TecMate Optimate 4 Battery Charger Review

Jeff Cobb
by Jeff Cobb

If you’re familiar with “smart” battery chargers, the TecMate Optimate 4 could be said to be an extra-super-smart charger.

How smart is it? It’s so smart, that if they gave out degrees to consumer battery chargers, some might say this one should have a PhD. It’s so transcendently gifted, in fact, it can even raise the dead!

Dead batteries that is. Even some sulfated ones, according to its maker, which boasts the Optimate 4 “saves batteries other chargers can’t,” by way of a 6-step charge program, and that it’s “recommended by eight major powersports manufacturers.”

To be frank, we can neither confirm nor deny all the benefits this $69.90 charger lays claim to. We tried to revive one dead motorcycle battery dug out of the musty confines of Mr. Duke’s garage full of aging moto-schwag, but alas, the battery was past the point of resuscitation.

Otherwise, the Optimate 4’s “weatherproof” case, hefty feel, and diagnostic display definitely look impressive. And, sure enough, we found it does recharge and maintain otherwise okay 12-volt lead-acid batteries, like any smart charger should.

tecmate optimate 4 battery charger review, What s in the box The charger and two optional harnesses Several more SAE connector equipped harnesses are also available
What’s in the box? The charger and two optional harnesses. Several more SAE-connector-equipped harnesses are also available.

Light Show

The Optimate 4 has no bells or whistles, but does have 10 LEDs. Its microprocessor uses these red, green, and yellow lights to communicate what it’s doing as it first analyzes a battery, then attempts to delsulfate it if needed, then bring it up to charge and keep it that way.

While the manufacturer says the Optimate 4 is good for 2 to 50 amp-hour batteries, its low 0.8-amp peak charging rate really means it’s best suited for powersports batteries and the like, and not so great for larger car or truck batteries, although it can work on these if you have the time.

Reading through the manual repeatedly to get a grasp of what all these lights mean, the one thing that soon becomes apparent is this is one complicated device. We realized this also when we requested clearer explanation and the TecMate rep sent us user guides, data sheets and flow charts all trying in different ways to explain how the Optimate 4 works.

tecmate optimate 4 battery charger review, Inside the front inside cover of the included instruction manual is a Quick Guide that serves as an abbreviated reference It shows what the solid and or flashing LEDs are communicating as the battery cycles through a potentially 6 stage program to analyze condition charge and maintain a 12 volt lead acid battery
Inside the front inside cover of the included instruction manual is a Quick Guide that serves as an abbreviated reference. It shows what the solid and/or flashing LEDs are communicating as the battery cycles through a potentially 6-stage program to analyze, condition, charge and maintain a 12-volt lead-acid battery.

Some Key Functions Briefly Explained

The Optimate 4 connects to a battery via one of two included twin-lead harnesses. On the battery connection end, one harness has crocodile clips, and the other has ring connectors. On their opposite ends, both utilize SAE couplers that plug into the charger’s sturdy output wiring.

As you might expect, the ringed harness is meant to be left connected to battery posts for periodic recharging, and the conventional crocodile clips are for quick connects as required.

There is no on/off switch for the Optimate 4. Plugging it in energizes it, and its lights go through a sequence before settling into a function with the task at hand.

If it’s not connected to a battery with more than 2 volts, a solid green power light comes on, but otherwise no current flows as a safety feature. If, for example, unconnected crocodile clips are being used, touching them together produces no spark.

Once connected to a battery, the charger’s brain first senses voltage. If the battery has more than 2 volts, it will begin analyzing the battery. If less than 2 volts, it won’t even try.

If it senses conditions for potential sulfation, it will try to fix them. The way it will attempt to shake loose said accumulation is by the only means it has – by sending surges of higher current. But since this could fry sensitive electrical components if it’s connected to a vehicle, it’s designed not to risk that unless you disconnect the battery.

tecmate optimate 4 battery charger review, The Optimate 4 communicates amperage being delivered whether it s in desulfate or charge mode and battery condition at the end of its 6 stage program
The Optimate 4 communicates amperage being delivered, whether it’s in desulfate or charge mode, and battery condition at the end of its 6-stage program.

