Hi,
Can you post a link to the relay you are using please.
If you are going to supply all of the 4A from the charger most of the time, the 2A DC rating may be too low.
If the relay has a pair of contacts you could parallel them together.
Tom.... 
Hi,
Can you post a link to the relay you are using please.
If you are going to supply all of the 4A from the charger most of the time, the 2A DC rating may be too low.
If the relay has a pair of contacts you could parallel them together.
Tom....