Battery voltages


#1

1996 Mazda Protégé, 129,000 miles. Tested out the car battery today using a new handy dandy Innova 3721 Battery Monitor. 11.40 v(red) when not running, 14.40v when running. The directions say even if there is low voltage, the battery may not be dead, check for loose cables, clean terminals or charge the battery. Walmart Everstart 35N Maxx battery installed in late fall, 2011.

  1. Where are the loose cables that I might check? I know where the terminals are and how to clean them.

  2. I am guessing I need to replace this battery?

Thankyou.


#2

The battery needs to be put on a slow charge for several hours and then tested. A good, full charged battery should show about 12.6-12.7 volts.

That 12 something volts will drop a little with the engine not running but if it drops to 11 volts within seconds of shutting the engine off there could be a serious parasitic voltage draw or an iffy battery; likely the latter.

It’s a bit more involved than that but it’s a start and odds are cleaning the cables is not an issue… :slight_smile: