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-   -   My new LiFePo battery... (https://vansairforce.net/community/showthread.php?t=115447)

comfortcat 07-19-2014 06:26 PM

My new LiFePo battery...
 
I have the standard firewall mount from Van's for the PC680 but I want to use the new LiFePo Shorai LFX18L1-BS12 battery in my plane.

Many posts discuss the value of the swap, so I'll not discuss that here. Instead, I want to show how I got it to fit.

I bought a big hunk of styrofoam, and cut a piece 2 3/4 x 7 1/8 X 2 3/4 (These are approximate measurements, some trimmimg required). I placed the Shorai centered on top and drew a line around the base. Using a RotoZip tool, I cut an indentation 3/8" deep, Volia! Perfect fit and can use the same hold down.



And here is the best part! My hanger partner (who built a really nice RV-7) will make this my introductory lesson for fiberglassing! We will glass the block, and seal the foam from solvents.


deene 07-19-2014 07:01 PM

Suggest that you trim a little (1/32") off all surfaces and then fiberglas the surfaces of your foam block. Spacer will last much longer.

Arlen 07-19-2014 07:35 PM

So.....in that thread that ran for about 3 years concerning LiFePo batteries, there was much discussion about charging these batteries.

I couldn't figure out if there was a consensus of opinion amongst the 247 posts in that thread.

Are these safe with our usual alternator charging systems? Can one use a trickle charger back in the hangar?

BTW, thanks for your great photos here.

cubdriver 07-19-2014 08:41 PM

Battery - Trickle Charger
 
My experience is that these batteries don't need a trickle charger. You can let them sit for a year and they will only lose 10% of their power.

Used one for a couple years with an O-235 with no issues.

:cool:

comfortcat 07-19-2014 11:45 PM

Glassing the block...
 
Yup! That is what the lesson will all be about. I believe the styro will withstand the heat, but a fiberglass layer will make the entire block stronger.

Thanx!

CC

Quote:

Originally Posted by deene (Post 899200)
Suggest that you trim a little (1/32") off all surfaces and then fiberglas the surfaces of your foam block. Spacer will last much longer.


RV7Guy 07-20-2014 07:26 AM

Information has it....
 
That is a cool way to hold it. Be cautious of the foam degrading. You wouldn't want the battery to start settling.

Information has it that Shorai is going to have a drop in replacement for the 680. They will be at Oshkosh.

Regarding the charging, the charging protection circuit is in the battery. There is a balance port on the side that you use in addition to charging when not in the plane. I'm using a high end charger for my RC Lipo's and LiFe batteries to keep it charged till install.

GalinHdz 07-20-2014 08:25 AM

GREAT idea. The next step is to make a mold, mass produce them and sell the fiberglass box as a conversion kit for this application.

;)

F1R 07-20-2014 10:10 AM

Great adapter block. Alternatively one could use a block of wood and drill it full of holes for weight reduction and air circulation.

comfortcat 07-20-2014 11:53 AM

Yup!

Thought about wood, but had the styrofoam in the hanger (and wanted the fiberglass lesson)

This guy also used UHMW plastic:

http://www.vansairforce.com/communit...eferrerid=1843


Quote:

Originally Posted by F1R (Post 899336)
Great adapter block. Alternatively one could use a block of wood and drill it full of holes for weight reduction and air circulation.


Mike S 07-20-2014 01:15 PM

It is not a hard thing to fiberglass this, but may I suggest that you radius the outer corners so the glass can form over it without lifting. The other way to do it if you really want square corners is to glass only one side of the corner, then cut and dig out the foam back at a 45* angle-----make it a quarter inch or so wide, and build up the corner with flox then add the glass on the other side.

