Why are airplane batteries terrible?

[RobertGary1]

19 hours ago, Igor_U said:

Years ago my dad had a 2nd car at the vacation place... it would often have a weak or flat battery after few weeks or month sitting idle.

Eventually he disconnected the clock and it never happened again. It turned out stock clock would drain it; perhaps being bad. YMMV.

All flood batteries also have internal resistance. They will go dead if let to sit on their own.

-Robert

[PT20J]

8 hours ago, RobertGary1 said:

All flood batteries also have internal resistance. They will go dead if let to sit on their own.

-Robert

Not to be nit picky, but...

The "internal resistance" of a battery is the series resistance. But you are correct in that all batteries have a self discharge rate -- some chemistries hold a charge longer than others.

Skip

[Ragsf15e]

On 9/11/2019 at 1:17 PM, ArtVandelay said:

I have to replace the battery anyway, so when I disconnect the battery, I will hook up my multimeter and do some definitive testing. In theory the master relay should prevent this.
The only parasitic circuits bypassing the relay is the cabin switch and possibly the clock keep alive circuit, yes?


Tom

And on mine, those “keep alive” circuits connect to a hot terminal on the master relay so it’s pretty easy to see what is connected or at least to disconnect everything and see what dies (clock, baggage light, etc).  You’ve gotta have a gremlin, I’ve had similar good Concorde experience in tough climates (both hot and cold) with no tender and I only fly 2 or 3 times a month sometimes.

[corn_flake]

@Austintatious  While lithium-ion batteries is far superior to lead-acid (Pb) battery, it does requires a rather sophisticated battery management system (BMS) to avoid thermal run away.  Such system isn't heavy in weight.  But, since everything in aircraft requires redundancy, I would only be comfortable to use Lithium-ion battery in a aircraft if there is dual BMSs or preferably duel lithium-ion battery with independent BMS for each battery.  I will also require individual ejection system for each battery in the event of fire.   . At the end, it's probably simpler and light to just use Pb battery.  

@RobertGary1  Beside CCA, there is also reserved capacity.   Comparing CCA alone doesn't tell the while picture.  For aviation battery, we also need to make sure avionic continues to run in the event of engine failure or generator failure.  As a general rule of thumb, mfg can build battery with hight CCA by using lead plate with lots of contact surface.  This will allow the battery to have high CCA value while maintaining the same size and weight.  The same design will have lousy reserved capacity.  In order to add reserved capacity, heavier lead plate will need to be used.  Aviation batteries try to strike a balance between CCA and reserved capacity.  This is also the reason why golf cart batteries are stupid heavy.  They only care about reserved capacity.  

 

[Sandman993]

On 9/7/2019 at 5:20 PM, PTK said:

I just replaced my Concorde RG-35-AXC after 11 years of service. Always on the batteryminder when airplane is in the hangar.

Be careful if there are field mice about... they will crawl up the cord and have a great time crapping in the airplane and possibly chewing on wires. I recommend using a shop rag to be stuffed in the opening of the access door. 
 

it’s almost time to start using those Engine oil heaters again, winter is approaching. Need something for that cord too. 
 

they do offer a spearmint rodent deterrent for inside the fuselage that’s supposed to be a good way to keep em out. Supposedly rodents cannot tolerate the smell of spearmint. Look to your local feed stores for that solution.

Am a big fan of battery tenders... a properly maintained lead acid battery should last 5 years... while some go longer, everything past 5 is a bonus. 

[Oldguy]

33 minutes ago, Sandman993 said:

Be careful if there are field mice about... they will crawl up the cord and have a great time crapping in the airplane and possibly chewing on wires.

And this is one of those "never thought about it" things for me.

Thanks!

[Austintatious]

On 10/14/2019 at 3:06 PM, corn_flake said:

@Austintatious  While lithium-ion batteries is far superior to lead-acid (Pb) battery, it does requires a rather sophisticated battery management system (BMS) to avoid thermal run away.  Such system isn't heavy in weight.  But, since everything in aircraft requires redundancy, I would only be comfortable to use Lithium-ion battery in a aircraft if there is dual BMSs or preferably duel lithium-ion battery with independent BMS for each battery.  I will also require individual ejection system for each battery in the event of fire.   . At the end, it's probably simpler and light to just use Pb battery.  

