A Group 24 battery is a 12-volt battery defined by BCI case-size standard, measuring about 10.25 x 6.8125 x 8.875 inches so it fits a specific tray and terminal layout.
For the full breakdown, see our best Group 24 Battery guide.
Two batteries can look identical and still not swap into your vehicle — one drops into the tray and reaches the cables, the other sits too tall or puts the posts on the wrong side. That mismatch comes down to group size, and Group 24 is one of the most common medium-size footprints in North America. Whether replacing a starting battery, sizing an RV house bank, or upgrading a trolling motor setup, the group number tells you what physically fits.
What “Group 24” Actually Means
Group 24 is a size and fitment code from the Battery Council International (BCI) system, not a brand, voltage, or chemistry. The number identifies case dimensions and terminal arrangement so a battery seats correctly in a given tray.
The label describes the box, not what’s inside it. A Group 24 housing can hold a lead-acid starting battery, an absorbed glass mat (AGM) model, a gel cell, or a deep-cycle unit. The standard confirms the shell fits; it says nothing about cranking power, capacity, or lifespan.
Battery Stuff’s BCI group size chart lists the standard Group 24 footprint at 10.25 x 6.8125 x 8.875 inches, though some charts round to 10 1/4 x 6 13/16 x 8 7/8 inches. It’s a medium case — bigger than a Group 35, smaller than a Group 27 or 31.
Typical Specs You’ll See
A Group 24 battery runs at 12 volts, and its performance depends on the chemistry and build inside. A starting battery and a deep-cycle battery can share the same shell and behave nothing alike. Common figures:
- Voltage: 12 V nominal
- Cold cranking amps (CCA): roughly 600–700 for starting batteries
- Reserve capacity: about 120–150 minutes
- Capacity: around 70–85 Ah for lead-acid and deep-cycle
These ranges are typical, not guaranteed. Treat the group number as fitment; compare CCA/Ah when shopping.
| Attribute | Group 24 Spec | What It Affects |
|---|---|---|
| Standard | BCI case-size code | Tray fitment only, not power |
| Dimensions | 10.25 x 6.8125 x 8.875 in | Whether it drops into your tray |
| Voltage | 12 V nominal | System compatibility |
| CCA range | ~600–700 | Cold-weather starting |
| Reserve capacity | ~120–150 min | Run time with alternator off |
| Capacity (Ah) | ~70–85 Ah | Deep-cycle and house use |
| Common chemistry | Flooded, AGM, gel | Cost, maintenance, lifespan |
| Subgroups | 24H, 24F, 24R, 24T | Terminal and hold-down layout |
What Are Group 24 Batteries Used For?
Group 24 batteries show up anywhere a medium-size 12-volt battery fits a fixed space: cars, trucks, RVs, boats, and off-grid setups. Their size is a practical sweet spot — enough capacity for real loads, small enough for common trays.
In automotive use, a Group 24 starting battery delivers cranking amps to turn over an engine and reserve capacity to keep electronics running if the alternator fails. AutoZone’s Group 24 listings show these in passenger cars, SUVs, and light trucks.
In RV and marine use, owners run Group 24 deep-cycle batteries as house batteries — powering lights, fans, pumps, and electronics when the engine is off. The same case lets you wire several together for more capacity, or run a single unit for lighter loads. Trolling motors, small solar banks, and backup power boxes rely on this size.
Shopping for a replacement and want tested options rather than guessing at brands? This roundup of the best Group 24 batteries narrows the field by chemistry and use case.
Common Mistakes and Subgroup Variations
The biggest error is treating “Group 24” as universal and grabbing the first one on the shelf. Subgroups exist — 24H, 24F, 24R, and 24T — shifting terminal position or height, so a 24F won’t necessarily drop into a tray built for a plain 24. Even within a subgroup, check four things:
- Terminal position and polarity: posts can sit on opposite corners or sides
- Height clearance: hood or compartment space can rule out a taller case
- Hold-down style: top clamp, bottom ledge, or strap
- Chemistry and rating: starting and deep-cycle aren’t interchangeable even at the same size
Verify dimensions and subgroup against your manual. A battery 1/4 inch too tall or with the positive post on the wrong side is useless regardless of ratings. Confirm your factory group size first, then match subgroup, terminal layout, and CCA. The BCI group size reference from Battery Stuff is a solid place to cross-check dimensions.
FAQs
Can I use a Group 24 battery in place of a Group 24F?
Not always. The “F” suffix signals a different terminal configuration, typically reversing post positions. If cables won’t reach or polarity is flipped, it won’t work even though dimensions match. Check your tray and cable routing before swapping.
Is a Group 24 battery good for deep-cycle use?
Yes, if the specific battery is built as a deep-cycle unit. Group 24 is a size, so deep-cycle versions rate around 70–85 Ah. Avoid using a standard starting battery for deep discharge — it wears out fast. Match chemistry to how you’ll use it.
How many CCA does a Group 24 battery have?
Most fall in the 600–700 CCA range, though this varies by brand and chemistry. AGM models often sit at the higher end. In a cold climate, prioritize a higher CCA within that range for easier winter starts.
References & Sources
- Battery Stuff. “BCI Battery Group Size Chart” Provides standard Group 24 dimensions and subgroup variations.
- AutoZone. “Group Size 24 Batteries” Shows real Group 24 product listings across chemistry types.
- GG Lotus. “BCI Battery Size Reference” Confirms case dimensions and the BCI group sizing system.