Is connecting LED camping lights (around 300 watts or less) to my car battery with the car off bad? will it harm or reduce the life of the battery? if not how many hours can I use them for?.
That light is too powerful. Your cars battery is optimized for cranking the starter. Running it down will reduce battery life quite a bit.
I would suggest using a lantern with a battery that can be charged up when the car is running.
A deep cycle battery would be best to use for the long use cycles. Or a new special use battery.
As for how long it would last you didn't say how many amps the LEDs use. Or even what amperage the battery has. Can't solve without details.
What is your goal? How long do you want to use the lights at one time? Can you recharge the battery while using the lights? What have you tried to do before? The best idea for portable lighting might be a few cheaper solar camping lights instead of trying to jury rig non-compatible items that will fail anyway.
@jimz
he said 300W
300W / 12v = 25A
Now I see said the blind man, LOL!
I still think using the car battery a bad idea. A one time use, maybe. More often, no way.
We find so many solar rechargeable battery powered lights for sale now it is easy to find one to suit the need.
It will be fine as long as you don't let it completely drain the battery. They are meant to be discharged every once in a while after all. But if you leave it on there too long and that battery drains completely dead there is a chance to cause harm to your battery.
Bad. Too much draw too fast.
