Kobalt 40V Max Lawn Mower Battery Review
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A kobalt 40v max lawn mower battery is a 40-volt lithium pack that has to match the Kobalt model number printed on your current battery and the charger you already own. The replacement pack reviewed here is listed at 6.0Ah and 240Wh, with a 4-LED charge gauge, and its listing names a long list of Kobalt 40V model numbers it is meant to replace, including KB440-03, KB240-06, KB640-06 and KRC60. Before you buy any replacement, compare the model number on your old battery with the list in the listing. A match on model number matters more than a match on the product title.
Quick answer
- Best fit for a review: eJiasu Kobalt 40V replacement, 6.0Ah, 240Wh, 4-LED indicator (ASIN B0D9LVSRCC).
- Capacity: the listing states 6.0Ah and 240Wh. Runtime depends on the mower or trimmer and the grass, and the listing gives no runtime figure.
- Check first: your battery model number and your mower model number. The listing says the 16-inch and 20-inch mowers need a model check before purchase.
- Charging: the listing names Kobalt chargers KRC60 and KRC40-06 as the chargers used with these packs.
How to check that a Kobalt 40V replacement fits
Kobalt 40V tools have used more than one battery model over the years, and the pack that fits a 20-inch mower is not always the pack that fits a string trimmer. Start by reading the model number printed on the label of the battery you have now. Then look for that number in the compatibility text of the listing. The eJiasu listing lists KB440-03, KB2540C-06, KB640-03, KB240-06, KB640-06, KB245-06, KRC40-06, KB440C-06 and KRC60 as replacement targets. The listing also names the KB540-06 and KB440-06 model numbers in its title.
Next, check the mower model. The listing says the 20-inch mower models KM 2041B-06 and KPM1040A-03 and the 16-inch mower KM-1640-06 are supported, and it tells buyers to confirm the mower model before ordering. That is a useful warning. A battery can share a voltage with a tool and still not be the right physical pack for that tool.
Finally, confirm the charger. A replacement pack is only half of the setup. The eJiasu bullets say the pack works across the whole Kobalt 40V tool line, but they do not name a charger model for the pack itself. If you do not already own a compatible Kobalt charger, look at the battery and charger kits covered later in this review.
What 6.0Ah and 240Wh mean for a Kobalt battery
Amp-hours describe how much charge a battery stores, and watt-hours describe the total energy. The eJiasu listing gives 6.0Ah and 240Wh in its title and bullets. Those two numbers are consistent with each other for a 40-volt pack: 40 volts multiplied by 6.0Ah comes to 240Wh. A higher amp-hour pack generally gives longer run time before it needs a recharge, but run time also depends on the tool. A mower working through thick grass pulls more current than a trimmer working along a fence line.
The listing does not publish a run-time figure for a specific tool, so this review does not claim one. What the listing does say is that the pack gives extended runtime compared with smaller packs, and that it has high-quality cells inside. Those phrases are the seller’s wording. Read them as the seller’s description, not as a measured result.
When you compare packs, put the watt-hour figure side by side. Several Kobalt replacements in this group list 6.0Ah. The TONAMO 4.0Ah pack in the same product family lists a lower capacity and is worth comparing if you mostly trim small areas and do not need the extra energy.
Protection, the LED gauge and storage
The eJiasu listing says the pack includes an integrated microchip that protects the cells, with automatic overload cut-off, short-circuit protection and over-voltage protection. It also says the pack has no memory effect, so it can be charged or discharged as needed without losing capacity. Those are the standard expectations for a lithium-ion pack, and the listing states them as features rather than as lab results.
The pack has a 4-LED indicator. The listing says you press the button near the LEDs to see the remaining charge, which is useful before you walk out to a large yard. A gauge is only a guide. Lithium packs in heavy use show less capacity over time, so a pack that reads full on the gauge may run out sooner after a season of use.
For storage, the listing does not give a storage temperature or a state-of-charge recommendation. Follow the charger and mower manual for those details. If you need a seasonal storage routine, the internal link below covers how to store a lawn mower battery over winter.
The eJiasu Kobalt 40V replacement in depth
The eJiasu pack is the main subject of this review. The listing title reads “eJiasu Kobalt 40V Battery Replacement 6.0Ah for Lawn Mower and Power Tools,” and the specs table gives the model as KB440-03H with part number E584B. Those are the identifiers to check against your original pack.
The listing describes the product as one 40V 6.0Ah lithium-ion battery, with the 240Wh rating in the title, a 4-LED fuel gauge, and the compatibility list covered above. It says the pack fits the whole Kobalt 40V tool lineup, including chain saws, weed whackers, leaf blowers, string trimmers, pole saws and hedge trimmers, and it names the mowers noted earlier. The listing also includes the phrase “fast charge,” and says the pack can be charged or discharged as needed.
The seller offers a 30-day money-back guarantee and a one-year exchange service, and says that buyers can contact the seller through the storefront or the order page with questions. Those terms are the seller’s own. Check them on the listing before you buy, because policies can change.
What the listing does not state: the pack weight, the physical dimensions, the cell manufacturer, a charge time, a discharge rate, the operating temperature range and the number of charge cycles. If any of those matter for your decision, ask the seller through the listing before you buy, or compare with another listing that does state them.
Close alternatives from the same product group
Two alternatives in the pack are worth a look if the eJiasu pack does not match your setup. Both are listed as Kobalt 40V replacements, and both name the same family of model numbers.
