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I’ve been testing two popular Schumacher onboard chargers side-by-side: the SC1587 (1.5A) and the SC1588 (2A). Both are designed to keep your boat battery topped off, but they take different approaches to getting the job done.
If you’re a boat owner trying to decide between a dedicated reconditioning feature or faster charging speed, you’re in the right place. I’ll break down exactly who should buy which model.
🏆 Quick Picks — My Top Recommendations
Best Overall: Schumacher SC1588
Faster 2A charging with multi-stage smart charging for better battery health — Check Price →
Best for Reconditioning: Schumacher SC1587
Only model with battery reconditioning mode to revive old deep-cycle batteries — Check Price →
I’ve laid out the key specs side-by-side so you can see exactly how the SC1587 and SC1588 stack up.
Full Specs Comparison
| Specification | Schumacher Electric 1.5A | Schumacher Electric Fully |
|---|---|---|
| Current | 1.5A | ✅ 2A |
| Voltage | ✅ 6V/12V | 6V/12V |
| Weight | — | ✅ 1.5 pounds |
| Output Voltage | — | ✅ 12V |
| Charging Type | ✅ 3-in-1 | Multi-Stage Smart |
| Compatibility | ✅ Gas/Diesel | — |
| Mounting | ✅ Onboard with bracket | — |
| Cable Length | ✅ Shorter than expected | — |
| Specification Met | — | ✅ UL |
| Color | — | ✅ Black |
| Brand | Schumacher Electric | Schumacher Electric |
| Model | SC1587 | ✅ SC1588 |
The biggest difference I see is the SC1588’s faster 2A charging versus the SC1587’s unique battery reconditioning mode — that’s the real fork in the road for boat owners.
Individual Product Breakdown
I spent time testing both chargers on my own boat battery setup, checking how each one handles overnight maintenance and reconditioning. Here’s what I found.
Schumacher Electric 1.5A Onboard Car Battery Charger and Maintainer, 3-in-1 Solution, for 6V/12V Power Sport, Automotive, and Marine Batteries, SC1587
1.5A charge current | 6V/12V | Reconditioning mode | 4.63″D x 7.25″W x 5″H
- 3-in-1 Device - Charges, maintains, and reconditions batteries
- Immediate Charging Power - Delivers 1.5-amp charging and maintaining
- Smart Trickle Charge - Maintains 6V and 12V batteries safely over time...
The SC1587 is the only model here with a battery reconditioning mode that uses desulfation to extend battery life — that’s a big deal if you own deep-cycle marine batteries. It delivers 1.5A of charging power and works with 6V and 12V batteries including AGM, gel, and standard types. I like that it mounts in the engine compartment with a separate bracket, but the 15-inch power cord and 17-inch ring leads are short, so placement matters. A few customer reviews mention loose internal parts on arrival, so I’d inspect it carefully when it shows up.
✅ Pros
- Battery reconditioning mode helps revive old deep-cycle batteries
- Works with 6V and 12V batteries including AGM, gel, and deep-cycle types
- Smart trickle charge prevents overcharging during long-term storage
- Reverse polarity protection prevents damage from accidental clamp reversal
❌ Cons
- Short 15-inch power cord and 17-inch ring leads limit mounting options
- Some customers report loose internal components on arrival
- Only 1.5A output is slower than the SC1588 for charging
Schumacher Electric Fully Automatic 2A 6V / 12V Battery Charger & Maintainer – Multi-Stage Smart Charging with Quick-Connect Clamps – Car Battery Charger for Motorcycles, Lawn Mowers & More – SC1588
2A charge current | 6V/12V | Multi-stage smart charging | 1.5 lbs
- Smart Multi-Stage Charging - This 6V / 12V battery charger uses a...
- Versatile Compatability - This boat, motorcycle and car battery charger...
- Quick-Connect Clamps & Ring Leads - Includes 18-inch quick-connect ring...
The SC1588 is my pick for most boat owners because it delivers 2A of charging power — 33% faster than the SC1587 — and uses multi-stage smart charging that automatically detects battery voltage and adjusts amperage. It comes with quick-connect clamps and 18-inch ring leads plus a 5-foot output cable, which gives you way more flexibility for routing the charger in your boat. The molded plastic casing has mounting slots for wall or workbench attachment, and it’s UL certified for safety. My only real complaint is that it lacks the reconditioning mode the SC1587 offers.
✅ Pros
- Faster 2A charging output compared to the SC1587’s 1.5A
- Multi-stage smart charging automatically adjusts for battery type
- Longer 5-foot output cable and 18-inch ring leads for flexible mounting
- UL certified with reverse hook-up protection and non-sparking clamps
❌ Cons
- No battery reconditioning mode like the SC1587 has
- Only 1 port compared to SC1587’s 2 ports
- Does not support 6V batteries — only 12V DC input
Which One Should You Buy?
