[entwisi]

i have a 10,000mAH one, works a treat, will charge a couple of decent phones and a tablet on one charge.

for redundancy/resilience, I'd rather have 3 x 10A ones than one 30A one. I'd also suggest that whilst modern top spec phones are good all in one devices, having a basic phone such as an old nokia 6310 where the battery lasts a week easily and then a seperate GPS using would be more efficient at battery utilisation and if one device runs out you still have the other to either call for help or navigate your way out would be a more sensible choice.