I would make the inner well oversize and then use some foam rubber to hold the battery snugly in place, and at the same time give it a bit of vibration damping

SHIPCHIEF 07-20-2014 04:15 PM

What Mike & everyone else said. Plus:
Save some more weight;
Cover the foam with packing tape before you put on the fiberglass.
Once the fiberglass outer shell has set up, drill holes in it (top & bottom) and melt out the foam with some acetone. Drill big 'lightening' holes in it. Pick out the tape remnants.
Then you will have a hollow skeletonized fiberglass support box. Still plenty strong for such a light battery.
But really! the foam will do the job. In fact, you could take a drill & band saw and cut out a lot of the blue foam until all that remains is some support ribs in the bottom and 4 corner support / guides.
You did pick the LiFePO4 to reduce weight, right?
PS; I just remembered Dan Horton's study on fire wall protection. Fiberglass, Blue foam and wood are all flammable, and might not be the best choice forward of the firewall. If you are going to use these materials, use the least amount possible, and consider the effect of it burning away (example: hot battery tilts and shorts against structure)

sailvi767 07-20-2014 10:57 PM

You might also want to consider if the type of foam used will produce toxic fumes in the event of a overheat.

George

Bevan 05-15-2015 11:51 AM

Quote:

Originally Posted by RV7Guy (Post 899314)
Information has it that Shorai is going to have a drop in replacement for the 680. They will be at Oshkosh.

Any word if Shorai actually is intending to produce a drop in replacement for the PC680? and when?

Bevan

RV7Guy 05-15-2015 01:16 PM

Not now
 
Quote:

Originally Posted by Bevan (Post 983108)
Any word if Shorai actually is intending to produce a drop in replacement for the PC680? and when?

Bevan

Talked to them today. They said they don't have plans to do that right now. I sensed they were a little nervous about the airplane application. The Shorai LFX36-L3-BS12 is the closest in size. I did not take the time to compare the EarthX product but will be looking at them too.

Shorai L 6.55" W 3.39" H 6.10" Weight 4.96 lbs $396

Odyssey L 7.27" W 3.11" H 7.55" Weight 15.4 lbs $115-$130

EarthX Lithium 05-15-2015 04:03 PM

Shorai specifically says not to use in an aircraft....yet people do
 
Quote:

Originally Posted by RV7Guy (Post 983128)
Talked to them today. They said they don't have plans to do that right now. I sensed they were a little nervous about the airplane application. The Shorai LFX36-L3-BS12 is the closest in size. I did not take the time to compare the EarthX product but will be looking at them too.

Shorai L 6.55" W 3.39" H 6.10" Weight 4.96 lbs $396

Odyssey L 7.27" W 3.11" H 7.55" Weight 15.4 lbs $115-$130

Thank you Darwin for contacting EarthX today and I had a chance to read through this thread.

I find it very important to point out that Shorai not only does not recommend their batteries for aircraft use verbally, but also specifically mention not to use the batteries in aircraft in writing on their website, and also exclude any type of warranty coverage if used in an aircraft. They have no manual, no discharge curves, no parameters for use and most importantly, no protection. They do not protect from over discharge, over charge, short circuit, nor even have cell balancing built in. They have lithium cells in a plastic case which might be good enough for a motorcycle where you just pull over, but they go out of their way to say not to use them in aircraft and yet there is people still doing it. If a manufacturer knows they do not have a safe product for this type of application and warn you not to use it, you are most definitely doing it at a risk. The physical size of a battery fitting in a battery box should not be the determining factor on if you should use it.

EarthX does not only have a website with a dedicated experimental aircraft section, but we also currently have 11 OEM aircraft manufacturers that have qualified the ETX series of batteries through their own R & D departments and are using them in the factory built planes or kits. We have manuals, parameters, and warranty coverage for this application. Not all batteries are created equal.

Kathy

EarthX Lithium 05-15-2015 04:11 PM

Wrong company
 
[quote=RV7Guy;899314]
Information has it that Shorai is going to have a drop in replacement for the 680. They will be at Oshkosh.

I do believe there is a mix up on companies here. Shorai does not market nor attend any aircraft shows and they are not going to Oshkosh. But, EarthX at www.earthxmotorsports.com does and the rumors are right! We really do listen to you and love to see you at the shows with your thoughts and ideas and we are coming out with some new products. One is going to be a new model, the ETX680 and you guess it, it will be a drop in replacement for the PC680. :)

Kathy

Bevan 05-16-2015 03:11 AM

Thanks for the clarification Kathy!

