On board battery(ies) for powering radios/Flarm etc

Just a quick question.
Had a brainstorm the other day, might have hit my head, don't remember, who knows...

What are y'all using for on board power these days?

Last I flew, we were using 6? amp hour gel cells by Hobbico from Tower Hobbies. (The kind that powered the little Powerwheels Jeep your kid/grandkid rode in 20 years ago)

What kind of power capacity are folks using?

I was working my big a$$ Milwaukee 10" chop saw and saw how compact the 18v, 9 amp LiPo was, and how fast it charged on the included rapid charger and got to thinking 1, 2 or 3 of those on a semi-custom mount with built in voltage regulator would be right dandy in these birds, and available at the big orange box store if a replacement is needed in a hurry.

Just a thought. Please return to your regularly scheduled mayhem.

Neal,

I think there are still a lot of pilot using Sealed Lead Acid (SLA) batteries in their glider. It works OK for gliders that maybe have an electronic Vario and a radio.

As you add other electric devices, especially a transponder, the capacity demands go up. You can get SLA batteries with 12-15AH capacity, but many ships are equipped with Lithium/Iron/Phosphate (LiFePo) chemistry batteries.

Most of the sailplane accessory distributors have them in stock, for example:

http://craggyaero.com/lifepo4_battery1.htm

Hope that helps,

Mike

On Monday, October 12, 2020 at 10:10:18 PM UTC-4, wrote:

What kind of power capacity are folks using?

Most popular are lithium iron phosphate (LFP) batteries in same form factor as those old 6AH SLAs, now typically with 9 - 10 AH capacity. Decent quality examples last for years and years with little change in capacity... and your radio still transmits
from the wave at -20C at 10% state of charge (however, do not recharge until battery warms up).

Modern (Chinese) SLAs are of poor quality, not nearly as good as what we had (at higher cost) from Western manufacturers in 1990s.

(btw, try the search function, works great, will return hours of reading on this very topic)

T8

Yes, I also looked longingly at the tool batteries as well. A 3d printer could make a holder/connector and there are plenty of demo boards around for switching powersupplies to make 12V.

But I decided to go with three K2's. So far I've never used the third K2.

They were already tested and in the physical and electrical form the glider expects.
LiFePo seemed more forgiving than LiIon.
I'd rather not divert the hobby from flying to building battery systems.
It seemed a thing that would be fun and easy to get close, but tricky to get right.

If the K2's didn't work so well, it might be a different story.

On Tuesday, October 13, 2020 at 9:35:47 AM UTC-4, wrote:
Yes, I also looked longingly at the tool batteries as well. A 3d printer could make a holder/connector and there are plenty of demo boards around for switching powersupplies to make 12V.

But I decided to go with three K2's. So far I've never used the third K2..

They were already tested and in the physical and electrical form the glider expects.
LiFePo seemed more forgiving than LiIon.
I'd rather not divert the hobby from flying to building battery systems.
It seemed a thing that would be fun and easy to get close, but tricky to get right.

If the K2's didn't work so well, it might be a different story.

And tricky to keep a home-made kludge safe. Other types of lithium batteries are prone to spontaneous combustion. You don't want a fire in flight! A ready-made LFP battery, with a built-in circuit protecting it from over-current etc, in a proper case that fits in your glider, can now be bought for around $40 - hardly more expensive than an old-tech SLA. It's a no-brainer.

On Monday, October 12, 2020 at 7:26:11 PM UTC-7, Michael Bamberg wrote:
Neal,

I think there are still a lot of pilot using Sealed Lead Acid (SLA) batteries in their glider. It works OK for gliders that maybe have an electronic Vario and a radio.

As you add other electric devices, especially a transponder, the capacity demands go up. You can get SLA batteries with 12-15AH capacity, but many ships are equipped with Lithium/Iron/Phosphate (LiFePo) chemistry batteries.

Most of the sailplane accessory distributors have them in stock, for example:

http://craggyaero.com/lifepo4_battery1.htm

Hope that helps,

Mike

Test Graph is include with every LIFEPO4 Battery sold by Craggy Aero.

Richard
www.craggyaero.com

Also keep in mind that AFAIK power tool batteries (certainly the Milwaukee) have no intelligence - all the BMS functions are built into the charger and tools. So you have a volatile, uncontrolled LiPo sitting behind your head.. You can get the same AH in a well constructed, controlled LiFePo4 for the same or less money.
On Tuesday, October 13, 2020 at 7:21:25 AM UTC-7, wrote:
On Tuesday, October 13, 2020 at 9:35:47 AM UTC-4, wrote:
Yes, I also looked longingly at the tool batteries as well. A 3d printer could make a holder/connector and there are plenty of demo boards around for switching powersupplies to make 12V.

But I decided to go with three K2's. So far I've never used the third K2.

They were already tested and in the physical and electrical form the glider expects.
LiFePo seemed more forgiving than LiIon.
I'd rather not divert the hobby from flying to building battery systems..
It seemed a thing that would be fun and easy to get close, but tricky to get right.

If the K2's didn't work so well, it might be a different story.
And tricky to keep a home-made kludge safe. Other types of lithium batteries are prone to spontaneous combustion. You don't want a fire in flight! A ready-made LFP battery, with a built-in circuit protecting it from over-current etc, in a proper case that fits in your glider, can now be bought for around $40 - hardly more expensive than an old-tech SLA. It's a no-brainer..

CTEK makes a dedicated LiFePO4 charger. Not cheap, but I get some six hours running radio, PowerFLARM, vario, Oudie and transponder on a K2.

My current gen 18v Milwaukee batteries all have on board intelligence and can signal when an issue occurs through flashing lights etc. They are highly protected against fire, shorts etc. The smaller 12v versions do not that I am aware of. The newer M28 batteries, 28 volts with capacities exceeding 40amp hours are coming around the corner. They will be integrated into generators, compressors etc. Exciting new battery tech out there.

This older platform on google groups is not very search friendly, and I was unable to locate much of anything, so I tossed the question out there.

On Monday, October 12, 2020 at 10:10:18 PM UTC-4, wrote:
Just a quick question.
Had a brainstorm the other day, might have hit my head, don't remember, who knows...

What are y'all using for on board power these days?

Last I flew, we were using 6? amp hour gel cells by Hobbico from Tower Hobbies. (The kind that powered the little Powerwheels Jeep your kid/grandkid rode in 20 years ago)

What kind of power capacity are folks using?

I was working my big a$$ Milwaukee 10" chop saw and saw how compact the 18v, 9 amp LiPo was, and how fast it charged on the included rapid charger and got to thinking 1, 2 or 3 of those on a semi-custom mount with built in voltage regulator would be right dandy in these birds, and available at the big orange box store if a replacement is needed in a hurry.
FSC
Just a thought. Please return to your regularly scheduled mayhem.


Like others I'm using two LiFePo4 batteries (10ah K2s). I've measured my current draw (Clearnav, Clearnav vario, Trig T21, Dittel FSG 2T) and it averages 1.26A in flight on a fresh charge. Other than a 1000K flight that lasted 9 hours, I've never had to switch batteries. After 3 years, the currently older K2 still measures about 9.2ah of capacity at full charge.

P3