Any ideas on Ways to jump start engine with cowl on?

[GraemeSmith]

I mounted an Anderson plug to the gear leg bracket its flush with the bottom of the cowl. Its mainly used as a charging port but I have used it as a jump starter on a couple of occasions. Sorry its not a great photo of the bracket itself, the bracket is made from left over 6061 angle

Charging - yes - I'm about to fit one of those in the side of the cowl so a solar panel will maintain the battery in the tie downs.

But a starting current over those thin wires?......

Look at the weight of cable you would fit to an External Receptacle like this one on Spruce - more like the gauge you use from the battery through contactor to the starter:

https://www.aircraftspruce.com/catalog/ ... errect.php

[sonex892.]

But a starting current over those thin wires?......

Yes those cables in the photo are smaller than the recommended battery to starter sizes. Disclaimer, I'm not recommending sizes for anyone here just saying what I used. But I think from memory I used 8 gauge (10mm2) to the Anderson plug. Main starter wire is 4 gauge (25mm2).
Unless the primary aircraft battery is totally cactus or dead flat or it wasn't starting due to a bad connection, the aux cable would not be carrying anywhere near the full starting current. Also in my opinion, if the battery was totally dead it would be a very stupid idea to attempt a jump start and go flying regardless.