Q: Battery voltage is low.

asked by on November 25, 2016

put new alternator in, now battery gauge went from like 16 to 9, also serpetine belt is NOT put on tightly charging system?

My car has 218000 miles.
My car has an automatic transmission.

Drive Belt Tensioner Replacement $149.81 - $643.33 Get a Quote

Hello. If the battery voltage reads low on the gauge then that is a sign that the charging system is not functioning correctly. If the alternator is brand new then there is little chance that it is the source of the issue. More likely then that, is the loose belt. The alternator functions using the serpentine belt to turn the pulley and generate power. If the belt is loose then the pulley may not be turning properly, which could potentially be causing your low voltage reading. It may be possible that the belt is worn, that the tensioner is bad, or that the belt was routed incorrectly when it was installed. I would take a careful look at the drive belt system, and verify that it is routed correctly. If everything looks okay, I would recommend having a professional technician, such as one from YourMechanic, come to your location to (determine if it is the tensioner that needs to be replaced](https://www.yourmechanic.com/services/drive-belt-tensioner-replacement) or if there is another issue present.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing


Experienced Mechanic?

Earn up to $70/hr

What others are asking

How do you manually adjust the driver’s seat?
If your Accord has manual adjusting front seats, you have many of the same controls as on a power model with only a few minor exceptions. Bar: At the front bottom of the seat is a bar. Pull it up...
Problems filling up my car.
The fuel inlet hose into the fuel tank has a vent system that if it gets blocked for some reason would not allow fuel to be put in too fast. The vent system would have to be checked for obstructions...
Air conditioning blowing hot and won't keep charge
If the AC system won't hold a charge, there is a leak somewhere in the lines or other components. Leaks can be tested for by using a UV dye. Due to the danger involved, I would recommend having a mechanic...
Freeze plugs opened on a '98 Plymouth Grand Voyager
No, it's not an easy job. A mechanic will need to run it on their computer to see what's the issue. There is not much working room there, but a good mechanic has special tools and they know how to...
My rpm needle moves down a little then up when im at a red light.
Many early 2000's Jaguars, including the X-Type and X-Type (R) had issues with faulty O2 sensors (https://www.yourmechanic.com/services/oxygen-sensor-replacement), air fuel sensors (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-air-fuel-ratio-sensor), and ignition sensors that would cause similar symptoms to what you're experiencing. However, an idle control valve (https://www.yourmechanic.com/services/idle-control-valve-replacement) that...
Clutch problems - 2000 Audi A4 Quattro
Hi there. The clutch for your vehicle is a Exedy OEM replacement clutch, Luk clutch, or ACT clutch that needs installed. The name of engines for your vehicle are AEG, AVH, AZG. You can look on the engine, usually on...
2015 Scion Tc, I would like to turn off my horn from going off every time I lock and unlock my car with my keyfob. How can I chang
For Scions, turn ignition on, then off. Then press the valet button on the keyfob 3 times to deactivate the horn from honking. The vehicle should emit only a light chirp instead. Some features on the keyfob are only dealer...

Related articles

The Best Used Cars to Buy If You're an Uber or Lyft Driver
Are Are you thinking of becoming a driver for Uber or Lyft? That could be an exciting career change – you’ll get to meet a lot of interesting people, and if you love to drive, what better way to spend...
The Best Used Cars to Buy If You Love Road Trips
If If you love to travel, comfort is very important in a vehicle. You want a nice, quiet ride, comfortable seating, and enough room. We have evaluated several used vehicles, and narrowed our favorite road trip vehicles down to the...
The Best Used Cars to Buy If You’re an Electrician
As As an electrician, you have to haul around wiring, tools and equipment, and tons of supplies. You can’t get by with a small used car, or even a big one. What you probably need is a good used cargo...