Enforcing trailing slash, and removing index.php with htaccess placed in subfolder

I have a CodeIgniter project placed in a subfolder of a domain. I want to have my .htaccess (placed in the CodeIgniter subfolder) to do the following, for any url involving the CodeIgniter directory:

1. Remove "index.php" from any url.
2. Always add a trailing slash to any url.

Currently my .htaccess look like this:

    RewriteEngine on
    RewriteBase /ci_folder/        #This is the CI Subfolder

    # Get rid of index.php
    RewriteCond $1 !^(index\.php|images|css|js|robots\.txt|favicon\.ico)
    RewriteCond %{REQUEST_FILENAME} !-f
    RewriteCond %{REQUEST_FILENAME} !-d
    RewriteRule ^(.*)$ ./index.php/$1 [L,QSA]

    # Add trailing slash
    RewriteCond %{REQUEST_URI} !(.*)/$
    RewriteRule ^(.*[^/])$ $1/ [L,R=301]

The problem is, that its only working partially; The index.php is removed fine, but when adding the trailing slash, instead of redirecting to a "fixed" url, its redirecting to the local path, fx.

domain.com/ci_folder/method

is redirected to:

domain.com/home/sites/domain.com/public_html/ci_folder/index.php/method/

which should have been : domain.com/ci_folder/method/ instead! (and also not include any index.php)

--- EDIT ---

This did it for me:

    RewriteEngine on
    RewriteBase /ci_folder/

    RewriteCond $1 !^(index\.php|images|css|js|robots\.txt|favicon\.ico)
    RewriteCond %{REQUEST_FILENAME} -f [OR]
    RewriteCond %{REQUEST_FILENAME} -d
    RewriteRule ^.*$ - [L]

    RewriteCond %{REQUEST_URI} !(.*)/$
    # dont rewrite if there was posted here!
    RewriteCond %{REQUEST_METHOD} !POST 
    RewriteRule ^(.*[^/])$ $1/ [L,R=301]

    RewriteRule ^(.*)$ ./index.php/$1 [L,QSA]