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Here is the part most battery tender listings do not tell you: if your Harley runs a lithium (LiFePO4) battery and you clip on an old-school lead-acid trickle charger, you are not just wasting your money. You can damage the battery. Lithium and lead-acid batteries want different charge curves, and a charger built for one chemistry can overcharge, undercharge, or trip the battery management system on the other.
Our research desk pulled charging specs straight from Harley-Davidson factory service manuals – Touring, Dyna, Softail, and Sportster – to figure out what amperage and voltage actually matter, then cross-checked which chargers on Amazon are explicitly built for lithium versus lead-acid/AGM only. Below is what we found: which tender fits which battery, why a bargain-bin “trickle charger” and a name-brand “smart maintainer” are not interchangeable, and which one to buy for your specific model.
Let’s get into it.
Quick Picks
- Best Overall (Lithium-Safe): NOCO Genius1 Check Price on Amazon
- Best for Lithium Batteries: Battery Tender 2A Selectable Check Price on Amazon
- Best Budget Pick: MOTOPOWER MP00205A Check Price on Amazon
Key Takeaways
Short on time? Here is the summary before you scroll.
- Not every “battery tender” is lithium-safe. The NOCO Genius1 and the Battery Tender 2A Selectable explicitly support LiFePO4; the classic Battery Tender Junior and Battery Tender Plus are lead-acid/AGM only.
- Battery size scales with model family: a 2019 Touring battery is rated 28Ah/405 CCA, while a 2013 Dyna is rated 19Ah/315 CCA and a Sportster runs as low as 12Ah/225 CCA, per Harley-Davidson factory service manuals. Bigger battery, more headroom for a higher-amp maintainer.
- Harley’s own Dyna service manual specifies a charging rate of 5 amps or less at under 14.6 volts for an automatic, constant-monitoring charger/tender, and explicitly warns against constant-current trickle chargers on sealed AGM batteries.
- Amperage ranges across our picks run from 750mA to 3A – the right one depends on your battery’s amp-hour rating, not just what is cheapest on the shelf.
- A quick-connect ring-terminal harness is the unglamorous accessory that actually gets a tender used all winter, because you are not digging under the seat every time.
| NOCO Genius1 (1A 6V/12V Smart Charger) |  |
Best Overall | Chemistry: Lithium + AGM/Lead-Acid | Output: 1A, 6V/12V | Rating: IP68 waterproof | VIEW LATEST PRICE | Read Our Analysis |
| Battery Tender 6V/12V 2A Lithium/Lead-Acid Selectable |  |
Best for Lithium | Chemistry: Switchable lithium/lead-acid | Output: 2A, 6V/12V | Brand: Deltran (Battery Tender) | VIEW LATEST PRICE | Read Our Analysis |
| Battery Tender Junior 12V 750mA |  |
Best Classic Maintainer | Chemistry: Lead-Acid/AGM ONLY | Output: 750mA, 12V | Fit: Sportster-size batteries | VIEW LATEST PRICE | Read Our Analysis |
| Battery Tender Plus 12V 1.25A |  |
Best for Dyna/Softail | Chemistry: Lead-Acid/AGM | Output: 1.25A, 12V | Fit: ~19Ah batteries | VIEW LATEST PRICE | Read Our Analysis |
| Battery Tender 3A Switchable Charger/Maintainer |  |
Best for Touring | Chemistry: Lead-Acid/AGM/Lithium | Output: 3A, 6V/12V switchable | Fit: 28Ah Touring batteries | VIEW LATEST PRICE | Read Our Analysis |
| MOTOPOWER MP00205A 12V 800mA |  |
Best Budget Pick | Chemistry: Lead-Acid/AGM | Output: 800mA, 12V | Includes: Clips + ring terminals | VIEW LATEST PRICE | Read Our Analysis |
| Battery Tender Ring Terminal Harness (Quick-Connect) |  |
Must-Have Accessory | Type: Permanent ring-terminal pigtail | Compatible: SAE quick-connect tenders | Use: Skip the seat removal | VIEW LATEST PRICE | Read Our Analysis |
More Details on Our Top Picks
NOCO Genius1 (1A 6V/12V Smart Charger)
If a battery tender only has room in the budget for one chemistry it needs to handle, this is the one to buy, because it handles all of them. The Genius1 is built to charge and maintain lithium (LiFePO4), AGM, gel, and standard flooded lead-acid batteries from the same unit, with a mode switch that tells it which chemistry it is looking at.
