[Richard]

I've seen it done...... Two 12 V dry cell batteries in the stock Skymaster battery box.

"Dry as in no liquid. Can be discharged 100% up to 400 times without harming the batteries. Lasts 5-8 years. 680 cranking amps and 16ah life. Plane approved, military approved."

I'll see if I can get some pictures next time I see it.