The thing about car batteries is that you don’t move them until they’re damaged or need replacing.
If you’re the diligent kind, you might check the acid levels every so often, top up the water levels, or clean off the batteries. For most of us, however, we only take a look at the battery when it’s flat or damaged.
Looking at a car battery doesn’t really give you a sense of how heavy it is. It’s not the largest part of the car but it certainly pulls and carries its own weight.
How Much Does a Car Battery Weigh?
There are a lot of mitigating factors that affect the weight of the car battery. We’ll take a look at these in a moment.
On average, though a car battery tends to weigh between 30lb and 50lbs. 41lbs is the most common weight for US car batteries.
So, those mitigating factors. Mainly it’s the size of the battery and its reserve capacity.
The size of the battery changes depending on the physical space available for the battery. Obviously bigger batteries weigh more.
There is a body called the Battery Council International that regulates the battery industry. They have a size guide that groups batteries based on the exact physical dimensions. This helps you select the battery that will fit under the hood.
Before you look at power capacities, you want to get the right group size. A battery that is too big or small won’t sit properly under the hood.
The reserve capacity is how much power the battery can store. This energy is used by lights and indicators and things even if the energy stops working. Again, the bigger the battery, the bigger the reserve capacity in general.
Below, you’ll find two tables. The first will give the dimensions and weights of different BCI size guides. The second table gives battery weights according to the reserve capacity.
Weight According to BCI Size
| Battery Group | Weight (lb) | Length (in) | Width (in) | Height (in) |
|---|---|---|---|---|
| 24 |
41 |
10 1/4 |
6 13/16 |
8 7/8 |
| 24F * |
41 |
10 3/4 |
6 13/16 |
9 |
|
27 |
48 |
12 1/16 |
6 13/16 |
8 7/8 |
|
34 |
39 |
10 1/4 |
6 13/16 |
7 7/8 |
| 35 | 40 | 9 1/16 | 6 7/8 | 8 7/8 |
| 47 (H5) ** | 35 | 9 1/19 | 6 7/8 | 7 1/2 |
| 48 (H6)** | 42 | 12 1/16 | 6 7/8 | 7 9/16 |
| 49 (H8) ** | 52 | 15 | 6 7/8 | 7 9/16 |
| 51R *** | 29 | 9 3/10 | 5 1/20 | 8 17/20 |
| 65 | 45 | 12 1/16 | 7 1/2 | 7 9/16 |
| 75 | 34 | 9 3/4 | 7 | 7 1/4 |
| 78 | 39 | 10 1/4 | 7 1/16 | 7 11/16 |
| 94R*** | 49 | 12 2/5 | 6 9/10 | 7 1/2 |
You’ll notice that some of the battery size groups have letters. There are a number of different reasons for these.
* The difference between 24 and 24F is a matter of size and polarity. The 24F is ever so slightly larger and has reversed polarity. This means that the positive and negative polarities are reversed. You need a special connector to use these batteries.
** Batteries with an H number just mean that they are equivalent to the German battery size guide.
*** Battery sizes marked with an r have reversed polarity.
Weight According to Reserve Capacity
This table will give you a general idea of the weight of batteries according to their reserve capacity. This is a less accurate measurement as the size has a much greater impact on the weight.
However, if you happen to know the reserve capacity and are thinking about moving your battery, this table will give you a good indication of what you’re lifting.
| Reserve Capacity | Weight (lb) |
|---|---|
| 80 | 30 |
| 85 | 30 |
| 90 | 34 |
| 95 | 34 |
| 100 | 37 |
| 105 | 38 |
| 110 | 39 |
| 115 | 37 |
| 120 | 41 |
So Why are Car Batteries so Heavy?
Do you know what they’re made from? It’s lead. Car batteries contain multiple sheets of lead and lead oxide that are submersed in sulphuric acid.
Lead is pretty dang heavy. It weighs 707.96 lbs per cubic foot. Aluminum, usually chosen for its lightweight properties, only weighs 168.48 lb per cubic foot. To put that into a more tangible way, a cubic foot of paper weighs 33lb.
To cut a long story short, lead is heavy. This is why car batteries are heavy.
Lightweight batteries are available but they tend to be prohibitively expensive. There is some research into lighter batteries but these are not readily available.
In general, healthy adults can safely lift 51lbs providing the object is close to the body and about waist height. This means that most batteries should be manageable for most healthy adults.
If you do find the battery too heavy, take the car to the nearest garage and they’ll be able to take care of it for you.
Disposing of Car Batteries
Seeing as car batteries contain both lead and acid they can’t go in your household trash. Both of these things are very harmful to the environment and need to be disposed of safely and responsibly.
You can use this site to find the nearest place that will take your old battery. Generally, Home Depots and Autozones will accept your old batteries.
Many cities also offer a refundable deposit for car batteries. When you return your battery they will refund you the cost of the deposit. This is a great incentive to recycle your old car battery.
If you have your battery changed at a garage, they will often dispose of the battery for you. Make sure to check with your mechanic when you have your battery changed.
Final Thoughts
You’re forgiven for not knowing how much your car battery weighs. You only need to change your battery every 4 or 5 years.
Most car owners replace their cars before they replace their batteries!
Now, however, you have a better understanding of the weight behind the power source beneath your hood.
