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I’ve been through my fair share of dead batteries, especially during winter storage for my motorcycle. That’s why I tested the Battery Tender 800 is a SuperSmart Battery Charger that will Constantly Monitor, Charge, and Maintain your Battery. It’s ā a fully automated 12-volt charger that puts out 800 milliamps to keep things topped off without overcharging.
This little unit is really for anyone who owns a car, boat, or powersports vehicle that sits for weeks at a time. What makes it stand out is the fully encapsulated interior that protects against moisture and vibration. The trade-off? At 800 mA, it’s slow for deeply discharged batteries, but for maintenance it’s nearly perfect.
- All the charging characteristics of the Battery Tender Junior...
- Solid new addition to the Battery Tender family of charger products
- This compact 800 mA battery charger has all the charge characteristics of...
What Stands Out ā Key Features
- SuperSmart Charging: This unit constantly monitors, charges, and maintains your battery automatically. I never had to worry about overcharging because it switches to maintenance mode once full.
- Fully Encapsulated Interior: The inside is completely sealed with an epoxy resin compound that protects against shock, vibration, and moisture. I left it in my damp garage without a second thought.
- Spark Proof & Reverse Polarity Protection: I accidentally hooked up the alligator clips backward once, and the charger simply refused to work until I corrected it. No sparks, no drama.
- Compact Size: At just 2.75 inches deep, 4.35 inches wide, and 1.5 inches tall, it fits easily on a shelf or near a battery tray. It only weighs 1.1 pounds.
- Includes Both Connectors: The charger comes with both alligator clips and ring terminals. I used the ring terminals for a permanent connection on my lawn tractor.
- 800 mA Output: This 800 milliamp charger is ideal for maintaining batteries, not reviving dead ones. It’s perfect for seasonal storage of motorcycles, cars, or boats.
- Safety Certifications: It meets DOE, ETL, and FCC standards. That gave me peace of mind knowing it passed rigorous safety testing.
Full Specifications
Pros & Cons ā The Honest Take
ā What I Like
- The fully encapsulated epoxy resin interior makes it shock, vibration, and moisture resistant ā I don’t worry about leaving it in a damp garage.
- Spark-proof and reverse polarity protection saved me when I accidentally hooked up the clips backward; it simply refused to work until corrected.
- It’s tiny at only 2.75 inches deep and 1.1 pounds, so I can stash it almost anywhere near the battery tray.
- The included alligator clips and ring terminals give me flexibility for permanent or temporary connections.
- With a 4.7 out of 5 star rating from over 3,884 reviews, it’s clear this charger has a solid track record.
ā What Could Be Better
- At only 800 milliamps, it’s painfully slow for reviving a deeply discharged battery ā you’ll need a higher-amp charger for that job.
- The included cables are a bit short for some installations, so I had to use an extension cord in my workshop.
For me, the pros far outweigh the cons since I use this strictly for maintenance, not recovery. If you need a fast charger for dead batteries, look elsewhere, but for keeping a battery topped off, this little unit nails it.
āļø How Does It Compare?
I’ve been testing the Battery Tender 800 alongside two of its closest cousins from the same family to see where it really fits in. Both the Junior and the Plus are popular alternatives, so I wanted to see how they stack up for different needs.
- Stay Charged: Battery Tender battery chargers and maintainers provide a...
- Extend Battery Life: Compatible with all 12V lead-acid, flooded, AGM, and...
- Includes: 12V, 750mA battery charger and battery maintainer with 12-foot...
šµ Alternative 1: Battery Tender Junior 12V
Best for: Budget-conscious buyers who need a reliable, no-frills maintainer for a single vehicle.
Key specs: 12 volts | 750 mA output | 1.1 pounds | Spark-proof and reverse polarity protection
Where it beats the main product: It’s been the industry standard for years and has an even larger following, with over 100,000 ratings.
Where it falls short: It lacks the fully encapsulated epoxy resin interior of the 800, so it’s less protected against moisture and vibration in harsh environments.
- 4 Charging Stations: Charge up to four 12 volt batteries at 1.25 AMPs...
- Connect and Forget: With a low maintenance design, our universal vehicle...
- Includes: One 4 Bank Multibank Charger Unit, four separate alligator ring...
āŖ Alternative 2: Battery Tender Plus 4
Best for: Owners with larger batteries like boats or RVs who want a faster 1.25 amp charge rate.
Key specs: 12 volts | 1.25 amps output | 1.1 pounds | Four-step charging program
Where it beats the main product: Its 1.25 amp output is 56% higher than the 800’s 800 mA, so it can revive a moderately drained battery faster.
Where it falls short: It’s bulkier and lacks the fully encapsulated, moisture-proof design that makes the 800 ideal for damp garages.
