Optimate PRO-1 Duo review | The benchmark in bike charging

Date reviewed: February 2025 | Tested by: John Milbank | Price: £169.90 | www.optimate.co.uk

Slapping the word ‘Pro’ on something doesn’t automatically make it good, but the Optimate Pro-1 Duo on review here really does deserve that moniker. Thanks to it focussing only on the most important features of a maintenance charger, it’s become a key tool in my garage, and one I highly recommend to anyone looking to invest in what could be the last charger they ever buy…

Pros & Cons

Features

The Optimate PRO-1 Duo is said to be for professional workshop and serious DIY use, but that’s no shallow claim. There’s no app-connectivity fluff here, just powerful output and the features that make a real difference:

• Charges and maintains lead-acid and lithium batteries

• Can safely ‘wake’ discharged or new lithium battery BMS systems

• Automatically variable 1.25A to 10A output for car and motorcycle batteries from 2 to 120Ah (down to 0.2A for some charging modes).

• Test mode shows battery health at end of charge cycle

• Will attempt to recover a battery down to 0.5V

• Supply mode provides 13.6V steady power at up to 8A

• Reverse polarity protection

• Includes screw-in wall bracket and hook for handlebar.

That may look like a rather short feature list for such a relatively expensive charger, but it’s proving to be exactly what I need out of a device like this.

The most common use will of course be keeping your bike ready to go; just connect it to the battery, turn it on (there’s a rocker switch on the side, so it doesn’t need to be unplugged during use), then press the mode button once for a lead-acid (Pb) battery, or twice for lithium (LFP). If you get it wrong, don’t panic as the Optimate will stop charging if it detects the wrong mode.

And that’s it. Leave it plugged in and the PRO-1 Duo will run through its recovery charge and test modes, then settle in maintenance, which alternates through 30 minute cycles of charge and test.

If you’re charging a battery that’s flat there’s no need to manually select a recovery mode – as long as there’s more than 0.5V in a lead-acid pack, the Optimate will start with pulses of just 0.2A as it tests for the ability for a charge to be held. If it can, then a voltage of up to 14.4V will be applied, varying between 0.2A and 1.25A for up to 2 hours. It’ll then test the battery again, and if all’s well the ‘bulk’ charge will begin, with the current automatically varied between 1.25A and 10A, depending on the capacity of the battery.

A flashing green LED means that charging’s complete and you could use the bike (or car) if you wanted, but after that a test cycle runs; If the green LED holds on steady, then the battery is in good health of 80-100% (12.7-13.0V).

If the orange LED is on too, and it’s a typical AGM motorcycle battery, it’s charged, but has a 60-80% state of charge health (12.5-12.7%). If it’s a ‘STD’ wet cell battery, LEDs 7 and 8 together mean it’s still up there at 80-100%, as those packs hold a lower voltage when charged. If the charger is left connected, it’ll then continue with a final cell-balancing charge, before the maintenance cycle begins.

If you’re charging a lithium battery and it’s below 0.5V, the charge sequence lights won’t illuminate, which most likely means it has a battery management system (BMS) that has detected a deep discharge and disconnected itself to prevent permanent damage. Or it’s a brand-new battery that’s not been activated.

Holding the mode button down for three seconds makes the BMS LED flash, and if the battery successfully activates, charging will start. Errors like a fault with the BMS, the ambient temperature being below -20°C or above 55°C (though I think you’d have noticed), or connecting the battery back to front will make the LED flash rapidly, but if the battery is severely deep discharged the initial checks can be overridden by holding the mode button for 10 seconds, which skips straight to the low current ‘save’ charge mode.

Granted, that might sound a bit complicated, but you’ll rarely need to worry about it as the charger really does handle pretty much everything automatically – it’s just got those extra professional modes that you won’t care about until the day you need them.

Optimate PRO-1 Duo

Full explanation of the features

There is one thing you need to be aware of though… in the event of a power-cut, the Optimate PRO-1 Duo will NOT automatically restart charging as you won’t be there to select the charging mode.

As the PRO-1 can detect if it’s connected to the wrong type of battery, while I understand that in a workshop environment the resetting of the unit makes sense, it would be good to have an option to allow the device to restart charging automatically.

There’s room for improvement in Optimate’s instruction manuals

Besides that, the one criticism I have of the Optimate PRO-1 Duo is that the instructions are quite hard work (they’re the same on the more entry-level chargers too) and the graphics on the faceplate are a bit confusing until you’ve got to grips with it. It’s worth the investment in time, but it’s not as user-friendly an owner’s manual as those usually supplied with the likes of CTEK, for instance. Both brands do supply printed manuals, but CTEK’s are much more accessible.

Connections

Optimate has for a very long time used SAE connectors, which give a positive (if a little stiff) connection, and are readily available if you want to make up your own leads. The mains lead is replaceable as it terminates in a two-pin connector, and measures a lengthy 1.8m. The output cable is only 22cm long, ending in an SAE connector, but a 1.9m SAE to SAE cable is supplied, giving the PRO-1 Duo plenty of reach.

A hook clips onto the top of the charger to hang it from a handlebar for instance, or it can be clipped onto the bottom, which is where I store it when the unit’s attached to the included wall hangar. The excellent quality crocodile clips that also come with the unit (fused, and 55cm long including the protected connector) can be hung from the bottom too, keeping them always on hand.

It is disappointing that the Optimate PRO-1 Duo doesn’t include a fly-lead to attach to your bike’s battery but you can buy one (with a very useful and secure seal on the end) for £11.90. There’s also a monitor version with LEDs that flash briefly to give you an indication of the battery’s health when not on charge, which is available in a lead-acid version for £28.90 and lithium for £25.90.

