I’m a little late to this but I’ve had my run Through with these. My son just finished his SR year on 50s and we had been racing the cobra CX50 and the CX5e.
Great little bikes. I’ve had 3 batteries brick on me but COBRA always sends me new batteries to replace the bad ones at no charge.
As far as charging they charge slow. There is a fast charging mode.
You may already know that, if not once you plug the charger in and turn the battery on it will start charging. You will know cause the light will blink at the battery level it is currently at.
To move into fast charge you hit the battery power button again. Don’t hold it down, just press it. The light will then start blinking rapidly. That is fast charging and it is roughly 50% faster from my experience.