Deep cycle RV batteries are designed to discharge to their maximum capacity. Because they have thicker plates, they can discharge deeply and recharge repeatedly. So they can offer a steady amount of current for a prolonged period. RV batteries (that supply at least 12-volts or more) should ideally be deep cycle batteries.
Yes, there's a difference between the two batteries. Deep cycle batteries have thicker plates that allow them to discharge down to 80% or more. Marine batteries are hybrid batteries that can be a mix of starting batteries, dual-purpose batteries, and in some cases, deep cycle batteries. Marine batteries have plates that are thinner than deep cycle batteries.
Sizes vary but it should be approximately 181 x 76 x 166 mm in dimensions. If you're selecting deep cycle batteries, then you should get a 12-volt battery. Starting batteries tend to be similar in size and voltage. Refer to your RV manual for more guidance on the battery size.
Some deep cycle RV batteries last only 2 years while others can last for up to 6 years. It depends on the manufacturers and several other factors. Also, if you're deeply discharging it a few times per week, it will last longer. You should ensure that the battery doesn't get damaged due to your handling.
Yes, it's recommended to use the charger that the battery company offers you. There's a separate charger for flooded, AGM, and GEL variants. Use the specific charger for a particular battery. Charging with regular chargers is possible, but it's not recommended since they can shorten the battery life. Moreover, they can produce excess heat.
Normally, 12-volt deep cycle batteries tend to last 20 hours or less depending on your usage. You have to refer to the amp-hours of the battery. If it states 90 amp-hours, then, in theory, it would supply one amp for around 90 hours. And practically, that's less than 90 hours.
Yes, you can overcharge any battery, and deep cycle batteries aren't an exception. If you exceed the amp-hours, you're essentially overcharging your battery. If you're charging on high voltage, then you're overcharging your deep cycle battery as well. It can lead to grid corrosion and reduce battery life.
You can measure your deep cycle battery using a multimeter. It can measure the voltage when you connect it to the battery. A fully charged battery should have the said output voltage, which can be 12 volts, 13 volts, or anything else. If the readings drop one volt or two when you retest, then it's perhaps a faulty battery.
It depends on whether you're using a 12V RV battery pr 6V. In the case of 12V, you need to wire them parallel to increase amp hours while keeping the voltage same. If you're using 6V batteries, then wire them in series to achieve the desired voltage. Refer to the manual for guidance.
Things like dome lights and headlights drain your RV battery faster. If your RV is consuming too much electrical power, then your battery will drain faster. When your RV is at rest, consider disconnecting the ground wire which would prevent the battery from draining when it's not in use. Also, check for leakages if your battery is draining fast.