The inadvisability of charging LiFePO4 batteries below 32F/0C (aka below freezing)

[son_of_flubber]

When researching a step up to LiFePO4, I stumbled across this tidbit at http://batteryuniversity.com/learn/article/charging_at_high_and_low_temperatures

"Many battery users are unaware that consumer-grade lithium-ion batteries cannot be charged below 0°C (32°F). Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a sub-freezing charge. This is permanent and cannot be removed with cycling. Batteries with lithium plating are more vulnerable to failure if exposed to vibration or other stressful conditions. Advanced chargers (Cadex) prevent charging Li-ion below freezing."

Advancements are being made to charge Li-ion below freezing temperatures. Charging is indeed possible with most lithium-ion cells but only at very low currents. According to research papers, the allowable charge rate at –30°C (–22°F) is 0.02C. At this low current, the charge time would stretch to over 50 hours, a time that is deemed impractical. There are, however, specialty Li-ions that can charge down to –10°C (14°F) at a reduced rate."

The also applies to lithium battery in your phone/computer. If you should happen to leave it in a cold place, you might want to warm it up before charging.

[Dan Marotta]

Well, what immediately comes to mind is the confusion between LiFePO4 and Lithium Ion. Those are different chemistries. I used LiFePO4 and charged them over the winter months in NM (lots of zub-freezing nights) using the chargers supplied with the batteries without any problems. After a year of removing the batteries and taking them home to charge, I had the confidence to leave them installed in the glider, in the hangar, with the chargers connected and plugged in. Again, no problems with LiFePO4. YMMV.

Dan

[son_of_flubber]

On Sunday, March 18, 2018 at 11:29:30 AM UTC-4, Dan Marotta wrote:
> I used LiFePO4 and charged them over the winter months in NM (lots of zub-freezing nights) using the chargers supplied with the batteries without any problems.

Thanks for reporting your first hand experience. Maybe your charger has a temperature sensor that stops charging below 32F.

I first came across the warning in the user manual for a combination
battery_charger+battery_isolator (www.westmountainradio.com 'Epic PWRgate') This device is programmable for LiFePO4 or AGM. The device uses a temperature probe to adjust charge rate. The device does not work with other Lithium based battery chemistry.

>"West Mountain Radio Operating Manual Page 10

>Optional Temperature Probe

>The temperature probe provides valuable data for the Epic for charging. If >the temperature of the battery is too high or low on a LiFePO4 battery, the >Epic will cease charging the battery. For Lead-Acid batteries, the Epic will >adjust the charge voltage dependent on the battery temperature. This allows >for the most optimum battery charging.

>>>>>>If a probe is not used, be sure to never charge a LiFePO4 below freezing temperatures for safety reasons.<<<<<<

http://www.westmountainradio.com/pdf/epic-pwrgate-manual.pdf

[son_of_flubber]

Just to clarify. I'm NOT planning to use the West Mountain Radio Epic PWRgate to charge batteries for a glider.

(I'm looking into using the Epic for a 'house battery' in a camper van.)

[Dan Daly]

I have two 12v 9AH Stark LiFePo batteries. On their website it gives –20°C to 60°C (–4°F to 140°F) as operating limits and a charge temperature range of 0°C to 45°C (32°F to 113°F).

The capacity graphs for 25, 0, -20, -40 C ( https://starkpower.com/product/12-volt-9ah-battery ) tab at the bottom shows they're good batteries down to 0 C, but perhaps a poor choice for the real cold.

This explains the voltage drop in the Lake Placid wave... I will have to put a voltmeter readout in for the next camp. I remove the batteries for charging.

[Dan Marotta]

My batteries had built-in battery management systems (BMS) which monitor
charge level, temperature (I think), and cell balance. Maybe that was
the difference.  BTW, this is the battery I used:
http://www.tenergy.com/31383. I bought the specified charger at the same
time and, during the first year, I would check regularly by touching
both the battery and the charger and never felt a noticeable temperature
rise.  The battery was also a drop-in replacement for the standard AGM
batteries used commonly in gliders.  It was considerably lighter.

--
Dan, 5J

[Tango Eight]

On Sunday, March 18, 2018 at 1:23:04 PM UTC-4, Dan Daly wrote:

> The capacity graphs for 25, 0, -20, -40 C ( https://starkpower.com/product/12-volt-9ah-battery ) tab at the bottom shows they're good batteries down to 0 C, but perhaps a poor choice for the real cold.

They don't specify the discharge rate, and it's probably much higher than typical glider use. I've taken LFP batteries to 31,000', they worked fine.

Evan Ludeman / T8

[jfitch]

I've seen a lot of information on the web about plating of the anode in LiPo batteries, but none on LiFePo4 which use a different alloy on the anode. On the other hand, every LiFePo4 battery I have has a charge spec of >0 deg C. Does anyone have a link to an authoritative source on this?

[Jim White]

My A123 LiFePO4 battery charging document says that operating range is -50C
to +60C. Nowhere does it say that you cannot or should not charge below
0C.

