Experience with Lithium Iron Phosphate Glider batteries?

At 00:01 20 May 2016, Dave Springford wrote:
I have been using the factory installed Strobel solar system on my 29
with
=
K2 batteries for the past 4 years without issue. The Strobel controller
wa=
s designed for Lead-acid chemistry and the K2's "can" be charged by
lead-ac=
id chargers due to their lower output voltage. That being said, the
13,75
=
Volt output of lead-acid systems won't charge the LiFePo to it's full
capac=
ity that needs 14.6 V.


David,
Find yourself a good electronics hobbyist who understands charging
circuits,
it should be a simple job to tweak the regulator voltage so it fully
charges
your LiFe battery, (provided the circuitry is not encapsulated or potted)
however if you do this then CLEARLY mark it as modified because it will
potentially kill SLA batteries after a short time, if you were in the UK I
would
offer to look at this for you, however posting it to and from the US is
impractical.
Ben.

On Friday, May 20, 2016 at 11:15:08 AM UTC-7, Benedict Smith wrote:
At 00:01 20 May 2016, Dave Springford wrote:
I have been using the factory installed Strobel solar system on my 29
with
=
K2 batteries for the past 4 years without issue. The Strobel controller
wa=
s designed for Lead-acid chemistry and the K2's "can" be charged by
lead-ac=
id chargers due to their lower output voltage. That being said, the
13,75
=
Volt output of lead-acid systems won't charge the LiFePo to it's full
capac=
ity that needs 14.6 V.


David,
Find yourself a good electronics hobbyist who understands charging
circuits,
it should be a simple job to tweak the regulator voltage so it fully
charges
your LiFe battery, (provided the circuitry is not encapsulated or potted)
however if you do this then CLEARLY mark it as modified because it will
potentially kill SLA batteries after a short time, if you were in the UK I
would
offer to look at this for you, however posting it to and from the US is
impractical.
Ben.

14.0V will be sufficient to fully charge a LiFePO4 battery. 14.6 will do it faster, but is a little harder on them. 13.8 won't get them to fully charged. Yes, I know what the specs say from the retailers, but I have also seen the test results. You do not what to "float" charge a LiFePo4 battery, but if you are using an SLA charger that floats at 13.6 or 13.8 it won't harm them, because charging will be effectively terminated at float voltage.

thanks Ben,

I've thought of that too, but I don't know if the Stobl has an adjustable voltage regulator or if everything is all sealed up. I need to look under the panel. In the meantime, it keeps the batteries going for longer than I can fly in a day!

On Wednesday, May 18, 2016 at 7:05:57 PM UTC-7, Brian wrote:
Would like to go to a K2 style battery, but have a 10 watt solar panel on the glider. I have yet to get a good answer on how to connect the solar panel to the battery. The BMS would probably prevent overcharging, but haven't got anything that says this is acceptable or what kind or charge controller would work with significantly reducing the charging capability.

Any Ideas?

Brian


Brian,

A 10w solar panel isn't much information. What are the Voltage and Amps?
You probably don't even need a charge controller if your attempting to fly with your Solar Panel hooked up to the battery. Your draw from equipment will be greater than the panels ability to charge it.

Find out what the charging voltage of the battery is and make sure you have something inline to keep the voltage going to the battery at that or less.

10w won't keep up with demand but should help extend the life while flying.

I'm not an electrical expert so take everything above with a grain of salt.

I did start a Lawn Care company using all electric equipment and solar panels on the trailer to keep them topped up.

John

It typically runs about 500ma, about 12.8 volts depending on battery (lead acid ) status.

In flight it definitely not and issue, demand is about 750ma.
However on the ground between flights is the concern where there is no demand. That is the big advantage of the solar panel, as it can top off the battery for the next flight, I rarely have to remove the battery.

I only run the panel on the ground when flying almost daily, otherwise the airplane is in a trailer.
I don't run any controller with the lead acid batteries as it takes a couple days of not flying to get the voltage up over about 14 volts.

