24/12 volts issue

[LRover74]

I am working on a diesel for my S3.The engine was automatic but I put a flywheel so it is now manual;however the starter will not spin fast enough with two batteries in parallel (12V)to start it-- it will spin like a partially discarged battery. It will spin good and start with a series (24V) set up. Is this normal?If so how will I set up the charging since the alternator is 12 V. Thanks a million.

[Lord Icon]

Is the starter a 12 or 24 volt ? Second and more important question... DO YOU HAVE A GREAT GROUND? I would highlight it if I could. The main issue with our rovers , and any old system , 90 % of the time the ground is weak. i assume you have a cable of short length from the starter solenoid direct to the starter. Where is the ground? Engine mounts are rubber, I have seen a throttle linkage smoke and melt as the starter had no other ground to use. . . My brother had a bad ground on his winch. The e-break cable turned orange and melted...
Start there.
Kris

[LRover74]

That's a good idea,thanks,I will check if the starter is 24 volts and update.I use the same ground for 12 and 42 hook up and it starts well with 24V so the ground should be OK. Just to give an idea: the starter has a solenoid. I attached the battery positive to the starter large wire and the starter switch to the solenoid,the ground goes to the engine directly from the battery.

[Lord Icon]

,the ground goes to the engine directly from the battery.[/QUOTE]

But does the engine ground well to the battery.......
24 volts on a 12 starter .... twice the voltage but half the amps. I am betting on a bad ground. Some here have added a separate wire direct from the starter to the batt neg. Not a bad idea. Have you tried turning on the headlights as you attempt to start the engine at 12 volts? If you do and the lights do not dim but the starter goes slow.... low power consumption. Alt approach... attempt to start engine with 12 volts for 30 seconds, at full power the cable should get warm . If not, poor power consumption.

[LRover74]

You were dead on target.It was the ground,I could not figure it out without your help,thanks a million. I checked the starter and it is 12V.I connected a thicker wire to the bolt that attaches the starter to the bellhousing and it kicked just as it did with 24 volts.