@RobertGary1  Beside CCA, there is also reserved capacity.   Comparing CCA alone doesn't tell the while picture.  For aviation battery, we also need to make sure avionic continues to run in the event of engine failure or generator failure.  As a general rule of thumb, mfg can build battery with hight CCA by using lead plate with lots of contact surface.  This will allow the battery to have high CCA value while maintaining the same size and weight.  The same design will have lousy reserved capacity.  In order to add reserved capacity, heavier lead plate will need to be used.  Aviation batteries try to strike a balance between CCA and reserved capacity.  This is also the reason why golf cart batteries are stupid heavy.  They only care about reserved capacity.  

 

Corn Flake.... I did not say LIthium ION....  I said Lithium IRON /  LI FE... this is completely different that  Lithium ion.  There IS NO thermal runaway.. in fact Lithium Iron (FE) is the MOST stable battery technology we have. 

 

It is VERY light

It requires NO sophisticated management (although for extended none use it is preferable to connect them to a charger designed for them )

They are high capacity and high current, especially considering their weight ( on par with lithium ion)

Edited October 17, 2019 by Austintatious

[jaylw314]

51 minutes ago, Austintatious said:

Corn Flake.... I did not say LIthium ION....  I said Lithium IRON /  LI FE... this is completely different that  Lithium ion.  There IS NO thermal runaway.. in fact Lithium Iron (FE) is the MOST stable battery technology we have. 

 

It is VERY light

It requires NO sophisticated management (although for extended none use it is preferable to connect them to a charger designed for them )

They are high capacity and high current, especially considering their weight ( on par with lithium ion)

I don't recall that LiFe batteries had significantly better energy density than other lithium batteries.  IIRC, charging them is a little wonky because you can't tell their state-of-charge from voltage, unlike all other lithium batteries, so they are tricky to keep multiple cells in series balanced.  In addition, they lose charge while idle faster than other lithium chemistries.

Still, the resistance to thermal runaway is a big deal, and it will be interesting to see if they make any inroads in the auto and commercial aviation industry.  The faster self-discharge will likely limit their use in GA, though...

[Austintatious]

4 minutes ago, jaylw314 said:

I don't recall that LiFe batteries had significantly better energy density than other lithium batteries.  IIRC, charging them is a little wonky because you can't tell their state-of-charge from voltage, unlike all other lithium batteries, so they are tricky to keep multiple cells in series balanced.  In addition, they lose charge while idle faster than other lithium chemistries.

Still, the resistance to thermal runaway is a big deal, and it will be interesting to see if they make any inroads in the auto and commercial aviation industry.  The faster self-discharge will likely limit their use in GA, though...

Do you have any experience with LiFe batteries ?

I do as I use one in my glider.    I never said they had better energy density than  other lithium batteries... only than Lead acid.

They can be stored for YEARS if put in the store voltage range.  

Yes, there is a special charger for them that will slow charge them.  However I charge mine regularly with a normal car battery charger as allowed by the manual.  

There are lots of motorcycles running around with them.

[jaylw314]

5 minutes ago, Austintatious said:

Do you have any experience with LiFe batteries ?

I do as I use one in my glider.    I never said they had better energy density than  other lithium batteries... only than Lead acid.

They can be stored for YEARS if put in the store voltage range.  

Yes, there is a special charger for them that will slow charge them.  However I charge mine regularly with a normal car battery charger as allowed by the manual.  

There are lots of motorcycles running around with them.

Yes, I tried them out as alternatives to LiPo's when I was messing around with RC helicopters and hexacopters.  In the end, it was the cost differential (which may be less now) and the difficulty assessing their SOC that made me decide against them.  There is a sizeable disadvantage in many applications of not being able to quickly measure the SOC.  Think of how often you look at your battery meter on your smartphone...

I admit I did not see significant self-discharge over time in that application, it's just a theoretical thing AFAIK

[Austintatious]

Just now, jaylw314 said:

Yes, I tried them out as alternatives to LiPo's when I was messing around with RC helicopters and hexacopters.  In the end, it was the cost differential (which may be less now) and the difficulty assessing their SOC that made me decide against them.  There is a sizeable disadvantage in many applications of not being able to quickly measure the SOC.  Think of how often you look at your battery meter on your smartphone...