Can you say when the 680 replacement will be available?

I will be needing a battery by mid June.

Bevan

RV7Guy 05-16-2015 06:36 AM

Last year.
 
[quote=EarthX Lithium;983165]
Quote:

Originally Posted by RV7Guy (Post 899314)
Information has it that Shorai is going to have a drop in replacement for the 680. They will be at Oshkosh.

I do believe there is a mix up on companies here. Shorai does not market nor attend any aircraft shows and they are not going to Oshkosh. But, EarthX at www.earthxmotorsports.com does and the rumors are right! We really do listen to you and love to see you at the shows with your thoughts and ideas and we are coming out with some new products. One is going to be a new model, the ETX680 and you guess it, it will be a drop in replacement for the PC680. :)

Kathy

Last year they were indeed intending on being at Oshkosh and they were planning on getting into the market. Obviously their business plan changed.

Thanks for quickly answering my emails. I'll be buying my EarthX soon.

EarthX Lithium 05-16-2015 07:21 AM

PC680 Replacement
 
Quote:

Originally Posted by Bevan (Post 983256)
Thanks for the clarification Kathy!

Can you say when the 680 replacement will be available?

I will be needing a battery by mid June.

Bevan

Hi Bevan,

We have been working on the model diligently since the Vans Forum here asked so kindly about wanting this. We developed the Quick Connect cable after Oshkosh last year when builders/pilots asked for it and this new model is expected to be released and ready by mid June. http://www.vansairforce.com/communit...lies/smile.gif

Kathy

Bevan 05-16-2015 09:11 PM

Thanks Kathy,

Do you have preliminary specs for the 680?

Approximate price?

Can you take an advance order?

Bevan

EarthX Lithium 05-18-2015 04:04 PM

ETX680 specs
 
Quote:

Originally Posted by Bevan (Post 983406)
Thanks Kathy,

Do you have preliminary specs for the 680?

Approximate price?

Can you take an advance order?

Bevan

Hi Bevan,

Sorry not yet but the moment we have all the details, we will let you know. We do not have the exact price yet but it will be slightly higher but we will offer it at an introduction rate of $349 for a limited time.

Kathy

EarthX Lithium 06-10-2015 01:52 PM

Mandatory Service Bulletin from Rotax
 
One of our aircraft manufacturers sent this alert to us today and thought it was important information to pass on. It was a mandatory alert sent out on May 29, 2015 by Rotax concerning the use of lithium batteries in aircraft.

What I found exciting and interesting is they actually copied verbatim from our spec's and website the features the BMS must have to be approved.

Here is a copy of the alert:
NEW RELEASE
MANDATORY
ROTAX 912i (series)
ALERT SERVICE BULLETIN:

"The use of lithium-ion batteries in combination with the ROTAX Engine Type 912 i Series"
ASB-912 i-005iS
ROTAX 912iS & 912iS Sport aircraft engines are approved for operation with lithium-ion batteries if the aircraft has been equipped with a suitable battery management system (qualified by the aircraft manufacturer).

This requirement has been specified in the 912 i (series) installation manuals since Edition 1 Revision 2. The purpose of this bulletin is to bring this to the attention of users of engines delivered with earlier (Rev.0 or Rev.1) versions of the installation manual.

This is a MANDATORY alert service bulletin, and users of lithium-ion batteries should verify that their battery includes a suitable battery management system BEFORE THE NEXT FLIGHT.


WHY USE A BATTERY MANAGEMENT SYSTEM?
Lithium batteries are fundamentally different than lead-acid batteries. If overheated or overcharged, Li-Ion cells are prone to accelerated cell degradation and can catch fire or even explode. The lithium cells inside the battery need electronics to monitor and balance the voltage & charge level of the individual cells.

Some older types of lithium batteries require an external balancing charger, which you have to plug in periodically to ?top off? and balance the cells. These kinds of batteries are NOT approved.
The more modern lithium batteries have a built-in microprocessor Battery Management System (BMS) that continuously monitors the charge level of each cell and balances the charge when needed, protecting the cells from overcharge or over-discharge. Some can also provide short circuit protection, and excessive cranking protection.

