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  #11  
Old 10-30-2019, 10:48 AM
RVDan RVDan is offline
 
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Dynon has stated in the past that the battery charge state is controlled by the Skyview display, which is how the battery is charged. If that is the case have you considered how the increased pack capacity might impact Skyview during the charge cycle?
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  #12  
Old 10-30-2019, 02:44 PM
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Raymo Raymo is offline
 
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Quote:
Originally Posted by NinerBikes View Post
The Dynon pack does indeed make it easy for you, but it never balance charges all of the cells, and that's a major cause of failure in LiPo battery packs. Lazy cells kill off the harder working cells.

It's all due to variance in production of the battery cells.

Storing LiPo cells with a full 100% state of charge is a good way to kill all the batteries. They do much better in storage, which is how your plane sits, most of the time, at a 50- 60% state of charge, long term. A Li Po cell stored at 3.9V will last easily 10 years, if not stored in extreme heat or extreme cold.
The Dynon battery is Lithium Ion. Nobody should have a LiPo battery in their airplane, IMO.
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  #13  
Old 10-30-2019, 03:21 PM
RVDan RVDan is offline
 
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Quote:
Originally Posted by Raymo View Post
The Dynon battery is Lithium Ion. Nobody should have a LiPo battery in their airplane, IMO.
LiThium Polymer (LiPo) batteries are lithium ion batteries. The polymer aspect is a manufacturing technique, and technically other differences also that allow them to overheat easier. The chemistry can vary, but Lithium Colbalt is common. Anything but LiFePo have are less safe. I test batteries under FAA qualification testing. The results make you wonder about carrying a phone in your pocket.
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  #14  
Old 10-30-2019, 06:50 PM
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emsvitil emsvitil is offline
 
Join Date: Oct 2019
Location: SoCal
Posts: 138
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Quote:
Originally Posted by NinerBikes View Post
The Dynon pack does indeed make it easy for you, but it never balance charges all of the cells, and that's a major cause of failure in LiPo battery packs. Lazy cells kill off the harder working cells.

It's all due to variance in production of the battery cells.

Storing LiPo cells with a full 100% state of charge is a good way to kill all the batteries. They do much better in storage, which is how your plane sits, most of the time, at a 50- 60% state of charge, long term. A Li Po cell stored at 3.9V will last easily 10 years, if not stored in extreme heat or extreme cold.
It depends on the capabilities of the built in balance circuit.

Does it keep every cell at the same voltage as the battery is charged....

Or just prevent each individual cell from overvoltage.

You could get long live by keeping each cell at the same voltage and then limiting pack voltage to a multiple of 3.9 (in your case).
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  #15  
Old 10-30-2019, 08:33 PM
Tassie Tassie is offline
 
Join Date: Oct 2014
Location: Cambridge, Tas. Australia
Posts: 54
Default Aircraft battery inventory

Quote:
Originally Posted by RVDan View Post
LiThium Polymer (LiPo) batteries are lithium ion batteries. The polymer aspect is a manufacturing technique, and technically other differences also that allow them to overheat easier. The chemistry can vary, but Lithium Colbalt is common. Anything but LiFePo have are less safe. I test batteries under FAA qualification testing. The results make you wonder about carrying a phone in your pocket.
A while back I wondered about a situation where someone stated they weren't willing to go down the "risky" path of installing an EarthX (LiFePo*) battery, yet at the same time were happy to take off with 2 phones, 1 tablet, a Camera that included a lithium ion battery, and a panel instrument that probably also included a lithium ion backup battery. We seem to care a lot about aircraft battery safety, and rightly so, but everyone just gets on board carrying the dangerous stuff anyway...
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  #16  
Old 02-25-2020, 08:41 PM
Aggie78 Aggie78 is offline
 
Join Date: May 2014
Location: Fort Worth, Texas
Posts: 428
Default Resurrecting this thread from last year...

Because my Dynon Skyview battery failed testing this year...and looking for options.

This thread seemed made-to-order, however when I called the local battery retailer, while they had the batteries I needed, they wouldn’t assemble them in packs as they said there is specialized equipment needed to solder Li-ion batteries, which they don’t have.