You can find a range of SAE accessory leads here, with a particularly useful one being an adaptor for heated clothing, which saves having multiple connections to the battery if you ride in wintere.

Supply mode is incredibly valuable to me

Versatility

Being able to charge and maintain lead-acid and lithium motorcycle batteries at a good speed with just the press of one button is great versatility on any charger, but it’s the supply mode that really stands out for me, only bettered in those I’ve tested by the CTEK CS One’s auto detection.

To use it, just press the mode button three times after powering up, then it’ll deliver a steady 13.6V at up to 8A, which is more than enough to keep the bike properly powered up with the ignition off.

While it might be of no obvious value when working on my 1999 Kawasaki ZX-6R, it’s made a huge difference with my 2019 BMW R1250GS.

The battery must be fairly well charged (over 12.6V for AGM, 13.2V for lithium and 12.4V for a STD wet battery), but having a constant power supply of over 12.5V is essential when using the Hex GS911 to change settings within my bike. It’s surprisingly just how quickly a battery can drop below that when the ignition’s on, so having the supply mode made changing the heated grip settings on my GS from the off and high or low that’s standard, to three levels of my choice (I could have added more if I’d wanted).

It was also essential when I was testing the current draw of a set of Wunderlich heated seats, as I needed the bike powered up for about 20 minutes. Despite the seats pulling 3A each, the spotlights on and of course the bike’s own electronics all running, the Optimate supplied all the power I needed, without having to start the bike, which meant I could work in the garage, not outside in the cold at night, annoying the neighbours with an idling motorcycle.

The Optimate PRO-1 Duo isn’t water-resistant – it’s only rated as IP40 – so don’t leave it outside in the rain. Having said that, after taking it apart I wouldn’t be worried if water was splashed on it, and I’d not be concerned about having it outdoors under the car bonnet if needs be.

Internally the construction appears solid, with chunky components and a simple design that seems to promise the same reliability as my old Optimate that I got almost 30 years ago.

The base is rubbery, so sits more stable on a bike’s tank or parts of a car if needs be.

Performance

The high current capability in charging and supply modes gives all the performance I need – there aren’t many motorcycle chargers that can achieve these currents. Even the flagship CTEK CS One reviewed here tops out at 8A charge, and that doesn’t have a supple mode.

I’ve tested this on a deep-discharged leisure battery that measured just 4.62V (way below the 8V that many chargers won’t work under). The PRO-1 Duo automatically entered ‘Save’ mode when I connected it at night, and when I came back the next morning the battery was fully charged with a steady green LED on the Optimate, showing that the automated test gave a state of charge of at least 80%.

I also tried it on an old Yuasa bike battery that was down to 9.8V, but the Optimate couldn’t resurrect that (and nor has any other charger I’ve tried on it).

Reliably and repeatedly testing a charger’s ability to resurrect a damaged battery is very difficult – I’m still trying to find a way – but the results I’ve had with the PRO-1 Duo give me every confidence in its abilities.

On the morning I was meant to be out testing the new BMW R1300GS with my wife (you can watch the video here), the bike was completely dead. It wouldn’t even turn on. It took a few minutes to remember that it has a lithium battery, and checking that with a multimeter showed it was reading zero Volts. After connecting up the Optimate PRO-1 Duo I selected lithium mode, held the button to reset the BMS, then the charger started work and after a short charge we were soon able to get going.

Three alternatives to the Optimate PRO-1 Duo

The high charge capability, lead-acid and lithium capability, and the supply mode make this an extremely versatile device, but here are some others to consider…

• CTEK CS One, £169 | CTEK is probably Optimate’s biggest competitor, and this is the company’s flagship charger. It can automatically detect lithium and lead-acid batteries, selecting the best current up to a maximum, of 8A. It will also connect to a smartphone app to give more details of the charge rate and change some modes, but this is its downfall too, the app being clunky and constantly logging itself out; I don’t want to have to register to use a charger, and this spoils what would be a great device if it had its own display. Read the full review of the CTEK CS One here.

• CTEK MXS 5.0 Test & Charge, £125 | Charging at 0.8A for motorcycle batteries and 5.0A for car batteries, you do have to switch over manually, but it still makes for a handy device. It doesn’t support lithium packs, but it does have a built-in tester for not just the battery’s resting voltage, but also its cranking capacity and the charging voltage when the engine’s running, to check the alternator. Read the full review of the CTEK MXS 5.0 Test & Charge here.

• Optimate 1 Duo, £50.90 | If all this seems too much, why not get the Optimate 1 Duo, which is an affordable 0.6A motorcycle maintenance charger that can work on lead-acid batteries down to just 4V, and can also charge lithium packs. It’s a great value device, and while we haven’t tested the 1 Duo, we have looked at the previous 1+ here.

These are just three of many alternatives – you can find all the motorcycle battery chargers we’ve tested here and be sure to regularly check for the discounts available through Bikesocial membership.

Optimate PRO-1 Duo review: Verdict

I have an Optimate that’s almost 30 years old and still going strong, so I’ve no doubt that the PRO-1 Duo will be just as reliable. Sure, it’s expensive, but this has all the features I NEED in a motorcycle (and car) battery charger.

The guide printed on the front takes a little deciphering, but along with the instructions it soon becomes simply a handy reminder when you’re using it. The ability to maintain and to charge all my motorcycle and car batteries is valuable, but the supply mode seals the deal, being pretty much an essential for anyone who works on their own, modern motorcycles.

If you only ever want to buy one charger, this is a highly-recommended investment.

If you’d like to chat about this article or anything else biking related, join us and thousands of other riders at the Bennetts BikeSocial Facebook page.