VansAirForceForums  
Home > VansAirForceForums

-POSTING RULES
-Advertise in here!
- Today's Posts | Insert Pics

Keep VAF Going
Donate methods

Point your
camera app here
to donate fast.

  #31  
Old 07-08-2015, 01:08 PM
ppilotmike's Avatar
ppilotmike ppilotmike is offline
 
Join Date: Jan 2010
Location: Denver, CO
Posts: 1,991
Default

Quote:
Originally Posted by EarthX Lithium View Post
when the battery is drained to about 98%, there is an electrical switch that opens so it can not be drained down to the point of destroying the cells or compromising their stability.
Kathy,

Regarding your "save the battery" switch routine: Could you give us a breakdown of how would this would play out in an in-flight emergency situation (loss of alternator), when the pilot would depend on the battery to support the essential bus for as long as possible?

I'd hate to think that the battery would "switch off" to save itself, but by doing so, would limit the duration that power would be available to operate essential equipment; especially if an electrically driven pump were part of that list.
__________________
Mike Rettig
EAA Chapter 301 www.eaa301.org
VAF Dues Current
RV-10 - Working on engine / prop installation
http://www.mykitlog.com/users/index....ig&project=803
F-14 (Pedal Plane - Daughter's Project) "Flying"
https://www.youtube.com/watch?v=zKCyX2FXrlw
Reply With Quote
  #32  
Old 07-08-2015, 01:16 PM
schristo@mac.com's Avatar
schristo@mac.com schristo@mac.com is offline
 
Join Date: Sep 2007
Location: WA
Posts: 993
Default Finally... something I want to buy ;)

Pre-Oshkosh news has been really slow... finally something shows up that makes me want to spend money
__________________
Stephen

RV7 powered by a lycoming thunderbolt IO-390
turning a whirlwind HRT prop

with more hours flying than building... 2,450 on the hobbs!
ORCA Flight
Race 771
margarita!
Reply With Quote
  #33  
Old 07-08-2015, 01:37 PM
EarthX Lithium EarthX Lithium is offline
 
Join Date: Feb 2014
Location: Windsor, CO
Posts: 258
Default

Quote:
Originally Posted by ChiefPilot View Post
Absolutely not true. If it were, a couple of non-EarthX LiFePO4 batteries I am aware of wouldn't still be working. I've accidentally left my master on, and after recharging my non-EarthX brand LiFePO4 battery it provided the same level of reserve as it did previously.

While it's awesome that EarthX is seeking opinions and such from VAF, information such as this crosses the line into FUD - "Fear, Uncertainty, and Doubt".
Just to clarify as I am not wanting to cross the line into "FUD" territory, I do not know exactly the time frame you had this happen, but if you leave a lithium battery discharged below 9V for even a few hours, they are permanently damaged. If you have the voltage dip below 9V for seconds, that is a different situation.

The amount of damage can vary, but they are damaged. (A fantastic site for information is Battery University). For all lithium's, including EarthX, if you over discharge them below a certain voltage, they are damaged. This is why all other brands do not cover the battery for a warranty if under their stated lowest voltage level in their policy. Some void the warranty at 12.8V (Shorai and Aerovoltz). As wonderful as a lithium battery can be, just like a lead acid they have cons as well. Over discharging them is one of them.

So I 100% stand behind my comments, but I will clarify it. If you over discharge a lithium battery past 9V for an extended period of time, you have compromised the performance and safety of the chemistry and I would not use it again.

Kathy
__________________
Fly Lightly,

Kathy
Reply With Quote
  #34  
Old 07-08-2015, 01:46 PM
EarthX Lithium EarthX Lithium is offline
 
Join Date: Feb 2014
Location: Windsor, CO
Posts: 258
Default

Quote:
Originally Posted by ppilotmike View Post
Kathy,

Regarding your "save the battery" switch routine: Could you give us a breakdown of how would this would play out in an in-flight emergency situation (loss of alternator), when the pilot would depend on the battery to support the essential bus for as long as possible?

I'd hate to think that the battery would "switch off" to save itself, but by doing so, would limit the duration that power would be available to operate essential equipment; especially if an electrically driven pump were part of that list.
Dear Mike,

This is an excellent question and one of the reasons why the capacity rating is so important to know for whatever battery you are using. If you are in flight and your alternator fails, you are then using whatever capacity you have in your battery to operate your instruments until you can land. If you are going to use "X" amounts of amps, then you need to know how long before you use up your capacity. For example, you are on battery power only, you are using 6 amps of energy/hour for your instruments. In this situation, you would have 2 hours to land your plane if you are using a 12 amp hour capacity battery. If it would take you longer than 2 hours to find a place to land, you will run out of capacity and have no power left in this battery. If you are really flying distances that you do not have the ability to land within a certain period of time, a back up alternator is an excellent idea and so is a back up battery. It's the same kind of situation if you run out of gas too. When it's empty, it is empty.

Kathy
__________________
Fly Lightly,

Kathy
Reply With Quote
  #35  
Old 07-08-2015, 01:50 PM
ChiefPilot's Avatar
ChiefPilot ChiefPilot is offline
 
Join Date: Jan 2005
Location: Twin Cities, MN
Posts: 1,576
Default

Quote:
Originally Posted by EarthX Lithium View Post
So I 100% stand behind my comments, but I will clarify it. If you over discharge a lithium battery past 9V for an extended period of time, you have compromised the performance and safety of the chemistry and I would not use it again.
After being discharged for >5 hours, the battery was recharged and was able to supply the same amount of reserve performance as measured by measuring the time it could power a subset of installed equipment until the voltage dropped to 10 volts. So there is at least one data point that is in conflict with your opinion.

