Place the rinsed split peas, diced ham, onion, carrots, and celery into the slow cooker.
Add the chicken broth, minced garlic, bay leaf, dried thyme, salt, and black pepper.
Stir everything together so the ingredients are evenly distributed.
Cover and cook on low for 7 to 8 hours, until the split peas are soft and the soup has thickened.
Remove the bay leaf before serving. Stir the soup once more to check the texture.