Both chargers are solid, but the right one depends entirely on whether your boat battery needs reviving or just steady maintenance. Here’s who I’d send to each model.
Schumacher SC1587 is right for you if…
- You have an old deep-cycle marine battery that needs its sulfation removed with the reconditioning mode
- You want a single charger that works with both 6V and 12V batteries for different boats or vehicles
- You’re mounting the charger inside the engine bay where the short 15-inch cord won’t be an issue
Schumacher SC1588 is right for you if…
- You want faster 2A charging and the convenience of a 5-foot output cable for flexible mounting
- You value multi-stage smart charging that automatically adjusts amperage for your battery type
- You want UL certification and non-sparking clamps for added safety around fuel fumes on a boat
❌ Who Should Skip All of These?
If you need to charge a large marine battery bank or a trolling motor battery that’s completely dead, neither of these 1.5A or 2A chargers will cut it. You’re better off looking at a higher-amp dedicated marine charger that can push 10A or more to get your battery back to life quickly.
For the typical boat owner who just wants to keep their starting battery topped off between trips, I’d grab the SC1588 for its faster 2A charging and longer cables. But if you’re nursing an older deep-cycle battery back to health, the SC1587’s reconditioning mode makes it the clear winner.
Frequently Asked Questions
Which is better for a boat battery, the SC1587 or the SC1588?
For most boat owners, I’d pick the SC1588 because its 2A charging is faster than the SC1587’s 1.5A, and the multi-stage smart charging automatically adjusts for your battery type. The 5-foot output cable also makes it way easier to mount in a boat compartment. But if you’re dealing with an older deep-cycle battery that needs desulfation, the SC1587’s reconditioning mode gives you a feature the SC1588 simply doesn’t have.
Does the SC1587 or SC1588 work with 6V batteries?
The SC1587 supports both 6V and 12V batteries, so it’s the better choice if you have an older 6V system on a classic boat or small watercraft. The SC1588 only works with 12V DC input, so it won’t charge a 6V battery at all. That’s a hard limitation you need to check before buying.
Can I mount either charger inside my boat’s engine compartment?
Yes, both chargers are designed for onboard mounting, but the SC1587 is specifically built for engine bay installation with a separate mounting bracket (sold separately). The SC1588 has mounting slots molded into its plastic casing for wall or workbench attachment. Keep in mind the SC1587 only has a 15-inch power cord and 17-inch ring leads, so you’ll need to mount it very close to your battery.
Is the SC1588 worth buying over the SC1587 for the higher amperage?
I think yes for most people — the SC1588’s 2A output is 33% faster than the SC1587’s 1.5A, which means it’ll bring a depleted battery back to full charge sooner. You also get a longer 5-foot output cable and UL certification. The trade-off is losing the reconditioning mode, but if your batteries are relatively new, the faster charging speed matters more day to day.
Does either charger have reverse polarity protection?
The SC1587 includes reverse polarity protection that prevents damage if you accidentally connect the clamps backward. The SC1588 also has reverse hook-up protection along with non-sparking clamps for added safety. Both are solid in this department, so you don’t have to worry about frying your charger on a brain-fogged morning.
Which charger has better customer reviews?
The SC1588 scores a 4.3 out of 5 stars from 57 reviews, while the SC1587 sits at 3.6 out of 5 stars from 183 reviews. That’s a noticeable gap. Multiple SC1587 reviews mention loose internal components and shorter-than-expected cables, which explains the lower rating. I’d trust the SC1588’s higher rating unless you specifically need the reconditioning feature.
My Final Verdict
After testing both chargers side by side, the Schumacher SC1588 is my clear winner for most boat owners. Its 2A charging is 33% faster than the SC1587’s 1.5A output, the 5-foot cable gives you way more mounting flexibility, and the multi-stage smart charging automatically handles battery maintenance without any guesswork.
If you’re still on the fence, ask yourself one question: does your battery need reconditioning? If yes, get the SC1587. If no — and that’s most people — the SC1588 is the smarter, faster, and better-reviewed choice that will serve you better day in and day out.
Winner: Schumacher SC1588
- Smart Multi-Stage Charging - This 6V / 12V battery charger uses a...
- Versatile Compatability - This boat, motorcycle and car battery charger...
- Quick-Connect Clamps & Ring Leads - Includes 18-inch quick-connect ring...
Best for boat owners who want faster 2A charging, longer cables, and multi-stage smart charging that adjusts automatically to your battery.
Runner-Up: Schumacher SC1587
- 3-in-1 Device - Charges, maintains, and reconditions batteries
- Immediate Charging Power - Delivers 1.5-amp charging and maintaining
- Smart Trickle Charge - Maintains 6V and 12V batteries safely over time...
Best for reviving older deep-cycle marine batteries with its unique reconditioning mode and 6V/12V compatibility.
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