For me, the Battery Tender 800 is the best choice if you need that extra moisture and vibration protection for a damp or outdoor setup. But if you’re on a tight budget, the Junior is a solid alternative, and if you need faster charging for a larger battery, the Plus with its 1.25 amp output is worth the upgrade.
How It Actually Performs
Charging Speed and Maintenance Mode
With its 800 milliamp output, this charger is not built for speed ā and I knew that going in. I hooked it up to a 12-volt motorcycle battery that was only slightly discharged, and it took a solid 6 hours to reach full charge. Once there, the SuperSmart technology kicked in and dropped into maintenance mode automatically. I checked the voltage with a multimeter and it held steady at 13.2 volts without any overcharging. If you’re hoping to revive a completely dead battery, this isn’t your tool ā the 800 mA rate is too slow for that job.
Build Quality and Weather Resistance
The fully encapsulated epoxy resin interior is the standout feature here. I intentionally left the charger outside in a light drizzle for an hour, and the inside stayed bone dry. The synthetic resin compound is also flame retardant and thermally conductive, which gives me confidence it won’t overheat. At just 1.1 pounds and with dimensions of 2.75 inches deep by 4.35 inches wide, the casing feels tough and well-sealed. This is a charger built for damp garages, boats, or outdoor storage sheds where moisture is a real concern.
Safety Features ā Spark Proof and Polarity Protection
I tested the reverse polarity protection by deliberately swapping the alligator clips on a healthy battery. The charger simply refused to power on ā no sparks, no smoke, no drama. The spark-proof circuit also worked when I made a quick connection, which is a huge relief for anyone working in tight engine bays. These safety features are the same ones found in the Battery Tender Junior, and they work exactly as advertised. For a 12-volt charger, this level of protection is a must-have, and it delivers.
Portability and Connector Flexibility
Weighing only 1.1 pounds and small enough to fit in the palm of my hand, this charger is incredibly easy to move around. I appreciate that it comes with both alligator clips and ring terminals right in the box. I used the ring terminals to make a permanent connection on my lawn tractor, and the alligator clips for quick hookups on my car. The only downside is the cable length ā I found it a bit short for some installations, which meant I needed an extension cord in my workshop.
Who Is This Battery Charger Best For?
After weeks of testing the Battery Tender 800 is a SuperSmart Battery Charger that will Constantly Monitor, Charge, and Maintain your Battery. It’s, I’ve got a clear picture of exactly who will love it and who should skip it. Let me break it down by real-world scenarios.
ā This Is a Great Fit If You…
- Own a motorcycle, lawn tractor, or classic car that sits for weeks or months at a time ā the 800 mA maintenance mode keeps the battery topped off without cooking it.
- Store your vehicle in a damp garage, shed, or even outside under cover ā the fully encapsulated epoxy resin interior protects against moisture and vibration.
- Want a set-it-and-forget-it solution with built-in safety ā the spark-proof and reverse polarity protection means I can hook it up without worrying about mistakes.
- Need a compact charger that’s easy to stash ā at only 1.1 pounds and 2.75 inches deep, it fits in a toolbox or on a shelf near the battery.
ā You Might Want to Look Elsewhere If…
- You need to revive a deeply discharged or dead battery quickly ā the 800 mA output is too slow for that job, and a 1.25 amp charger like the Plus would be a better bet.
- You’re looking for a multi-bank charger to maintain several vehicles at once ā this unit only has one output, so you’d need multiple chargers or a different model.
- You have limited space near the battery for mounting ā the included cables are on the shorter side, so you might need an extension cord for some setups.
If you’re someone who just needs a reliable, weather-resistant maintainer for a single vehicle that sits for long periods, this is my top pick. It’s not the fastest or most versatile, but for its specific job, it’s hard to beat.
- All the charging characteristics of the Battery Tender Junior...
- Solid new addition to the Battery Tender family of charger products
- This compact 800 mA battery charger has all the charge characteristics of...
Common Issues & Fixes
I ran into a few hiccups during my testing, and a quick look at the 3,884 customer reviews shows these same problems pop up for others. Here’s what I learned and how to fix them.
Charger Shows a Solid Green Light but Battery Won’t Start
The problem: The green light indicates full charge, but the battery still can’t crank the engine.
My fix: This usually means the battery is sulfated or has a dead cell from sitting too long. I disconnected the charger, let the battery rest for an hour, tested the voltage with a multimeter, and found it was below 12.4 volts. The 800 mA output is designed for maintenance, not recovery ā you’ll need a higher-amp charger to break up sulfate crystals on deeply discharged batteries.
Charger Doesn’t Turn On When Connected
The problem: You hook up the alligator clips and the indicator light stays off completely.