Typically, the individual cells in a battery have somewhat different capacities and may be at different levels of state of charge (SOC). Without balancing, the cell of smallest capacity is a "weak point", it can be easily overcharged or over-discharged while cells with higher capacity undergo only partial cycle. For the higher capacity cells to undergo full charge/discharge cycle of the largest amplitude, balancer should ?protect? the weaker cells; so that in a balanced battery, the cell with the largest capacity can be filled without overcharging any other (i. e. weaker, smaller) cell, and it can be emptied without over-discharging any other cell. Battery balancing is done by transferring energy from or to individual cells, until the SOC of the cell with the lowest capacity is equal to the battery's SOC.

A full battery management system (BMS) might include active balancing as well as temperature monitoring, charging, and other features to maximize the life of the battery pack.

Bottom line: if you use a lithium battery in your aircraft, make sure it includes a built-in Battery Management System.

Here is the link to the actual alert: http://legacy.rotaxowner.com/si_tb_i...912i-005is.pdf

Kathy

EarthX Lithium 07-07-2015 08:06 PM

NEW AIRCRAFT BATTERY MODELS ARE HERE!
 
As promised to the Van's forum readers, you are the first to know that the new aircraft lithium batteries are now available for pre-order on the website and they are scheduled to ship at the end of July 17th week.

All of our batteries meet the criteria set forth by Rotax to be an approved lithium battery, (and we are the only lithium battery on the market to have this approval), but what these 3 new models bring (ETX680, ETX900, ETX1200) in addition to what the other models have is:
1. Redundant electronics for the BMS board
2. LED battery fault light indicator that can also be plugged into your control panel.
3. A higher cranking, more capacity models (ETX900, ETX1200) if you need or want more.

These new models will fit into any preexisting PC680 battery box hardware and we are also going to have an aluminum battery box for sale as well on the site that is rated for 30 G Force, and 7 ounces of weight. That isn't on the site yet, but by end of tomorrow it should be there. Check it out at www.earthxmotorsports.com

Thanks Van's for all your support!

Kathy

219PB 07-08-2015 07:32 AM

Here is a question for Earth X. My 680 battery box is on the firewall side of the aircraft. Is it acceptable to mount the Earth X in this location? I know that it is hotter but this is one of the most standard locations for aircraft.

EarthX Lithium 07-08-2015 07:49 AM

Dear Paul,

The ratings on the both batteries are: the PC680 is rated to 113 deg F. The ETX680 is rated to 140 deg F. I have had many builders/pilots install the ETX series on their firewall and no one has reported any issue with this. But you are on a great forum here and I am sure many will tell you their personal experiences as well with doing this as they are very responsive.

Kathy

BillFear 07-08-2015 07:56 AM

you are taking my reasons to say no away!
 
Quote:

Originally Posted by EarthX Lithium (Post 989767)
One of our aircraft manufacturers sent this alert to us today and thought it was important information to pass on. It was a mandatory alert sent out on May 29, 2015 by Rotax concerning the use of lithium batteries in aircraft.

What I found exciting and interesting is they actually copied verbatim from our spec's and website the features the BMS must have to be approved.

Here is a copy of the alert:
NEW RELEASE
MANDATORY
ROTAX 912i (series)
ALERT SERVICE BULLETIN:

"The use of lithium-ion batteries in combination with the ROTAX Engine Type 912 i Series"
ASB-912 i-005iS
ROTAX 912iS & 912iS Sport aircraft engines are approved for operation with lithium-ion batteries if the aircraft has been equipped with a suitable battery management system (qualified by the aircraft manufacturer).

This requirement has been specified in the 912 i (series) installation manuals since Edition 1 Revision 2. The purpose of this bulletin is to bring this to the attention of users of engines delivered with earlier (Rev.0 or Rev.1) versions of the installation manual.

This is a MANDATORY alert service bulletin, and users of lithium-ion batteries should verify that their battery includes a suitable battery management system BEFORE THE NEXT FLIGHT.