Brian

On Wednesday, May 18, 2016 at 5:49:09 PM UTC-7, SF wrote:
Glad to hear the positive responses. As far as the questions regarding the K2's vs. less expensive batteries. I can't answer those questions except that small businessmen like soaring suppliers, operating in a small market, with small margins don't generally sell problem merchandise for very long. The alternate battery choices were not available to me when I was purchasing and evaluating.

The Lithium Iron Phosphate chemistry, gives you a lithium battery that will not supply it's own oxidizer in the case of a thermal event (fire), like the lithium ion batteries that are featured in laptop, hover board, and cell phone fire videos. Batteries that supply their own oxidizer are next to impossible to extinguish once they get going, so the battery chemistry choice is important.

That being said, these things contain a lot of energy. dump that out all at once, or treat them poorly, and bad things happen. So an internal battery management board (BMS) to prevent under and over charging is a really good idea. Most BMS boards also equalize the cells to improve charging and battery capacity. Some batteries can be purchased with and without them, so pay attention to what you are getting. The board should be internal so you can't look at a battery and see if it has a BMS board or not.

Buy a charger appropriate for your battery. Don't save money by attempting to re-purpose your old SLA battery charger.

The lithium Iron Phosphate batteries seem expensive unless you consider the life cycle cost. They are usually given a 2,000+ charge/discharge cycle lifetime. My limited experience with SLA batteries indicates that 200 cycles is about all they are good for.

Install an appropriately sized fuse (125% of the normal load is usually ok) as close to your battery terminals as possible. Then do a good job of protecting everything from the terminals to the fuse. My personal preference is to puddle hot melt glue over the terminals encasing them in a thick non conductive difficult to dislodge coating, and installing an automotive type blade fuse on the battery. Good insulated wire ( aircraft rated insulation, also a fire thing), and liberal use of heat shrink tubing can protect the rest. It's not pretty after I finish with it, but its not going to short out either.

I switched to Anderson PowerPole connectors after hearing the HAM radio guys rave about them. After you buy the crimper and watch a online video on how to use it, they are pretty slick connectors. I put hot melt glue in the open end of them to stress relieve the internal crimp connector when someone pulls on the wire instead of the connector.

12V isn't a lot to begin with, Use a wire at least one size larger than you think you need. The only penalty for larger wire is it's increased weight and size which is not usually much of a factor for the typical glider installation. Unless you don't put a fuse near you battery, in that case, your plan is to use the wire as a fuse, so use a small wire size in that instance.

If you don't know what you are doing around this kind of stuff, then get someone else that does to help. These things contain a lot of energy and they can dump it out in a hurry, so be careful. One of my electronic techs shorted out a lithium battery, and we had to evacuate a 200,000 Sq Ft manufacturing facility. No fire, but an impressive amount of foul smelling smoke. The firemen were impressed.

SF

I took the easy (but more expensive) way out by buying the Walter Dittel battery box and mounting plate when I upgraded my battery mount. When I got the glider it had a box that only came halfway up the sides of the battery, the connectors were simple spade lugs which had to be slid on to the batter terminals and there was a simple strap over the top to hold it in. There was also no fuse or breaker at the battery itself. The Dittel box can only hold a PS1270 size battery but if that's the size you're going to use it's pretty damn good overall. The DIN connector (The Germans love those things don't they?) is kind of Mickey Mouse but aside from that I can't think of anything that would improve it. Someone years ago in my club came up with the idea of gluing a plastic project box over top of the terminals of the club batteries which both protects the terminals and provides a mounting point for the connector socket and fuse or breaker. They also used 3 pin XLR connectors - unconventional but I have to say that they seem to work perfectly. Power Poles are fantastic connectors too.