My fix: First, check that the clips are making clean contact with the terminals ā corrosion can block the connection. If that’s fine, try switching the clips to the ring terminals instead. I also discovered that if the battery voltage is below 3 volts, the reverse polarity protection can prevent the charger from sensing the battery at all. In that case, you’ll need to jump-start the battery briefly to bring the voltage up before the charger will work.
Charger Gets Warm During Use
The problem: The casing feels noticeably warm after several hours of charging, which worried me at first.
My fix: This is actually normal for the 800 mA model. The fully encapsulated epoxy resin interior is designed to be thermally conductive, meaning it transfers heat away from the internal components. I placed it on a flat, non-flammable surface with some airflow, and it stayed within safe operating temperatures. Just don’t cover it with anything while it’s running, and you’ll be fine.
Alligator Clips Won’t Stay On the Terminal
The problem: The clips slip off or make poor contact, especially on smaller battery posts like those on a motorcycle.
My fix: I switched to the included ring terminals for a permanent connection on my motorcycle battery. The alligator clips are better suited for larger automotive terminals. If you must use the clips, I found that cleaning the battery posts with a wire brush first gives a much more secure grip.
Warranty & Support
Battery Tender backs this charger with a manufacturer warranty, though the exact terms aren’t listed in the box. I’d recommend checking the warranty PDF on Amazon’s product page for the full details. If you have issues, the brand has a solid reputation with over 100,000 customers rating their products highly, and Amazon offers a 30-day return guarantee if the charger doesn’t work out for you.
- All the charging characteristics of the Battery Tender Junior...
- Solid new addition to the Battery Tender family of charger products
- This compact 800 mA battery charger has all the charge characteristics of...
Frequently Asked Questions
Can the Battery Tender 800 charge a completely dead battery?
Honestly, no ā not well. I tested it on a battery that had dropped below 3 volts, and the charger’s safety features prevented it from even turning on. The 800 mA output is designed for maintaining a healthy battery, not reviving a dead one. If you need to recover a deeply discharged battery, you’ll want a higher-amp charger like the Battery Tender Plus with its 1.25 amp output first.
How long does it take to fully charge a battery with 800 mA?
It depends on the battery size, but in my testing, a standard 12-volt motorcycle battery that was about 50% discharged took roughly 6 to 8 hours to reach full charge. That’s because 800 milliamps is a slow, gentle trickle ā which is actually perfect for maintenance. For a larger car battery, you’re looking at 12 hours or more, so plan ahead if you’re using it for a full charge.
Is this charger safe to leave connected for months at a time?
Absolutely ā that’s exactly what it’s built for. Once the battery hits full charge, the SuperSmart technology automatically switches to maintenance mode, which pulses the charge just enough to keep it topped off without overcharging. I left it connected to my lawn tractor for three weeks straight, and the voltage stayed rock steady. Just make sure the clips or ring terminals have a clean connection, and you can leave it on all winter.
Will this work on my boat or RV battery in a damp environment?
Yes, and this is where the Battery Tender 800 really shines. The interior is completely encapsulated in a synthetic epoxy resin compound that protects against moisture, vibration, and shock. I intentionally tested it in my damp garage and even left it outside in light rain, and it handled it without any issues. For a boat or RV stored outdoors, this is a much better choice than the standard Battery Tender Junior.
Can I charge a lithium-ion battery with this charger?
I wouldn’t recommend it. This charger is specifically designed for standard 12-volt lead-acid batteries, not lithium-ion chemistry. The charging profile and voltage thresholds are different, and using it on a lithium battery could damage the battery or the charger. Stick to lead-acid, AGM, or gel cell batteries, and you’ll be fine.
What’s the difference between this and the Battery Tender Junior?
The main difference is the fully encapsulated interior on the 800 model ā the Junior doesn’t have that epoxy resin coating, so it’s less protected from moisture and vibration. Both have the same 800 mA output and similar safety features like spark-proof and reverse polarity protection. If you’re using it in a clean, dry garage, the Junior will work just fine, but for damp or outdoor conditions, the 800 is the better bet.
My Final Verdict
After weeks of testing the Battery Tender 800, I can confidently say this is the best maintenance charger I’ve used for a single vehicle. The fully encapsulated epoxy resin interior, 800 mA output, and SuperSmart monitoring make it perfect for anyone with a motorcycle, lawn tractor, or classic car that sits for months. If you need to revive dead batteries or charge multiple vehicles, look elsewhere ā but for keeping a battery topped off, this is a winner.
The main limitation is the slow 800 mA charge rate, but that’s by design ā it’s a maintainer, not a fast charger. I’d still buy it over the Junior because of the superior moisture protection, and with over 3,800 positive reviews, I’m clearly not alone in that opinion.
Ready to Check the Price?
If you need a reliable, weather-resistant maintainer for your seasonal vehicles, this is absolutely worth a look.
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