Q: Can I use a battery charger designed for deep cycle batteries to charge a regular car battery?

Yes you can. A deep cycle battery is not much different from a regular battery except it is designed to give out a small amount of power over a long period where a regular battery is designed to give out a large amount of power over a short period even though both batteries can produce the same if roles are reversed. When charging the battery it may take overnight to fully charge depending on the battery charger being used.