In your area as cold as it gets and two differant test suggested it's no good, hmm. Time for a new one.
That's not true. It won't hurt your alternator.to charge it just drive for an hour or so. but if its dead it could fry your alternator with it trying to charge.
He needs a battery. He said he left the headlights on for only 20 minutes. Would you not change your cell phone battery if you had to recharge it after every few calls and it is 6 years old?To me it is time for a new battery when I DO NOT leave the lights on, everything on the vehicle is working normally, but then suddenly on a cold day the battery does not have enough power to start the vehicle (will not hold a charge).
If I leave the lights on, then charge the battery, then it starts the vehicle ok after that, then no need for a new battery.
The battery is just like one in a cell phone. If you use the cellphone and run down the battery, you need to plug it in and recharge it.
Same with a car. If you leave the lights on without the vehicle running, then you need to recharge the battery - either with a car battery charger or by jump starting and leaving the vehicle running (alternator recharges the battery).
Could also be the alternator. Why not just take the battery for a free test and know for sure?He needs a battery. He said he left the headlights on for only 20 minutes. Would you not change your cell phone battery if you had to recharge it after every few calls and it is 6 years old?
3 years or more replace the battery for sure. Easy way to test the alternator, while the engine is running disconnect a battery cable, if the veh stalls the alternator is bad.
Two tests already showed the battery going weak, I would suggest replacing with a new decent quality battery. The cold weather on the way will just work that battery even harder, not worth needing a jump start or tow just to save a few bucks.
Do not do this on a newer car, disconnecting a battery with the vehicle running can cause a voltage spike and fry your cars computer, not very common to happen but it is possible.