The output is modest at 1A, which is intentional. NOCO markets this as the smallest unit in its Genius lineup, meant for smaller batteries and slower, gentler maintenance charging rather than a quick top-off. For a Sportster-class battery in the 12Ah range that is plenty; for a 28Ah Touring battery it will still work, it will just take longer to bring a deeply discharged battery back to full.
What sets it apart from a basic trickle charger is the onboard diagnostics: it monitors the battery during the maintenance phase and can attempt to recover a battery that has dropped below the voltage most chargers give up on. It is also rated IP68, which matters if the bike lives in an unheated garage or a shed with humidity swings over winter.
This is the pick for riders who are not sure what chemistry their replacement battery is, who own more than one powersport vehicle with mixed battery types, or who simply want one charger that will not need replacing the next time they upgrade to a lithium battery.
- Output:1A
- Input voltage:6V / 12V selectable
- Chemistry support:Lithium, AGM, gel, flooded lead-acid
- Waterproof rating:IP68
- Connector:Alligator clips + ring terminal harness
- Reverse polarity protection:Yes
- Best for:Sportster-size batteries, mixed-chemistry garages
- Charging mode:Multi-stage, automatic maintenance
Battery Tender 6V/12V 2A Lithium/Lead-Acid Selectable
Deltran built the original Battery Tender brand on lead-acid maintenance, so it says something that this is the model they redesigned specifically to add a lithium mode. If your Harley has been converted to a lithium battery, or came with one from the factory, this is the closest thing to a purpose-built option from the same company that made the Junior and the Plus.
The physical switch on the front lets you pick lithium or lead-acid/AGM before you plug in, which changes the charge profile the unit runs. That matters because lithium batteries do not want the same float voltage a lead-acid battery tolerates indefinitely – get it wrong and you either undercharge a lithium pack or push it outside the range its internal battery management system is designed to accept long-term.
At 2A, it charges noticeably faster than the entry-level Junior, which is useful if you are bringing a battery back from a deep discharge rather than just maintaining one that is already topped off. It also runs on both 6V and 12V systems, so it covers older Panhead and Shovelhead-era bikes that some riders still run on 6V.
Buy this one if you already know your battery chemistry and want a single charger that will not care which bike in the garage it is plugged into next.
- Output:2A
- Input voltage:6V / 12V selectable
- Chemistry support:Lithium (LiFePO4) or lead-acid/AGM, selector switch
- Brand:Battery Tender (Deltran)
- Connector:Quick-connect SAE harness
- Housing:Weather-resistant
- Best for:Lithium-converted or lithium-factory Harleys
- Charging mode:4-step, chemistry-specific
Battery Tender Junior 12V 750mA
This is the tender most Harley owners already picture when someone says “battery tender” – it is the one that has been sitting on garage shelves for two decades. Here is the wedge issue up front: it is built for lead-acid and AGM batteries only, not lithium. If your Harley has a lithium battery, skip this one and look at the two picks above instead.
For a lead-acid or AGM battery, though, it does exactly what it says. At 750mA it charges slowly and gently, which is the right approach for a small Sportster-class battery where a higher-amp charger risks overshooting. Deltran’s four-step charging program (initialization, bulk charge, absorption, float/maintenance) is the same logic used across the Battery Tender lineup.
The low amperage is also its main limitation. On a fully depleted 19Ah Dyna or Softail battery, 750mA is going to take considerably longer to bring it back than the 2A or 3A units above. It is a maintainer first and a charger second – great for a battery that is already mostly charged and just needs to stay that way through winter.
Pair this with the ring-terminal harness below so you are not disconnecting the battery from the bike every time you hook it up.
- Output:750mA
- Input voltage:12V
- Chemistry support:Lead-acid/AGM ONLY – not lithium-safe
- Brand:Battery Tender (Deltran)
- Connector:Quick-connect SAE harness
- Charging mode:4-step automatic
- Best for:Sportster-size lead-acid/AGM batteries
- Indicator:Two-color LED status light
Battery Tender Plus 12V 1.25A
The Plus is the Junior’s bigger sibling, and it is the one our research desk would point Dyna and Softail owners toward. Harley’s own 2013 Dyna and 2007 Softail service manuals rate those batteries at roughly 19 amp-hours, and a 1.25A maintainer is a sensible match: enough current to actually recover a battery that has drained over a few cold weeks, without the risk of a higher-amp charger overshooting a mid-size battery.
