hi frosty,
Its important to note, if you apply a constant charge voltage to a battery, the current will reduce as the battery charges up to the constant charge voltage. This effect will occur with SMPS as well as Linear chargers.
This effect is increased when you have a series diode in the output of the charger, as the current thru the diode falls, the forward drop across diode is non linear with current.
If you want to 'force' charge your battery, you require a constant current charger with a upper voltage cut off.