Jim

[OHM Ω http://aviation.derosaweb.net]

I contacted Bienno for their Lithium Iron Phosphate (LiFePO4) Battery Model BLF-1209WS and they said the following;

The operating temperature is from -20 deg C to 60 deg C (14 deg F to 140 F). Then charge between 0 deg C to 40 deg C (32 F to 104 F)

[Dan Daly]

On Monday, March 19, 2018 at 1:20:31 PM UTC-4, OHM Ω http://aviation.derosaweb.net wrote:
> I contacted Bienno for their Lithium Iron Phosphate (LiFePO4) Battery Model BLF-1209WS and they said the following;
>
> The operating temperature is from -20 deg C to 60 deg C (14 deg F to 140 F). Then charge between 0 deg C to 40 deg C (32 F to 104 F)

I left a message for Stark, and will forward the response here.

[moshe....@gmail.com]

The manufacturers and distributors have to publish an official temperature range that will minimize their liability, and satisfy the needs of all, or most of, their customers. Funny how the round number "0C" was chosen. The electrolyte is not water and thus this temperature has no special significance. In reality both "charge" and "discharge" are fuzzy concepts. How much current? Sellers of LiFePO4 batteries used for starting engines of ATVs and such recommend not starting (a high-current discharge) below freezing. In this world where people want ever-faster charging (15 minutes, 30 seconds...), it's safer to say "charge above 0C". But various sources say that one can charge at freezing temperatures - slowly. For that matter, at temperatures only slightly above freezing, too, it's probably best to charge slowly. Personally, I charge all my batteries slowly if I can, at all temperatures. If I have all night, why force all the charge in 2 hours? Any charge rate that makes the batteries hot to touch is damaging in the long run. I always use my BC700 charger for NiMH cells (awesome device!) at its lowest charge current (200 mA). I charge the batteries I use in my glider (SLA, 4AH to 12AH capacities) at half an amp or less.

[Dan Daly]

"Hi Dan,

Both of the charts on the 12V9Ah battery page are based on 1C discharge rates.

With regards to charging below 0C, because the 12V9Ah battery is fairly small, it is always best to charge when it is above 0C. If you have been using the battery and it is just below 0C, your battery will still be above freezing internally and you will be able to charge with you 4A charger without damaging your battery.

Thank you,
StarkPower Customer Care"

[2G]

There's no confusion between LiFePO4 and Lithium Ion because LiFePO4 IS a Lithium Ion battery. Lithium Ion is a generic term that includes all lithium chemistries.
http://batteryuniversity.com/learn/article/types_of_lithium_ion

[jfitch]

There should not be, but unfortunately there is confusion, because of the loose use of the terminology. If it has lithium in it, it is a Lithium Ion battery, but beyond that there are big differences in chemistry and mechanical construction. The concern about sub zero charging has to do with plating on the anode, however each of these different battery chemistries use a different anode material. One might assume that with different anode material they would be more, or less, susceptible to the plating problem. I cannot find any scholarly paper that discusses LiFePo4 in particular, with respect to charging temps.

[Dan Marotta]

... And so is "gas".  Try putting jet fuel in your piston engine and see
what happens.  Or diesel in your car or vice versa.  I used to gas up
the jet and the King Air after a mission or flight, but I never used
avgas or mogas in any of them.

The Boeing 787 didn't use LiFePO4 batteries, either, if I"m not
mistaken.  Their "generic" lithium ion batteries had a tendency to burn
during ground charging.  Generic terms can get one killed in certain
circumstances.

--
Dan, 5J

[Charlie M. (UH & 002 owner/pilot)]

I would argue that.
If you stated "fuel", then your argument carries more weight.
I think most peeps, when they hear "gas" assume (yes, I know what that may also mean...) you mean gasoline/petrol.
When you say "fuel", yes, there can be a mix up.
Heck, coal is a fuel, don't think anyone is shoveling coal into an aircraft.....LOL.......

Yes, LiFe is a lot different than LiPo or LiOn.
LiFe is a lot closer in safety to LA than other Lithium chemistries.

[Tango Eight]

On Wednesday, March 21, 2018 at 1:10:56 AM UTC-4, jfitch wrote:

> If it has lithium in it, it is a Lithium Ion battery...

Given the different charging/discharging *requirements* associated with "LiIon" vs "LiPo" vs "LFP", that's a very dangerous statement.

T8

[jfitch]

The truth is never dangerous, but ignorance is. What people need to do is get used to saying LiPo or LiCo, or LiMn or LiFePo4 (LFP for short). The danger is in ignorance that these are different batteries. You don't charge NiCads the same as SLA the same as flooded LA do you? Yet they are all batteries. The details matter. Even in your post you imply that LiIon is different than LFP. An LFP is a LiIon (it uses a lithium compounded anode or cathode, and ions to transport current). There is a wide variety of lithium based batteries just as there is a wide variety of carbon, nickel, and lead batteries. Treat them the same at your own peril - please educate yourself.