CPY Replacement for Kobalt 40V Battery 6.0Ah
The CPY listing is a 40V 6.0Ah lithium-ion pack with the model number KB64006 in its specs. The bullets name KB540-06, KB440-06 and KB240-06 as compatible models and describe a 4-LED fuel gauge. The listing also describes overcharge, overheat and short-circuit protection, and it describes the case as made of ABS and PC with a fire-resistant rating. Those are seller claims. The listing does not give a separate certification number for them.
The CPY listing says “3X longer runtime.” That phrase is a comparison the seller makes, and the listing does not name the baseline pack. Read it as a marketing statement and compare it with your own use.
TONAMO 2 Pack 6.0Ah 40V Replacement for Kobalt 40V Battery
The TONAMO two-pack listing is useful if you run two packs in rotation. It lists 40V, 6.0Ah and 248Wh per pack, and the model number KB64006 in its specs. Its bullets name a 3rd-generation battery management system with six protection layers, and say the pack is certified by CE, FCC and RoHS. The listing also names KRC60-06, KRC40-06 and KRC840-03 as compatible chargers, which is the most specific charger list in this group.
Two packs means a second battery to charge while the first one is in use. The listing does not say whether the two packs are sold as matched units, so check the listing before you buy if matching matters to you.
AURIVO 6.0Ah Battery Replacement for Kobalt 40V Battery
The AURIVO listing is the most detailed in the group. It names a long list of Kobalt 40V models including KB440-03, KB2540C-06, KB240-03, KB540C-06, KB540-06, KB640-03, KB240-06, KB640-06 and KB245-06, and it lists KRC60-06, KRC40-06 and KRC 840-03 as compatible chargers. The bullets describe a smart battery management system and a 1,200-plus cycle life, and state UL, FCC and UN38.3 certifications. The listing also describes a 5-year protection plan with replacement, not repair.
The cycle-life and certification claims come from the seller’s listing text. The pack does not show a certificate number, so check the listing for the documents before you rely on them.
Charger and kit options
If you need a charger along with the pack, the pack lists include two kits and one charger. The ActZone kit combines a 40V 6.0Ah battery with a fast charger and lists KB240-06, KB240C-06, KB245-06, KB340C-06, KB640-03, KB640-06, KBK0140-06, KRC-03, KRC40-06 and KRC 60-06 as compatible models. The bullets say the charger has a smart chip that prevents overheating and overcharging, with three-sided cooling fins and LED charge indicators.
The Sydelway charger is listed as a replacement for the KRC 40-06 and 4080-06 Kobalt chargers. Its bullets give approximate charge times for three capacities: about 45 to 60 minutes for 2.5Ah, about 100 to 120 minutes for 4.0Ah and 5.0Ah, and about 160 to 180 minutes for 6.0Ah. The bullets also state that it weighs 1.81 pounds, and that it plugs into a standard 120V outlet and has wall-mount keyholes. The listing says it is designed for 40V packs and is not compatible with 24V models.
Both charger listings state the same caution. Confirm the battery and charger model against your existing equipment before ordering.
Common mistakes when buying a Kobalt 40V battery
The most common mistake is matching by tool name instead of by model number. A pack labeled for a leaf blower may not share the mechanical design of a mower battery, even when the voltage matches. Read the model list in the listing and compare it with your label.
The second mistake is ignoring the charger. A new pack will not charge properly on a charger it does not match, and a charger that is only listed for a different model may not give the expected charge profile.
The third mistake is buying the highest amp-hour pack without checking the physical fit. The listings here do not state dimensions or weight, so measure your old pack and compare it with the seller’s photos before ordering. The fourth is treating the LED gauge as a precise measure. It shows steps of charge, not an exact capacity reading.
Frequently asked questions
Will a 6.0Ah pack fit every Kobalt 40V mower?
Not necessarily. The eJiasu listing names specific mower models and asks buyers to check their mower model before purchase. Compare your mower model with the list in the listing before you order.
What does 240Wh mean for a lawn mower battery?
Watt-hours show the total stored energy. A 240Wh pack holds more energy than a 4.0Ah pack at the same voltage, which generally gives longer run time per charge. The actual run time depends on the tool and the grass.
Are these batteries compatible with Kobalt chargers?
The listings name specific Kobalt charger models, including KRC60, KRC40-06 and KRC840-03. Confirm the charger model on your own charger before you buy the pack.
Does the eJiasu pack have a warranty?
The listing describes a 30-day money-back guarantee and a one-year exchange service handled by the seller. Check the current terms on the listing, because seller policies can change.
Are Greenworks batteries in this group Kobalt batteries?
No. Two listings in the source pack are Greenworks replacement batteries, and they name Greenworks models. They are not Kobalt packs, so this review leaves them out.
How should I store a spare Kobalt battery?
The listings do not give a storage recommendation. Follow your charger and mower manual. The internal link below covers winter storage in more detail.
Bottom line
Buy a kobalt 40v max lawn mower battery only after you match the model number on your old pack and the model number on your charger. If the model list in the eJiasu listing includes your model and your mower is on the supported list, the 6.0Ah and 240Wh rating gives you a larger energy store than a smaller pack. If you need two packs for continuous mowing, the TONAMO two-pack listing is the alternative to compare.
Related reading
For more on keeping a mower battery in good shape, read How to Store a Lawn Mower Battery for Winter and How Long to Charge a Lawn Mower Battery.
