Car battery selection guide. CA

Car Battery Types Groups Sizes – Which Do You Need?

Getting the right battery type and group size for your car is crucial, but it’s easy to go wrong with so many types, sizes, categories, and sub-categories to choose from. This guide will help clear things up for you and make sure you get the most suitable option for your ride.

Last Updated: June 24, 2023

We love the convenience of battery-operated devices and backups for when the power goes out.

When the batteries go kaput in your Xbox controller or your TV remote, chances are you’ve got a package of spares lying around somewhere. If not, you can pick up new AAs, AAAs, 9-volts, etc., at just about any store.

But what happens if it’s your car battery that’s stopped working? You won’t find that at the corner store!

If you own a car battery charger, you could try re-juicing it, but there are no guarantees. Sometimes, dead is dead.

So, now you need to buy a new car battery.

battery, guide

Yeah, you could take it to your dealer or mechanic, but this is a simple DIY project. First, though, you need to get the right battery for your vehicle and your particular needs. For this, you’ll need to know a little more about car battery types and group sizes – which is where we come in!

Key Takeaways

  • 3.1 1. SLI (Starting, Lighting, Ignition)
  • 3.2 2. Deep-Cycle Batteries
  • 3.3 Dual-Purpose
  • 3.4 A Note on Serviceable vs. Maintenance Free (MF) Batteries
  • 4.1 Absorbed Glass Mat (AGM)
  • 4.2 Gel Cell
  • 4.3 Lithium-Ion (Li-Ion) Batteries
  • 5.1 Side-Post Batteries
  • 5.2 Standard Top Post Batteries
  • 5.3 Recessed Top Post Batteries

There are many different kinds of batteries out there, even if you ignore everything but the 12V automotive varieties.

Fortunately, they can all be lumped into one of two main categories:

Here’s a look at both categories and their respective sub-groups.

Wet Cell / Flooded Batteries

These are the old-school lead-acid batteries we’ve been using for years. Probably your parents and grandparents used them too.

Within this category, there are two main types of vehicle batteries, plus a hybrid style.

SLI (Starting, Lighting, Ignition)

This is your typical automotive battery. It delivers short, quick bursts of power to get the engine running and the systems started. While the engine is running, the alternator takes over the job of powering the electricals.

Many vehicles come from the manufacturers with this style installed.

This type is best for:

Deep-Cycle Batteries

These batteries deliver sustained power for extended periods of time. They are so named because they can be run down repeatedly and recharged without damage, something not possible with an SLI battery.

They’re great for powering lots of electrical/electronic devices when the engine isn’t running. They aren’t so great at delivering the big surge of power needed to start a large engine, however.

The most common applications for deep-cycle batteries are boats, golf carts, RVs, and ATVs. You’ll sometimes see these referred to as ‘marine batteries.’

As you might have guessed, these are not the batteries you’d typically select for your car or truck.

This type is best for:


As the name implies, these batteries combine the starting power of an SLI battery with the gadget-driving power of a deep cycle.

So why doesn’t everyone just have one of these?

Because you get dual performance with a compromise – it isn’t as good at either function as its single-function counterparts.

Since every vehicle has an alternator to run the audio system, power Windows, GPS, etc., you don’t typically need deep-cycle capabilities. Even if your vehicle is off, there’s usually enough power in the battery to run these systems for a short period.

You might want a dual-purpose battery if you are often in situations where you need power for a long time without turning on the engine. Maybe you take your van or truck to the lake, or to tailgating parties and want to listen to music, or power external devices. If that’s the case, a dual-purpose battery might be right for you.

As you might expect, these batteries are more expensive than a standard SLI.

This type is best for:

  • Power-hungry vehicles used at rest, like RVs, show cars
  • Great for day-use camping, and small RVs

A Note on Serviceable vs. Maintenance Free (MF) Batteries

Inside a Wet Cell battery, you’ll find diluted acid. Over time, some of the acid will evaporate. When this happens, the battery will need to be topped up with distilled water.

A Maintenance Free, or MF, (or even “sealed”) battery uses a partially solid electrolyte to cut down on evaporation. There may still be some evaporation, especially during times of extremely high temperatures. Ironically, your Maintenance Free battery can still be topped up to extend its life.

An MF type should last longer than a serviceable battery but may cost a bit more. Make your choice based partly on budget, but also partly on your level of comfort with performing service on your own battery.

How to choose a battery?

When choosing a battery, you should take the following characteristics into account:

  • The battery capacity in milliampere-hours (mAh) (calculation method provided below).
  • The voltage, which is dictated by the materials used for the electrodes and can range from 3.2 to 4 V for lithium batteries and from 1.2 to 2 V for others.
  • The operating temperature.
  • The size and shape of the battery.
  • The type of use.
  • The price.

