Group 45 Battery [Uses, Size, and Replacements]

If you’ve ended up here, you might be struggling to replace your vehicle battery whether it’s in your tractor, lawnmower, or car.

But don’t worry. 

Below you’ll find a clear and easy to understand look at group 45 including retailers and recommendations. Plus I’ll answer your biggest questions.

What is a Group 45 Battery?

BCI group 45 batteries are manufactured as relatively small starting batteries to use in passenger cars, lawnmowers, tractors, and LTVs. They are known to be used in vehicles brands such as Honda, Chevrolet, John Deere, and Gehl.

At less than 10 inches long and 5 ½ inches wide, these are one of the smallest BCI sizes. It delivers 450 – 500CCA at 12V. You’ll also benefit from 60 to 80RC and around 30Ah.

They’ve become rare in automobiles with no modern cars using this group size. John Deere tractors are the most common type of vehicle still using a group 45.

In fact, if you’re reading this you are likely to be looking for a replacement for your tractor. If you’ve asked your local car parts dealer, they might give you a confused look as they are unlikely to stock a group 45. You might need to ask for it to be ordered specially. Or you can find them online at specialist retailers like Batteriesplus or Canadiantire.

If you’re still struggling, consider an equivalent replacement like group 51. You can read more on this further down.

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BCI Group 45 Dimensions and Weight

The dimensions of a group 45 battery are:

• Length: 9 7/16 inches (240mm)
• Width: 5 ½ inches (140mm)
• Height: 8 15/16 inches (227mm)
• Average Weight: 30lbs (13kg)

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Chemistry Type and Application

Group 45 batteries mostly used traditional flooded lead acid technology. These are reliable and durable. You’ll need to do maintenance every so often to refill the water in the battery acid. Plus be careful when handling and installing, always use gloves incase of spillage.

There are a small number of sealed lead acid although they are hard to find. If you’re looking for an AGM option to increase performance and lifespan, then CAT makes one for you to check out.

In terms of application, these are only built as starting batteries for cranking engines. You won’t find any deep cycle or marine options. So don’t go using one on your boat or RV. You’re better off choosing a more common group size anyway to save yourself multiple headaches.

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Pros and Cons of Group 45 Batteries

Let’s look at the advantages and disadvantages of these batteries. 

Pros:

• Fits tractors like John Deere
• Relatively small and lightweight
• Can be bought online
• Good for engine cranking

Cons:

• Can be hard to find
• Rarely used in modern vehicles
• No deep cycle or marine options

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Group 45 vs Group 22NF Batteries

You can use group 22NF as a replacement for group 45. Take a look at the table below, they are the exact same dimensions. This means you can slot it into your vehicle battery compartment with no worries.

Group	Length (inch)	Width (inch)	Height (inch)
22NF	9 7/16	5 1/2	8 15/16
45	9 7/16	5 1/2	8 15/16

22NF batteries are more common and easier to buy online. Be careful to install the correct type. You need to ensure it is a starting battery, and not a marine or deep cycle which are abundant in this group size. Plus match the chemistry type, if you use an AGM instead of a flooded or sealed battery you will run into charging issues.

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Group 45 vs Group 51R Batteries

Group 51R is not exactly the same dimensions, it’s slightly smaller. This means you can easily slot it into your vehicle battery compartment. The ‘R’ means the polarity is reversed. In this case, it’s good news as the terminal poles match the position of a group 45. (You could also use a normal group 51 and just spin it around).

Group	Length (inch)	Width (inch)	Height (inch)
51	9 3/8	5 1/16	8 13/16
45	9 7/16	5 1/2	8 15/16

51R is an incredibly popular car battery which is available in all chemistry types including flooded, sealed, AGM, and even lithium. So be careful to buy the matching type to your current group 45.

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FAQ

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Summary

I hope this article gives you a clear insight into BCI group 45 batteries.

Truth is: They are becoming uncommon but tractors, lawnmowers, and small industrial vehicles still use them. Brands like John Deere and CAT still manufacture this battery size. You struggle to find them at your local car parts supplier so you should ask for it to be ordered in or use special online retailers. Failing that, try contacting the manufacturer directly.

They are relatively small and lightweight as they are less than 10 inches long and under 30lbs. You’ll find normal flooded lead acid batteries to crank your engine, but don’t expect to find cyclical applications in this group.