Quote:
Originally Posted by 97 SL320
It is critical to understand that 10V does not always = bad battery and to determine if there is a charging system problem.
Recharge the battery then have it load tested or try to start the car. With a fully charged battery, engine running, you should see 13.2 - 14.2 ish. The voltage will be a bit low as the alternator recharges the battery, if you see anything over 15 V, don't run the car as the high voltage will damage the electrical system.
If the battery has not been charged / loaded in the past 8 hr, a fully discharged battery is anything below 11.70 V, a fully charged battery is 12.66 V
If the battery is fully discharged but still good, the starter won't operate or will just click because the fully loaded voltage will drop even farther.
If there is a shorted cell ( failed battery ) and the battery is fully charged, the voltage will drop to 10.55 ( Lead acid batteries at full charge are 2.11 volt per cell. ). This will still crank the engine but it will be slow.
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Yes thanks . I've dealt with generator output with my 6 Volt Vw . I did not know about the load part though .
Compression is the only way to start the car now . Solenoid has a light click with the key turned .
We checked the battery at Autozone and it is fine in both categories . Same thing as a horrible Fiat X1-9 . Intermittent, of turning the key and nothing .....
I removed the plastic contact clips on the Fiat ignition to out harness . Hard soldered the wires together and the problem was fortunately solved .
The Mercedes was gradual . Occasional no start . First thing I thought of was the battery . The problem came back . Then came back as in not activating the solenoid . Although I do get a light click .
It was an interesting day . I called a few mechanics and they wouldn't touch it . They knew what I was explaining . The ones who may take it . The car could sit there for months and months .
Once I can start it I will check the alternator as you say . I did find a slightly loose ground strap to the alt .
I wire brushed all grounds and sprayed on DE-OXIT in the contact areas .
Going to the starter is the + Battery and the ignition . And then proper ground of the starter and engine . And to the Chassis . That's where I'm at .
