Dad has wireless indicators - bad idea?

Hi all.
My Dad has a Defender and a trailer. He has paid £75 for some wirless indicators. When showing them me yesterday, they didn't work as the batteries had run out. They seem a terrible idea to me, if only for this reason. He can get his money back and I urged him to.

Thoughts?

A mate off mine has then and uses them on his forestry equipment and swears by them as long as you remember to charge them and have steel to attach them too.

A few use them on a boating forum I'm on & in the main are happy with them.
I still use normal board & wire plugged into the vehicle socket & TBH they can be just as big a PITA.
To date I've had wires corroded in the vehicle socket, ditto in the plug on a couple of occasions, corrosion on the individual sockets/pins & this year a break in one of the wires inside the multicore cable. Easy to find the one that had broken but not where in the 9 metres of cable it was so replaced the cable.
I always plug in & check at least a week before I need to use it!

Thanks for this. Anyone else have any thoughts?

i can see them as useful as emergency/short term, but why would you not hard wire a trailer? sure you need to check they are working, but you need to do a walk around anyways

They have to be on trailers that don’t bounce incessantly, otherwise it breaks the magnetic hold, and they are always flat when you need them most

Wonder if there would be a problem with insurance if they knew the lights were battery powered and not powered oft the towing vehicle.