All batteries have two common characteristics:

  • Their voltage, expressed in volts (V): rechargeable batteries are generally 12 V. For larger cells with voltages of 12 V, 24 V or 48 V, separate 2 V cells are used, intended to be assembled in series, and which have a lifespan of about 10 years.
  • Their capacity, expressed in ampere-hours (Ah): to increase it, several batteries must be connected in parallel.

When you multiply the voltage by the capacity, you get the amount of electricity stored in kilowatt-hours (kWh). For example: A 12 V – 100 Ah battery theoretically contains 12 x 100 = 1,200 Wh = 1.2 kWh.

Depending on these characteristics, you will have to choose the technology, or battery type, and chemical composition: lead-acid, nickel or lithium. There isn’t one battery technology that’s better than the others. Each type of battery has its own strengths and weaknesses, and it is up to the operators of battery-requiring applications to choose the one that best meets their requirements.

Batteries have a predetermined lifespan and number of cycles depending on the climate (ambient temperature) and type of use (depth of discharge). In order to increase their lifespan and optimize their operation, it is advisable to follow the storage and use recommendations.

How do you correctly calculate the size of a battery?

In order to calculate the size of the battery you need, you will have to to calculate the expected consumption in a day and divide this sum (in watts per day) by the direct current voltage (in volts). It is not recommended to let some batteries, especially lead-acid batteries, discharge to less than 50%. To obtain the minimum power you need, divide this result (in amperes/day) by 0.5. Working in 24 V allows you to halve the power required compared to using 12 V, or even divide it by four if you work in 48 V. If you have several devices operating at the same time, it is better to have more power.

A lithium battery is an electrochemical accumulator that uses lithium as a chemical element. Any material containing lithium can be the basis of a lithium-ion battery. It is therefore very difficult to speak generally about this type of battery as high-volume markets (i.e. cameras, mobile phones, etc.) and high-energy markets (i.e. hybrid or electric vehicles, aeronautics, etc.) do not have the same needs in terms of lifespan, cost or power. There are different types of lithium batteries:

  • Lithium-ion (Li-ion): very stable batteries with a very high energy density (the highest on the market).
  • Lithium polymer (Li-Po): this lithium-ion technology uses a polymer electrolyte instead of a liquid electrolyte. This electrolyte is formed by semi-solid polymers with high conductivity. This is promising dry technology.
  • Lithium iron phosphate (LiFePO4): the energy density of this type of battery is lower than other technologies but it offers excellent lifespan and safety. These batteries are ideal for emergency power supplies (UPS).
  • High energy density, which reduces the weight and volume of your batteries.
  • Low maintenance.
  • Rechargeable.
  • Long lifespan.
  • Very low self-discharge.
  • Wide variety of shapes.
  • Limited memory effect.
  • expensive than other types of technology.
  • Require a protective circuit as they are dangerous.
  • Strict regulations for transportation.
  • Wear out even without use.
battery, guide

Cycles: provide approximately 1,300 cycles at 100% discharge.

Applications (all types of lithium batteries):

  • Can store solar and wind energy.
  • Can store electric energy.
  • Autonomous applications (lighting of public spaces, parking meters, security cameras, radar speed signs, traffic lights, etc.).
  • Mobility (electric bicycles, electric vehicles [utility ou industrial], robotics, aeronautics, drones, boats, etc.)
  • Portable energy (batteries, converters, power packs).

Why choose a lead battery?

There are two types of lead batteries:

  • Lead-acid batteries opened with a sulphuric acid electrolyte diluted with water. This type of battery is characterized by the fact that they are reliable and use a technology that has been well-known since the 19th century and is well mastered. These batteries have the disadvantage of being influenced by temperature changes. They also require regular maintenance (refilling with distilled water), as their electrolyte evaporates over time.
  • Lead-acid batteries closed with a gel electrolyte. They have the advantage of being maintenance-free and easy to handle (no leaks) with stability that’s perfectly controlled by the manufacturer. They generally provide about 400 cycles at 80% discharge.
  • Reliability.
  • Good lifespan.
  • No memory effect.
  • Inexpensive.
  • Low self-discharge rate, 5 to 10% per month
  • Heavy.
  • Low autonomy.
  • Sensitive to cold.
  • Require regular maintenance (only open batteries).
  • Low energy density.
  • Industry.
  • Equipment for rail and automotive vehicles (including trucks), airplanes, satellites, etc.

Deka Ultimate Battery Series

The Ultimate battery series is built with the powerful design, performance, and protection that discriminating drivers demand for their vehicles.

