Ebay item arrived with no charger.

I'd argue the opposite. If sold as Used, there's an expectation that the item is in full working order and complete as originally sold ( but maybe minus original box etc), which would include the original charger. If anything deviates from this expectation, it has to be mentioned in the listing.

This is a perfect case for a partial refund to cover the cost of buying a charger. (edited)

Yes I suppose I could however had I known I wouldn't have paid the price I paid because I assumed it came with genuine charger which would have been useful incase of any charging issues or incase I decided to sell on.
I have tried my phone charger and it isn't actually charging it.

Or to put yet another way..what you see is what you get.Maybe just an oversight by the seller or they knew what they were doing,if it isnt in the worded description i would guess they knew and they hoped someone wouldnt pickup on it.So assuming could be a costly error.I dont know how Ebay works but you could lodge it with them.Whats there feedback % ?That might give a clue.

So many USB plugs around these days they shouldnt have to come supplied.But i would rather they were to get the right charge rather than get a dodgy one that buggers the item up through faulty charging or worse starts a fire.

I agree with most of what you're saying. What I don't feel is fair is stating about the feedback. Surely the buyer should see what the seller has to say first. People like you so quick to leave feedback or say leaving feedback is an option....(I assume negative based upon the content of the thread) really can make it an unpleasant experience as a seller. Always give the seller a chance to rectify or clarify the situation before jumping the gun and leaving feedback. Just my thoughts. (edited)