Solar charger

no way a 50W panel would have enough current to melt the wires. Max current would be on the order of 4 amps, most likely in the range of 3A from a typical PWM controller. even 20ga wire can handle 3 A continous,

My guess is that the issue is with the connection to the battery, and it was reversed, damaged the controller, caused a overcurrent in the cables.

However, the controller should have protected against reverse hookup w/o any damage.

So.... w/o more info puzzling.

Was it a real bright sunny day?

Reverse polarity is the usual culprit with melted wires.

i'd guess the controller has a short or if no controller the panel is shorted.

For a followup check the panels Voc and Isc to be sure it's OK. Then reconnect with new wires and check V and A on the battery wires.

Clamps are a poor means of connection. Bad connections cause heat. However, that little panel shouldn't generate enough current to make much difference.
Did you install a fuse on the positive cable near the battery? It should have one to prevent this sort of thing.
Do you have a charge controller or did you just hook the panel straight to the battery? You really should have at least a basic charge controller to keep the battery from being over charged.
I'm going to guess a cheap solar panel that shorted out with no fuse or charge controller to protect it.

KD4UPL wrote:
Clamps are a poor means of connection. Bad connections cause heat. However, that little panel shouldn't generate enough current to make much difference.
Did you install a fuse on the positive cable near the battery? It should have one to prevent this sort of thing.
Do you have a charge controller or did you just hook the panel straight to the battery? You really should have at least a basic charge controller to keep the battery from being over charged.
I'm going to guess a cheap solar panel that shorted out with no fuse or charge controller to protect it.

I'd say cheap fuse..... a length of 20ga or so wire as a fuseable link!!!! something shorted in the panel and the battery tried to light it up!!

Did you use a controller?
If you did then it was probably reverse polarity.