Battery too Low to Crank at 12.1 V??

[gearya]

My SC felt like it was running underwater (maybe a miss?) and wouldn't idle. When I got home it died (again) as I rolled into the garage. I thought I'd try to start it and check the timing, but it would not crank over, just a rrrr, rrr sound.

I measured the voltage at the battery as 12.1 V.

Does it sound like I found my problem was just a low battery?

my guess is that the low battery would make the ignition not fire very well - it has an msd unit.

yes, it's an old battery and is on trickler now

thanks!

[Peter Zimmermann]

I had to replace the 8-year warranty Sears battery in my SC a couple years ago, at 6.5 years. Reason? No crank (only rrrr, rrrr...), 12 volt reading, battery on trickle for two days. I don't have a load tester at the house, took the battery to Sears, they put it on their machine and in three minutes pronounced it junk.

The replacement battery registers 12.7 volts. I've contemplated buying a load tester to have at home, but haven't done it yet. Would be nice to have, might avoid a starter replacement!

[djpateman]

Yes, if the voltage is measured before trying to start the car is under 12.7 volts, then it is likely discharged and may not be able to produce cranking current. A fully charged battery should be 12.8 volts or higher. A 12 volt battery is just a nominal figure of speech. You are lucky to get 5 years of service out of a car battery these days. The next thing to check is the charging voltage with the engine running above 2500 rpm; it needs to be close to 14 volts +/- .3. Too high or too low indicates charging problems.

[Algernon]

A load tester is a great idea, and cheap from HF. But if you measure voltage while having dipped headlights and driving lights on, then pull headlamp flasher that's 6 filaments! More than 30Amps! Good battery should cope, bad one will show itself pretty quick!

[DRACO A5OG]

Our cars need a minimum of 12.6v to start. if you do not drive it daily, disconnect the neg side or get a CTek 3000 to keep charged and maintained.

Just solved buddy's no start issue, his battery was down to 10.5 ( dead ) put jumper on it. VArooom. He is getting replacement.

[theiceman]

im thinking you have an alternator issue...

[mdripley]

I just went through this recently, I ended up having to replace the alternator and the Alt. warning light Diode behind the gauge. I am in the process of installing an ammeter in place of my Clock I want to know when the voltage regulator is out of spec before it can damage other components.

Mike