I use the tenergy tb6b. It hsa a pig tail that will let you charge many differnt battery types and connectors.

This will fit fine in the tiger1. https://www.amazon.com/Venom-5000mAh-Battery-Universal-Traxxas/dp/B00FE13L10/ref=sr_1_6?ie=UTF8&qid=1495460644&sr=8-6&keywords=nimh+battery+rc+5000+venom

This fits your PZ4 https://www.amazon.com/Venom-3000mAh-5-Cell-Receiver-Battery/dp/B0006O6GIA/ref=sr_1_8?ie=UTF8&qid=1495460722&sr=8-8&keywords=nimh+battery+rc+3000+venom

Once you get familiar with batteries you might consider a LiPo but unless you understand the charge / fire risk and discharge damage don't go LiPo.