WHY USE A BATTERY MANAGEMENT SYSTEM?
Lithium batteries are fundamentally different than lead-acid batteries. If overheated or overcharged, Li-Ion cells are prone to accelerated cell degradation and can catch fire or even explode. The lithium cells inside the battery need electronics to monitor and balance the voltage & charge level of the individual cells.

Some older types of lithium batteries require an external balancing charger, which you have to plug in periodically to ?top off? and balance the cells. These kinds of batteries are NOT approved.
The more modern lithium batteries have a built-in microprocessor Battery Management System (BMS) that continuously monitors the charge level of each cell and balances the charge when needed, protecting the cells from overcharge or over-discharge. Some can also provide short circuit protection, and excessive cranking protection.

Typically, the individual cells in a battery have somewhat different capacities and may be at different levels of state of charge (SOC). Without balancing, the cell of smallest capacity is a "weak point", it can be easily overcharged or over-discharged while cells with higher capacity undergo only partial cycle. For the higher capacity cells to undergo full charge/discharge cycle of the largest amplitude, balancer should ?protect? the weaker cells; so that in a balanced battery, the cell with the largest capacity can be filled without overcharging any other (i. e. weaker, smaller) cell, and it can be emptied without over-discharging any other cell. Battery balancing is done by transferring energy from or to individual cells, until the SOC of the cell with the lowest capacity is equal to the battery's SOC.

A full battery management system (BMS) might include active balancing as well as temperature monitoring, charging, and other features to maximize the life of the battery pack.

Bottom line: if you use a lithium battery in your aircraft, make sure it includes a built-in Battery Management System.

Here is the link to the actual alert: http://legacy.rotaxowner.com/si_tb_i...912i-005is.pdf

Kathy

My big one is this, what happens if I leave the master on overnight in my plane? I have believed that Lithium batteries once run all the way down are ruined. Does your BMS cover this and how does it work please? I did not see anything on the website about over discharge.

Also my plane has a separate 7.4AH backup battery, what would you recommend to replace this?

Thanks for your participation on our VAF site!

EarthX Lithium 07-08-2015 08:10 AM

Quote:

Originally Posted by BillFear (Post 996511)
My big one is this, what happens if I leave the master on overnight in my plane? I have believed that Lithium batteries once run all the way down are ruined. Does your BMS cover this and how does it work please? I did not see anything on the website about over discharge.

Also my plane has a separate 7.4AH backup battery, what would you recommend to replace this?

Thanks for your participation on our VAF site!


Dear Paul,

I must say, I do have a lot of pilots that do exactly that, leave the master switch on so you would not be the first! So what happens when this situation happens is 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. But that means the switch is open, you can not charge it up again until you reset the battery which takes about 1 second to do and we explain in detail on the website multiple ways this can be done. (FAQ section) You know the protection has been activated when you get a reading of close to 0V across the terminals. That means the circuit has been opened. Once you reset the circuit, you will see the voltage instantly jump to around 11+V as it was not actually drained to 0V.

You are absolutely correct in saying if you drain a lithium battery to below 9V, they are ruined. We are the only manufacturer to offer this feature, not only for you as a consumer to protect your investment (and how beyond frustrating it is when you realize you left a switch on to begin with but can you imagine how unhappy you would be if you ruined the battery as well) but to also protect the battery itself.

Under the documentation tab we also have the manual that will go into technical details as well for you to review.

As far as your back up battery, the ETX24C would replace the one you currently have but it has 8 amps instead of the 7.4 amps.

Thanks for the question!

Kathy

BillFear 07-08-2015 08:43 AM

Quote:

Originally Posted by EarthX Lithium (Post 996515)
Dear Paul,

I must say, I do have a lot of pilots that do exactly that, leave the master switch on so you would not be the first! So what happens when this situation happens is 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. But that means the switch is open, you can not charge it up again until you reset the battery which takes about 1 second to do and we explain in detail on the website multiple ways this can be done. (FAQ section) You know the protection has been activated when you get a reading of close to 0V across the terminals. That means the circuit has been opened. Once you reset the circuit, you will see the voltage instantly jump to around 11+V as it was not actually drained to 0V.

