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..