Battery charger tripping MCB. Any ideas?

[tombo1983]

Hi,

I’ve just fitted a leisure battery and charger, along with EHU, consumer unit and two 240v sockets to my van.
It’s a small consumer unit with 1x40 amp RCD and 2 MCBs. I’ve hooked the two sockets up to the 16A MCB and cut the plug off the charger (Victron Energy Blue Smart IP65 Charger - 12V 15A) and wired it directly into the 6A MCB. The 240v sockets work fine, but when I throw the 6A breaker on, it trips immediately.

Any ideas why?
The charger claims it will only draw 1.7A at 240v, so I thought 6A would be plenty?
Next step is to remove the charger , put the plug back on and measure the current it draws, but I thought I’d ask here first.

thanks in advance!

 

[Murdoch]

Do you understand how rcds work ?

 

[Pete C]

An RCDS doesn’t trip because of excess current.
I would do what you describe and put the plug back on and see what happens.

Pete

 

[tombo1983]

Yes, I understand how an RCD works, it compares current flowing in live and neutral to detect current leaving a circuit via a fault to ground.

The RCD is not tripping out, only the breaker (MCB) which is why I suspected a high current on powering on the charger. If the RCD was triggered, it would shut off power to both circuits, right?

I will try the charger in the house. But does anyone have one of these chargers, and if so what size breaker do you use?

 

[Pauly]

An mcb only measures current and will only trip when too much current is drawn so unless it’s faulty you are drawing more than 6A through it

There’s probably a small inrush current when the charger fires up ?
If that’s the case then changing the type to a C6 may cure the issue ?

 

[Murdoch]

Lots of transformers have high start up current so changing the MCB to a type C of the same value is the next step

 

[tombo1983]

Thanks all, I'll try that.
Appreciate the help!