If it turns the engine over at a good speed initially it's unlikely to be a connection issue. More likely the capacity has dropped off to an unviable level, bearing in mind it is a consumable. This will happen naturally with age and is often masked by an easy starting regularly used engine. However the batteries demise can be hastened dramatically if it's not fully charged at some point regularly. There is a scenario which aligns with your use where short runs only charge the battery to say 90%. Then the next time it only takes charge to 90% of the 90%, and so on in a downward spiral. I would guess yours has fallen foul of this situation.
Suggest a new battery and if then not used regularly for runs long enough to fully charge, leave it on a conditioner or smart charger, particularly in the winter.
ETA: an electrolyte check, if possible given most are sealed nowadays, will indicate the state of charge of the individual cells but not necessarily their remaining capacity as a fraction of that when new.
Last edited by Richard Wood; 10/11/20 07:46 PM.
