A. Rechargeable batteries should not be used in our devices because they do not supply the proper voltage needed to run our products. They will not ruin the devices, but most will not work properly.
Most of our products run on AA,D size batteries. These batteries have an output of 1.5 Volts each (when new out of the package, the output will be closer to 1.6 Volts if they are good name-brand batteries). New and fully charged rechargeable batteries of the same size have an output of only 1.2 Volts. For most keyboards this is not enough voltage for them to work.
Also, the rechargeable battery's voltage drops very quickly during use compared to a non-rechargeable battery of the same size.
Another issue is that if the keyboard has rechargeable batteries stored for a length of time, these will need to be recharged again before use because the latter have a much higher rate of self-discharge (about 20-30% per month) than alkaline.