Deep Cycle vs Regular Starting Batteries

The deep cycle batteries also provide for many charge cycle between 50% to 90% charge states. i.e. you can run one down to around 50% charge state (around 12.0VDC) and then re-charge back up to the 90% charge state (around 12.6-7VDC) several hundred times without doing damage to the battery cores.

The motor start battery on the other hand will almost last for two such charge cycles and you will have to replace the battery then. i.e. if you ever run down a start battery it almost never will operate good for you when charged back up... Been my experience at any rate...

If you never run your batteries below 12.0VDC then just use regular start batteries. If you like to camp off the power grid and run all your 120VAC and 12VDC toys off the batteries down to 12.0VDC typically and re-charge them back up to 90% charge every morning then you will need deep cycle batteries.

There is also dual function start/deep cycle batteries available as well and these work pretty good to a fashion when having to re-charge them on a regular basic but of course no where as good a true deep cycle marine battery will do.

Been my experience at any rate...

Roy Ken

Son of Norway wrote:
You mentioned in the other thread that you have two Duralast Marine Batteries. Those are known as "dual-purpose" batteries that can be used for both starting and deep-cycle applications.

Miles

Some marine batteries are starting only.

Marine could mean that there is a larger space under the plates to catch shedding from the plates. In this context, marine means the battery can tolerate pounding or rough riding better without shorting out internally.

The two terms to look for on your dual-purpose battery are deep cycle or trolling along with a prominent display of AH or a label like DC27.

HTH;
John

A starting battery has a lot of very thin lead plates with a great surface area which can provide a large surge of power, out or in, for high amperage starting needs.

A deep cycle battery has fewer, thicker lead plates with much less surface area. They don't provide the massive power surges required for starting engines, but do provide lower power levels for much longer periods of time, perfect for running lights and pumps in an RV.

The thin plates of a starting battery don't stand up well to deep discharge/recharge cycles.

You mentioned in the other thread that you have two Duralast Marine Batteries. Those are known as "dual-purpose" batteries that can be used for both starting and deep-cycle applications. I actually own two of those same batteries myself. Mine are 7 years old. I have maintained them carefully, and they still test out at near-new capacity. A marine battery doesn't have the same type of deep-cycle capability as a set of golf cart batteries or an AGM battery, but they are fine for average use for an RV'r who doesn't camp very often without hook-ups. You might want to look up some online references like "the 12-volt side of life" or "battery university" to learn more. That way you can assess your power needs and decide what type of battery you want to buy when you replace the Duralasts.

Miles

Hi,

Are the battery banks meeting your needs? If so, wait until they start to fail to replace them.

One is your starting battery and that should remain. It is dedicated to the engine. The other battery is your "house" battery and a deep cycle battery will tolerate the discharging and recharging better than a starting battery. However, both will work. In fact, if you do little boondocking, you won't notice the difference, so just wait until the house battery fails and needs replacement. Now, if you have two house batteries and both are starting batteries, when it comes time to replace them you should consider two 6 volt deep cycle batteries. Those 6 volt batteries tolerate the charge/discharge cycles better than their 12 volt counterparts due to the size of the cells.

Why deep cycle?

Battery FAQ
This tutorial may be of some help. 12v side of life.