Starting battery vs. deep cycle – why consider any of them for your car?


Let us be honest here: the types of batteries that are available in the market are confusing. It does not help that there are a ton of battery manufacturers who will tell you that their product is unique from all others, even as a comparison of features reveals more similarities than differences. However, we aim to dispel all the notions through this article focusing on starting batteries vs. deep cycle ones.

If you are reading this, you might wonder why batteries come in so many types. Yet an investigation of these types reveals that each battery you look at has a specific purpose and functionality, and many of these are not interchangeable.

When it comes to the world of car batteries, the use and the type you choose will vary on the end goal you have.

There are few instances of this being more evident than in the primary types of car batteries – the deep cycle and the starter batteries.

The reason for their differing is due to the discharging and demands they can go through, which we will discuss in the article below to give some added insight.

What are the differences between starting batteries and deep cycle batteries?

Battery model
Starting batteries
Deep cycle batteries
Plate thickness (approx. inches)
0.25 to 0.11
Discharge rate (approx.)
Between 0.3 and 10%

Starting battery vs. deep cycle – How they compare

Power supply

All batteries are meant to provide power to the machine they operate, but in this case, these two go about the process differently.

For the deep cycle battery, the aim is to provide power over a long time, while the power supply remains consistent instead of providing power in surges. While a deep cycle battery can still give you surges of power, it is not the primary purpose for their existence, as their cranking power will be lower compared to that of starting batteries.

They also charge slower than a starting battery – therefore, if you recharge them for short periods that will eventually result in the overall battery life to be shorter and eventually damage the battery. The best thing to do when recharging them is doing so for a longer period on a lower amp rating.

On the other hand, a starting battery is meant to give surges of power supply, bust at a shorter time, which is also why they have higher cranking amps compared to deep cycle battery types.

Ability to discharge

Because of the structure of deep cycle batteries, they are better at handling deep discharges (where the battery is completely or almost-fully drained) without suffering from internal damage. This is because they have thicker plates, which are also the reason behind their slower surge power, as the electrolyte reacts with the plates slower.

Because of their structure and ability for deep discharges, they come in handy when powering plug-in accessories and electronics, as well as other applications that place a high power demand o them such as marine applications. In addition to that, some can work as starter batteries (although these types are referred to as dual purpose), but you will need to check the CCA (cold cranking amps) of the battery to ensure it can handle that task.

On the other hand, a starter battery cannot handle deep discharges – or else the battery will suffera shortened lifespan and eventual permanent damage. This is due to the thinner lead plates – while they ensure the battery can give power surges when necessary due to faster reactions with the electrolyte, this structure limits the extent of the discharge. The maximum they can go is 10%, and even then they will need recharging to keep them well-functioning.

Recharging process

As we mentioned earlier, the deep cycle battery needs some time to recharge due to its internal structure and working mechanism. You cannot just ‘top them off’ quickly as you would do in the case of a starting battery, as quick charging will eventually shorten its lifespan.

Starting battery vs. deep cycle – a comparison review

Starting battery – Overview and key features

Anyone that is new to the world of car batteries will tend to buy starter batteries anyway because they need to upgrade what they have, or looking for a source to power their car because that is why they know. In many cases though, especially in more extreme temperatures, starter batteries cannot handle the shifts in temperature.

There are a few features that all car batteries must have, especially for a starter battery. These criteria include:

Size – this is the first thing to think about, as you want the battery to fit well inside your engine. This is usually indicated through a number called Group Size, which all batteries will have, and will indicate the width, length and height of the battery.

Durability – this will depend on the terrain you are driving on, as some places will need the use of a more durable choice than others. For instance, a case of off-road driving will need a battery that is strong enough to withstand vibrations, and also spill-proof (if you can get it, the better).

Power – the battery needs to have enough power to start the car engine, as well as meet any other electrical requirements. Moreover, the reserve capacity also needs to be large enough, to allow you to run other electrical components even when the engine is off.

Additional features – these include the service life and the warranty.

There are a variety of starting batteries, and your choice will also depend on what you are looking for. They are:

  • SLI – also known as Starting, Lighting and Ignition batteries. They are the most common type of starter batteries, and many cars will use them by default.
  • Li-ion – they are an updated version of the SLI battery. Due to their structure (and that they use calcium as their cathode rather than lead), they can store larger amounts of energy, can recharge quickly, are compact, and lightweight.
  • VRLA – these are a sealed battery type, which means that they will not need maintenance.
  • Wet cells – these are among the most affordable options of car batteries.

Some good starting battery models in the market include:

Mighty Max ML35-12 battery

Mighty Max Battery ML35-12 -...
  • ML35-12 SLA is a 12V 35AH Sealed Lead Acid (SLA)...
  • Dimensions: 7.68 inches x 5.16 inches x 7.13 inches. Listing...
  • SLA / AGM spill proof battery has a characteristic of high...

This option is good at delivering power when you need it, at a maintenance-free level. This also makes it good for use in a variety of environments, and can give you good performance regardless of external temperatures.