Like the Junior, this is lead-acid/AGM only – Deltran does not rate the standard Plus for lithium chemistry, so if your Dyna or Softail has been upgraded to a LiFePO4 battery, use the 2A Selectable model above instead.
The Plus adds a couple of features the Junior skips: a more detailed LED charge-status readout, and in some versions a battery-condition diagnostic before it starts charging. It is a small step up in price for a meaningful step up in both output and information.
This is the one to leave connected through a Midwest or Northeast winter, where a bike might sit for three or four months without a single start. The 4-step program means it will not overcharge sitting on the tender that long – that is the entire point of a maintainer versus a basic charger.
- Output:1.25A
- Input voltage:12V
- Chemistry support:Lead-acid/AGM ONLY – not lithium-safe
- Brand:Battery Tender (Deltran)
- Connector:Quick-connect SAE harness
- Charging mode:4-step automatic
- Best for:Dyna/Softail-size batteries (~19Ah)
- Indicator:Multi-LED charge status
Battery Tender 3A Switchable Charger/Maintainer
Touring models carry the biggest battery in the Harley lineup – a 2019 Touring service manual we checked lists it at 28Ah / 405 CCA, roughly 50 percent bigger than a Dyna or Softail battery. A 750mA or 1.25A maintainer will still technically charge it, just slowly. This 3A unit closes that gap.
The switchable 6V/12V input covers both modern Touring bikes and older 6V-system bikes if you own more than one Harley. At 3A it will bring a deeply discharged Touring battery back up meaningfully faster than the smaller units in this roundup, then step down into a lower-current float/maintenance stage once the battery is full – it is not running 3A continuously, which would be too aggressive for long-term maintenance.
Per its Amazon listing, this switchable model handles lead-acid, AGM, gel, and lithium batteries, which makes it a rare higher-amp maintainer that is also lithium-safe. If you have converted your Touring bike to a lithium battery and want faster recovery than a 1A lithium maintainer can give, this is the pick that covers both jobs.
Good fit for anyone running a full-dress Road King, Street Glide, or Electra Glide who wants their battery topped off fast after a long trip, not just maintained through storage.
- Output:3A
- Input voltage:6V / 12V switchable
- Chemistry support:Lead-acid, AGM, gel, and lithium (per its listing)
- Brand:Battery Tender (Deltran)
- Connector:Quick-connect SAE harness
- Charging mode:Multi-stage, switchable
- Best for:Touring-size batteries (~28Ah)
- Use case:Faster recovery after deep discharge
MOTOPOWER MP00205A 12V 800mA
Not everyone needs a name-brand maintainer for a bike that gets ridden most weekends and only sits for a month or two over winter. The MOTOPOWER MP00205A covers the basics at a fraction of the price of the Battery Tender lineup: automatic maintenance charging at 800mA for a standard 12V lead-acid or AGM battery.
It ships with both alligator clips (for occasional use across multiple vehicles) and a ring-terminal harness (for a permanent hookup on one bike), which is more flexible out of the box than some of the pricier options that sell those separately.
This is a lead-acid/AGM charger, not a lithium-rated one – budget chargers in this category rarely include the lithium-specific charge profile, so do not use it on a LiFePO4 battery. It is also a simpler charger overall, without the diagnostic recovery mode the NOCO Genius1 offers for a badly discharged battery.
Good for a second bike, a lawn tractor, or a rider who wants a “set it and forget it” option without paying for features they will not use.
- Output:800mA
- Input voltage:12V
- Chemistry support:Lead-acid/AGM ONLY – not lithium-safe
- Brand:MOTOPOWER
- Connector:Alligator clips + ring terminal harness (both included)
- Charging mode:Automatic maintenance
- Best for:Budget-conscious riders, secondary vehicles
- Reverse polarity protection:Yes
Battery Tender Ring Terminal Harness (Quick-Connect)
This is not a charger – it is the accessory that determines whether you actually use the charger you bought. Most Harley batteries sit under the seat or behind side covers, which is not a big deal to access once, but becomes real friction if you have to do it every single week over a winter.