  • Delivers dependable starting and reserve power in extreme service
  • All weather battery: high cranking power in cold; reinforced design handles accelerated internal corrosion in heat
  • Heavy-duty Power-Perform™ plates with full-frames prevent shorts and maximize energy storage and delivery
  • Fortified posts, straps, and welds resist vibration damage, maximize current transfer

Additional Resources

Deka Gold Battery Series

The Deka Gold battery series features our exclusive Power-Perform® Plate technology, delivering high quality and reliable performance.

  • Premium starting and reserve power
  • Power-Perform™ plates with full-frames prevent shorts and maximize energy storage and delivery
  • Fortified posts, straps, and welds resist vibration damage, maximize current transfer
  • Flush cover design enhances overall battery performance, maintenance, safety, and convenience

Additional Resources

AUX AGM Batteries

East Penn AUX batteries are specially designed and uniquely capable of delivering dependable auxiliary support to critical vehicle functions.

  • Superior electrolyte in glass mat retention maximizes long-term capacity
  • Ultra-dependability from enhanced valve-regulation system
  • Best electrical connection with exclusive terminal design
  • Long service life with poly composite case and cover

Additional Resources

FAQs on Different Types of car batteries

How do I decide on the replacement battery?

The specifications as set out by your vehicle manufacturer, the customer service and the quality of the materials used by the brand in question, the type of battery must be the factors you consider when making a choice of a replacement battery.

Which are the popular brands for car batteries in India?

Exide and Amaron are the most well-known brands in India. Other reputable quality manufacturers are Okaya, Lento, Luminous, Su.Kam, HBl and Hi-Power.

Which battery is used in EV’s and does it make cost sense to buy an EV considering its battery replacement costs?

Lithium-Ion Batteries are used in EV’s. Yes, It most certainly does. The running costs and the maintenance of EV’s are far lower. And even though the battery packs would need to be replaced every 8 years, if we look purely at the warranty offered, affecting its resale value, we can also look forward to economies of scale bringing down the price of the batteries. This is not even taking into account the positive effects on the environment and health of people exposed to noxious fumes.

Battery Life and Performance

The average battery life has become shorter as energy requirements have increased. Two phrases I hear most often are my battery won’t take a charge, and my battery won’t hold a charge. Only 30% of batteries sold today reach the 48-month mark. In fact 80% of all battery failure is related to sulfation build-up. This build-up occurs when the sulfur molecules in the electrolyte (battery acid) become so deeply discharged that they begin to coat the battery’s lead plates. Before long the plates become so coated that the battery dies. The causes of sulfation are numerous:

  • Batteries sit too long between charges. There are two states when it comes to batteries: They are either being charged or they are self-discharging.
  • Battery is stored without some type of energy input. Even if you disconnect the battery it will still self-discharge.
  • Deep cycling an engine-starting battery. Remember these batteries can’t stand deep discharge.
  • Not completing the charge cycle. Undercharging a battery will allow the sulfation buildup that occurred during discharge to harden. When this happens, it reduces the area on the lead plates for the chemical reaction to occur thereby reduces the capacity of the battery.
  • Heat of over 100°F increases internal discharge. As temperatures increase so does internal discharge. A new fully charged battery left sitting 24 hours a day at 110°F for 30 days would most likely not start an engine.
  • Low electrolyte level. Battery plates exposed to air will immediately sulfate.
  • Incorrect charging levels and settings. Most cheap battery chargers can do more harm than good. See the section on battery charging.
  • Cold weather is also hard on the battery. The chemistry does not make the same amount of energy as a warm battery. Also a deeply discharged battery can freeze solid in sub zero weather. We recommend gel batteries by MK Battery for subzero weather as some of their batteries are rated down to.76°F.
  • Parasitic drain is a load put on a battery with the key off. Depending on the parasitic load we have seen batteries discharged in a few days to a few months. We recommend testing your parasitic load so you know what to expect.

Increase Life

There are ways to greatly increase battery life and performance. All the products we sell are targeted to improve performance and battery life.

An example: Let’s say you have toys such as an ATV, classic car, antique car, boat, Harley, etc. You most likely don’t use these toys 365 days a year as you do your car. Many of these toys are seasonal, so they are stored. What happens to the batteries? Most batteries that supply energy to power our toys only last 2 seasons. You must keep these batteries from sulfating or buy new ones. We sell products to prevent and reverse sulfar buildup on batteries. The BatteryMINDer products are patented electronic devices that reverse and prevent sulfation. Also Battery Equaliser, a chemical battery additive, has proven itself very effective in improving battery life and performance. Other devices such as solar trickle chargers are a great option for battery maintenance.

Parasitic drain

Most vehicles have clocks, engine management computers, alarm systems, etc. In the case of a boat, you may have an automatic bilge pump, radio, GPS, etc. These devices may all be operating without the engine running. You may have parasitic loads caused by a short in the electrical system. If you are always having dead battery problems, most likely the parasitic drain is excessive. The constant low or dead battery caused by excessive parasitic energy drain will dramatically shorten battery life. If this is a problem you are having, check out PriorityStart! battery switches to prevent dead batteries before they happen. This special computer switch will turn off your engine start battery before all the starting energy is drained. This technology will prevent you from deep cycling your starting battery.

