URGENEX 3.7V Lipo 850mah Rechargeable Lipo with JST Plug X5 Charger for MJX Syma Holy Stone Sky Viper RC Quadcopter Drone X56W X400 X400W X300C X400C X800 HS110 HS200 S670 V950hd S1750 V2450

Great Little Package for the price. cool, simple charger. DOES NOT FIT LaTrax Alias Drone without modification to the battery holder.

This works with a Traxxas Alias Quadcopter. It’s thicker than the Traxxas battery, and is a tight fit. Plug is the mating end for the Alias interface plug, an adapter isn’t necessary. Once it slides into the bracket, it does have a tendency to want to stay at a slight angle. If you gently push from the front and guide it with a slight lift at the back, it falls into place. Removing is the process in reverse. I use a small popsicle stick to help push it out. First flight after charge was 20 minutes. I think this is worth the money.

I previously stated that these batteries are unable to deliver 3 amps without dropping below 3 volts. I was wrong. The mating cables I was using in the test had excessive resistance. I don't know if they are really 25C, but URGENEX deserves 5 stars for their customer service. They refunded my money when I didn't even request a refund.

2 out of the 5 don’t charge. When they are charged, I get about 3-5 minutes with my stock alias quadcopter which they do NOT fit in. They are too wide. Super cheap though. Edit: I received a full refund and got to keep the working batteries after writing this review. Very good service!

Great batteries

TLDR: original battery that came with drone provided more flight time than all 5 batteries combined. Followed instructions for charging. Once fully charged I installed one of the batteries into my Sky Viper GPS drone. Controller app showed battery at 100%. Immediately upon takeoff (before even 2 feet off the ground) the charge dropped to 77%, then immediately to 55%, then 32%, and 12%. The drone didn't even make it to elevation before it gave me the "Battery critically low: activating return" type message. Similar results with all 5 batteries. Attempted multiple recharges to full with the same result each time.

Charger and adapters are fantastic! The C rating on the batteries is a bit low though- equivalent lipos I bought 3 years ago are outperforming these.

works well, good value.