How to charge a 12v 10ah lead-acid battery

Updated March 23, 2017

Lead-acid batteries rated at 12 volts and 10 ampere-hours are used in recreational vehicles such as motorcycles, scooters and ATVs. They tend to be sealed so their electrolyte doesn’t evaporate. They also tend to use an electrolyte other than water, such as fibreglass, so the battery can be operated at a wider range of angles. It would be impractical for a motorcycle to use a battery that leaked acid whenever turned on its side.

Make sure the donor vehicle’s battery is also 12 volts. Otherwise, you could fry your electronics. The donor vehicle can be a car. Though older recreational batteries wouldn’t have handled the charge as well, newer batteries are more robust.

Turn off your vehicle’s electronics (such as headlight or radio.).

Move the vehicles close so the jump leads can reach between batteries. Don’t get them so close as to risk touching and causing an improper grounding.

Turn off both vehicles’ ignitions.

Gain access to the battery.

Put on shatterproof glasses and protective gloves.

Clamp one of the red jumper clamps onto your vehicle’s positive (+) battery terminal. Attach the adjacent black clamp to your vehicle’s negative (-) terminal. This may be different from how you attach jump leads between cars. The point is that you want to complete the circuit far from your own battery, because of risk a spark so close to the engine, gas tank and possible battery gas.

Clamp the unattached red clamp to the donor battery’s positive (+) terminal, and the adjacent black clamp to a grounding piece of unpainted metal 18 inches or more from the donor battery. The edge of the body panel will do if the metal is partially exposed. Do not start the donor vehicle's ignition.

Allow the donor battery to charge your vehicle’s battery for 15 minutes. Leaving the jumper clamps still in place, start your vehicle.

Let your vehicle run for 15 seconds before disconnecting all the clamps, this time in the reverse sequence in which you connected them. Let your vehicle idle a few minutes before riding off, to get the battery charged up a little more.

Disconnect the battery from its cables later on and recharge it overnight with a three-step recharger at a low amp setting (preferably 2 to 4 amps). Three-step rechargers work best because they recharge the battery fully without overcharging. Charging the battery fully after a significant discharge is important because chemicals left uncharged in the electrolyte can cause sulfation, which weakens the battery’s ability to hold a charge.


The battery should not have needed a charge in the first place, so you need to find out the cause. One possibility is that the battery tender (a type of trickle charger) is failing. It prevents sulfation--the build-up of sulphur molecules on the metal plates inside the battery—by keeping the battery topped off when not in use. If you couldn’t get the battery to recharge off a car, then your vehicle could have a short.


Don’t let the clamps’ metal parts touch each other. This could damage both the donor and the flat battery. If your vehicle’s battery is dead because of a short, jumping it could damage your battery and the donor’s.

Things You'll Need

  • Jump leads
  • Working 12-volt battery
  • 3-step recharger with a low amperage
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About the Author

Paul Dohrman's academic background is in physics and economics. He has professional experience as an educator, mortgage consultant, and casualty actuary. His interests include development economics, technology-based charities, and angel investing.