The Beachtek Pro5180 are a new battery in the rechargeable 9v market a 2 pack is $48.00 which puts them at the same price per battery ($24.00) as the I power Rechargeable 9V which have been a long winner among sound mixers. However the BeachTek are 200MAH more making them last longer. They also will charge on the Ipower Chargers as well saving an investment on a new type of charger. Below is some more info from Beachtek you should pick them up and try them
At 700mAh, it is among the world’s highest-capacity rechargeable 9V batteries. It can also be recharged hundreds of times while remaining free of memory effect. The battery works with Beachtek audio adapters and a variety of other professional equipment.
PRO5180 rechargeable 9V batteries
Lithium polymer chemistry
Lasts for up to 3 times as long as alkaline batteries and is far more cost-effective
Its 700mAh capacity is among the highest in the world for rechargeable 9V batteries
Can be recharged hundreds of times without developing any memory effect, which means full battery capacity will continue to be usable after each charge cycle