I have 2 gens ace 2s 5000mah 40c lipos. The reason why they started to go to direct wire and why they are more popular is due to their design. They tend to desolder themselves around the bullet connector inside the case. I had to mod mine to a direct wire after having this problem several times. Not sure if its due to a banana plug issue or what, I tried several things but the connector always desoldered. After I hard wired it 3 months ago no problems.

Great Batteries otherwise.