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K2 battery endurance



 
 
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  #1  
Old May 8th 20, 08:21 PM posted to rec.aviation.soaring
John Silverberg
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Posts: 3
Default K2 battery endurance

Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them. I'm not sure how old they are but they're at least 3 years old as this is my 3rd season with the ship. Yesterday, after a little over 5 hours I got a low battery warning with the batteries at 11.3 volts. I had all the above avionics on but did virtually no transmitting on the com, just listening. They were fully charged at takeoff.

I'm not sure if this normal endurance for these batteries or not, any advice would be appreciated.

Thanks,

John S.

  #2  
Old May 8th 20, 09:18 PM posted to rec.aviation.soaring
Eric Greenwell[_4_]
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Posts: 1,939
Default K2 battery endurance

John Silverberg wrote on 5/8/2020 12:21 PM:
Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them. I'm not sure how old they are but they're at least 3 years old as this is my 3rd season with the ship. Yesterday, after a little over 5 hours I got a low battery warning with the batteries at 11.3 volts. I had all the above avionics on but did virtually no transmitting on the com, just listening. They were fully charged at takeoff.

I'm not sure if this normal endurance for these batteries or not, any advice would be appreciated.



I recommend charging each battery separately and completely, then doing a
discharge test on each battery individually at it's 20 hour rate. For example,
discharge the 10 AH battery at 0.5 amps during the test.

While the test is under way, determine the current draw of your instruments. I'd
guess it's high, and over 1.5 amps at 12.8 volts.

Once you know your current draw and the capacity of each battery, you can consider
your options.

If you decide to replace them, try to use a single 20AH battery, instead of
paralleling two 10 AH units, or perhaps a single 15AH if size matters.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
  #3  
Old May 8th 20, 09:23 PM posted to rec.aviation.soaring
[email protected]
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Posts: 465
Default K2 battery endurance

On Friday, May 8, 2020 at 3:21:11 PM UTC-4, John Silverberg wrote:
Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them. I'm not sure how old they are but they're at least 3 years old as this is my 3rd season with the ship. Yesterday, after a little over 5 hours I got a low battery warning with the batteries at 11.3 volts. I had all the above avionics on but did virtually no transmitting on the com, just listening. They were fully charged at takeoff.

I'm not sure if this normal endurance for these batteries or not, any advice would be appreciated.

Thanks,

John S.


John: At 3 years of age the batteries (I assume they are LiFePO4 type) should hold almost as much charge as new ones, assuming they were stored under reasonable conditions (not in a hot trailer). You know from your experience what is normal endurance with your avionics, so compare with that. If this is way lower than normal then that's bad news. But try recharging them and trying again, perhaps the capacity will return. Was this the first use after the winter lay-over? Some types of batteries need "exercise" after a long rest, although LiFePO4 are less prone to that AFAIK. If there is still an issue, try using one battery at a time, perhaps one is bad but the other still good.
  #4  
Old May 8th 20, 09:28 PM posted to rec.aviation.soaring
2G
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Posts: 1,439
Default K2 battery endurance

On Friday, May 8, 2020 at 12:21:11 PM UTC-7, John Silverberg wrote:
Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them. I'm not sure how old they are but they're at least 3 years old as this is my 3rd season with the ship. Yesterday, after a little over 5 hours I got a low battery warning with the batteries at 11.3 volts. I had all the above avionics on but did virtually no transmitting on the com, just listening. They were fully charged at takeoff.

I'm not sure if this normal endurance for these batteries or not, any advice would be appreciated.

Thanks,

John S.


I am not sure which K2 batteries you are using, but they are likely at the end of their life. I have all of the avionics you have, and am drawing 2 - 2.1 A at a higher voltage (meaning you are drawing even more). I put in a Bioenno 20AH lithium battery and it can handle an 8 hr flight. You should only be discharging an SLA battery no more than 50% of its capacity.

Tom
  #5  
Old May 8th 20, 09:33 PM posted to rec.aviation.soaring
[email protected]
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Posts: 9
Default K2 battery endurance

My 8 year old 9 Amp Hour K2 battery, just tested about a month ago, delivered 8.33 Amp Hours at a 1 amp rate. Capacity new was right at 9 Amp Hours.

Danny Brotto
  #6  
Old May 8th 20, 09:55 PM posted to rec.aviation.soaring
[email protected]
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Posts: 317
Default K2 battery endurance

There was a thread about this, K2's mentioned, a rew years ago that Steve Keorner replied too. He asked the K2 engineers about reduced capacity he was getting, IIRC, their answer was to leave them on the charger for weeks at a time so they can balancecout the cells with the BMS on board.