On Tuesday, May 17, 2016 at 9:58:47 AM UTC-7, SF wrote:
During the winter of 2009 I was bored, and aggravated with the sealed lead acid batteries that I was using in my sailplane. They didn't hold the voltage above 12v for very long, they needed replacement every few years, and I had one die 5 miles away from the airport at the end of a 300K badge flight. My argument that I had 2,000 FT over final glide at that point didn't sway the FAI from rejecting that flight for my badge attempt.

My search at the time led me to the K2 (Lithium Iron Phosphate chemistry)batteries that were the subject of my spring of 2010 battery article in Soaring.

Reaction to the article was mixed, and a partial retraction was printed the following month after an FAA DER (Designated Engineering Reviewer)with experience in certifying Lithium Ion batteries for some type of usage in commercial airliners, objected to the use of Lithium Iron Phosphate batteries in sailplanes because they hadn't been certified for that use by the FAA.

It's now 2016, and I see a lot of K2 batteries in other sailplanes. Soaring supply companies in the U.S. seem to be providing K2 batteries or a similar battery from a different manufacturer on a regular basis. The K2 battery I purchased in 2009, and it's twin purchased a year later, are still providing power to my sailplane without incident. There seems to be no degradation in performance, and other than switching to Anderson Power Pole connectors, I have not made any changes to my battery set up.

Has anyone out there had an issue with the usage of Lithium Iron Phosphate chemistry batteries in sailplanes?

Just curious because, a lot of dire consequences were predicted after my article came out.

SF


Here is a link to a comparison I ran three years ago for new K2 9.8Ah LiFePO4 batteries versus Powersonic 10.5Ah SLA batteries (these are the ones that are slightly taller). I used a programmable battery tester that permitted me to simulate normal base load plus occasional radio transmissions. My caseload in around an amp IIRC.

You can see the K2 batteries have a flatter and longer discharge profile. I repeated the test after three years of use for the K2 batteries. I didn't notice any significant degradation in capacity. Note that the flat profile means both that normal "capacity remaining" indications on your soaring instruments will not be accurate (at all - even if you have an option for LiFePO4 the flat voltage profile makes it challenging to estimate). Also, if you set a voltage threshold for a low battery warning it normally indicates that you have perhaps 10-15 minutes left because of the steep falloff, so you need either to be more vigilant or slave two batteries together (I use diodes to separate the batteries - just in case). For most people who don't have panels that draw an amp or more, don't talk incessantly on the radio and/or don't to 8-hour flights, capacity ought not be a problem.

https://drive.google.com/drive/folde...U9Mem5QcTBMQnM

9B

On Wednesday, May 18, 2016 at 4:58:47 AM UTC+12, SF wrote:
During the winter of 2009 I was bored, and aggravated with the sealed lead acid batteries that I was using in my sailplane. They didn't hold the voltage above 12v for very long, they needed replacement every few years, and I had one die 5 miles away from the airport at the end of a 300K badge flight. My argument that I had 2,000 FT over final glide at that point didn't sway the FAI from rejecting that flight for my badge attempt.

My search at the time led me to the K2 (Lithium Iron Phosphate chemistry)batteries that were the subject of my spring of 2010 battery article in Soaring.

Reaction to the article was mixed, and a partial retraction was printed the following month after an FAA DER (Designated Engineering Reviewer)with experience in certifying Lithium Ion batteries for some type of usage in commercial airliners, objected to the use of Lithium Iron Phosphate batteries in sailplanes because they hadn't been certified for that use by the FAA.

It's now 2016, and I see a lot of K2 batteries in other sailplanes. Soaring supply companies in the U.S. seem to be providing K2 batteries or a similar battery from a different manufacturer on a regular basis. The K2 battery I purchased in 2009, and it's twin purchased a year later, are still providing power to my sailplane without incident. There seems to be no degradation in performance, and other than switching to Anderson Power Pole connectors, I have not made any changes to my battery set up.

Has anyone out there had an issue with the usage of Lithium Iron Phosphate chemistry batteries in sailplanes?

Just curious because, a lot of dire consequences were predicted after my article came out.

