Slow cranking on 99 Deville

[Bill Brennan]

New sudden issue on my 99 DeVille.  Extremely slow cranking but will eventually start.  Slow float charged battery overnight.  Battery seems fine.  Clock on radio has to be reset after starting.  What can I check or try to resolve.  Thanks

[rockfangd]

Check the ground cable from the battery to the engine. It goes to a stud right by one of the pulleys, the other part of the cable goes to a stud behind the right headlamp

Closely inspect the battery connections. These side terminals are very picky. Pull the boot off the cable end and inspect the cable. Also inspect the mating surface on the battery terminals. There are teeth on the cable end that kind of bite into the battery terminal. If they are flattened or dirty you will have issues.

Check the battery. What is the age and condition?

IF all this does not help remove the cover on the driver side to the electrical distribution center and have a good look at where the battery cable connects. It may be corroded.

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[BodybyFisher]

11 hours ago, Bill Brennan said:

New sudden issue on my 99 DeVille.  Extremely slow cranking but will eventually start.  Slow float charged battery overnight.  Battery seems fine.  Clock on radio has to be reset after starting.  What can I check or try to resolve.  Thanks

Slow charge means nothing if you don't perform a LOAD TEST.   A battery can charge up, but as soon as a load it put on it, it drops to 9 volts due to an internal short or cell issue.   Try a known good batter of the right CCA or have the battery load tested.