I just picked up a used boat that has a BPS 3bank charger. My (?) differnt brand- 2 bank chargers have lights on them letting me know when batts are charging (red) and when charged (green). Is there a light on these? maybe the way its mounted I can not see it-- Or no lights and it just turns of as each batt is charged? ( I really don't know for sure how they work)-- when I got it- it only had 2 batts connected -- is that OK?