hn45

Have 50/50 no start; '87 944S likes fully charged battery to start; https://rennlist.com/forums/graemlins/banghead.gif
MTP Interstate 700CC Amp 6 month old battery.
14.62 V - Alternator.

Any thoughts?

xsbank

Grounds, probably. What does it do? Little short on info...

944Ross

Is the issue the cranking of the motor (lack of), or it cranks and cranks but won't start?

Cyberpunky

No starts have so many possible causes it's going to hard to find a cure with just what battery you have and that you have a working alt(no offence). when my car died it was the DME and that took a while to work out. For me only cure was a good mechanic, but the folks around here may be able to help you cure it with a little more info. good luck

hn45

Thanks everyone, did some more tests.
Always cranks. Putting a Fluke 16 multi meter on the battery terminals and setting to record min and max.
When minimum voltage reads below 10.0 volts (that's during cranking) and battery was 12.7 to start off, engine will not start. When minimum reading, same procedure as above reads greater than 10 volts during cranking, engine starts.
Hence, I have to charge battery before I want to start car; then the battery starts off at 13+ volts and does not dip below 10 when cranking. Two Interstate dealers put their meter in the battery and say the battery is very good.
Dead draw on battery is 0.09 Amps with Radio fuse and DME relay pulled; I did this by disconnecting the battery Negative cable and connecting a different meter, the Fluke 16 can't measure Amps, set to Measure Amps with one lead to battery negative and other lead to disconnected Negative battery cable; not sure if I did that right.
Voltage difference between Battery Positive and Starter Positive was 0.000. Not sure of condition of my starter or Alternator except that they seam to work as they always have. Well. New cap rotor, coil. Might try a new battery... Any other thoughts... Will try a few more tests tonight. Steve

944Ross

Very thorough test, but the 0.000 v difference between battery terminal and starter lug is with 0.00 amps flowing thru it. Offhand, I wonder if your starter or starter solenoid is on its way out, either drawing too much current or bad/burned contacts.