[Charlie M. (UH & 002 owner/pilot)]

While I usually don't disagree with you, if you READ what Tango8 posted, he is saying the same thing as you.
"Lithium in the name does make it the same", as I read it.

Your thoughts?!

Yes, I am going from early (late '70's NiCads to more modern LiFe or LiOn/LiPo) rechargeables including LA of various flavors.

I have a bunch of cash tied up in chargers for various battery chemistries, mostly in RC use, but also for my main income.

Hey, hey find an issue with my read of Tango8's post, I am willing to learn, but I believe you read it wrong.

[jfitch]

I don't believe it is dangerous to refer to Lithium Ion batteries as Lithium Ion batteries. But in T8s post he said it was, and further said '"LiIon" vs "LiPo" vs "LFP"' which implies that Lithium Ion batteries are a type of Lithium Ion batteries. The semantics matter. Had he quoted my post in context (the complete sentence was "If it has lithium in it, it is a Lithium Ion battery, but beyond that there are big differences in chemistry and mechanical construction.") perhaps he would have not thought what I said dangerous. You cannot charge a LiIon battery differently than an LFP, because an LFP IS a LiIon battery. LiIon includes all the different chemistries but the members of that group differ in their associated charge requirements.

It is much better to use language precisely when the result of a misunderstanding can be an explosion and fire. If you specify an LFP charger you should get want you want. If you specify a LiIon charger you have no idea what you are going to get.

[moshe....@gmail.com]

On Wednesday, March 21, 2018 at 2:15:26 PM UTC-4, jfitch wrote:
> ... If you specify a LiIon charger you have no idea what you are going to get.

- not so in the real world. The lithium polymer (and similar) batteries that everybody now seems to have in their cellphone, laptop, etc etc, all have cells with a nominal voltage of 3.6 or 3.7, are universally referred to as "lithium ion", and can generally use any charger with that same label. (If charging one cell at a time - of course cells of unusual size or shape, and multi-cell packs, need special chargers.) A charger specific for LFP (cell voltage about 3.2) is NEVER labeled as "lithium ion".

I do have at least one charger (for small cylindrical cells) that has a switch so you can choose 3.2V or 3.7V. That's dangerous, so I've glued it on the 3.2V setting since for cylindrical cells I only use LFP, never "lithium ion". That charger is not labeled at all, only a brand name...

And that's still living dangerously, since I need to make sure not to put alkaline (1.5V) and NiMH (1.2V) cells in that charger, and not to put LFP cells in a device designed for 1.2-1.5V cells unless paired with "dummy batteries".

Modern life is way too complicated.

[Tango Eight]

On Wednesday, March 21, 2018 at 2:15:26 PM UTC-4, jfitch wrote:

Jon, you're clearly unfamiliar with the terminology as it is used out in the real world. There are many (millions) multi-mode chargers out there that use the terms as I have used them, "LiIon, LiPo, LFP". Semantics matter? Sure. Safety based on correctly matching charging cycles to chemistry matters more.

Here's a link to the instructions for a commercial charger that illustrates what I am talking about. They use the terms LiIo, and LiFe instead of LiIon and LFP.

http://www.ircha.org/sites/default/files/Digital%20Library/Bantam%20BC6.pdf

[jfitch]

I am well aware of the loose and incorrect usage of terms, and it is what I am arguing against as potentially dangerous. As I said in my second post in this thread, "unfortunately there is confusion". What exactly is the voltage and chemistry of a LiIo, or LiIon, or Lithium battery? In the real world, Google "lithium ion battery" will correctly return hits on all types, not just lithium polymer, with recommended charging voltage of between 3.2 and several hundred volts. Even in the last few of posts we have the conflation of several chemistries. The news media is horribly guilty of this, from them we know that lithium batteries cause cars and aircraft to catch fire and burn, and hoverboards to self immolate. I have been told on this very forum that lithium ion batteries should not be used in gliders because they cause Boeing 787s and Chevy Volts and Samsung S7s to burn - never mind that those batteries are quite different than the ones we use.

If I have a charger than says "LiIo" or "lithium" charger on it, that tells me little or nothing about what battery I can charge with it. This is my point. "Correctly matching charing cycles to chemistry" can only be done if the specific chemistry or voltages required are stated. "Lithium ion" is the term used for the collection of chemistries using lithium anodes or cathodes. If that is not the correct term, then what is? And why is it "dangerous" to use the correct term? And if speaking in a context where the specific chemistry dangerously matters, shouldn't the specific term be used, rather than the general?

[Andrzej Kobus]

John, I am sorry, but aren't you the one who uses unapproved, for starting, LiFePo4 batteries in your ASH-26E for engine starting? I am surprised you seem to lecture others while you do questionable things yourself, just saying.