The ring-terminal harness bolts directly to the battery terminals and stays there permanently, with a weatherproof SAE quick-connect plug routed out to somewhere accessible – a saddlebag gap, under a seat lip, wherever you can reach without tools. When it is time to charge, you plug the tender’s pigtail into this harness in about two seconds. When you are riding, you unplug it and tuck the connector away.
It is compatible with the SAE quick-connect style used across the Battery Tender lineup and most other maintainers that ship with the same connector standard – check that your charger of choice uses SAE quick-connect (all of the Battery Tender products above do) before assuming a drop-in fit.
Our research desk considers this close to mandatory for anyone planning to actually maintain their battery through a full winter, rather than buying a tender and using it twice before it ends up in a drawer.
- Type:Permanent ring-terminal pigtail
- Connector:SAE quick-connect
- Compatible with:Battery Tender and most SAE-standard maintainers
- Weatherproofing:Sealed connector cap
- Install time:Under 5 minutes
- Best for:Anyone tendering a bike stored under the seat/side cover
- Fuse protected:Yes (inline fuse on most versions)
- Use case:Eliminates seat/panel removal for every charge session
How to Choose a Battery Tender for Your Harley
Picking the right tender comes down to two questions: what chemistry is your battery, and how big is it. Everything else is a nice-to-have.
Why Lithium Changes the Math
The core issue: lithium (LiFePO4) batteries and lead-acid/AGM batteries do not want the same charge curve. A charger built for lead-acid can push a lithium battery to a voltage its internal battery management system was not designed to sit at long-term, which shortens its life or, in worse cases, triggers a protective shutdown. This is the single most common mismatch we see riders make when they upgrade to a lighter lithium battery and keep using the tender that came with their old lead-acid one.
Of the chargers in this roundup, the NOCO Genius1, the Battery Tender 2A Selectable, and the Battery Tender 3A Switchable are rated for lithium as well as lead-acid and AGM. The Junior, the Plus, and the MOTOPOWER are lead-acid/AGM chargers – fine for the battery that likely came stock on most Harleys built before the last few years, wrong for a lithium upgrade. If you are not sure what chemistry you have, check the label on the battery itself or the paperwork from whoever installed it before buying a tender.
Matching Amperage to Your Battery’s Amp-Hour Rating
Bigger battery, more current headroom – within reason. Harley factory service manuals put battery capacity at roughly 12Ah for a Sportster, 19Ah for a Dyna or Softail, and 28Ah for a Touring model. If you are shopping for a replacement battery to go with your new tender, our guide to batteries for the Street Glide covers fitment in more detail.
A rough rule from the charger manufacturers: pick an amperage roughly in the 5-10 percent range of the battery’s amp-hour rating for maintenance charging. That puts a Sportster comfortably on the 750mA Junior or the 1A Genius1, a Dyna or Softail on the 1.25A Plus, and a Touring model on the 2-3A chargers. Going bigger is not automatically better – too much current for a small battery risks overshooting the charge curve, which is exactly what the 4-step automatic programs on these chargers are designed to prevent, but it is still not the goal.
Understanding Float Voltage and Why Some Chargers Warn You Off AGM
Per Harley-Davidson’s 2013 Dyna Service Manual, the recommended charging approach is “an automatic, constant monitoring battery charger/tender with a charging rate of 5 amps or less at less than 14.6 volts,” and the same manual explicitly states that constant-current chargers, including basic trickle chargers, are not recommended for sealed AGM batteries. That single spec explains why every charger worth buying for a Harley advertises itself as “automatic” or “smart” rather than a flat trickle charger – it needs to back off the voltage once the battery reaches full charge, not just keep pushing current indefinitely.
If your charging system itself seems to be the problem rather than the tender – a battery that will not hold a charge even after a fresh maintainer session – that usually points somewhere else. Our guide to Harley charging system problems and our voltage regulator symptoms breakdown both walk through the difference between a dying battery and a charging system that is not replenishing it properly while you ride.
Do You Need to Disconnect the Battery Before Charging?