Again, this was on a non-EarthX battery. Perhaps the EarthX batteries can be more easily damaged if they go below 9 volts; I do not know as I have never tested one.
__________________
Brad Benson, Maplewood MN.
RV-6A N164BL, Flying since Nov 2012!
If you're not making mistakes, you're probably not making anything
Reply With Quote
  #36  
Old 07-08-2015, 02:04 PM
erich weaver's Avatar
erich weaver erich weaver is offline
 
Join Date: Aug 2006
Location: santa barbara, CA
Posts: 1,712
Default

Quote:
Originally Posted by ChiefPilot View Post
Absolutely not true. If it were, a couple of non-EarthX LiFePO4 batteries I am aware of wouldn't still be working. I've accidentally left my master on, and after recharging my non-EarthX brand LiFePO4 battery it provided the same level of reserve as it did previously.
Damage to lithium batteries due to over discharge is pretty well known and goes well beyond "FUD" or just being Kathy's opinion. What say you let us in on the brand and model of lithium battery that supposedly doesn't have this trait so that others can independently evaluate your claim? We all want to buy the best product, right?

erich
Reply With Quote
  #37  
Old 07-08-2015, 02:13 PM
ChiefPilot's Avatar
ChiefPilot ChiefPilot is offline
 
Join Date: Jan 2005
Location: Twin Cities, MN
Posts: 1,576
Default

Quote:
Originally Posted by erich weaver View Post
Damage to lithium batteries due to over discharge is pretty well known and goes well beyond "FUD" or just being Kathy's opinion. What say you let us in on the brand and model of lithium battery that supposedly doesn't have this trait so that others can independently evaluate your claim? We all want to buy the best product, right?

erich
Shorai LFX18L1-BS12, installed as I documented in this thread.

I'd also point out that this is the same battery as this thread started with and was about until EarthX made the claim that "Shorai specifically says not to use in an aircraft". I was unable to find any such claim on the Shorai website - the closest I could find was their warranty statement "Applications Not listed on the Shorai website product finder such as: Aircraft, Automotive, Motive power (LFX as main power source, not engine starter)" as found here. This seems different than what EarthX claims. For reference, the shorai site was searched via Google using "site:shoraipower.com aircraft" as the search string.
__________________
Brad Benson, Maplewood MN.
RV-6A N164BL, Flying since Nov 2012!
If you're not making mistakes, you're probably not making anything

Last edited by ChiefPilot : 07-08-2015 at 02:36 PM.
Reply With Quote
  #38  
Old 07-08-2015, 04:19 PM
ppilotmike's Avatar
ppilotmike ppilotmike is offline
 
Join Date: Jan 2010
Location: Denver, CO
Posts: 1,991
Default

Quote:
Originally Posted by EarthX Lithium View Post
For example, you are on battery power only, you are using 6 amps of energy/hour for your instruments. In this situation, you would have 2 hours to land your plane if you are using a 12 amp hour capacity battery.
Kathy,

So, for your "amp/hour" capacity ratings, you have taken into account the moment at which your switch trips over, thus turning the battery "off," instead of using the theoretical curve all the way to zero. Correct?
__________________
Mike Rettig
EAA Chapter 301 www.eaa301.org
VAF Dues Current
RV-10 - Working on engine / prop installation
http://www.mykitlog.com/users/index....ig&project=803
F-14 (Pedal Plane - Daughter's Project) "Flying"
https://www.youtube.com/watch?v=zKCyX2FXrlw
Reply With Quote
  #39  
Old 07-08-2015, 04:25 PM
EarthX Lithium EarthX Lithium is offline
 
Join Date: Feb 2014
Location: Windsor, CO
Posts: 258
Default

Quote:
Originally Posted by ppilotmike View Post
Kathy,

So, for your "amp/hour" capacity ratings, you have taken into account the moment at which your switch trips over, thus turning the battery "off," instead of using the theoretical curve all the way to zero. Correct?
When the battery turns "off" the capacity is drained to approximately 98% and there isn't much of anything left in there at that point anyway. This discharge curve for a lithium is very different than a lead acid. (We have it listed on our website in multiple places for you as well) but the switch turns off when the "tank" is almost completely empty. Do you know at what voltage your instruments need in order to operate?

Kathy
__________________
Fly Lightly,

Kathy
Reply With Quote
  #40  
Old 07-08-2015, 04:47 PM
RVDan RVDan is offline
 
Join Date: Jun 2012
Location: Frederick, MD
Posts: 897
Default

The way it works is that the rated capacity ends before the battery reaches the minimum voltage cutoff. So, if you need the rated AH for emergency power you will get it, unless the battery is experiencing a failure.

Earthx has data published to support this that is consistent with other industry data for this cell chemistry.
__________________
Dan Morris
Frederick, MD
PA28-140
Hph 304CZ
RV6 built and sold
N199EC RV6A flying
Retired Aerospace Engineer and A&P/IA
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 08:12 PM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.