[Dan Daly]

When I first considered moving from SLA to LiFePo batteries, I looked for knowledge and found what I consider to be a useful website:
http://batteryuniversity.com/

[jfitch]

Andrzej, the Schleicher maintenance manual (which specifies SLA batteries for both engine AND avionics) was written in 1995, and is not likely to consider a battery technology invented in 1996. Anyone flying an ASW 27 or 29 should similarly not use an LFP battery for avionics as they are not an approved type. Yet nearly every glider supply outlet sells them for this purpose, and I note that Schleicher ships LFP batteries for both start and avionics in many of their current gliders.

I'm not lecturing (or even recommending) people to use or not use anything. I educated myself on what was required and acted accordingly based on facts, not questions. I AM asking that they use precise language, where precise language is important. Schleicher does not say "use a lead battery", rather they say "use a maintenance free lead-dry-gel battery" - because installing a flooded lead acid battery on its side near your butt is a bad idea. Even then they are imprecise - the battery they call out is an AGM, not a gel and these have different charge requirements. The terminology matters.

[Tom BravoMike]

(...)

> > John, I am sorry, but aren't you the one who uses unapproved, for starting, LiFePo4 batteries in your ASH-26E for engine starting? I am surprised you seem to lecture others while you do questionable things yourself, just saying.
>
> Andrzej, the Schleicher maintenance manual (which specifies SLA batteries for both engine AND avionics) was written in 1995, and is not likely to consider a battery technology invented in 1996. Anyone flying an ASW 27 or 29 should similarly not use an LFP battery for avionics as they are not an approved type. Yet nearly every glider supply outlet sells them for this purpose, and I note that Schleicher ships LFP batteries for both start and avionics in many of their current gliders.
>
> I'm not lecturing (or even recommending) people to use or not use anything. I educated myself on what was required and acted accordingly based on facts, not questions. I AM asking that they use precise language, where precise language is important. Schleicher does not say "use a lead battery", rather they say "use a maintenance free lead-dry-gel battery" - because installing a flooded lead acid battery on its side near your butt is a bad idea. Even then they are imprecise - the battery they call out is an AGM, not a gel and these have different charge requirements. The terminology matters.

From 'Fiddler On the Roof' (not to be confused with Sean Fidler):

Tevye: He is right.
A Jew: He is right and he is right? They can't both be right!
Tevye: You know, you are also right!

[Andrzej Kobus]

John, the battery you are using was not designed for starting purposes. The CTC LFP128198 is only rated for 100 Amps for 30 sec, not as you stated in another thread at 160 Amps for 30 sec. 160 Amp is the rating of the protection circuit with is not enough in this application (http://sepbatteries.com/media/add_info/LFP128198.pdf). You are simply operating this battery at very thin safety margins. I am surprised that this does not bother you. A more appropriate solution would be EarthX battery specifically build for experimental aircraft as an engine starting battery, http://earthxbatteries.com/product-category/experimental-aircraft
Yes, it is very expensive but your life is priceless, or a better solution; or better yet the Odyssey PC680 Battery

[jfitch]

Andrzej, I appreciate your concern for me. I did misstate the spec, it is 100 amps for 30 seconds. (In a conversation with the designer, he said 150 amps for several seconds). Fortunately that is more than adequate to start the engine (I have measured the starting current, typically 80 amps for 3 seconds, and it has been routinely starting my engine for 3 years now). CTC in their marketing literature has stated that the battery is designed for engine start use. But perhaps the biggest problem I have is the characterization that this is a safety issue. It is not a safety issue. In the worst case, the battery will go into overcurrent protection and disconnect. If you are flying a motorglider in any situation where a dead starting battery is a safety issue, you need to review your flying practices. Even the ASH flight manual warns against this in section 4.5.1, "One must always be prepared for the possibility that the power plant will fail to deliver the hoped for propulsion." I love that sentence.

Second, you apparently have not looked into the specifications of the SLA battery Schleicher specifies. It is the Yuasa 18-12, the data sheet spec's a maximum discharge of 112 amps. Are they "simply operating this battery at very thin safety margins"? It is much more likely to reach that maximum than the CTC, because the internal resistance is much higher and the starter voltage lower. It is not advertised or spec'd for engine start use. The Odyssey PC680 is a TPT starved electrolyte battery and does not meet Schleicher's specification of a "lead-dry-gel battery". These batteries ARE a safety issue as they have no internal overcurrent protection and will literally melt down in a fault. There is no fault protection in the starting circuit of an ASH26.

The earthX battery does not fit in the hole. There are other LFP motorcycle "starter" batteries that will, but most do not have the same true AH capacity.

You may use whatever battery you like, but don't worry about me - I'm perfectly safe.

[Andrzej Kobus]

John, sorry to disappoint you, Schleicher does not install "lead-dry-gel batteries" in their gliders. They install AGM batteries with maximum discharge current for 5 seconds of 330 Amps. Try that with your battery. Relying on Chinese mass produced circuits for your safety is not something that I would be willing to do at these current levels. Odyssey PC680 is an AGM battery, which is the same type as the one installed by Schleicher.

[2G]

The Maintenance Manual for the 26e says "YUASA Type NPG 12-18 12 Volt 17.2 Ah, or similar." The NPG is definitely an AGM, not a gel-cell. Basically, you can't use a wet-cell for obvious reasons.

