Optima Digital 400 12V Performance Maintainer and Battery Charger

The Optima Batteries Digital 400+ 12V Battery Maintainer and Charger has quickly become my go-to charger for everything from automotive AGM batteries to powersports batteries. It’s super easy to use, with clear indicators and smart charging logic that keeps the battery healthy instead of overcharging it. I especially appreciate the maintainer mode — I can leave it connected during long-term storage and know the battery will be ready to go. Build quality is excellent and it feels solid and professional — not like a bargain-bin charger. It recovers low batteries well and works great with AGM setups. One thing that really made this charger even more convenient was pairing it with the OYMSAE 25ft SAE Extension Cable. The extension plugs right into the charger leads and gives a ton of extra reach, so I can keep the charger in a safe spot while the vehicle stays parked where it is. The connectors fit snugly and the cable feels heavy-duty, so there’s no power or connection issues. If you’re getting the Digital 400+, I highly recommend grabbing that extension cable too — together they make an awesome setup for maintaining and charging multiple vehicles.

NOCO GB40 Boost Plus & Optima Charger Initial Setup & Battery Issues - Upon arrival (04.27.25), connected the Optima Charger directly to my AGM battery. - Battery showed 1.5V—manual states device requires <2.5V to connect, and indeed, it wouldn't connect. NOCO GB40 Boost Plus - Emergency Jump Start - Borrowed a NOCO GB40 Boost Plus to attempt increasing battery voltage. - Turned the key in the car—no lights, no reaction. - Used the "!" button (hold for 3 seconds) on NOCO to deliver extra voltage. - Bam! Car lights switched on, and I was able to start it—pretty amazing. Charging with Optima Charger - Let the car run briefly to charge the battery, but it shut off after a few minutes (Toyota Prius Hybrid). - Disconnected NOCO, then immediately plugged in Optima Charger (already connected to battery). - Charger powered on, connected instantly, and displayed 13.2V—AGM battery appeared nearly fully charged (unexpected). - Within 5 minutes, voltage increased to 13.3V. Optima Charger Features & Observations - Easy operation—simply plug in, and it turns on automatically. - No power switch—just a power indicator light (not a button). - Requires selection of battery type using one of four buttons: - Confusion between two AGM options: - Optima AGM Common - Auto/Marine (Flooded & AGM) - Since I don’t have an Optima AGM battery, I selected Auto/Marine option. Overall Verdict - NOCO GB40 Boost Plus – Exceptional performance, saved my car, 5-star device. - Optima Charger – Reliable, straightforward, and well-built: - Reads voltage & amps, providing real-time battery status. - Bulky but durable—manual advises not to drop it. - LED screen looks outdated, but functionality matters more than aesthetics. - Comes with a 3-year warranty. - Worth keeping—serves as a trickle charger for long absences. - Cost comparison: - New battery (Toyota AGM): $250 - Optima Charger: Approx. $139 with tax - Savings: $111 Final Thoughts For anyone dealing with AGM battery maintenance, the Optima Charger is a no-brainer. It works as expected and delivers crucial real-time data. Highly recommended.

6 months back I purchased a few new Optima Yellow Top batteries for my cars. My 75 Datsun 280Z rarely gets driven and I had forgotten to disconnect the battery before it sat for over a month without being started. When I went to start the car the battery was so dead that it wouldn't even start with the jump box attached to the battery. I pulled the battery out and took it to my local O'rileys Auto Parts where they took it and told me they would get it charged over night and call me. I waited 2 days without hearing from them and decided to go into the store. When I got there the guy said my battery still wasn't charged but they would keep it on the trickle charger for another night and see if it was up to 12v. It was sitting at about 11v when I picked it up the next say. The employees of the O'rileys told me that the battery was reading as good though and that most likely the battery was down to about 1/4 of its capacity and at the end of its life. When I told Amazon about the battery they immediately sent out a replacement. The replacement arrived looking like it had fell through the box so I was concerned about the condition of the battery. Amazon decided to refund my money for the battery. Instead of buying a 3rd battery I decided to buy a nice Optima charger, check the batteries out and charge them if possible. I left the original Optima on the charger overnight and found it at 13.4v and 100% capacity the next morning. Delighted with my find I grabbed the 2nd battery and placed it on the charger. Turns out that it was good as well but only about 40% charged. That was taken care of by the next morning. I guess the guys at O'rileys should invest in a good Optima charger. The charger seems well built and has a nice digital face. Simple options make setting up easy. Safety features like a warning and internal killswitch when on the wrong polarity. Goes through all stages of charging, conditioning and maintaining a battery on it own. Will charge a deeply discharged battery. Safe for Acid, gel or AGM style batteries. Monitors air temperature to provide the perfect charge. Feels very durable but looks nice at the same time.

