Can you tell a major difference between the batteries in these two Phase One battery boxes below?What about the difference between these three batteries? The difference is subtle, but the effects are now significant. Battery capacity levels can change suddenly and without notice, and unless you know about it, you may completely miss that the change happened at all. Have you been a long-term user of Phase One digital backs? Have you upgraded your back recently? Are you using batteries and have no idea how old they are or their storage capacity? Do you have any idea what mAh your batteries are? Stop reading right now, and go check your camera bag. What power batteries are you currently using? Most people don’t know which batteries they are using. They trust that the manufacturer or their dealer will keep them informed of any important changes. Well, that is what this article will finally sum up….. Since the introduction of the P/P+ series digital backs, any BP-911/914/915 battery was and is compatible with the system. Anywhere from 1800mAh to 2600mAh all worked perfectly well. The only noticeable differences between these batteries was the length of time in each charge cycle. The size or capacitance of the battery did not make the P/P+ digital backs any less stable. Phase One upgraded their capacitance during the middle of the P back (non +) lifecycle to 2600mAh. However, no one that we have spoken to at Phase One knows exactly when this occurred and there is no documentation as to why. Phase One IQ1 series backs started to ship in June of 2011. Our records show that Phase One changed their part number and capacitance of their batteries in March 2012, almost 9 months after the IQ’s began to ship. Again, there is no documentation on this other than this tech support article stating not to use “third-party” batteries. IQ1 series backs still do work with lower capacitance batteries. However, they are less stable than the recommended 2900mAh. Many users experience problems when these batteries get to 1/2 or 1/3 charge. And for this reason, we highly recommend that all IQ user begin to switch out all of their older batteries to the newer capacitance. And Very Importantly, if you use an IQ2 series digital back, you MUST be using 2900mAh batteries. We have seen many issues arise that are resolved simply by changing to the 2900mAh batteries. If you have any older in your bag, then call us right away and lets fix this. P/P+ Phase One backs = 1800-2900mAh batteries work without issue IQ1 Phase One backs = 2900mAh or higher recommended for most stability IQ2 Phase One backs = 2900mAh or higher There hasn’t been much information about this anywhere that we could find, so we posted it here. If you have any questions, please don’t hesitate to get in touch with us! If you need to purchase new batteries, you can order them through our online store or call us.