Q: New battery still gives a poor voltage when driving it gives the proper voltage.

asked by on November 10, 2017

My battery went out and I now got the new one in my truck, When I start the car it’s on like 10 volts then it’s doest move until I start to drive and it goes up to its regular voltage.. I checked to see with my bad battery. If the it could be the alternativer So I jumped the car and the took the cable off the car stayed running. So I know it’s not the alternater. What could this be.

My car has 28800 miles.
My car has an automatic transmission.

The test you performed doesn’t really tell the whole story. The alternator may be charging, but not up to capacity. To be sure you need the equipment to load test the charging system and see if the alternator output is up to specifications. It could also be that you have an electrical leak. Some part of the car’s systems might not be turning off completely when you shut off the car so the battery has a slow drain when it is parked. Checking for that has gotten complicated with cars built since 2000 so you might need to leave that up to a professional. To get a professional you can contact YourMechanic. They can send a technician to your home or office to check out your battery and charging system and let you know what it will take to fix it.

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