Usb chargers

[jakemate]

Good day everyone!

I'm sorry if I'm posting in the wrong section.

I have a small off gris setup for my garage.

12v 1200va victron phoenix multiplus
Victron 50a charge controller
1x 300w panel
2x rolls 6v batteries

Whole system works well apart from recently when I connected a mains socket with built in usb 2a sockets.

Was all working well until one day when I went in I noticed the inverter light was on red and had shut down.

On turning back on it immediately shut off again.

Noticed my RCD in the fuse panel wouldn't stay on either even when I disconnected the loads.

Found that the usb part of the mains socket had burnt out so I replaced it with a normal socket, also the RCD was dead so replaced that too.

Thought that was the end of it but since then if I plug in a normal phone usb charger in a mains socket they instantly start smoking and burn out!!!!

Everything else I plug in, computer charger, TV, power tool chargers they work fine.

Checked output voltage which is 230v

I'm totally confused why it blows usb phone chargers????

 

[DThames]

When you plugged in the phone charger, was the USB charging cable plugged into the charger? I am wondering/guessing maybe a shorted cable? I would expect the charger to protect itself from a bad cable, but who knows?

 

[jakemate]

No, two different usb chargers, different brands both went up in smoke.

No leads connected

 

[DixieMtCR]

If you can, send us a photo of where the USB charger is plugged in.

 

[mikefitz]

I suspect its caused by the Multiplus neutral to earth bond and/or phase reversal.

The complete circuit on the Multiplus output must connect to the Multiplus output, including the protective earth conductor of any socket or distribution board, MCB/RCD. The continuity of live and neutral must be maintained

Check carefully for phase reversal.

Mike

 

[jakemate]

Well I feel a bit daft, it was in fact all caused by a usb cable.

There was one hiding that I didn't see, only realised when I could smell it melting.

Can't understand why it didn't trip the distribution board.

So kicked the victron back up and has been working fine for a couple of weeks.

Went into the garage today and the victron showing an alarm led, when I try and turn back on I get a loud buzzing noise and a second later goes to alarm state again.

I've disconnected mains from the inverter still the same, swapped out batteries to test with good ones and the same.

Checked voltage and current on batteries when turning on, voltage drops to 9 volt instantly and current well over 10 but shuts off so can only get a reading for a second.

Guessing the inverter is dead, disconnected the toroidal transformer and getting zero ohms on primary and secondary ac windings so does this sound like the transformer is toast?

Cannot see any signs of burning but I'm guessing AC side has a short on transformer as I'd expect some resistance there.

Happy days

 

[jakemate]

Does anyone know a ball park figure on toroidal transformer resistance?

Or where to get a replacement?

Thank you

 

[crossy]

Cannot see any signs of burning but I'm guessing AC side has a short on transformer as I'd expect some resistance there.

It does sound awfully like a sort on the HV side (annoyed buzzing), but it may not be the transformer, disconnect the beast and check if something else is providing a low resistance path.

Give the LV side a feed of say, 6V AC, from a small transformer and see if the HV side produces an output. No output (or your little transformer gets very hot) then probably time for a new transformer

In reality transformers are pretty indestructible, I'd be looking towards fried power devices.

 

[jakemate]

How would best to create 6v AC to apply to the transformer safely?

I'm trying to think what I might have lying around.

Sorry for the novice question.

 

[crossy]

If you have an old type wall-wart power supply with a conventional transformer (it will be heavy compared to a modern one) you could open it up and connect directly to the secondary of the transformer.

Old style doorbell transformers output AC, similarly for older 12V transformers for halogen lighting. (the output will be marked on the rating label).

I have a couple of wall-warts from network kit which are actually AC output so it's worth looking around in your "might come in handy one day" box.