Replacing a battery should be easy, but for some reason the world makes it far too complicated.
It’s not a fun job anyway because your current car ain’t working so good! I hope you’re not stranded somewhere unable to start your engine.
Don’t worry. Below you’ll find clear and helpful information discussing 40R batteries to get you back on the road quickly.
⚡BCI Group 40 Key Facts⚡
- Length: 10 15/16 inch
- Width: 6 ⅞ inch
- Height: 6 ⅞ inch
- Weight: 35 lbs
- 12V
- 600 – 650 CCA
- WET, SLA
- Starting / Cranking
What is a Group 40R Battery?
BCI group 40R batteries are built to be used as a starting battery to crank your car engine.
It is a 12V automotive battery for passenger cars, small vans, and light trucks.
Ford is the major brand using this size, although it is becoming less and less common in modern vehicles. As a mid sized battery producing 600 – 650CCA, it is perfect for starting car engines and small vans. For example, newer Ford Transit Connects from 2014 onwards still take a group 40R.
You’ll also see these batteries in older Japanese brands like Mazda.
BCI Group 40R Dimensions and Weight
The dimensions of a group 40R battery are:
- Length: 10 15/16 inches (277mm)
- Width: 6 ⅞ inches (175mm)
- Height: 6 ⅞ inches (175mm)
- Average Weight: 35lbs (16kg)
When looking at the exterior dimensions you should take into account the ‘R’ in 40R. This denotes that it has reverse polarity. This means the positive and negative terminals are in the reverse position to normal. In this case, the positive terminal pole is on the right and the negative on the left.
Chemistry Type and Application
The majority of manufacturers produce group 40R as a flooded lead acid (WET) chemistry type. This means the inside cells are flooded with battery acid electrolyte. You should be careful when handling, always wear gloves and safety glasses incase of spills. These also require maintenance by refilling the electrolyte which slowly evaporates over time.
You can find a small number of sealed lead acid (SLA) 40R batteries. These have the advantage of being maintenance free and reduce risk of spillage. Although, this can reduce the lifespan and must be charged carefully.
You won’t find many AGMs as there is minimal demand. Likewise manufacturers don’t make lithium equivalents.
As we discussed earlier, these are built as starting batteries to crank vehicle engines. They are not made for cyclical or dual purpose application, like in an RV or boat.
Pros and Cons of Group 40R Batteries
Let’s look at the advantages and disadvantages of these batteries.
Pros:
- Made for large car brands like Ford
- Easy to buy online
- Available as WET or SLA
- Not too expensive
Cons:
- Not for deep cycle or marine
- Only in reverse polarity
- Becoming less common
- No AGM or Lithium options
Group 40R vs Group 96R Batteries
What is the difference between a 40R and 96R battery? Well, they have some subtly different attributes to be aware of.
Take a look at the table below. You’ll quickly see they are different in length. 96R is nearly over 1 inch shorter. The height and width is similar. This means you could potentially replace a 40R with a 96R as it is smaller. But a 40R might not fit in a 96R battery compartment as it is too long.
| Group | L (inches) | W (inches) | H (inches) |
| 96R | 9 9/16 | 6 13/16 | 6 ⅞ |
| 40R | 10 15/16 | 6 ⅞ | 6 ⅞ |
96R batteries are more common which might make it easier and cheaper to use instead of a 40R.
They both have reverse polarity so the pole terminals will be in the correct position for your vehicle.
Adding to this, the CCA of both is 600 – 650 so they are suited to cranking the same size engines.
So you could replace a 40R with a 96R, just make sure it is secure once installed and the chemistry type is the same.
Group 40R vs Group 41 Battery
You might be considering the difference between 40R and 41 group batteries. It’s only natural, as they sit next to each other on a BCI size chart. Does that mean they are similar or equivalent replacements?
Take a look at the table below. The big difference is the length, with a group 41 being nearly ½ an inch longer. But the width and height is the same. This means you need to carefully measure your battery compartment to see if it has enough room to fit the length of a group 41. Many times you can squeeze it in.
| Group | L (inches) | W (inches) | H (inches) |
| 41 | 11 3/16 | 6 ⅞ | 6 ⅞ |
| 40R | 10 15/16 | 6 ⅞ | 6 ⅞ |
The performance is similar with both being built with 600 to 650CCA to use on passenger car engines and small vans.
You should compare the position of the positive terminal too. Both should have this positioned on the right to correctly fit your vehicle as an equivalent.
Group 40R vs Group 48R Battery
When you compare group 48R and 40R batteries you’ll quickly see they have different exterior dimensions. The 48R is much longer and taller which means you’ll struggle to fit it into a 40R battery compartment. In this case, it is best to stick to your current battery size.
| Group | L (inches) | W (inches) | H (inches) |
| 48R | 12 1/16 | 6 ⅞ | 7 9/16 |
| 40R | 10 15/16 | 6 ⅞ | 6 ⅞ |
FAQ
Cars that take a 40R battery include:
Ford Transit Connect (2014 – 2021)
Ford Escape (2001 – 2011)
Mercury Mariner (2005 – 2010)
Ford Mustang (2005 – 2009)
Mercury Milan (2006 – 2007)
Ford Focus (2004 – 2007)
Mazda 6 (2002 – 2007)
It has a cold cranking amps of 600 to 650.
This stands for reverse polarity. The terminal poles are mounted in the opposite position. For example, the positive terminal is on the right rather than the left.
Summary
I hope you’ve found this page about group 40R batteries helpful and answers your questions.
As you have found out, they are built predominantly as starting batteries for cranking passenger car engines and small vans.
With dimensions of 10 15/16 by 6 ⅞ inches it is a mid sized battery which delivers 600 – 650CCA. You’ll find them in modern Ford Transit Connects and Ford Mustangs until 2007.
Don’t forget they are reverse polarity so the positive and negative terminals are switched to opposite locations.
As for chemistry types, they’re mostly flooded but you can find sealed lead acid too.
