Ride-on car battery replacement

This is the repair almost every ride-on needs at two to three years old, and the one most often misdiagnosed as the vehicle wearing out. It takes about twenty minutes and a screwdriver.

The distinctive end-of-life symptom for sealed lead-acid: it takes a charge, reads close to the correct voltage with nothing connected, and then collapses within minutes of the vehicle moving. The plates have lost capacity, so there is surface charge and no reserve.

Three things that are not the battery:

• Nothing happens at all. Usually the charger, the connector or a fuse. See ride-on battery not charging.
• Reverse works but forward does not, or one side only. A gearbox, motor or shift switch. See ride-on car won’t drive.
• Gradually slower over a season, with a child who has grown. Check the weight limit before buying a battery — an over-limit vehicle produces identical symptoms. See weight limits.

Open the battery compartment — usually under the seat or behind a panel, two to four screws — and read the label on the existing battery. You need three things:

1. Voltage. 6V, 12V or 24V. Must match exactly.
2. Capacity in Ah. Commonly 4Ah, 4.5Ah, 7Ah, 10Ah or 12Ah. You may go up but never down.
3. The connector. Photograph it. Power Wheels 12V is a gray/orange plug; Power Wheels 6V and Peg Perego use blue; most generics have bare F1 or F2 terminals; Kid Trax and some 24V vehicles use a proprietary wired pack.

Then measure the tray in all three dimensions, because a 12Ah pack is physically larger than a 7Ah one and a few millimeters decides whether the seat goes back on.

Like-for-like restores the vehicle to how it was and is the cheapest option — a 12V 7Ah replacement is around $43.

Upgrade the capacity if the tray allows. 7Ah to 12Ah is roughly 70% more run time for about $40, which is the best value change available to a ride-on. See 7Ah vs 10Ah vs 12Ah.

Switch to lithium if the vehicle gets heavy use and the budget allows — lighter, far quicker to charge, tolerant of partial charges. It must use its own charger.

1. Disconnect the old battery first, before removing any retaining strap or bracket.
2. Note the polarity. Photograph the terminals before disconnecting. Red to positive, black to negative — and check twice, because reversing it on a bare-terminal pack can damage the speed controller.
3. Clean the connector contacts. Light gray oxidation wipes off. Green or white crust means moisture; clean it and fix the storage. If the connector is discoloured, deformed or smells of hot plastic, replace it — it is a $13 part.
4. Seat the new pack and secure the retainer. A battery that moves will chafe its leads.
5. Connect positive first, then negative, and check nothing is pinched under a panel.

Longer than a normal charge. A new sealed lead-acid pack has been sitting partially discharged in a warehouse, and the first full charge sets its usable capacity for life. The genuine Power Wheels packs publish 14 hours for a first charge against 18 normal; some vehicles publish 10 to 12 hours first against 8 to 12 subsequently.

Charge it overnight before the first ride. Then charge after every session rather than when it is flat, which is the single habit that decides whether the new pack lasts one year or three. See the maintenance checklist.