question

simon-clemence avatar image
simon-clemence asked

What Size Charger do I need

I have just purchased 4 x 200ah Lithium Phosphate batteries that have a BMS that allows for parallel connection to four batteries. They are for a houseboat. I have two banks of solar that input to 28v (2 x 14) although they are facing opposite directions so never actually reach the full 28v (usually around 19v). With sunny days the previous AGM batteries (900ah) lasted 4 days before they needed to be charged (primarily running two 12v fridges). I just purchased a Victron battery charger Bluesmart IP22 12V/30A. I'm not sure if I purchased the right size charger or should have gone bigger. I am of course concerned for safety and charging too hard. What is your advice please. Did I buy the right size or should I send it back a get one bigger.

bluesmart ip22
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1 Answer
snoobler avatar image
snoobler answered ·

Your 4X 200Ah LFP batteries in parallel are 800Ah. Depending on the BMS rating, they likely have a MAX charge current between 200 and 400A.

The 30A charger would take...

800Ah/30A = 26.7 hours to fully recharge a depleted bank.

If that timeframe is acceptable, the 30A is fine. If you want it to charge faster, higher current or additional charger(s) is warranted.

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