Not wishing you to suck eggs, I assume you are buying good quality batteies. These days I only use Procell (non rechargeable) batteries which are the commercial range made by Duracall, and seem to last longer than all the competitors. They have to be bought in bulk (minimum quantity-10), and usually only on line, but they are cheaper than normal domestic batteries. For items which use a lot of battery power, like fairy lights etc, I use Duracell 2500 mAh rechargeables, which I charge using a Uniross Ultimate multi charger. I have noticed no significant difference in the light output between non-rechargeable or rechargeable batteries, and lifespan appears to be fairly similar. Of course it is a good idea to have more rechargeables available than you use at any time enabling you to immediate replenish flat ones, as they do take several hours to re-charge.