The Difference: U1 vs. U1R Battery [with best mower batteries review 2022]

The U1 and U1R type battery group is generally used for ride-on lawnmowers, garden tractors, mobility scooters, wheelchairs, and similar vehicles. The battery is there to simply start the engine and make using the machine more convenient.

Of course, as with all batteries, they only have a finite working life. If your lawnmower won’t start, then an excellent place to start investigating is the battery. If you need to replace your U1 or U1R battery, it is worth knowing their differences.

What is the difference between U1 and U1R batteries?

U1 vs. U1R Batteries for Mowers

The only difference between the U1 and the U1R batteries is the position of the terminals.

You can assess the terminal position with the battery label facing you. If the positive terminal is on the left, you have a U1 battery. If the positive terminal is on the right, you have a U1R battery type. 

Within a brand, this is usually the only difference. But different brands of a battery may offer more amp-hours or more Cold Cranking Amps (CCA).

Choosing the correct battery version is essential, as the mower’s battery cables may be too short to reach the battery if the terminals are in the wrong positions.

Most gas-powered lawnmowers use the U1 type battery, but it’s essential to make sure before you order a new battery. If in doubt, contact the manufacturer or speak to a specialist.

See U1 and U1R Batteries For Lawnmowers/ Tractors here:

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Weize U1 Battery For Cordless Mower

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Deka U1R Battery For Mower

What are the similarities?

Physical dimensions: 7.72 x 5.14 x 6.14 inches

You would expect all U1 and U1R batteries to have the same dimensions, and to a degree, you are correct. The standard size for a U1 group battery is:

  • Length – 7.72 inches
  • Width – 5.14 inches
  • Height – 6.14 inches

However, not all manufacturers stick strictly to the standard size. Before you order a replacement U1 battery, measure the dimensions of the battery tray to make sure the battery will fit. If you fit a larger battery than standard with a greater CCA, then this could be useful. We explain what CCA is later.

Voltage: 12V

All U1 and U1R batteries provide a 12V output. This voltage is just about the standard across all small to medium vehicles now. However, you may find a tiny number of small engine vehicles using 6V electrical systems, but it is rare.

CCA: Important specs for gas-powered lawn mower battery

The Cold Cranking Amps (CCA) of a battery is the power available to turn over your engine in cold conditions. The engine oil is thicker in a cold environment, and the engine is more difficult to start. This is why fitting a battery with the highest CCA is advisable.

The average CCA for U1 type batteries is around 300 – 320 CCA, but some examples are available up to 350 CCA. If you live in a cold climate area, a higher CCA is definitely worth the extra.

For gas-powered mowers or tractors, the CCA is more important than having a deep cycle battery. Your battery is there only to start the engine, and then it is recharged by an alternator, just like your car.

See High CCA Batteries For Gas Mowers here:

Mighty Max Group U1 Battery

Mighty Max 320 CCA Group U1

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Deka 320 CCA Group U1R

Amp-hour: Value to look for in an electric lawnmower battery

The amp-hour (Ah) rating of your gas-powered lawn mower battery is not particularly important compared to the CCA. However, for battery-powered cordless lawnmowers, the Ah value will determine your mowing time between charges.

The U1 group batteries give around 30 – 42 Ah, depending on the battery technology and the manufacturer.

When you are looking for a new battery for your cordless lawnmower, aim for the highest Ah rating available. That said, a good-quality branded battery will probably last longer than a cheap version.

Are U1 and U1R batteries interchangeable?

The U1 and U1R batteries from a particular manufacturer will likely be identical in size, AH and CCA. The only difference will be the position of the terminals, as discussed earlier.

This means they are interchangeable, but it depends on the location of your lawnmower’s battery. In some cases, the battery cables on the lawnmower will not reach if you use the wrong type of battery.

4 Best Group U1/ U1R Batteries for Mowers

Weize Deep Cycle U1 BatteryWeize Deep Cycle U1 Battery
  • Size: 7.75×5.19×7.13 in
  • CCA: --
  • Capacity: 35 Ah
Check Price
VMAX857 U1 Dual-Purpose BatteryVMAX857 U1 Dual-Purpose Battery
  • Size: 7.7x5x 6.1 in
  • CCA: 300
  • Capacity: 35Ah
Check Price
Mighty Max U1 Starting BatteryMighty Max U1 Starting Battery
  • Size: 7.75×5.11×6.25 in
  • CCA: 320
  • Capacity: --
Check Price
Deka U1R Dual-Purpose BatteryDeka U1R Dual-Purpose Battery
  • Size: 7.75×5.15×7.25 in
  • CCA: 320
  • Capacity: 45 mins
Check Price

#1. Best Deep Cycle Battery For Cordless Mowers

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Weize 35Ah U1 Battery

Battery-powered devices require a power source that provides constant voltage and amp-hours for extended periods. This is where the Weize TL 1235 excels.

Built using the absorbed glass mat (AGM) technology, the TL1235 has been designed for applications where continuous power is paramount. It is perfect for battery lawnmowers, wheelchairs, scooters, or trolling motors.

#2. Best Dual Purpose U1 Battery

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VMAX857 300CCA 35Ah U1 Battery

The VMAX857 AGM 35AH Group U1 Battery offers many of the other batteries’ features but is built explicitly for deep cycle use. The CCA rating of this battery is the lowest in the review, but it is a compromise between a deep cycle and a starting battery.

For smaller engine lawnmowers, this will be an excellent battery, offering both a good starting and a long-running time.

#3. Best Budget U1 Battery

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Mighty Max Battery U1 Battery

Mighty Max Battery ML-U1 Battery is an excellent choice if you need a U1 battery on a budget. At under $70, it’s the cheapest here but still packs a punch.

Using the absorbed glass mat (AGM) technology, the Mighty Max gives you a useful 320 CCA rating and offers good deep cycle capabilities.

The ML-U1 battery is very close to the standard size, so it should fit most lawnmowers.

Overall, the Mighty Max is an excellent choice at a brilliant price.

#4. High CCA U1R Battery

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Deka High CCA U1R Battery

With a CCA rating of 320 Amps, the Deka U1R AGM Battery is the most potent starting battery on the review. Manufactured using the AGM method, the battery can be mounted at any angle, making it very versatile.

The biggest downside to the East Penn battery is the price, at more than double the cost of the Weize and the Mighty Max batteries.


Replacing the battery on your lawn mower/ tractor is a simple process. The majority of lawnmowers use a U1 or a smaller number using the U1R type battery.

Remember, the difference between the U1 and the U1R battery is simply the terminal position. But make sure you get the correct version of the battery or that the mowers battery leads will reach.

Lastly, for gas-powered lawnmowers, remember that the CCA value is essential. In contrast, in battery-powered lawnmowers, the Amp Hours is the deciding factor.

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