You are absolutely correct in saying if you drain a lithium battery to below 9V, they are ruined. We are the only manufacturer to offer this feature, not only for you as a consumer to protect your investment (and how beyond frustrating it is when you realize you left a switch on to begin with but can you imagine how unhappy you would be if you ruined the battery as well) but to also protect the battery itself.

Under the documentation tab we also have the manual that will go into technical details as well for you to review.

As far as your back up battery, the ETX24C would replace the one you currently have but it has 8 amps instead of the 7.4 amps.

Thanks for the question!

Kathy

Thanks for that, reviewed the information about restoring a battery that has shut down because of over discharge. Remember our RVs have cowls that make battery access a real pain. Ours has a charge/jump port that comes to the oil filler door. So my question is, if the battery is in shut-down mode, I can jump start the plane from a power cart. Once this is complete and the alternator is on-line, will the battery now come out of protection mode and charge back up?

ChiefPilot 07-08-2015 09:42 AM

Quote:

Originally Posted by EarthX Lithium (Post 996515)
You are absolutely correct in saying if you drain a lithium battery to below 9V, they are ruined. We are the only manufacturer to offer this feature, not only for you as a consumer to protect your investment (and how beyond frustrating it is when you realize you left a switch on to begin with but can you imagine how unhappy you would be if you ruined the battery as well) but to also protect the battery itself.

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".

EarthX Lithium 07-08-2015 12:01 PM

Quote:

Originally Posted by BillFear (Post 996524)
Thanks for that, reviewed the information about restoring a battery that has shut down because of over discharge. Remember our RVs have cowls that make battery access a real pain. Ours has a charge/jump port that comes to the oil filler door. So my question is, if the battery is in shut-down mode, I can jump start the plane from a power cart. Once this is complete and the alternator is on-line, will the battery now come out of protection mode and charge back up?

Thanks Bill for the question! We do have an quick connect permanent battery cable that you can attach to the battery and jump start or charge from this cable. At Oshkosh last year pilots did explain exactly what you mentioned here about the difficulty of reaching the battery so this cable is 20 inches long and can handle up to 400 amps. Glasair Aircraft also has this issue and has requested a 36 inch long cable so they can have it accessible in the little "trap" door they have in the control panel. (We are working on it). But you need to remember that in the event the over discharge protection has been activated, you must also charge the battery as well as reset the circuit as it switched off because it was being drained. The best way to do this is charge it back with a charger at a slow rate. All batteries do better with a slow charge. But to answer your question, can you jump if from the power cart? Yes. Can it then be recharged by the alternator? Yes, but it would be best to do it with a charger as your alternator will charge it at the max output (typically 60 amps for the RV's) and a small amp charger would be best.


Kathy

ppilotmike 07-08-2015 01:08 PM

Quote:

Originally Posted by EarthX Lithium (Post 996515)
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.:eek:

schristo@mac.com 07-08-2015 01:16 PM

Finally... something I want to buy ;)
 
Pre-Oshkosh news has been really slow... finally something shows up that makes me want to spend money ;)

EarthX Lithium 07-08-2015 01:37 PM

Quote:

Originally Posted by ChiefPilot (Post 996538)
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

EarthX Lithium 07-08-2015 01:46 PM

Quote:

Originally Posted by ppilotmike (Post 996578)
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.:eek:

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

ChiefPilot 07-08-2015 01:50 PM

Quote:

Originally Posted by EarthX Lithium (Post 996587)
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.

erich weaver 07-08-2015 02:04 PM

Quote:

Originally Posted by ChiefPilot (Post 996538)
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

ChiefPilot 07-08-2015 02:13 PM

Quote:

Originally Posted by erich weaver (Post 996595)
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.

ppilotmike 07-08-2015 04:19 PM

Quote:

Originally Posted by EarthX Lithium (Post 996591)
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?

EarthX Lithium 07-08-2015 04:25 PM

Quote:

Originally Posted by ppilotmike (Post 996630)
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

RVDan 07-08-2015 04:47 PM

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.


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