Here’s a comprehensive look at HART 40 V 20″ Brushless Self‑Propelled Electric Lawn Mower Kit (and similar HART-brand mowers) — including its specs, common problems, root causes, fixes, and what you should watch out for. If you own one of these mowers (or plan to buy), this will help you understand how to get the most out of it.
✅ Specs & Overview
Here are the key specifications (for the 20″ self-propelled HART model) pulled from the manufacturer listing:
- Cutting width: 20 inches (≈ 50 cm) for the 20″ deck.
- Battery: 40 V lithium-ion, 6.0 Ah included in the kit. Cuts up to approx ½ acre with that battery.
- Deck height adjustment: Single-point height adjustment with cutting range from 1.5″–4″.
- Drive type: Self-propelled (rear-wheel drive) model.
- 3-in-1 capability: Bagging, mulching, and side-discharge.
- Weight: For related models (18″ push version) about 48.6 lb. (Walmart.com)
- Kit includes: Mower, battery, charger, bag frame, mulch plug, side-discharge chute, start key, operator’s manual.
- Intended area: Up to about ½ acre (given good conditions). (harttools.com)
So overall it’s a mid-budget cordless electric mower from HART, aimed at homeowners with medium lawns, offering a self-propelled option and decent battery kit.
⚠️ Common Problems
While the specs are attractive, users and reviewers have reported a number of recurring issues with HART mowers. Here are the major ones — along with what causes them and how to fix or mitigate them.
1. Battery Runs Out Too Quickly / Not Enough Runtime
Symptoms: Cuts short time, battery drains fast, mower stops mid-cut.
Cause: The included 6.0 Ah battery may struggle under heavier loads or thick/tall grass; also battery degradation over time. One review said:
“With ideal cutting conditions… up to 30 minutes runtime… real-world closer to 20 minutes.”
Fixes:
- Ensure grass is not too tall or overly thick — cut more regularly so load is lower.
- Use a second battery or upgrade to a higher capacity if available/compatible.
- Fully charge the battery before use; avoid using when low or in extremely hot conditions (battery can degrade faster).
- Clean deck underside so motor/battery aren’t overloaded by extra resistance.
2. Mower Won’t Start / No Drive / Self-Propel Issues
Symptoms: Press start and nothing happens; self-propel drive doesn’t engage; wheels lock.
Cause: Could be battery connection issue, handle/lever safety switch not engaged, self-propel drive belt/gear may be malfunctioning. For example:
Advice: “When your Hart electric mower won’t start, it’s usually one of three things. It’s often the battery, the handle not being fully extended or locked…
Also: Review noted on one model “Some self-propelled lawn mowers have trouble releasing the drive wheels when you pull the mower back” though the HART model reviewed did not have that issue.
Fixes:
- Ensure battery is properly seated, clean battery contacts, charger working.
- Verify all handle safety levers/clamps are locked/engaged (many cordless mowers have safety features).
- For self-propel: inspect the drive belt or gear mechanism if you hear slippage or nothing happens.
- Check manual for any drive disengagement lever or setting (e.g., pulling back may disengage drive).
- If wheels lock when reversing: check drive system lubrication or ensure correct use of controls.
3. Uneven Cut / Struggles on Taller Grass
Symptoms: Grass is left uneven, mower bogs down, bagging vs mulching struggle.
Cause: The mower may be optimized for regular maintenance cuts (2-inch removal) but struggles if grass is overgrown or the deck/motor load is high. One reviewer:
“If you’re taking off more than that [>2 inches of growth], we recommend you switch to bagging… this isn’t the kind of battery mower you want to tame overgrowth with.”
Fixes:
- Maintain your lawn regularly so the mower isn’t cutting too much at once.
- Raise deck height, make two passes instead of one heavy cut.
- Sharpen blades — dull blades cause more resistance.
- Clean deck underside of grass buildup (which restricts airflow).
- Consider side discharge or bagging if mulching isn’t working well with thick growth.
4. Battery/Charger Failures & Durability Concerns
Symptoms: Battery won’t charge, charger light stays red, battery dies after very few uses.
Cause: Some user feedback indicates battery quality or durability issues for certain HART units. For example:
“Bought a Hart lawnmower… both batteries won’t charge at all… most customers are having problems with them, being unable to charge them.” > (Reddit)
Fixes & Mitigation:
- Confirm charger and battery are compatible and not damaged.
