What an Everstart Maxx charger does and when to use it
An Everstart Maxx is a 12-volt battery charger sold at Walmart that can charge a dead car battery, maintain a battery that is losing charge slowly, or jump-start a vehicle without a second car. The charger connects to your battery terminals with clamps, plugs into a wall outlet, and delivers power over several hours. You use it when your battery will not turn the engine over, when you want to charge a battery before winter storage, or when you need to keep a battery topped up during long periods of non-use.
The Everstart Maxx comes in different models — some are basic chargers only, others include a jump-start function, and some have additional features like a maintainer mode. The steps below cover the standard charging process that works across all versions. Always check your specific model's manual first, because button placement and display screens vary.
Key Takeaways
- Turn off the engine and all vehicle electronics before connecting the charger clamps to avoid electrical damage.
- Connect the red clamp to the positive battery terminal first, then the black clamp to the negative terminal, then plug the charger into the wall.
- Set the charger to the correct amperage — usually 2 amps for a slow overnight charge or 10 amps for a faster charge — and press start.
- Leave the charger running until the display shows the battery is fully charged, which typically takes 4 to 24 hours depending on how dead the battery is and what amperage you chose.
- Disconnect the black clamp first, then the red clamp, then unplug the charger from the wall before attempting to start the vehicle.
Prepare the vehicle and charger before connecting
Park the vehicle in a safe, well-ventilated location — ideally outdoors or in a garage with the door open. Turn off the engine if it is running. Turn off all lights, the radio, the climate control, and any other electronics. This prevents a sudden surge of power from damaging the vehicle's electrical system when you connect the charger.
Locate the battery under the hood. It is a rectangular plastic case with two metal terminals on top — one marked with a plus sign (positive) and one marked with a minus sign (negative). The positive terminal is usually red or has a red cover; the negative terminal is usually black or has a black cover. If the terminals are corroded (covered in white, blue, or green crusty buildup), clean them with a wire brush or a cloth before proceeding. Corrosion blocks the electrical connection and slows charging.
Remove the Everstart Maxx charger from its box and place it on a flat, dry surface near the battery — close enough that the clamp cables reach comfortably. Do not plug it into the wall outlet yet. Inspect the red and black clamps at the end of the cables to make sure they are clean and undamaged.
Connect the charger clamps in the correct order
Always connect the positive (red) clamp first. Open the red clamp by squeezing or twisting the handle, depending on your model. Clamp it firmly onto the positive battery terminal — the one marked with a plus sign. The clamp should grip the terminal tightly enough that it does not slide or wiggle. A loose connection will cause the charger to work slowly or not at all.
Next, connect the black (negative) clamp to the negative battery terminal — the one marked with a minus sign. Squeeze or twist the handle to open the clamp, then clamp it firmly onto the negative terminal. Again, make sure the connection is tight.
Do not reverse this order. Connecting the negative clamp first can create a spark or short circuit, especially if the positive clamp accidentally touches any metal part of the engine or frame. The correct sequence — red first, then black — prevents this risk.
Set the amperage and start the charge
Now plug the charger into a standard 120-volt wall outlet. The display should light up. Most Everstart Maxx models have buttons or a dial to select the charging amperage. Common options are 2 amps, 10 amps, or 50 amps (for jump-start mode). Choose based on how quickly you need the battery charged and how dead it is.
Use 2 amps for a slow, gentle charge that takes 12 to 24 hours but is safest for an older or weak battery. Use 10 amps for a medium charge that takes 4 to 8 hours and works well for most dead batteries. Use 50 amps (or the jump-start button) only if you need to start the vehicle when ready — this mode delivers a large burst of power but should not be used as a regular charging method.
After selecting the amperage, press the start button. The display will show that charging has begun. Some models show a progress bar or percentage; others show the current flowing to the battery in amps. Leave the charger plugged in and running. Do not unplug it or disconnect the clamps while it is actively charging.
Monitor the charger until the battery is fully charged
Check the display periodically, but you do not need to watch it constantly. The charger will continue delivering power until the battery reaches full charge. Depending on the model, the display may show "Fully Charged," "100%," a green light, or a message that charging is complete. Some chargers automatically switch to a maintenance mode once the battery is full, which keeps it topped up without overcharging.