Also, the battery must be able to deliver the inrush current of the starter, which is typically 50% more than the current once running. This is essential because the running starter generates a back EMF that reduces the current draw - without it running you don't get the back EMF.

Tom

[jfitch]

The Schleicher spec is "lead-dry-gel batteries, quoted directly from the AS maintenance manual, section 2.8. I don't make this stuff up. That is not an AGM battery. They currently ship LiFePo4 batteries in a new glider. I'd like to know what you are going to do with 330 amps for 5 seconds? Arc weld with it? The starter does not draw anywhere near that, even with the propeller locked. The wires are only #6, and before than 6x#14. The rated carrying capacity of #6 is 102 amps. You will fry the wires. You will fry the switch and the solenoid and connectors. The starter will burn to a crisp. I do not wish to try that with any battery in my glider, it is exactly why I prefer the safety of the LFP with a disconnect, as opposed to a PC680 which can short circuit far more than that. I don't want to start a fire, I just want to start my engine. This isn't a "my battery is bigger than your battery" situation.

The Yuasa and Panasonic AGM batteries most are using are likely made in China, as are at least half of the electronics in your glider. The main tire and tube are made in Brazil or China, I'm a lot more concerned about that than the battery. We risk our lives everyday on Chinese mass produced circuits - where do you think the circuits in your car's ABS and air bag system come from?

[jfitch]

Right before your quote in the maintenance manual is my quote. A good case in point that precise language is important. They say gel then call out an AGM. A gel would actually not be good with their charge circuit, set too high for a gel but fine for an AGM. Or an LFP.

I'm quite aware of the inrush current, I've measured the current in real time with a 100 KHz bandwidth current probe on a 2 GHz recording oscilloscope. This is well understood engineering - we don't need to guess and speculate, we can measure.

[Andrzej Kobus]

John, again not true. Schleicher did not want to install LiFePo4 as a starting battery in my glider. I was told they will not do it for safety reason. The whole point is that you are using your LiFePo4 battery close to its design current output and you are relying on the mass produced Chinese electronics to keep you safe. That might work in a motorcycle but it is not really a good idea in an aircraft. The AGM batteries are also produced in China but they don't rely on a cheap circuit board to function properly.
The circuit in my car does not concern me in this discussion. I am not flying my car. Did you check with FAA in regards to installing LiFePo4 battery in your glider?

[jfitch]

Andrzej, you are just talking nonsense. Schleicher does install LiFePo4 batteries in gliders now (after they have been invented). My LiFePo4 is being used no closer to its design current output than the original equipment Yuasa, and then only for 2 seconds while the starter button is pressed. Read the specs. All electronic circuits are mass produced, and most of them in China. Did you check with the FAA before you put the Odyssey battery in your glider? It is a TPT AGM battery, and not similar to the Yuasa which is a traditional thick plate AGM, their characteristics are significantly different. It is not a gel which Schleicher explicitly requires.

Literally thousands of people are using LFP batteries in gliders. I'm not the first. But you need to explain to me why my safety is at risk. *** Exactly what failure mode are you concerned about?***

I'll give you a scenario for yours: the cheap Chinese cable clip used in the engine bay to secure the battery cable falls out, letting the positive battery cable fall against the engine. That short circuits the battery when the starter button is pressed, sinking 1000 amps and setting the entire wiring harness on fire, which passes right under your butt and next to the fuel tank. "Houston, we have a problem...."

I may have only "mass produced Chinese circuits" to prevent this from happening in my glider, but at least I have something.

[moshe....@gmail.com]

Can you explain what was "bad" with this battery, and can such a problem develop eventually in a good battery? I'm puzzled what would cause the fuse at the battery to blow when there wasn't a short circuit downstream.

On Friday, March 23, 2018 at 12:56:41 PM UTC-4, Jonathan St. Cloud wrote:
> Not a direct reply, but I took delivery of a brand new glider from Schleicher that had one (out of four) bad LFP battery. All the batteries are fused at the battery with circuit breaker on panel for each instrument. Kept blowing fuses. Schleicher told me they had not heard of a battery going bad, but quickly refunded monies to purchase a new battery. No problems with new battery. I have also had a NiCad runaway on a helicopter (at sunset of course in the mountains). Batteries burn really well. Life is full of risk v reward. Know your risks and reward.

[Andrzej Kobus]

Wow, don't twist my words. I said they don't install them as starter batteries, that does not mean that they don't install them in low current applications.

I did not have to check with FAA because my battery is lead acid battery of AGM type the same type Schleicher installed in my glider. Thousands of people use LiFePo4 batteries in their gliders but not as starter batteries.

If that cheap circuit of yours gets overloaded and starts fire it will be right under your body parts and releasing the starter button will not extinguish that fire in anyway.