Battery Charging

Remember, for proper battery maintenance you must put back the energy you use immediately. If you don’t, the battery sulfates, which will affect performance and longevity. The alternator is a battery charger. It works well if the battery is not deeply discharged. The alternator tends to overcharge batteries that are very low and the overcharge can damage batteries. In fact, an engine-starting battery on average has only about 10 deep cycles available when recharged by an alternator. Batteries like to be charged in a certain way, especially when they have been deeply discharged. This type of charging is called 3-step regulated charging. Please note that only special Smart battery chargers using computer technology can perform 3-step charging techniques. You don’t find these types of chargers in parts stores or big box stores.

  • The first step is bulk charging, where up to 80% of the battery energy capacity is replaced by the charger at the maximum voltage and current amp rating of the charger.
  • When the battery voltage reaches 14.4 volts this begins the absorption charge step. This is where the voltage is held at a constant 14.4 volts and the current (amps) declines until the battery is 98% charged.
  • Next comes the Float Step. This is a regulated voltage of not more than 13.4 volts and usually less than 1 amp of current. This in time will bring the battery to 100% charged or close to it. The float charge will not boil or heat batteries, but it will maintain the batteries at 100% readiness and prevent cycling during long term inactivity. Note: Some gel cell and AGM batteries may require special settings or chargers.

Battery Dos

While that was a detailed look at battery types and how to maintain them, there’s always more to learn.

StevenJust trying to understand the AGM batteries behavior. I have 8-6v batteries used for a small solar system of 48v. When charging the batteries get up to 57v, but when discharging they start out at 50v and then slowly discharge. Why does it start discharging at such a low voltage

TECHWhile a 48v system may charge in the 59v range and float and maintain in the 56v range, they are still considered 100% fully charged off the charger at 50.92v. So, depending on the load, a voltage reading of 50v would seem perfectly normal. While it is good to know how your battery reacts under load, knowing the recovery voltage and how to interpret the voltage in terms of capacity is also important. In a 48v system, it is considered 50% discharged when the voltage reaches 48.4v in an open circuit reading.

Joslyn SchicchiI have a 2009 tao tao moped with a TPE Lithium Motorcycle Scooter Battery. im having issues getting it connected again when j do screw thevterminals in therss no power i also did charge after use

TECHUnfortunately, we do not sell that brand, but it sounds like the battery has been excessively discharged if there is no voltage. I suggest contacting the supplier and talking to them regarding their troubleshooting steps. Typically, you will need a lithium charger with a safe recovery mode, such as the Optimate TM-471 we sell, but I would follow up with them before purchasing anything.

Steve ZDoes a deep cycle lead acid battery discharge faster than it charges? I ask because I am using an 80ah battery to power the small refrigerator in my camper when I’m boondocking. I have a 200w Solar suitcase and a 100 watt panel on the camper. Their controllers are often in a “float” or “full” state when the sun is out and the fridge is on. indicating the battery won’t take any more charge. But the battery monitor shows it is just at 60 or 70 percent capacity. Does this make sense? Thank you!

BatteryStuff TechSteve, as far as if a battery discharges faster than it charges depends on the amperage being pulled from a battery and the amperage charging the battery. Typically, most Smart chargers will taper off the amperage towards the end of the charge to not heat the battery, so that can add about 10 to 20% extra time than the straight math might indicate. However, I think your issue might be a different problem. It sounds as if your controller is shutting down prematurely or is set to go to a float mode after it has been charging for a certain amount of time. I would suggest contacting the manufacturer of the controller to determine why it would be going into float mode when the battery is not full. You may also consider an MPPT controller such as our Victron Controllers as they can be programmed via a smartphone and give you more options to control your charging.

Carl OhHi great article…I have a TT with 2 trojan 6v batteries hooked up to a renogy 30amp controller and a LG 350 solar panel When I hooked them up at the beginning of year the hydrometer reading was 1265. Now the reading is 1225 but the controller says 100% 13.4v. I have been watching and the controller does boost and float and is always at 100%. Why is the hydrometer reading in the recharge area. The whole system is only 1 year old.

BatteryStuff TechCarl two things maybe happening. The batteries could be sulfated and while the controller is able to bring them full charge the batteries will not hold their after they are disconnected. Or, the controller is simply not charging the batteries correctly. I would suggest charging the batteries with your normal plug in charger and see if it is able to get the batteries to full charge with a good specific gravity reading. If it is then you know the solar charge controller isn’t functioning properly. If it isn’t then you know your batteries maybe sulfated.

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