Thread: SPARE BATTERY (Ne auto sparkys out there)

When out hunting I'm a few ks from any help if I have a problem with a flat battery or the alternator stops charging.Its happens twice over the yrs.So I carry a spare battery 750cranks even tho the 4.2tdi has 2 battery's,12v parallel.Battery weighs 22kgs.
Is there a smaller battery with not so many cranks,but capable of helping turning the engine over a few times if needed.Engine normally starts on 1st turn of the key,has been for the last 19 yrs iv own it.Only needs one battery to be flat and engine will not turn.I put 2 new batterys 4 yrs ago,generally they last about 7yrs.But you never know when something goes wrong.
Any info appreciated,thanks.