Car battery dies at 12V

[Yong Cheng]

I have a NS40 maintenance free battery, I did not know it is maintenance free because the label was peeled until I google the battery model. Anyways, I added distilled water into the battery was thinking to extend the battery,who knows the battery dies after a week :angry: , I jump start it and my car run for few days and it dies again.

I am uncertain the battery life.

Measured at 12V no load, drop to 10V when crank then slowly back to 12V, lights radio all fine…Is the battery problem or starter problem? :pinch:

Please tell me what have I done to the battery?! Thanks a lot

Topic

[Brad]

Well…if it is a maintanence free battery you should not be adding water or acid to it, in fact most dont even have any ports you can open to add anything to it. Regardless of that…I suppose it would depend on how much water you added and if u added any acid with the water or not and how much.

Without getting into all that I would suggest trying to place a battery from a diff car into it and giving it a go, if it starts then ur other battery is dead if not then its a connection or starter problem.

Do you get any clicking or whining from the starter when you key the ignition?

If you dont have an extra battery laying around and you have a jump box or a battery charger u could hook that up and try cranking it and it it turns over its your battery, if not then connection or starter.

Another thing I would suggest is try tapping on your starter lightly with a smallish hammer…many times light tapping will jar the starter into either re-making the electrical connection that has gone bad or droping the starter wheel into position so it can do what it is supposed to do…(this is not a fix…just a diagnostic trick!!!)

FYI…ur battery should be registering about 14v at rest and drop to around 11-12v when under load if your battery is OK, at least this is my experiance when buying used batterys from the junk yards.

Also…another common problem is the post connectors on the car side that connect to the batteries. Remove the connection and check for corrosion…then clean with post cleaner and a wire brush and or sandpaper, then reattach and check again. I personally like to start here cause I like to start with cheapest possible options first and work up from there.

Good luck…check these things I recommended and report back any new info and what has occured!

[Bluesnut]

A fully charged battery should show 12.6 volts or slightly more. Six cells X 2.1 volts per cell.
You might disable the engine where it will not start (remove fuel pump relay) and crank on it for about 7 or 8 seconds. The voltage should not go below 10.2.
If it sinks to 8 or 9 the battery is no good.

That’s a backyard method but it works.

[Yong Cheng]

Thanks for your lengthy reply, I have no idea what kind of battery is that, it was 6 ports but not opaque case to see the level. The label I mentioned should stick on those ports not allow user to access the port, for some reason, it went missing.

I jumped started the car last time measured with 13.6V when car running and 12.4V with accessories. Now I start the car then voltage drop to 10V when crank with clicking sound, then I test again the battery after few mins come back at 12V.

The connection have clean contact with the terminals, I guess not an issue there.

[Yong Cheng]

I did check the fuel fuse and start with removed fuel fuse. The voltage keep drop when I crank the car, was worry crank too much would damage the starter…

[Author]

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