Battery chargers and inverters, a warning

[Dp707]

Today I arrived at to visit my Avondale Orestes and was shocked it was no longer there. In fact it had been burned to the ground. At first I thought it was vandalism but after a few hours dwelling on the disaster, the following theory occurred to me:

On my previous visit to the van (as it is off grid)I had been experimenting with an 800 watt inverter (not pure sine) to power the vans 240v electrics from a separate battery with a view in the long term to keeping this charged by solar and wind.
Out of curiosity I switched on the vans internal battery charger for a few minutes to see if it put some charge in the leisure battery in the van, it appeared to work an power the lighting. Thinking back I noticed a slightly different smell from the charger.
On leaving the van I disconnected everything except the wiring between the charger and the leisure battery.
My theory is I had damaged the charger electronics by powering it using a none pure sine inventor and current from the battery had somehow flowed through the damaged electronics thereby causing the fire eventually......anyone any thoughts or experience of anything similar.
Can't recall the make of the charger on the Avondale but was a basic looking black box with on/off switch.

 

[ProfJohnL]

I'm sorry you have lost your caravan, Obviously all we can do is theorise about the incident. , But I have seen what can happen when a stepped square wave is fed to a conventional 230V 50hz transformer. They will often hum or buzz, and on even quite light loads they will tend to get much hotter. You will get similar results if you try run a motor.

It's all to do with forcing very sudden changes in current into inductors.

Certainly older caravans tended to have battery chargers that used conventional power transformers, these would be affected by a non sinusoildal wave form.

More recent chargers double up as power supplies, and the most recent ones use Switch Mode high frequency inductors. These modern units ofte rectify the mains voltage, Store the power in relatively small capacitors so they are not so sensitive to a chopped wave form.