 12V so that people know they can use it as a replacement.
We are considering changing how the industry labels the batteries, or at least our batteries, and want to call the voltage 13.2V but we are afraid consuemrs will think they can not use it as a replacement for a 12v battery. Any thoughts?
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Maybe list it as 13.2V and put (12V replacement) somewhere?
Quote:
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Second question, any input on how to label the amp hours? This is an area that is all over the charts from battery manufacturer to battery manufacturer. (and marketing material as well) We want to state exactly how much amperage you have in the event you are using the battery as a deep cycle application such as when your alternator fails. We list both now, what type of equivalent amperage a lead acid battery would have for the amount of cranking power and the usable amp hour. We want to go to listing only the usable amperage but the numbers of what a lead acid might say will look much more in comparison even though it might be less as very few will list the true usable amperage. As an example, if we list the ETX680 as 12.4ah, and the PC680 list theirs as 18, (but only have 12.8 usable) it is confusing. And if you compared another lead acid manufacturer, their listed 18 amp hour might only be 10 usable by design.
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If usable energy changes with the rate at which I'm withdrawing it (which is my understanding of what all batteries do), I don't want just one number. I'd like a graph that showed current draw on one axis and usable lifetime on the other at the specified end-of-life condition for the battery (so if the battery only has, say, 85% of its new capacity after 5 years, give me that graph, not the as-new condition). Otherwise, the number may not be conservative. I know that's not as easy to fit in a spec table, though.
The reason I mention it is that, in a modern electrically-dependent airplane, your current draw may be a lot higher than one or two amps in the event that there is a failure of the alternator(s). I'd rather see a lower figure that I know is realistic for real-world conditions than an arbitrary "standard" figure that might mislead me.
__________________
RV-7ER - finishing kit and systems installation
There are two kinds of fool in the world. The first says "this is old, and therefore good"; the second says "this is new, and therefore better".
Last edited by rmartingt : 05-18-2015 at 06:52 PM.
Reason: More details in light of new info
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05-18-2015, 07:18 PM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by enielsen
How about labeling the batteries and your marketing material with a "Lead Acid Equivalent" marking something like (L.A.E 12v - 18ah) or L.A.Q might be catchier.

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THIS! Anything else is nice for "techno-geeks" but only makes things more confusing for the vast majority of your target market.
My 2 cents.

__________________
Galin
CP-ASEL-AMEL-IR
FCC Radiotelephone (PG) with Radar Endorsement
2020 Donation made
www.PuertoRicoFlyer.com
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05-18-2015, 07:30 PM
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Join Date: Aug 2007
Location: Wichita Falls, TX
Posts: 2,182
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Could you make a lithium battery with the equivalent amp-hours rating and external dimensions of a Concorde RG25XC that has a 20lb weight embedded in it so I can keep my CG forward enough?
(now where's that smiley face emoticon with the black eye and missing teeth)
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Neal Howard
Airplaneless once again...
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05-18-2015, 08:25 PM
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Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
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Lithium batteries have a negative label because of fires that have occurred with cell phones, lap top computers and even the Boeing Dreamliner.
Successful marketing of the product to GA pilots may depend more on addressing the impression of the fire issue than comparative technical information.
Has the cause of fires been positively identified and fixed?
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
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05-18-2015, 08:25 PM
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Join Date: May 2006
Location: Pocahontas MS
Posts: 3,884
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Quote:
Originally Posted by GalinHdz
THIS! Anything else is nice for "techno-geeks" but only makes things more confusing for the vast majority of your target market.
My 2 cents.

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A lot of lithium battery makers already use that term, and that's what's wrong with their marketing. They use it to describe the battery's ability to crank an engine, which has almost nothing to do with the total *energy* in the battery. Cranking takes 3-5% of a lead acid battery's energy content. With some lithiums, it might consume 20-30%, meaning that the total energy in the lithium is much lower than the lead acid 'equivalent'.
Think Corvette with one gallon of gas vs a Civic with a full tank. The Corvette will be ahead the 1st couple of miles, but the Civic will win the race by several hundred, and move a lot more weight in the process.
Charlie
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05-18-2015, 09:03 PM
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Join Date: Oct 2012
Location: New Ulm, Minnesota
Posts: 283
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Battery safety
I'm hiding behind the lines of safety! The most powerful battery might be the lightest but if it poisons me with toxic gas or self ignites to barbeque me in flight that is a problem.
I'm sure that there are many that would like to purchase a light weight battery if they knew it was safe including me.
As far as the amp hour rating, I think most aircraft can be run on 10 amps or so in an emergency to the nearest airport. I use about 8 amps running port fuel injection, and 2 fuel pumps. I'm sure most builders look at the amp hour rating before purchasing a battery for their aircraft just for that reason, so it is important to list as much detail as possible so we can get an idea how long it will hold up.
Odyssey battery does a good job listing the details of their batteries on their web site so one can make a well informed decision.
__________________
Robin Mckee
New Ulm, MN 56073
RV3b N219BB
420 hours and counting
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05-19-2015, 08:09 AM
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Join Date: Aug 2010
Location: Wichita, KS
Posts: 1,958
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Quote:
Originally Posted by RV3bpilot
Odyssey battery does a good job listing the details of their batteries on their web site so one can make a well informed decision.
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I agree. Whether you like it or not, the Odyssey was the first sealed small form factor battery to market in RVs. There are probably close to 9,000 Odysseys flying in RVs, with more than 9k planes in the air. The Odyssey battery is (relatively) well understood and has lots of data for us to digest. So naturally, anything you do will, and must, be compared by the end user to the Odyssey.
If you really have a better mouse trap, you have to perform identical tests and publish identical data so that the masses can make a direct comparison and see for themselves that the mouse trap is better. Otherwise folks get skeptical that you're trying to baffle them with bull___.
Read the Odyssey literature (I'm sure you already have), perform the same tests, and publish the results. If some of the data doesn't make sense because the technology is different, that's fine. Publish it anyway, and then explain why it's different. The more clarity you provide, the more likely folks are to embrace your product.
Our lives can depend on our battery. We strive to make well-informed decisions, and we can't be well-informed without directly comparing data.
Unfortunately, even after all that, the entire Lithium chemistry battery industry has a long way to go to convince some of us that the technology won't kill us.
__________________
Kurt W.
RV9A
FLYING!!!
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