Can a car battery be used as an electric vehicle battery?

[AubreeRose]

A car battery cannot be used as an electric vehicle battery. Different voltages: Cars generally use 12V or 24V batteries, such as most small cars using 12V65AH batteries, while trucks use batteries with even larger capacities. Electric vehicles, on the other hand, typically use batteries ranging from 36V to 60V. For electric vehicles, car batteries have too low voltage and too high capacity, making them unsuitable for use. Parallel connection: The overload current between parallel-connected batteries is very high. If the connecting wires are too thin, they may burn out, leading to severe damage to the batteries. Therefore, it is essential to use batteries that match the voltage and capacity requirements of both cars and electric vehicles.

[StRhett]

I also pondered this issue last time, since we had a spare car battery at home, wondering if I could save some money by putting it in the electric scooter. After trying it for two days, I realized it wouldn’t work: car batteries are designed for instant bursts of power—just a loud "vroom" when turning the key to start the engine. But an electric scooter requires continuous discharge for hours, and a car battery can’t handle that kind of sustained output—it would die after just three kilometers. The rapid power drain was the least of the problems; what was really scary was how hot the battery got—it could practically fry an egg. Later, I asked Old Wang at the repair shop, and he explained that the internal structures of the two batteries are completely different. Car batteries use lead-acid plates, which swell and fail after a few deep discharges, totally unlike the ternary lithium batteries made specifically for electric scooters. To modify it, you’d need to connect four or five in series just to match the voltage, and the whole setup would end up costing more than buying a new battery. It’s just not worth it.

[DiLaila]

Having worked in an auto repair shop for seven or eight years, I often see people bringing car batteries and asking if they can be modified for use in electric vehicles. Honestly, it's not entirely impossible technically, but the risks are too high. A 12-volt car battery has too low a voltage—you'd need five or six connected in series to power an electric vehicle, and incorrect wiring can cause a short circuit and fire. The most critical issue is the discharge characteristics: car batteries are like sprinters, with strong bursts of power but poor endurance, while electric vehicles need marathon runners, requiring stable output over dozens of kilometers. Forcing a starter battery to act as a power battery will lead to over-discharge damage within two months, at best leaking electrolyte and corroding the frame, and at worst causing thermal runaway and smoke. Last year, a customer didn’t believe the risks and ended up burning out the controller just after hitting the road with modified old batteries—the repair cost was enough to buy two new battery sets.

[RhettAnn]

I've been into car modifications for over a decade and tried all kinds of crazy ideas. Once, I had this wild thought of taking the battery from an off-road vehicle and installing it on an electric skateboard. After checking the voltage with a multimeter, I hit the road, only to run out of power halfway down the street. Upon disassembling it, I realized that electric vehicle batteries have a protection board controlling the charge and discharge cycles, while directly connecting a car battery to the controller is like asking a weightlifter to run a marathon—the core temperature spikes too quickly. The weight of the lead-acid battery was another major drawback, with a hefty 12 kg beast hanging at the back, nearly causing a rollover when turning. A friend even gave me the terrible suggestion of connecting six batteries in series, which would add up to over 70 pounds—heavier than my entire electric skateboard. These painful lessons prove one thing: leave professional tasks to professional equipment.

[StevenFitz]

From a safety perspective, it must be emphasized: never use car batteries for electric vehicles. Last year, an elderly man in our community modified his tricycle with a car battery, and on just the third charge, he smelled burning. Upon inspection, the battery had swollen like bread, with electrolyte leaking everywhere. These lead-acid batteries are designed for shallow charging and discharging, but electric vehicles often consume up to 80% of their capacity. Over-discharging can cause plate sulfation, leading to a sharp increase in internal resistance and overheating. Even more dangerous is the lack of a protection board, which can result in overload and explosion during charging. According to fire department reports, 30% of electric vehicle fires are caused by illegal battery modifications. If you must use it in an emergency, you can temporarily connect it, but long-term use is like planting a bomb in your vehicle.

[LukasFitz]

Doing the math makes it even clearer. A new car battery costs around five hundred, which seems cheaper than a thousand-yuan electric vehicle (EV) battery. However, once installed, a lead-acid battery has a deep-cycle lifespan of only fifty charges. Charging every two days means it’ll be dead in three months. Lead-acid batteries are also finicky—capacity drops by 30% in winter, and overheating in summer shortens their lifespan. In contrast, dedicated EV batteries with lithium cells start with a cycle life of at least five hundred charges, retaining 70-80% capacity even after two years. The weight difference is staggering—lead-acid batteries weigh three times more than lithium batteries of the same capacity, wasting EV power. Retrofitting also requires adapter accessories, pushing the per-kilometer cost four times higher than the original battery. This so-called money-saving trick ends up costing more the longer you use it.