Going to the drive-in is a fun, nostalgic way to see movies. However, running your car stereo or using battery-powered speakers for several hours can quickly drain your car’s battery. Fortunately, there are some simple things you can do to enjoy the drive-in audio without killing your battery.
Quick Answers
– Use a separate battery or power pack to power radio transmitters or speakers.
– Keep car engine running and charging system active.
– Charge battery before and let car run in intervals.
– Use more efficient audio options like LED transmitters.
– Park strategically near power outlets.
Don’t Run Down Your Car Battery
The biggest battery drain at a drive-in is running your car’s stereo for several hours. Most car radios draw 10-20 amps, so listening to the movie audio for 3+ hours could use 30-60+ amp hours (Ah). With the average car battery around 50 Ah, it’s easy to see how it could get completely depleted after a double feature.
Similarly, portable Bluetooth speakers or FM transmitters also use your car battery to power their operation. While not as much of a draw as a car stereo, extended use all night will still add up and contribute to draining your battery.
Use a Separate Battery or Power Source
The easiest way to avoid using your car’s battery is to use a separate, dedicated battery source just for your audio equipment. A deep cycle marine or RV battery with 50-100 Ah would be ideal, providing more than enough power for multiple nights at the drive-in. Just connect it directly to your radio transmitter or speakers.
Another option is a portable power station, which is essentially a large external battery pack with AC and DC power outlets. Many models with 150+ watt-hour capacity would have enough juice to last through double features. Be sure to get an inverter model if you need AC power for certain devices.
You could also run a power cord from a nearby outlet (if available) to provide continuous power instead of battery. This works best if parked near structures, but be sure to use an outdoor-rated extension cord.
Benefits of Using Separate Power Source
- Avoids any drain on your car battery
- Provides consistent power for whole night
- Allows using more powerful audio system
- Dedicated source easier than manually charging battery
Keep Car Charging System Active
If you don’t have an alternate power source, you can keep your car engine running the whole time. This keeps the alternator charging the battery continually. Just be sure not to turn off the engine and electronics when stopping at the snack bar or bathrooms.
The charging system provides around 60-100 amps, which is far more than most sound systems would draw. This ensures the battery stays fully charged.
An even better approach is using a voltage booster in line with your car battery. This device monitors voltage and automatically starts your engine as needed to recharge the battery. Once voltage is back up, it shuts off the engine again to conserve fuel.
Tips for This Method
- Don’t turn off engine and electronics at any point
- Use heavy duty charging system for older cars
- Install voltage booster for automatic charging
- Check battery and recharge after each movie night
Charge Battery Fully Beforehand
Make sure your car battery is 100% charged before you head to the drive-in. Use a trickle charger or go for a drive to top it off. That gives you the maximum amount of capacity so any drain during the show has less impact.
You can also periodically start your car for 10-15 minutes during any intermissions or between movies. Letting the alternator charge for short bursts will help offset the power drain and keep voltage higher.
Testing voltage periodically with a multimeter is also wise. If voltage starts dropping below 12.4-12.6v, it’s time to give the battery a quick charge boost.
Tips for Pre-Charging Battery
- Fully charge right before leaving home
- Use a battery tender for optimal charging
- Run engine for 15 mins between movies
- Check voltage hourly and recharge if needed
Use More Efficient Audio Equipment
Using audio devices designed for efficiency and low power draw can greatly minimize drain on your battery. Here are some good options:
LED Transmitters
LED transmitters use less power than older incandescent bulb models. High efficiency LEDs in newer models like the Lasonic i930 use around 10% the power of older transmitters.
Small Bluetooth Speakers
A small portable Bluetooth speaker powered off the car battery will use far less power than running your car stereo. Use one rated 5-10 watts instead of high powered entertainment systems drawing 50+ watts.
Smartphone and App
Using just your smartphone with an app like RadioLoyal tuned to the drive-in’s broadcast frequency is very power efficient. Reduce screen brightness and avoid streaming video for best battery optimization.
Benefits of Efficient Audio Equipment
- LED transmitters use far less power
- Small portable speakers optimized for efficiency
- Smartphones use very little power for just audio
- Conserve battery charge compared to car stereo
Park Near Power Outlets
At some drive-ins, certain spots may be available adjacent to power outlets on nearby buildings. Call ahead to see if any power access is available. An extension cord from an outlet eliminates battery drain entirely.
You may also be able torequest a spot next to a light pole with an outlet at some drive-ins. They will accommodate when possible to make power available.
Some portable power stations can be recharged via solar panels. Parking in sunlight lets the panel continually charge the station during the daytime.
Tips for Parking Near Power
- Call drive-in ahead to ask about outlet access
- Use heavy duty outdoor extension cord
- Solar charge portable power station during day
- Reserve special spots early to guarantee access
Use a Vehicle Running Capacitor
A running capacitor is a device that stores power from your running vehicle engine, then discharges it gradually after the engine is off. This allows powering electronics for 1-2 hours without the engine.
They work by charging up while you drive to the drive-in. Once parked, you turn off the engine and use the capacitor’s stored power to run your audio equipment without battery drain. Just be sure to monitor voltage as capacity eventually depletes.
Benefits of a Running Capacitor
- Stores power from running engine to use later
- Provides 1-2 hours of power without the engine
- Simple installation under the hood
- More convenient than continually charging battery
Use Your Vehicle’s Second Battery
Many pickup trucks, RVs, and specialty vehicles have multiple dedicated batteries for different functions. If your vehicle has an auxiliary battery for accessories or camper functions, consider using that one instead of the primary starting battery.
The secondary battery powers things like lights, winches, andelectronics without risk of draining the starting battery. Charge both fully beforehand and disconnect after using the auxiliary battery at the drive-in. That way all drain is on the secondary battery.
Tips for Using Second Battery
- Fully charge both batteries before leaving
- Only use secondary battery at drive-in
- Disconnect auxiliary battery when back home
- Recharge both batteries fully before next use
Use Rechargeable Batteries
For battery powered FM transmitters, receivers, or portable speakers, using rechargeable batteries allows you to offer consistent power without draining expensive alkaline batteries.
Opt for high capacity rechargeable like Eneloop AAs. Use a separate charger to charge up all your batteries before going to the drive-in. Having spares on hand makes it easy to quickly swap fresh batteries.
Tips for Rechargeable Batteries
- Use high capacity rechargeable like Eneloop
- Have a dedicated charger and extra batteries
- Remember to charge depleted batteries when home
- Swapping fresh cells gives continuous power
Conclusion
Listening to audio at a drive-in for hours can really kill your car battery if you’re not careful. But with some smart planning and gear selection, you can easily enjoy the movies without the next day hassle of jump starting your battery.
Having a separate power source is ideal if you regularly attend drive-ins. But even periodic charging, parking near outlets, and using efficient electronics can minimize any battery drain.
The drive-in is such a fun experience, it would be a shame to have it cut short by a dead battery. Implement some of these tips so you can sit back, relax, and enjoy the show without worries.