The problem with much of your write is that it is not credible and here it is why:
In 2016 you wrote
"Not a DG, but I have been using an LiFeP04 for the engine start battery in my ASH26E for a year now. While the engine start battery can power the avionics, I have a separate (LiFePo4) battery for that. You need to find a Li battery that fits in the same spot, has charge/discharge/current protections built in, and has a max discharge capacity sufficient to crank the starter reliably. I measured the ASH starter at 150 amps stall current and 100 or so while cranking. The battery I am using is a CTC LFP128198, rated at 19.8 AH and 160 amps discharge for 30 seconds. "

This year you wrote:
"Fortunately that is more than adequate to start the engine (I have measured the starting current, typically 80 amps for 3 seconds, and it has been routinely starting my engine for 3 years now)."

Maybe you should make up your mind what the real numbers are for what the starter can take in terms of current and what the battery can deliver, because you were wrong on that too.

You were also wrong on the battery type that Schleicher puts in our gliders. I got my 31 very recently delivered in 2016 and I asked Schleicher about LiFePo4 battery for a starter. They refused to do it on the grounds of safety.

John, treat yourself to the last word on this subject because that what you need to feel better. You wore me out...

[BobW]

On 3/23/2018 5:35 PM, Jonathan St. Cloud wrote:
> I have no idea why is was "bad". I just knew that every time I took glider
> out of box fuse was melted. We checked the trailer top solar chargers with
> controllers, they were fine as was solar charger and controller in glider.
> One bad one out of bunch, replaced it no further problems.

>
>
> On Friday, March 23, 2018 at 12:28:46 PM UTC-7, moshe....@gmail.com wrote:
>> Can you explain what was "bad" with this battery, and can such a problem
>> develop eventually in a good battery? I'm puzzled what would cause the
>> fuse at the battery to blow when there wasn't a short circuit
>> downstream.
>>
>> On Friday, March 23, 2018 at 12:56:41 PM UTC-4, Jonathan St. Cloud
>> wrote:
>>> Not a direct reply, but I took delivery of a brand new glider from
>>> Schleicher that had one (out of four) bad LFP battery. All the
>>> batteries are fused at the battery with circuit breaker on panel for
>>> each instrument. Kept blowing fuses. Schleicher told me they had not
>>> heard of a battery going bad, but quickly refunded monies to purchase a

>>> new battery. No problems with new battery... <Snip>
Since this thread has drifted already...

...on the subject of "explaining battery 'badness'," ~2012 I encountered a
wet-cell SLA starter battery in a friend's car; it/she was suffering from
'intermittent/sudden deadness,' in the 'car won't start/suddenly quits
running' sense of things. Got lucky while troubleshooting, and noted the
battery's voltage suddenly halve (12.6->6.3V as I recall)...to eventually
return to 12.6V. Ultimately confirmed it started/ran-fine when DVM-showing
12.6V, and was 'quite silent' when the battery showed 6.3V (big surprise).
Since the battery was ~1yr-old from A-zone, I advised her to return it for a
new one (and don't take, "But it checks out OK on our tester," as an
acceptable - though quite possibly true - return-outcome).

Return accomplished; problem hasn't recurred in the years since then.

An EE brother said he'd never heard of such a failure (nor had AE-degreed I).

If it happens, it must be possible. 'Weird internal shorts,' weird internal
opens,' I wouldn't bet agin' either of 'em being possible...

Bob W.

---
This email has been checked for viruses by AVG.
http://www.avg.com

[2G]

Let me remind you that most Apple products are produced in China, and they generally of high quality (maybe higher than they deserve, but that is a design issue, not a manufacturing one).

The ASH26e Maintenance Manual, section 2.8 states that EITHER the YUASA (or similar) or the Sonnenshein Dryfit A212 may be used. Nowhere does it say ONLY a gel cell battery is permissible. Speaking as an electrical engineer, I consider the Odyssey PC680 to be "similar" to the YUASA in form and function. The LiFePO4 definitely is not and should necessitate a 337 STC for certificated gliders like mine, not to say that it can't be done.

Tom

[jfitch]

*** Exactly what failure mode are you concerned about?*** I'd like to know....

A "cheap circuit getting overloaded" isn't very exact. I'm not sure what you are on about Chinese mass produced electronics, for example every modern commercial airliner has them saturated throughout all of their safety systems. Your own 31 has plenty of them running the fuel injection and ignition systems. The one you seem most concerned about is the high current disconnect, this can either fail open (engine won't start, never an emergency or a panic) or closed (exactly the state your SLA battery is stuck in).

Apparently you don't understand the physics of DC starter motors, which have a direct and inverse relationship between voltage applied and current drawn. As I said in the post you quote, the LPF battery held the voltage 3 volts higher at the starter than the SLA (11 vs. 8) and the current is proportionately less.

I have never advocated anyone using any battery they don't understand or are uncomfortable with - not in that thread and not in this one. I didn't bring it up in either thread. Particularly if you don't understand the issues or characteristics of different kinds of batteries, you should stick to what the book says, and let them do the thinking for you.