Perfect charger! As a mechanic, it’s the best trickle charger I’ve ever seen/used! I am very happy with charger, would recommend this to anyone looking for a Charger! I use when my race car is in storage, my father uses it to not only charge his lawnmower batteries in the winter but also his neighbours car that’s in storage for the winter months when they are gone to Florida. It test the battery, gives results, charges based on results and then has a maintenance mode. If you want a good trickle charge this one is definitely worth every penny!!!

My fault ! Plugged it in with an adapter but forgot a converter for volts ! Optima went pop and circuit breaker tripped !! 😫

El producto llegó antes de lo previsto y en buen estado. Tuve que utilizarlo ese mismo día ya que mi auto no encendía desde un día anterior por un error mío. Yo cuento con una batería Optima Amarilla y mi auto tiene la batería en la parte trasera. Por comodidad pensaba quitar la batería y después conectar directamente el Cargador Optima a la batería sin embargo el manual indica que en ese caso se debe utilizar otras conexiones, esto se me hizo raro por lo que busqué en internet y en el sitio de Optima viene una actualización al manual (recomendable descargarlo y leerlo antes de utilizar el Cargador). Siguiendo las instrucciones, decidí mejor dejar la batería en mi coche y conecté el Cargador Optima a las conexiones que tiene mi coche en el cofre. La operación fue muy sencilla, después de un diagnóstico inicial seleccione mi tipo de batería y comenzó el proceso. Todo iba bien hasta que ocurrió una tormenta eléctrica. Temía que fuera a suceder algún percance en la conexión eléctrica de mi casa ya que es común la perdida de energía en lluvias fuertes. El proceso (llevaba como 5 horas) indicaba una carga de 75%, y en el manual se indica que el proceso consiste en Carga, Acondicionamiento, Mantenimiento, Re-Acondicionamiento y un último Mantenimiento, todo dura, según el manual desde 9 a 36 horas dependiendo del estado inicial de la batería. Desafortunadamente en el manual no se indica alguna precaución o paso a seguir si es necesario interrumpir el proceso. Me imagino que lo ideal sería dejar al Cargador Optima hacer su trabajo pero en esta situación no era opción para mí. Tuve que tomar el riesgo (unos minutos después se fue la luz) de desconectar el Cargador Optima, afortunadamente no sucedió algún daño y al día siguiente continué con el proceso. El Cargador Optima me ha parecido muy sólido y con buen material. Hubiera estado muy bien en contar con algún tipo de gancho para colgar del cofre del vehículo por que el pedazo de plástico, que en el manual dice que es gancho o soporte, es inservible. Es recomendable dejar el Cargador Optima en un lugar con buena ventilación ya que se calienta bastante, el proceso de carga se puede ver interrumpido por la temperatura por lo que el aparato se pausa hasta volver a condiciones óptimas de operación.

使えなかったので星0です。 他にもいろいろ買い揃えてお金をゴミ箱見捨てたのと変わりません。 オプティマに繋いで充電モードを選択→突然電源が落ちて充電不可！ もう要らないな！何とかメイトとかシーテックにします。ｗｗｗ

This is a really nice and compact charger that really fulfills all of the needs you would have from a larger charger, as long as you don't mind waiting a few more hours for the charging to finish compared to the larger ones. I haven't tried a lot of other chargers to compare to, but there was nothing extra I would have wanted from this. The size is great because it's also an excellent battery tender if you need one, which means you can just leave it in the engine bay with the hood closed. It's also great during cold weather for that reason - you can just pug it in where you park like a block heater and it won't be stolen. It wasn't 100% perfect though - you'll see a number of concerns in reviews on the LCD quality, and for sure it was variable. When I first used it the digits were all in a state of half on half off, which made it almost impossible to read. I almost returned it but after charging the battery over night the screen was fine again. It got worse again and improved again, and I wonder if the -30C temperature had something to do with that, but it doesn't impact the function. This isn't a complaint, but I was a bit worried by the clicking sound that comes from the ground while connected to the frame while charging, but nothing bad happened, it did it on both vehicles, and it eventually stopped. I still don't know what it was, but it turned out ok so I'm less worried. There's some ambiguity if this one can also do conditioning (desulphating) abused batteries compared to the larger Optima charger (even from Optima's literature). I really can't say, however both batteries were undercharged for a year and this charger did do a conditioning phase after charging. Both batteries are now functioning as original and I think they would have surely had sulphation, so I'm inclined to believe that it works on this one too.