Not with any of the tenders in this roundup. All seven are designed to stay connected to the bike’s electrical system while charging or maintaining – that is the entire point of the quick-connect ring-terminal harness. Full disconnection matters more for long-term storage without a tender at all, where a parasitic draw from an alarm or accessory could slowly drain a battery with nothing replenishing it.
Winter Storage: Where a Tender Actually Earns Its Keep
A battery tender is one piece of a bigger winter storage routine. If your Harley is going to sit for more than a few weeks, our winter storage guide covers the rest of it – fuel stabilizer, tire pressure, and where to actually park the bike so moisture is not working against you at the same time the battery is discharging. Speaking of tire pressure, it is worth checking before the bike goes into storage and again before the first ride back out; our tire pressure chart has the spec by model.
Battery Tender Comparison Table
All seven picks side by side, so you can scan specs without scrolling back up.
| Product | Output | Chemistry | Voltage | Connector | Best For |
|---|---|---|---|---|---|
| NOCO Genius1 | 1A | Lithium + AGM/Lead-Acid | 6V/12V | Clips + ring terminal | Sportster-size, mixed chemistry |
| Battery Tender 2A Selectable | 2A | Lithium or Lead-Acid/AGM (switch) | 6V/12V | SAE quick-connect | Lithium-converted batteries |
| Battery Tender Junior | 750mA | Lead-Acid/AGM only | 12V | SAE quick-connect | Sportster-size lead-acid |
| Battery Tender Plus | 1.25A | Lead-Acid/AGM only | 12V | SAE quick-connect | Dyna/Softail (~19Ah) |
| Battery Tender 3A Switchable | 3A | Lead-Acid/AGM/Lithium | 6V/12V | SAE quick-connect | Touring (~28Ah) |
| MOTOPOWER MP00205A | 800mA | Lead-Acid/AGM only | 12V | Clips + ring terminal | Budget, secondary vehicles |
| Ring Terminal Harness | n/a | n/a (accessory) | n/a | SAE quick-connect | Permanent quick-connect mount |
Frequently Asked Questions
The questions our research desk sees most often around battery tenders and Harley-Davidson batteries.
Is a regular battery tender safe for a lithium Harley battery?
Not automatically. A charger has to be explicitly rated for lithium (LiFePO4) chemistry to be safe on a lithium battery. Of the picks in this roundup, only the NOCO Genius1 and the Battery Tender 2A Selectable qualify. Standard Battery Tender Junior, Plus, and most budget chargers are built for lead-acid/AGM only and are not rated for lithium use.
How long can I leave a battery tender connected on my Harley over winter?
An automatic maintainer with a 4-step charging program, like the ones in this roundup, is designed to be left connected for months at a time. Once the battery reaches full charge, the charger drops into a float/maintenance mode that keeps it topped off without overcharging. This is the entire feature that separates a “tender” from a basic trickle charger, which the Dyna service manual specifically cautions against using on sealed AGM batteries for extended periods.
Do I need to disconnect my Harley’s battery before connecting a tender?
No. All the chargers in this roundup are designed to charge or maintain the battery while it stays connected to the bike, which is the whole reason the SAE quick-connect ring-terminal harness exists – it lets you plug and unplug the tender without touching the battery terminals each time.
What amperage battery tender do I need for a Touring model’s battery?
Harley-Davidson’s 2019 Touring service manual rates the factory battery at 28Ah/405 CCA, the largest in the current lineup. A 2-3A charger, like the Battery Tender 3A Switchable in this roundup, will recover a deeply discharged Touring battery meaningfully faster than a sub-1A maintainer, then step down to a lower-current float stage for long-term storage.
Can I use the same tender across a Sportster and a Touring model?
Yes, as long as the chemistry matches both batteries. A single charger will simply take longer on the bigger Touring battery than the smaller Sportster one. If both bikes run the same chemistry, a mid-range 1.25-2A charger with a quick-connect harness installed on each bike is a practical one-charger-two-bikes setup.
What is the difference between a trickle charger and a battery tender/maintainer?
A basic trickle charger applies a constant current with no feedback, which can overcharge a battery if left connected too long. A tender or maintainer, like every charger in this roundup, monitors the battery’s voltage and cycles through charge stages, dropping into a low-current float mode once the battery is full. Harley’s own service manual language specifically distinguishes “an automatic, constant monitoring battery charger/tender” from constant-current trickle chargers, and recommends the former.
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