question

cverhoofstad avatar image

Battery charge greater than shore power breaker?

Let me first provide our setup:

  • Phoenix charger 12/50
  • Phoenix inverter
  • Phoenix control panel
  • 2 x12V 220ah AGM blue energy batteries
  • 2 x 12V Exide batteries (I think there are start only batteries)

If I understand correctly, we have 16 amp shore power. But when I connect our boat to the shore power I can read on the Phoenix control panel the battery charge is often time >30A. I am very confused how this is possible and why the shore based 16 amp breaker is not tripping?

I notice when I turn down the charge control on the control panel to 30 ish % the display shows a charge of 12 A.

My question really is… how should I read the battery charge amperage on the control panel and relate it to the shore power? and what is the recommended setting of the charge current % given the shore power available?

Lets say that the boat uses about 5 amps when docked and not used (inverter on, fridge on, security camera on, MiFi router on).

Thanks!



battery chargingchargercharge current limit
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3 Answers
nickdb avatar image
nickdb answered ·

Power = V x A.

So 1000W at 230V is 4.3A

1000W at 12V is 83A.


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So basically if I have 16 amps of shore power at 230, I have 16 * 230 = 3680. On the 12V side this would translate to 3680 / 12 = 306 amps.
Just remember inverters aren’t 100% efficient.

You will lose some power converting from ac/dc or from dc/ac.

Apart from that all the usual formulas apply.

cverhoofstad avatar image
cverhoofstad answered ·

Some additional pictures: one with the dialed down charge current and one with the shore breaker of 16a. Note you see 10 breakers but that’s because there are 10 shore connections.

img-6941.jpg



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harold avatar image
harold answered ·

Your shore breaker is on your 230V input side.
But your charge current is at the 12V side!

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