9V batteries that aren't 9V

Thread Starter


Joined Mar 1, 2017
I purchased a few EBL 9V 600mAh LiIo rechargable batteries recently. Now, I do know that LiIo cells are 3.7v cells and charge to 4.2V and that these batteries can only therefore go to 8.2v at full charge.

But, won't I have trouble with many 9v devices that require 9V ?
These things will start at only 8.4v MAX and then drop off to under 8V fairly quickly.


Joined Jun 4, 2014
There are NiMh versions of the 9V battery (and there used to be NiCd versions too). These also start at 8.4V.
All these rechargeable types maintain their terminal voltage during discharge much better than the original primary cell versions so generally they work well.


Joined Mar 31, 2012
With a 50 mA draw, a typical alkaline 9V battery will be down to about 8 V after just a couple hours. So nearly any well-designed, general-purpose circuit won't notice the difference too much.


Joined Mar 14, 2008
Typically a circuit designed for a "9V" battery should work down to 1.2V per cell or less for a 6-cell alkaline battery or 7.2V.

-live wire-

Joined Dec 22, 2017
A 9V battery is at 90% when at 9V, and will drop a lot under load. They are at 0% at about 6.6V. So most 9V devices are designed to work fine with 6-8.4V.