Group 31, 950 CCA, Heavy Duty. Diesel engines have much higher compression than gas engines and demand significantly more cranking power — Group 31 is the standard heavy-duty size used in Ford Super Duty, Ram 2500/3500, and GM 2500/3500 HD diesel trucks, plus commercial and fleet vehicles. Apex Auto Spare Parts stocks Group 31 batteries ready to ship across Canada and the US.
Quick Specs
| BCI Group Size | 31 |
| Cold Cranking Amps (CCA) | 950 |
| Reserve Capacity | 200 minutes |
| Voltage | 12V |
| Construction | Heavy duty flooded or AGM (specify when ordering) |
| Dimensions | 13.00 in x 6.81 in x 9.44 in (330 x 173 x 240 mm) |
| Terminal Layout | Top post, heavy-duty terminals |
| Warranty | Free replacement — ask for current term |
Vehicle Compatibility
- Ford F-250/F-350/F-450 Super Duty diesel (6.7L Power Stroke and earlier diesels)
- Ram 2500/3500 with Cummins diesel — often used in dual-battery setups
- Chevy Silverado / GMC Sierra 2500HD/3500HD Duramax diesel
- Commercial vans, RVs, and fleet vehicles specifying Group 31
⚠️ Dual battery diesel trucks: If your diesel truck has TWO batteries, both should be the same age, group size, and type. Replacing only one creates an imbalance that shortens the life of both. Ask us about matched pairs.
Why Diesels Need More CCA
- Diesel compression ratios are roughly double that of gas engines — much harder to crank, especially cold
- 950 CCA provides the cranking reserve diesel starters demand
- 200-minute reserve capacity supports glow plugs, block heaters, and extended idling for cabin heat
- Heavy-duty internal construction withstands constant vibration from diesel engines
Signs Your Diesel Truck Battery Is Failing
- Engine cranks noticeably slower, especially below -10°C
- Glow plug wait time increases or warning light stays on longer
- One battery in a dual setup reads significantly lower voltage than the other
- Battery case bulging — stop use immediately
- Battery older than 4 years under heavy commercial use
Frequently Asked Questions
What battery do diesel trucks need?
Diesel engines require higher CCA than gas engines due to higher compression — Group 31 with 900-1000+ CCA is the standard for most diesel pickups and commercial trucks.
Do I need AGM or flooded for a diesel truck?
Both are available in Group 31. AGM offers better cold performance and longer life but costs more. Flooded is a solid economical choice for moderate climates. Ask us which we have in stock.
My Ram 2500 has two batteries — do I need to replace both?
We strongly recommend replacing both at the same time with matched batteries. An old and new battery in parallel charge unevenly, shortening both their lifespans.
How often should I test a diesel truck battery?
Test annually after year 2-3, especially before winter. A load test reveals weakening capacity before it leaves you stranded on a cold morning.
Not sure if this battery fits your truck?
Call or WhatsApp us with your year, make & model — we confirm the correct group size and CCA before you order.
📞 +1 (512) 236-5489 💬 WhatsAppQuestion:
- What battery do diesel trucks need?
- Do I need AGM or flooded for a diesel truck?
- My Ram 2500 has two batteries — do I need to replace both?
- How often should I test a diesel truck battery?
- Is Group 31 the right size for my Super Duty?
- What’s the difference between Group 31 and Group 27?
- How many CCA does a Cummins diesel need?
- Can I use a Group 31 battery in a gas truck?
- Why does my diesel truck have two batteries?
- How long does a Group 31 battery last in commercial use?