[jfitch]

Tom, I can't post pictures but please read the sentence in the maintenance manual just above Types of Batteries. I quote it here directly and in its entirety: "Only mainentence-free lead-dry-gel batteries must be used as a power supply." The manual could hardly consider LiFePo4 batteries as they were invented after the manual was written.

Speaking as an electrical engineer, I consider the Odyssey PC680 to be significantly different than the Yuasa (short circuit current is twice as large for one, far greater than the capacity of any component in the circuit). But I'd have no problem using one even so. The battery I use is similar in form and function to the Yuasa, closer is specs than the PC680.

[Jim White]

When I wanted to install LiFeP04 batteries in my 27, I asked the factory
and Uli Kramer's response was as follows:

"in principle we have approved these batteries with TN 2-2008 (attached):

“3. Parts not belonging to the Minimum Equipment

• Electric equipment and its aerials may neither in themselves nor by
their mode of operation
or by their effect upon the operating characteristics of the sailplane and
its equipment
constitute a hazard to safe operation.
Every electric equipment has to be checked for reciprocal influence by
systematically
turning off and on and operating all other instruments.
The equipment and its control and monitoring devices must be arranged so as
to be easily
controllable. Their installation must be such that they are sufficiently
ventilated to prevent
overheating.“


So a battery is also an electric equipment…..

Kind regards

Uli"

TN 2-2008 applies to all Schleicher gliders.

Jim

>The ASH26e Maintenance Manual, section 2.8 states that EITHER the YUASA

>(or=

> similar) or the Sonnenshein Dryfit A212 may be used. Nowhere does it say

>O=

>NLY a gel cell battery is permissible. Speaking as an electrical
engineer,

>=

>I consider the Odyssey PC680 to be "similar" to the YUASA in form and

>funct=

>ion. The LiFePO4 definitely is not and should necessitate a 337 STC for

>cer=

[Charlie M. (UH & 002 owner/pilot)]

You're too specific, ANY circuit will draw less current at a higher nominal voltage everything else being the same. Does not matter if AC, DC, single phase, multi phase.

As to battery rating, a marginally sized battery, when new, will age and give less ampacity. As the ampacity (sometimes shown as CA-cranking amps for starter batteries) the voltage will drop more causing more heating of wires.

As to wiring, the current rating (ampacity) is based on continuous current in free air, momentary higher amperages can be handled with no ill effects.
Enclosing the wire reduces the continuous current rating since it is no longer in free air.
This part of why a smaller wire can be used for starting and yet deal with the short term inrush current as the circuit is energized. Multiple start attempts WILL start to heat the wire.

No, I'm not an EE, many years in facilities doing wiring and 15 years working with large UPS batteries.

I did stay at a Holiday Inn Express a few times though. ;-)

[Dan Marotta]

On 3/23/2018 6:21 PM, Jonathan St. Cloud wrote:
> Ended up getting stalked by mountain lion. My batteries are double fused and each instrument has a breaker.
Just another reason for always being armed while flying, as was required
by state law when I lived in Alaska.  And how do you double fuse a
battery, a switch to select one or the other?

I recall that the Saberliner 40 had the NiCd battery mounted in a lower
aft compartment which had the elevator control cables passing through. 
A battery overheat warning (read thermal runaway) was a no-shit, get it
on the ground now, situation, or death would soon follow...
--
Dan, 5J

[son_of_flubber]

> On 3/23/2018 6:21 PM, Jonathan St. Cloud wrote:
> > Ended up getting stalked by mountain lion.

Note to Tom... please add 'Catamount Evasion' to pre-solo training syllabus.

[jfitch]

Charlie, you are little too general :). A resistor (or any resistive circuit such as light bulbs, etc.) WILL draw more current at higher voltage. Most electronics these days have internal switching supplies, and will draw less current as input voltage increases, i.e., constant power. A DC motor similarly does due to back EMF, except at stall where it is (mostly) a resistive device.

The thermal constant of the wire is greatly depended on by Schleicher and others for their starter wires. They are using PVC insulated wires (not Tezel) so 100 or perhaps 120 deg (it does not say). The wires run for several feet in a very tight bundle with a bunch of others, not free air. In the engine compartment, they may be operating at elevated ambient as well. All of these affect ampacity. But they are typically energized for only a few seconds. Ampacity for wire is stated for both free and bundled cases. "Momentary higher amperages can be handled" - yes, depending. If you short circuit a #6 with 1000 amps, "momentary" is going to be very momentary, one way or another! That is one of the advantages of a proper BMS in and LPF: it will disconnect the load if shorted to protect itself, protecting the wiring as a collateral benefit.

I am a degree carrying EE, that and $5 will get me a latte at Starbucks.....:)

[jfitch]

As neither the engine nor it's battery is required equipment in an ASH26, it appears the TN2-2008 allows the installation of an LFP starter battery, provided it meets the other requirements of TN2-2008 (which it does).

[moshe....@gmail.com]

In the circuit of a strobe (flash) built into or mounted on a camera, at the moment it is triggered, the current from the capacitor (charged to about 300 volts), through a transistor and into the flash tube, is around 100 amps. The wires connecting them are amazingly thin - gauge 18 or even thinner. That works because the current pulse only lasts about a millisecond.