CH
  #7  
Old May 8th 20, 10:00 PM posted to rec.aviation.soaring
Dave Springford
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Posts: 320
Default K2 battery endurance

The batteries are most likely not at the end of their life.

There are a few things that you can do.

1. Check the battery type on your LX9000, is it set to LiFe?
2. Check the voltage reported by the LX9000 and compare it to the voltage reported by another instrument. Most radios have a voltage readout and often this is more accurate than the 9000 readout. IF they are different use hte voltage offset function in the 9000 to have it read the same voltage as the radio.
3. If 1 and 2 don't help, put the K2 batteries on an extended 10 day charge cycle. This helps balance the cells and restore capacity in the K2's.
4. If this doesn't work, put them on a longer 20-30 day charge cycle.

The K2 batteries should never be stored for a long duration at full charge. Always store them at about 1/2 charge and then when they come out of storage put them on a 10 day float charge. Do this once a year.
  #8  
Old May 8th 20, 10:41 PM posted to rec.aviation.soaring
Bob Youngblood
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Posts: 390
Default K2 battery endurance

On Friday, May 8, 2020 at 3:21:11 PM UTC-4, John Silverberg wrote:
Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them. I'm not sure how old they are but they're at least 3 years old as this is my 3rd season with the ship. Yesterday, after a little over 5 hours I got a low battery warning with the batteries at 11.3 volts. I had all the above avionics on but did virtually no transmitting on the com, just listening. They were fully charged at takeoff.

I'm not sure if this normal endurance for these batteries or not, any advice would be appreciated.

Thanks,

John S.


I run a similar system and I don't think you have a problem. Charge them for a couple of days and go fly.
  #9  
Old May 9th 20, 02:37 AM posted to rec.aviation.soaring
Piet Barber
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Posts: 58
Default K2 battery endurance

On Friday, May 8, 2020 at 3:21:11 PM UTC-4, John Silverberg wrote:
Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them.


I'm guessing your LX9000 was the one making the complaints about the battery levels, right? Under the Hardware settings, what setting do you have for a battery? The LXNav flight computer doesn't have a "K2 Battery" setting. You should consider going into the setup page, go to hardware, select battery type and select "Custom"
For the battery settings under "Custom" enter the numbers they have printed on the side of the K2 battery. The numbers, as listed on the side of the K2 battery a

Discharge Voltage Cutoff | 10.0V

That number is the absolute bitter end of the battery. I wouldn't recommend discharging your battery all the way to that level! But theoretically you can set the custom settings to that number for the "this whole system could shut off at any moment" value. Try playing around with the numbers to see what you can come up with that seems right.

I remember going into this setting immediately after turning on the system, finding out what the maximum battery charge is.

If you choose one of the other settings like Lead Acid, LiFe or LiPO, the numbers aren't quite right. I have a two seater, and like clockwork, I turn on the system and the passenger says, "Uh, the battery meter is already showing yellow"
  #10  
Old May 9th 20, 03:08 AM posted to rec.aviation.soaring
Richard Pfiffner[_2_]
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Posts: 319
Default K2 battery endurance

On Friday, May 8, 2020 at 6:37:33 PM UTC-7, Piet Barber wrote:
On Friday, May 8, 2020 at 3:21:11 PM UTC-4, John Silverberg wrote:
Hi,

I'm hoping someone with experience with K2 batteries can help determine if mine are due for replacement. I have dual K2 batteries wired in parallel to supply avionics power. I have an LX9000, S8 and V8 varios, trig transponder, FLARM core, and becker com radio running off them.


I'm guessing your LX9000 was the one making the complaints about the battery levels, right? Under the Hardware settings, what setting do you have for a battery? The LXNav flight computer doesn't have a "K2 Battery" setting. You should consider going into the setup page, go to hardware, select battery type and select "Custom"
For the battery settings under "Custom" enter the numbers they have printed on the side of the K2 battery. The numbers, as listed on the side of the K2 battery a

Discharge Voltage Cutoff | 10.0V

That number is the absolute bitter end of the battery. I wouldn't recommend discharging your battery all the way to that level! But theoretically you can set the custom settings to that number for the "this whole system could shut off at any moment" value. Try playing around with the numbers to see what you can come up with that seems right.

I remember going into this setting immediately after turning on the system, finding out what the maximum battery charge is.

If you choose one of the other settings like Lead Acid, LiFe or LiPO, the numbers aren't quite right. I have a two seater, and like clockwork, I turn on the system and the passenger says, "Uh, the battery meter is already showing yellow"


Read before you comment on how to charge a LiFEPO4 Battery

https://www.planetanalog.com/how-to-...le-batteries/#

Richard
www.craggyaero.com

 




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