Assuming the battery is disconnected from a vehicle, and the Optimate 4 sees the battery as deeply discharged, it will use one of two desulfating modes indicated by the orange #3 LED.

Its basic mode is shown by a solid LED as it delivers a 16-volt, 0.2-amp charge to hopefully knock loose sulfation. If the charger’s diagnostic program deems a battery to be severely discharged, its “turbo recovery” mode will send 22 volts at a lower (but unspecified) amperage.

In either mode, the manufacturer says its circuitry reads the condition of the battery as it’s working it over with the higher than usual voltage. When the charger’s diagnostics decide a battery is able to take a normal charge, the high voltage tapers down.

At a point when the battery is considered ready for normal recharging, or at two hours, whichever comes first, the “charge and charge verification” mode kicks in.

In “bulk charge” mode, indicated by a solid #4 LED, the charger is designed to take the battery up to 14.3 volts at 0.8 amps – we verified voltage with a voltmeter – then drops off. At this point, the voltage is reduced to 13.6 volts for 30 minutes for the “absorption and charge verification stage.” If it senses the battery needs it, the charger will revert to full charging cycle again, then repeat as necessary.

Once the battery’s current demand is proven able to remain below 0.2 amps at 13.6 volts – ”which is consistent with a battery that has accepted as much charge as its basic conditions allows” – the microprocessor switches to a “voltage retention test” for another 30 minutes. This is alternated with a “maintenance” charge – for as long as the battery is hooked up.

Some Diagnostic Features

In the “test” and “maintain” period, the battery is essentially given a report card. If the battery is going to be a keeper, the #5 green LED will flash and eventually go steady. If it’s sketchy, the yellow #6 LED may alternate with the #7 LED.

A flashing red #7 or flashing or steady #6 and #7 LEDs together are indicators that a “significant problem exists.”

If you bypassed the desulfating mode and left the battery connected to a vehicle, and it gets a failing grade, TecMate points out that it could be getting pulled down by problems in a vehicle’s electrical system that are unrelated to the battery.

The way to find this out is to disconnect it. If, upon recharging, the battery comes up good, then that is an indicator the problem is with the vehicle’s electrical system, not the battery itself.

If, however, the disconnected battery itself is a dud, and even the desulfating feature didn’t revive it, a solid red #7 LED will tell you it’s time to replace it.

TecMate also makes load testers and other more sophisticated diagnostic equipment, and recommends suspected bad batteries – or vehicle wiring – may need further testing, as needed.


We summarized highlights from the Optimate 4’s operating procedures as much as possible. A full explanation of every last variable this smart charger contemplates and communicates could be prohibitively long. If you want to know more, we’ve included some of the teaching aids TecMate gave us.

tecmate optimate 4 battery charger review, This flow chart indicates processes the Optimate 4 goes through
This flow chart indicates processes the Optimate 4 goes through.

An Optimate 4 owner who really wants to understand all that the Optimate 4 attempts to do would also want to read the detailed, 4-page instruction manual, and re-read it if necessary. Having the Quick Guide (pictured) nearby to keep your memory fresh would also be a good idea.

Or, if you want to set it and forget it, you can practically do that, too. Assuming the battery and vehicle electrical system are good, the Optimate 4 will at least charge and maintain a battery with or without your knowing what it’s thinking.

If you leave the charger hooked up for weeks or months, the manufacturer does recommend checking connections every two weeks. Also, unsealed batteries need to periodically have their electrolyte level checked and replenished if needed with distilled water. Even smart chargers can cook off the electrolyte from unsealed batteries.

As for the desulfating feature, all we can say is we suspect this is at best for batteries that have only been left sitting for months, and not years-old batteries like the one that Duke should have recycled long ago.

Considering that the Optimate 4 appears well designed and is priced within range of competitive brands, we think it’s worth considering. It should at least do what other smart chargers also claim to be able to do, if not also a few things more.

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Jeff Cobb
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