I am not quite sure that smaller versions such as for RC helis are a fair comparison for the larger versions for vehicles. 

[jaylw314]

3 minutes ago, Austintatious said:

I am not quite sure that smaller versions such as for RC helis are a fair comparison for the larger versions for vehicles. 

True.  I think that scaling up usually produces additional unforeseen problems or magnifies existing problems, aka Boeing 787...

If you need to balance 4 LiFe cells in a 12V vehicle, the difficulty balancing 8 LiFe in a 24V vehicles magnifies the problem even further.

[Austintatious]

11 hours ago, jaylw314 said:

True.  I think that scaling up usually produces additional unforeseen problems or magnifies existing problems, aka Boeing 787...

If you need to balance 4 LiFe cells in a 12V vehicle, the difficulty balancing 8 LiFe in a 24V vehicles magnifies the problem even further.

I just dont believe this is an issue for the batteries I am talking about... here is a link to battery car for Shoria batteries.

https://shoraipower.com/dl-377291/TopTipsSheet-032015.pdf

They say as long as you are using the battery in a vehicle that has no draw when not in use, you will only need to use the special charger once per year.  They also give advice for starting in sub freezing weather.  They can be stored for VERY long periods of time. 

Here is a link to one that is 34 amp hr with 540 cranking amps  https://shoraipower.com/lfx36l3-bs12-p130

it weighs like 6 lbs!  You could have 2 of these in parallel and have 1100 cranking amps with 68 amp hours... for 12 lbs... what do concord batteries weigh?

 

Here is a blurb on the chemistry

A lithium-iron battery is also a rechargeable type of battery but made with lithium iron phosphate (LiFePO4) as the cathode material.

While lithium-iron is a newer version in the lithium battery family, its anodes are also made up of carbon in batteries.

Phosphate based technology possesses superior thermal and chemical stability which provides better safety characteristics than those of Lithium-ion technology made with other cathode materials. Lithium phosphate cells are incombustible in the event of mishandling during charge or discharge, they are more stable under overcharge or short circuit conditions and they can withstand high temperatures without decomposing. When abuse does occur, the phosphate based cathode material will not burn and is not prone to thermal runaway. Phosphate chemistry also offers a longer cycle life.

Lithium Iron Phosphate (LiFePO4 ) characteristics:

•         Most stable
•         Good density
•         Long life
•         Economical

 

Maybe I need to think about getting an STC to put them in various aircraft.  Could do the industry a ton of good

 

 

Edited October 18, 2019 by Austintatious

[bradp]

On 9/10/2019 at 7:25 PM, Hank said:

My first Concorde went seven years, split almost half and half between WV and much warmer AL. New Concorde just turned three, doing great. 

Do not own, have never used and would not recognize a battery minder . . . .

The previous owner replaced Gill batteries every other year. When it died a year after I bought the plane, I got a Concorde AGX for extra CCA, living where winters were pretty cold (for a Southern boy!). 

Today was my first cold start in about 7 years that the Concorde battery was a little sluggish.  Might either desulfate and try to see if it can be revived or just say thank you for the reliable seven years of service and get a new Concorde. 

[larryb]

Today was my first cold start in about 7 years that the Concorde battery was a little sluggish.  Might either desulfate and try to see if it can be revived or just say thank you for the reliable seven years of service and get a new Concorde. 

Sounds like you got good service. I would buy a new one. You don’t want to be stranded away from home with a bad battery.

[jaylw314]

2 hours ago, bradp said:

Today was my first cold start in about 7 years that the Concorde battery was a little sluggish.  Might either desulfate and try to see if it can be revived or just say thank you for the reliable seven years of service and get a new Concorde. 

I had some problems with a cold start when it was about 40 degF out last week.  My wife has been taking flying lessons, so I took the time to point out that batteries don't put out as much current when they're cold.  Then I realized the throttle had been all the way closed for some reason.  When I opened it a little and tried again it started on the first turn.  I felt a little embarrassed.