SF

I'm flying with the 19amphr Shorai LFX 19 battery - rated capacity is closer to 6 or 7 amp-hr but very lightweight and the avionics love the 13.8 volt nominal output. Very happy with is on 5-6 hr flights, running LX Nano3, S80, Transponder Mode A & C, radio and 8" mounted Galaxy tablet. Nil problems except of the regulatory type - I understand various manufacturers are specifying LiFePO4 batteries now so I imagine the Aviation Authorities will ahve to deal with this issue at some time. Currently looking to double up this battery for true 10hr plus potential although a 20amp-hr would be ideal from another manufacturer. Look for some kind of UN spec - I think it is UN38.2 specification.

Cheers,
Andy
New Zealand

This one: 19.8 AH, same size at the 18 to 19 AH lead acid used in Schleicher ASH26E. You will need to get the charger from them too.

http://www.batterypete.com/batteries...ery-lfp128198/

bumper

On Thursday, December 1, 2016 at 6:43:11 PM UTC-8, wrote:
On Wednesday, May 18, 2016 at 4:58:47 AM UTC+12, SF wrote:
During the winter of 2009 I was bored, and aggravated with the sealed lead acid batteries that I was using in my sailplane. They didn't hold the voltage above 12v for very long, they needed replacement every few years, and I had one die 5 miles away from the airport at the end of a 300K badge flight. My argument that I had 2,000 FT over final glide at that point didn't sway the FAI from rejecting that flight for my badge attempt.

My search at the time led me to the K2 (Lithium Iron Phosphate chemistry)batteries that were the subject of my spring of 2010 battery article in Soaring.

Reaction to the article was mixed, and a partial retraction was printed the following month after an FAA DER (Designated Engineering Reviewer)with experience in certifying Lithium Ion batteries for some type of usage in commercial airliners, objected to the use of Lithium Iron Phosphate batteries in sailplanes because they hadn't been certified for that use by the FAA.

It's now 2016, and I see a lot of K2 batteries in other sailplanes. Soaring supply companies in the U.S. seem to be providing K2 batteries or a similar battery from a different manufacturer on a regular basis. The K2 battery I purchased in 2009, and it's twin purchased a year later, are still providing power to my sailplane without incident. There seems to be no degradation in performance, and other than switching to Anderson Power Pole connectors, I have not made any changes to my battery set up.

Has anyone out there had an issue with the usage of Lithium Iron Phosphate chemistry batteries in sailplanes?

Just curious because, a lot of dire consequences were predicted after my article came out.

SF

I'm flying with the 19amphr Shorai LFX 19 battery - rated capacity is closer to 6 or 7 amp-hr but very lightweight and the avionics love the 13.8 volt nominal output. Very happy with is on 5-6 hr flights, running LX Nano3, S80, Transponder Mode A & C, radio and 8" mounted Galaxy tablet. Nil problems except of the regulatory type - I understand various manufacturers are specifying LiFePO4 batteries now so I imagine the Aviation Authorities will ahve to deal with this issue at some time. Currently looking to double up this battery for true 10hr plus potential although a 20amp-hr would be ideal from another manufacturer. Look for some kind of UN spec - I think it is UN38.2 specification.

Cheers,
Andy
New Zealand

Shorai uses a sort of lead acid "starting battery" AH equivalent rating as their batteries are intended for motorsports and are popular for use in motorcycles. The cell spacing is optimized for high current for short periods. Other LiFePO4's are made that are optimized for storage and have a more moderate current demand capability - often limited by an on-board BMS (battery management system), and the AH rating on this type would be more in keeping to the Pb batteries traditionally used in gliders. With a a few additional advantages, more cycles, lighter weight/higher power density, and voltage doesn't drop off during discharge (until the end!) etc. Some, like the CTC brand I posted earlier, have a storage AH rating and can also deliver enough current for short periods to be used for the starter on the Wankel engine on my ASH26E.