Source for $20 SLA Pocket Power battery: Vector Mfg Co. I got mine at Pep Boys. I just read a webpage where someone upgraded the power outlet on the battery--it is low end. In fact, because the recharger plug doesn't want to stay in, I didn't get a good recharge last night. I think with a few dollars I can upgrade the power outlet and recharger plug and have a very reliable power source.