View Price on Amazon

Optima 8025-160 RedTop

Optima Batteries 8025-160 25...
  • 12-Volt, 720 Cold Cranking Amps, Size: 10 5/16" x 6 13/16" x...
  • Reserve capacity of 90 minutes for constant performance;Up...
  • Optimal starting power even in bad weather

As we mentioned before, power is a great consideration to make when you are buying a car battery for your car – and this one delivers just that. You will not even need to worry about bad weather issues, has 15 times greater vibration resistance, and delivers strong surges of power that get our car up and running.

View Price on Amazon

ACDelco ACDB24R Automotive battery

ACDelco ACDB24R Advantage AGM...
  • NOTE: Refer user manual before use

If you own a truck, this is among the best options you can get for a starter battery, and it is also among the most durable choices in the market. This is likely due to the enhanced alloy, which allows the service life of this battery to last longer than most options.

View Price on Amazon

What we like

  • Most good models are relatively affordable
  • They have a high CCA
  • They are good for general purpose use
  • You can use them to power electronics quickly

What we do not like

  • Some have issues with durability
  • Some are high maintenance (especially those that are non-AGM types)

What can you see with the starter battery?

  • They are easy to use and mount
  • High CCA that allows them to power engines
  • Cannot endure deep discharge
  • Affordable

Deep cycle battery – Overview and key features

Deep cycle batteries definitely have their fair share of applications, as they can power everything from marine vessels like yachts to solar grids. If you buy the right type for your needs, it can last you a lifetime (as long as you take good care of it), but the wrong one will force you to throw your money away as you try to adjust it to your needs.

There are plenty of great options to choose from, as deep cycle batteries will come in the following forms:

  • Absorbent Glass Mat/AGM – these use flat plates comprised of fiberglass and are sandwiched between the lead plates, which then keep the electrolyte in place and absorb any spillages that occur, like a sponge. They are in two types: spiral plate (where the plates do not come into contact due to the close arrangement of the cells) and flat plate (look like flooded batteries, and their plates are packed in rows of 6).
  • Flooded – these can go through regular complete discharging, making them great for RVs and campers.
  • Gel – very similar to AGM batteries, but the difference is that they use silica as the electrolyte, as well as calcium acting as a replacement for the antimony.
  • Lithium-ion – these use a graphite carbon anode and LiFePO4 as the anode.

Some of the deep cycle battery options you can use include:

Lifeline marine battery

Lifeline Marine AGM Battery -...
  • Voltage: 6 Volts
  • Amp. Hrs. 20 Hr Rate: 220
  • Minutes of Discharge @ 25 Amps - 492

This is an AGM battery that works well for marine applications, and it is of very high quality – at least based on its approval by the U.S. Military.

View Price on Amazon

Battle Born deep cycle battery

It is among the best batteries of the lithium-ion type, coming with an impressive cycle life of 3000 to 5000. It also includes a manufacturer’s 3-year replacement warranty.

View Price on Amazon

What we like

  • Can be useful for deep discharge situations
  • They have versatile usage compared to starting batteries
  • Very durable and strong build
  • Can power applications for longer times

Wheat we do not like

  • They are expensive
  • Have less output of specific energy
  • Many cannot handle starting of engines (unless they are dual purpose)

What can you see with deep cycle batteries?

  • Rarely have problems with electrolyte spillage
  • They are strong enough to handle deep discharge
  • Lower CCA compared to starting batteries
  • Usually maintenance-free

Verdict: So which is better? The starting battery or the deep cycle battery?

The answer to this will really depend on what you want to achieve wen using the battery, as different applications will demand different batteries. Starting batteries are great for applications that require you to initially power an engine, while the deep cycle is good for a variety of applications that require power for long periods.

However, if we were to look at one pick that satisfies your needs in the long term, then the deep cycle battery is best, as the starting battery can be limited in many regards.

Frequently asked questions

Are all AGM batteries deep cycle batteries?

Yes they are, although not all deep cycle batteries will be of the AGM type. There are additional designs, and each type uses a different method to achieve the same purpose.

The reason why AGM batteries seem to be the preferred type of deep cycle battery is due to their low maintenance. The other types might need you to keep them upright to avoid spillage, and also add water (though not in all cases). AGM batteries do not have this kind of concern, which makes them a good low-maintenance choice for many users.

How many years can I expect my deep cycle battery to last?

This will be dependent on the type of battery you use. In the case of most AGM batteries, they will last for about 4 to 7 years, and the most durable will last a maximum of 10 years.

The use of the battery also affects how long it will last. For instance, using the battery for light applications will help it last longer than if you deep discharge it all the time.

Moreover, you will get a longer lifespan if you keep the battery charge levels above 80% (any regular use of the battery when it is below 50% will reduce the lifespan to 2 years at most).

Is it good to use deep cycle batteries for my car?

Generally speaking, not really. The problem of deep cycle batteries in most car applications is their tendency to draw too much voltage when they recharge, which eventually damages the alternator of the car. As much as possible, stick to starter batteries for the car.


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