Experience with Lithium Iron Phosphate Glider batteries?

On Tuesday, May 17, 2016 at 10:36:21 PM UTC-7, Jonathan St. Cloud wrote:
What are the differences between the K2 battery offered for $145 and the generic lifepo4 offered for $95, besides price?

An appropriate battery contains a BMS that has overcharge and undercharge protection, and cell balancing. Some of the cheaper batteries do not have a BMS or have a less featured one.

I also use the Starkpower for instruments and a CTC for engine start, have had no problems in several years.

On Wednesday, May 18, 2016 at 7:24:20 AM UTC-7, jfitch wrote:
On Tuesday, May 17, 2016 at 10:36:21 PM UTC-7, Jonathan St. Cloud wrote:
What are the differences between the K2 battery offered for $145 and the generic lifepo4 offered for $95, besides price?

An appropriate battery contains a BMS that has overcharge and undercharge protection, and cell balancing. Some of the cheaper batteries do not have a BMS or have a less featured one.

I also use the Starkpower for instruments and a CTC for engine start, have had no problems in several years.

And some less expensive ones do have the BMS with a more featured one.

Richard
www.craggyaero.com

On Tuesday, May 17, 2016 at 12:58:47 PM UTC-4, 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 switched to the K2 batteries a year before Scott wrote the article since I was weight-challenged in my H301. These batteries held up very well with no sign of degradation at all.
I now fly a two-seater and have two of them in parallel to power all the essentials like a small fridge, espresso machine and a massage cushion and they still show 12V+ after a long flight!

Uli

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

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

On Wednesday, May 18, 2016 at 8:05:57 PM UTC-6, 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

Bioenno Power 12V/24V, 10A Solar Charge Controller for LiFePO4 Batteries (SC-122410T)
Availability: In stock
$39.99
Bioenno Power 12V/24V, 10A Solar Charge Controller (Model SC-122410T) is a versatile controller for solar systems, that can charge LiFePO4 (Lithium Iron Phosphate) batteries! This solar controller accepts either 12V/24V input from solar panels and can handle up to 10 Amps. The solar controller provides a regulated voltage output for charging 12V or 24V LiFePO4 batteries. The solar controller also provides a regulated 12V or 24V output for electrical loads (depending on whether a 12V or 24V battery is used). Solar controllers are required for all solar systems in order to maintain a regulated output voltage to charge batteries and for maintaining a regulating output voltage for loads.

Best. #711.

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

https://www.bioennopower.com/pages/o...solar-products

Richard
www.craggyaero.com

https://www.bioennopower.com/pages/o...solar-products

Richard
www.craggyaero.com

Thanks Richard, I have looked at these before but a 10amp controller seems a bit large for my 600ma panel. A 1amp controller would seem more appropriate.
This one may work just fine, but I can't find any data on power loss or efficiency of the controller. If it draws 200ma, that is a 30% loss for my small solar panel.

Brian

On 5/19/2016 12:48 PM, Brian wrote:
Thanks Richard, I have looked at these before but a 10amp controller seems
a bit large for my 600ma panel. A 1amp controller would seem more
appropriate.
This one may work just fine, but I can't find any data on power loss or
efficiency of the controller. If it draws 200ma, that is a 30% loss for my small solar panel.

Your 200 MA guess might be very high! The 12-amp controller for my
little home solar system (Xantrex C-12) draws only 7 MA when charging
and 3 MA at night. That is data that should be included in any solar
controller specification sheet.

Actually, if your controller drew 200 MA 24/7, then your solar system
could be a net loss with that panel, because on a daily basis you are
lucky to get more than a few hours of equivalent full-sun power from any
solar panel. Also note that a solar panel only delivers its rated
output under a very specific set of conditions. If all of those
conditions don't simultaneously exist (which is almost always) then you
get less. Probably much less!


Still, charging lead acid batteries without a controller (as you state
later in the thread) is a chancy proposition. I've seen lots of
perfectly good lead acid batteries ruined by overcharging.

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 was designed for Lead-acid chemistry and the K2's "can" be charged by lead-acid 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 capacity that needs 14.6 V.