You could probably, but I wouldn't recommend it. I'm not sure of the power mAh of the 510 battery, but I can imagine that it would either take just as long to charge or longer. Each charger is designed to charge the specific battery by delivering a known current over time. I would assume this is different for all different models.
I can't say if it will work or not, but if the 808 battery charger is designed to charge a more powerful battery, it could cause the 510 to explode.