- Store battery in moderate temperature (avoid extreme heat/cold).
- Ensure you follow manufacturer’s charging instructions (e.g., fully charge before first use).
- If under warranty, contact HART or retailer; keep proof of purchase.
- Consider checking for battery firmware or updates (some cordless systems have software/firmware for battery management).
5. Parts / Service / Support Issues
Symptoms: Hard to find replacement parts, limited service centers, warranty issues.
Cause: Some users report limited service network or support for HART mowers. For example:
“They told me they aren’t servicing Hart anymore and the next closest one is in another state.” Fixes / Advice:
- Before purchase, check local service availability for HART products and parts availability.
- Keep your manual and model/serial number handy so you can order blades/belts/parts.
- Consider stocking up on common wear parts (blade, belt, battery) early if you rely on the mower.
🔍 Causes Summary
Here’s a quick summary of root causes behind the problems above:
- Battery limitations or degradation — cordless electric models have runtime and age/fatigue issues.
- Drive mechanism or safety switch issues — self-propel systems and safety levers increase complexity.
- Overload from heavy cutting — thick grass or mowing too much at once strains motor/battery.
- Poor service/support infrastructure — can lead to delays or inconvenience for repairs/parts.
- Maintenance neglect — dull blades, clogged deck, worn parts reduce performance and increase issues.
🧰 Suggested Fixes & Maintenance Tips
To get the best from your HART mower and reduce problems, here are recommended actions:
- Before first use or each season:
- Fully charge the battery.
- Ensure blades are sharp and clean.
- Clean the deck underside of any factory residue.
- Check tire/wheel condition if applicable (for drive models).
- At each mowing session:
- Ensure lawn height is manageable (don’t cut too much at once).
- Choose appropriate deck height for your lawn.
- Monitor battery runtime — if cuts shorten over time, battery may be aging.
- After each use:
- Remove battery and store in a cool, dry place.
- Clean any grass clippings from underside and around moving parts.
- Inspect for any unusual noises or drive issues.
- Periodic maintenance:
- Replace blade when chipped/dull.
- Inspect drive belt (for self-propel) and drive components.
- Check battery contacts and charger condition.
- Keep firmware (if applicable) up to date — check HART’s website/manuals.
- Keep a maintenance log (date, battery hours, any repairs).
- Battery care best practices:
- Avoid storage in hot environments.
- Don’t leave battery fully depleted for long periods.
- Before storing long-term, charge to about 50% if advised by manual.
- Only use HART approved batteries/chargers to avoid compatibility problems.
🎯 Who Is This Mower Right For / When It Makes Sense
- Best suited for small-to-medium lawns (up to ~½ acre) when using the 6 Ah battery.
- Ideal for homeowners looking for a cordless electric solution (no gas/oil) with self-propel drive.
- If your lawn is large, overgrown, or you cut long grass irregularly, you may find the performance limiting.
- If you live in an area with good service/parts access for HART products, it’s more viable.
🧾 Final Thoughts
The HART 40V self-propelled mower offers a strong value proposition on paper — good specifications for the price range and the convenience of cordless operation. However, as with many budget models, the support, battery life, and suitability for heavier workloads become key factors. The reported issues around battery charging, service availability, and performance in tougher conditions aren’t universal but are significant enough to consider before purchase.
If you decide to go ahead:
- Choose the version with the larger battery (6 Ah) if possible.
- Keep good care of the battery.
- Do regular maintenance.
- Be realistic about lawn size and condition (not ideal for very large or very overgrown lawns without a second battery or upgrade).
📚 References
- HART tools product page for the 40V 20″ self-propelled mower kit: HLPM051VNM. (harttools.com)
- Pro Tool Reviews for the HART 40V mower performance and cut area. (Pro Tool Reviews)
- Home-based troubleshooting article for Hart electric mower won’t start. (dfarq.homeip.net)
- Reddit user feedback on Hart mower battery and durability issues. (Reddit)
- JustAnswer discussion of Hart self-propelled drive belt issues. (JustAnswer)
I’m David man behind Lawn Mowerly; I’ve been dealing with lawnmowers and Tractors with my father since I was a kid. I know every make and model and what each one is capable of and love helping people find the perfect equipment for their needs.