Anyone else run into this? What was your workaround.

While I have modest soldering skills, I don’t need a battery fire caused by improper technique or materials.

Thanks,

Rob S.
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  #17  
Old 02-26-2020, 11:17 AM
12vaitor 12vaitor is offline
 
Join Date: Aug 2012
Location: Panama City, FL
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The 18650 cellls are not something you should fool with unless you understand the risk. That being said, if you want a custom built 2x3 pack you should find a battery shop that can spot weld the connecting tabs vs trying to solder them.

I bought a six pack of individual 18650 cell holders with wire leads and a Comidox 3S 12V 10A 18650 Lithium Battery Protection Board BMS. I used LG HG2 3000ma/h cells with that BMS. Another route is to buy a 6 cell, 12V 18650 case from Amazon such as the Cuawan DIY 6X 18650 Battery Storage Case Box 12V Power Supply (nice compact unit, however I would check the BMS).

It turned out the problem with the Dynon Backup Battery was the BMS board had failed, it was replaced and has been working fine for the past two years.

John Salak
RV-12 N896HS
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  #18  
Old 02-26-2020, 01:33 PM
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airguy airguy is offline
 
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Location: Garden City, Tx
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Quote:
Originally Posted by 12vaitor View Post
The 18650 cellls are not something you should fool with unless you understand the risk. That being said, if you want a custom built 2x3 pack you should find a battery shop that can spot weld the connecting tabs vs trying to solder them.
If you're lucky enough to find a shop to do that, I would suggest you do NOT tell them it's for an aircraft. "Offroad vehicle" should be just fine but nobody wants the liability associated with an aircraft.
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  #19  
Old 02-26-2020, 10:09 PM
Aggie78 Aggie78 is offline
 
Join Date: May 2014
Location: Fort Worth, Texas
Posts: 428
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Quote:
Originally Posted by 12vaitor View Post
The 18650 cellls are not something you should fool with unless you understand the risk. That being said, if you want a custom built 2x3 pack you should find a battery shop that can spot weld the connecting tabs vs trying to solder them.

I bought a six pack of individual 18650 cell holders with wire leads and a Comidox 3S 12V 10A 18650 Lithium Battery Protection Board BMS. I used LG HG2 3000ma/h cells with that BMS. Another route is to buy a 6 cell, 12V 18650 case from Amazon such as the Cuawan DIY 6X 18650 Battery Storage Case Box 12V Power Supply (nice compact unit, however I would check the BMS).

It turned out the problem with the Dynon Backup Battery was the BMS board had failed, it was replaced and has been working fine for the past two years.

John Salak
RV-12 N896HS
John,

Thanks for the info...how does one “check the BMS” with one of these things...swap the pigtail over to the new unit/batteries and see if the Skyview “sees” it and charges it up? Or something else?

For instance, I found this on EBay:

https://www.ebay.com/itm/Battery-Pac...H8svo1-EkBmBOg

They have a 3S2P setup, with BMS for ~$38.

If the form factor of their unit fits into the old Dynon case, it would be great (no specs for the backup battery on Dynon’s website so I gotta go out to the airport and pull the bad one to measure) to open it up, pull the old cells out, swap the pigtail and see if it works.

I like that it says it has cells made by someone I’ve heard of before...

Comments appreciated, especially in attaching the pigtail to the BMS board (soldering?)...do’s/dont’s etc..

Thanks!

Rob S.
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  #20  
Old 02-29-2020, 12:56 PM
12vaitor 12vaitor is offline
 
Join Date: Aug 2012
Location: Panama City, FL
Posts: 128
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Rob,

I like the 3S2P battery pack you found, that is exactly what you need. I suspect it may not fit in the Dynon battery case or will be a tight fit. You should be able to remove the lead from the old battery pack and solder to the + and - tabs on the BMS.

I made a two piece replica battery case with a larger volume for the same type of 18650 cell holders you see on the ebay battery. I would be glad to send you the 3D print file if you want to print one.

John Salak
RV-12 N896HS
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