[Charlie M. (UH & 002 owner/pilot)]

Say what?

"Work" in an electrical circuit is volts and amps.
Double the volts, basically halve the amps.
Part of why some home equipment (eg, window AC unit) goes to 220VAC because the normal load is beyond a typical 15A breaker, maybe even beyond later 20A breakers.
Cost (buying the unit vs. running a dedicated 220VAC single phase circuit) vs. benefit.

Hmmmmm....let me think......inductive loads are a bit different. Resistive loads are fairly linear.
Coil or motor loads are on the inductive load end, they vary. They typically have an inrush current.
Resistive loads are fairly linear, they are what they are, minor variance based on temp.

OK, not arguing a field guy vs. an EE, way beyond the topic of this thread.

I will say I am looking for info about the "plating issue" in some battery chemistries, never heard that before, I may learn something new (which is a good thing......).

[jfitch]

For resistive loads, Ohms law rules: V=IR. Fixed resistance means if volts go up, current goes up. AC and inductive loads get complicated real fast. Transients are even more complicated. For things that draw power to do "work", like a DC starter motor, ignoring transients, then Power = VA, so at a fixed power if volts go up, amps go down. Inrush current on motors is actually limited because they are inductive. But stall current can be quite high as they look like a very small resistor.

It must be winter. :) I'm still looking for that scholarly paper that discusses LiFePo4 charging at low temps. Closest one I've found is a study to see how they work in a satellite, which spends half it's time on the dark side of the earth at very low temp (but doesn't charge much, there being no solar radiation....)

[kinsell]

On 03/21/2018 08:29 AM, Charlie M. (UH & 002 owner/pilot) wrote:
> I would argue that.
> If you stated "fuel", then your argument carries more weight.
> I think most peeps, when they hear "gas" assume (yes, I know what that may also mean...) you mean gasoline/petrol.
> When you say "fuel", yes, there can be a mix up.
> Heck, coal is a fuel, don't think anyone is shoveling coal into an aircraft.....LOL.......
>
> Yes, LiFe is a lot different than LiPo or LiOn.
> LiFe is a lot closer in safety to LA than other Lithium chemistries.
>

What's so funny about shoveling coal into an aircraft?

http://www.thevintagenews.com/2016/11/13/the-nazi-aircraft-fueled-by-coal/

[Martin Gregorie]

...and somewhat to my surprise, I found out that anthracite and
bituminous coals have about the same energy density (MegaJoules/litre) as
diesel, petrol or jet fuel. Less surprisingly high quality coals are
50-75% worse for specific energy (MegaJoules/Kilogram).

IOW a 'tank' of coal will have more or less the same energy content as
the same sized tank of jet fuel or diesel but will be quite a bit
heavier.


--
Martin | martin at
Gregorie | gregorie dot org

[2G]

Jon,
I saw that, and what I quoted from the manual was directly below it. The Yuasa battery is definitely not a gel-cell, yet it is listed as an acceptable battery for the 26e, so I conclude that Schleicher is not literally requiring a gel-cell. You and I may have different interpretations of the word "similar," but any AGM battery of the same form factor is similar as far as I am concerned.
Any lithium chemistry (or any non-lead-acid chemistry), however, is clearly not similar.
Tom

[jfitch]

Tom, I hear what you are saying, but I don't see that clearly. A battery that has the same AH capacity, runs at the same nominal voltages, has the same physical dimensions, produces the same load current, and runs all the same equipment seems pretty similar to me. Form, fit, and function. The specification most different is the weight. Of course "similar" can be interpreted many ways and I'm happy to have anyone run whatever battery they like. But if someone volunteers - unasked and off topic - that the battery I chose to like is dangerous, an explanation of why they think so, beyond "it might catch fire", is a fair question. The SLA might catch fire (they can and do). My engine might catch fire, my ailerons might catch fire, my hair or my pants might catch fire - better leave them on the ground too. ;) Heck, the Ilec engine controller is required equipment on the ASH26, and it's full of "Chinese mass produced circuits", could catch fire and explode....

[2G]

Jon,
I don't think Schleicher has a specification on what kind of hair the pilot can have. We were talking about compatible BATTERIES. You claimed that ONLY gel-cells were permitted by Schleicher. When I pointed out that Yuasa AGM batteries are ALSO permitted per the Maintenance Manual, you went off the deep end and starting talking about ailerons and hair! Let's get out of the Twilight Zone and return to reality.
Tom

[jfitch]

The Twilight zone is where this thread is (or should be).

My point about the Schleicher maintenance manual is that it is inconsistent. It says 'only gel batteries' AND calls out an AGM battery as permitted. Both cannot be true at once. Schleicher does not say "also".

My point about things catching fire is directed at a different respondent. If we are worried about the unlikely possibility of unexplained spontaneous combustion, there may be many targets of that worry.

Let's leave it at that.