Charging time varies widely. A completely dead battery charged at 2 amps may take 20 to 24 hours. The same battery charged at 10 amps might take 4 to 8 hours. A battery that is only partially discharged will charge faster. If the charger shows no progress after 30 minutes, disconnect it and check that both clamps are making firm contact with the terminals. Corrosion or a loose clamp is usually the cause.
If the battery is extremely old or damaged, the charger may not be able to charge it fully. If the display shows an error code or if charging stalls at 80 or 90 percent, the battery may need replacement. Consult your vehicle's manual or a mechanic to determine whether the battery can be salvaged.
Disconnect the charger in the correct order
Once the display shows the battery is fully charged, unplug the charger from the wall outlet first. This cuts power to the charger and prevents any electrical surge when you remove the clamps.
Next, remove the black (negative) clamp from the negative battery terminal. Squeeze or twist the handle to open the clamp and pull it away from the terminal. Then remove the red (negative) clamp from the positive terminal in the same way. Reversing this order — removing the red clamp first — can create a spark, so always remove black before red.
Coil the cables neatly and store the charger in a dry place. Close the hood of the vehicle. Wait a few minutes, then attempt to start the engine. If the battery was the only problem, the vehicle should start normally. If it does not start, the battery may be damaged or another electrical issue may be present.
Troubleshooting common problems
The charger shows no activity or a red light. Check that both clamps are making firm contact with the battery terminals. If they are loose, tighten them. If the terminals are corroded, disconnect the charger, clean the terminals with a wire brush, and reconnect. Also verify that the wall outlet is working by plugging in another device, like a lamp.
The charger beeps or displays an error code. Consult the manual that came with your charger — error codes vary by model. Common errors include reversed polarity (clamps connected backward), a short circuit, or a battery that is too damaged to charge. If you connected the clamps correctly, disconnect them and try again, making sure the red clamp goes on the positive terminal first.
The battery charges slowly or stops before reaching 100 percent. This usually means the battery is old or damaged and cannot hold a full charge. A battery that will not charge past 80 percent after several hours is likely at the end of its life. If the charger is set to 2 amps, try switching to 10 amps to see if a faster charge completes. If it still stalls, the battery should be replaced.
The vehicle still will not start after the battery is fully charged. The battery may be charged but unable to deliver the power needed to start the engine — a sign of internal damage. Alternatively, the problem may not be the battery at all. Have the vehicle's electrical system checked by a mechanic to rule out a faulty starter, alternator, or wiring issue.
Frequently Asked Questions
Can I charge the battery while it is still in the vehicle?
Yes. The battery does not need to be removed. straightforward open the hood, connect the clamps to the terminals, and proceed as normal. Removing the battery is only necessary if the terminals are so corroded that you cannot make a good connection, or if you need to replace the battery.
How often should I charge my battery with the Everstart Maxx?
If your vehicle starts normally, you should not need to charge the battery regularly. Charge it only when the battery is dead or dying — when the engine cranks slowly or will not turn over at all. If you need to charge it more than once every few months, the battery or the vehicle's charging system may be failing and should be inspected.
Is it safe to leave the charger connected overnight?
Yes, if the charger has an automatic shutoff or maintenance mode. Most modern Everstart Maxx models stop charging once the battery reaches full capacity and switch to a trickle charge that keeps the battery topped up without overcharging. Check your manual to confirm your model has this feature. If it does not, disconnect the charger once the battery is fully charged.
What if the charger clamps do not fit my battery terminals?
Most car batteries have standard-sized terminals, and Everstart Maxx clamps fit them. If the clamps are too small or too large, the battery terminals may be damaged or the battery may be a non-standard type. Do not force the clamps. Instead, have the battery inspected by a mechanic to determine whether it needs replacement or repair.
Can I use the jump-start mode to start the vehicle when ready?
Yes, if your Everstart Maxx has a jump-start or 50-amp mode. Connect the clamps as normal, select the jump-start mode, and press start. Wait 2 to 3 minutes for the charger to build up power, then attempt to start the vehicle. Jump-start mode is faster than waiting for a full charge, but it should be used only when you need to start the vehicle right away, not as a regular charging method.