Lawn Mowers and Electric Tools Battery Types

Regardless if they are powered by an internal combustion engine or electric motor, lawn mowers and electric tools commonly have some sort of built-in battery. Such batteries can be used for cranking, powering lights, remote controls, holding BIOS charge of advanced microcontroller-based devices, powering main motors, etc.

Knowing battery types, their strength, and their weaknesses can significantly help in prolonging their runtime and their operating lifetime and can help to unitize better unify electric tools that use such batteries.

Published: October 13, 2022.

Most Common Battery Chemistry Types

Most common battery chemistries include both non-rechargeable and rechargeable batteries. Probably the MOST important advice regarding rechargeable batteries is: for charging rechargeable batteries, always use ONLY the battery charger intended/designed for such batteries.

The most common ones are:

Nickel Cadmium (NiCd) Batteries

Rechargeable NiCd batteries are rarely used today because they use heavy metal cadmium, which is dangerous to the environment.

NiCd batteries can provide strong currents and are suitable for use in cheaper cordless tools in the form of pre-made battery packs consisting of 5-12 or even more NiCd batteries soldered in series.

Their nominal voltage is 1.2 volts per cell.

However, NiCd batteries suffer from memory effects, high self-discharge rate, they are far from being environment friendly, have a limited number of charging/discharging cycles, etc.

Thus, in modern cordless tools and lawn mowers, NiCd batteries are phased out. If you happen to stumble on the tool powered via NiCd batteries, stay away from it, regardless of how cheap it is - who knows what else is wrong with it ...

Nickel Metal Hydride (NiMH) Batteries

Generally, Nickel Metal Hydride batteries are similar internally to NiCd batteries, but they are a much more environmentally friendly type of batteries, and when charged and used properly, they can last much longer.

Their nominal voltage is 1.2 volts.

Also, modern NiMH batteries have a very low-self discharge rate and practically almost no memory effect.

NiMH batteries come in the form of standard household battery sizes (AA, AAA, C, Sub-C, and other sizes) intended for general use or in the form of pre-made battery packs intended for specific tools or sets of tools.

Also, their capacity and maximum output current depending on the battery construction, with high-capacity/low-current and low-capacity/high-current models being available on the market.

NiMH batteries are being phased out by various rechargeable lithium batteries.

Lead Acid Batteries

Commonly, starting lead acid batteries are used as cranking/starting batteries in cars, trucks, boats, RVs, and similar.

Also, deep-discharge lead acid batteries are used in electric vehicles to power drive and utility (winches, pumps, etc.) motors.

Dual-purpose lead acid batteries have good cranking features, but they also tolerate deep cycle use.

However, lead acid batteries' construction varies significantly:

• Wet/flooded cells - sulfuric acid (electrolyte) is placed among the battery plates and is free to move around. Such batteries must be operated in an upright position, or the acid may be spilled out, which can be very harmful.
• Gel cell - sulfuric acid (electrolyte) is mixed with silica powder and forms the gel, which is then placed between the battery plates. Such batteries are vibration resistant, can operate in almost any condition, and are practically maintenance-free.
• Absorbent Glass Mat (AGM) batteries use a finely woven mat of glass fibers that are used to hold the sulfuric acid. AGM batteries are resistant to vibrations, can be operated in any position, and are maintenance-free batteries.

Electric, battery-operated riding lawn mowers are commonly powered using lead-acid batteries.

When replacing batteries in such units, AGM (non-spillable) lead-acid batteries are highly recommended.

Note that some manufacturers offer lithium drop-in replacement batteries for replacing lead-acid batteries (AGM batteries included) not only in electric riding lawn mowers, but also in cars, golf carts, RVs, ATVs, etc.

Such drop-in lithium battery replacements cost much more, but they are also much lighter and can withstand much more charging/recharging cycles.

Rechargeable Lithium Batteries

Rechargeable lithium batteries come in various sizes, shapes, and of course, chemistries.

Note: again, all batteries should be charged with the battery chargers intended for such batteries. For example, GreenWorks Pro 80V lithium batteries should be charged ONLY with GreenWorks chargers designed for such batteries. Never, but really never try to 'adapt', 'try', 'test' or anything similar with lithium batteries - they pack plenty of energy in a lightweight battery and when overheated, can catch fire or even explode. This is a SERIOUS warning, not 'just another' disclaimer or something similar ...

The most common rechargeable lithium batteries' chemistries are:

• ICR lithium-ion batteries feature LiCoO₂ (Lithium Cobalt Oxide) chemistry, 3.6-3.7 volts per cell, and a maximum charging voltage of 4.2 volts, they feature high capacity but must be drained using low currents.
• IMR lithium-ion batteries feature LiMn₂0₄ (Lithium Manganese Oxide) chemistry, 3.6-3.7 volts per cell, and a maximum charging voltage of 4.2 volts, they feature smaller capacities, but they are able to deliver rather strong currents.
• INR lithium-ion batteries feature LiNiMnCoO₂ (Lithium Manganese Nickel) chemistry and share the most common features with IMR batteries.
• IFR lithium-ion batteries feature LiFePO₄ (Lithium Iron Phosphate) chemistry, a nominal voltage of 3.2 - 3.3 volts per cell, with the maximum recommended charging voltage of 3.5 - 3.6 volts per cell. They can provide rather strong currents but not as strong as IMR/INR batteries.

However, IFR batteries are one of the safest lithium chemistries and are often used as drop-in replacement batteries, combined with a good Battery Management System (BMS).

Of course, there are other chemistries on the market and much more chemistries in development, like Lithium Nickel Cobalt Oxide (LiNiCoO₂), Lithium Nickel Cobalt Aluminum Oxide (LiNiCoAlO₂), etc.

Lithium Ion Battery Drop-In Replacements batteries are lithium batteries designed to replace lead-acid batteries. Such drop-in replacements are optimized for starting/cranking use, dual purpose, or low-current, deep cycle use.

Thanks to the built-in BMS, such drop-in replacement batteries usually can be charged using lead acid chargers and sometimes can even be connected in series and parallel in order to achieve higher voltage and/or higher capacity.

Note: Before connecting drop-in lithium replacement batteries in series and/or parallel, check the manual to see if their BMS systems allow such connections. If you are not sure, contact the manufacturer directly.

Deep Cycle Lithium Batteries are commonly used in electric vehicles (golf carts, RVs, ATVs, cars, etc.), boats (for example, as lightweight trolling motor batteries), and also in cordless lawn mowers and other cordless tools.

Battery-operated riding lawn mowers can save plenty of weight and may prolong their runtime on a single battery charge if lithium batteries are used.

Which batteries may be used depends on the riding lawn mower model and the list of batteries recommended/allowed by the manufacturer - be sure to check the manuals.

Other cordless lawn mowers and power tools MUST use batteries specifically intended by their manufacturer in order to function properly. If other batteries are used, not only that warranties are void, but also some sort of damage, injury, or worse may happen.

When designing their batteries, manufacturers like DeWalt, GreenWorks, and similar, try to find a very fine balance between discharging/discharging currents, voltages, temperatures, operating times, etc., and they test their batteries thoroughly.

The least one can do is to use such batteries according to the recommendations given by their manufacturer.

Also, most brands make many different tools that can be powered with a single model, not just lawn mowers, making future tools purchases much cheaper.

For Short: If you are looking for a replacement battery for your lawn mower, be sure to get the same battery model or go for some other models recommended by their manufacturer.

Using the wrong batteries can lead to damage, injuries or something even worse. So be careful. Lithium batteries are lightweight and powerful, but when misused, they can 'fight' back ...