[dookie]

You definitely have a bad battery or battery contact...

Any time you plug in a Mogul / 6800 without a battery you get a solid red light, if you have access to another one, you can try it yourself...

I would plug one it without the battery, get the red light and then put in the battery, if the battery is good and makes contact the red light will go out for about 2 seconds and then come back on with the solid yellow charging light...

My first mogul when bad and I replaced it with a new one, but the old one will still charge my spare battery, so I see this all the time when I swap out one battery with the other...