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I was looking through a very legitimate well known product, noticed the battery pack is stamped with 4.4V. I think this is actually the nominal voltage it provides.

The reason I think that is that this is a $100MM+ company, and I know from professional experience, LiPo battery markings and regulatory compliance has gotten extremely tight in the last few years when you ship batteries in products. These guys ostensibly are dotting all the i's and crossing all the t's.

The 4.4V stamped battery, has a much higher mAh stated amount than any corresponding 3.7V LiPo, on a volume basis, then we've ever been quoted.

Is there such a thing as a 4.4V LiPo?

PICTURE AS REQUESTED:enter image description here

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  • \$\begingroup\$ They have two cells connected together in some way. Maybe the marking is for the nominal voltage of the pair? \$\endgroup\$
    – Leroy105
    Commented Oct 19, 2017 at 19:34
  • \$\begingroup\$ I'm assuming the marking is per cell, I have to cut them apart. These things are 350 mAh at 4.4V, and are 25mm x 14mm x 5mm. I think the regulatory requirement is a marking on each cell.... \$\endgroup\$
    – Leroy105
    Commented Oct 19, 2017 at 19:41
  • \$\begingroup\$ Strange. They don't tolerate 4.4 V very long without damage. \$\endgroup\$
    – winny
    Commented Oct 19, 2017 at 19:43
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    \$\begingroup\$ @winny There are, in fact, a recent generation of "High Voltage" LIPOs with different construction which are marketed as being suitable for a 4.35v charge termination. And charger ICs for that voltage exist. Type "LiHV" into your favorite search engine. \$\endgroup\$ Commented Oct 19, 2017 at 20:22
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    \$\begingroup\$ It's become customary to speak of these by their charge termination voltage. The middle voltage isn't really very meaningful - in higher drain applications by the time you see an unloaded reading of 3.7 or 3.8 volts it's nearly time to start thinking about finding the charger. But no, 4.4 (or more realistically 4.35) isn't a counterpart to the 3.7 number, it's a counterpart to the traditional 4.2 charge termination. \$\endgroup\$ Commented Oct 19, 2017 at 20:30

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4.4 V and 3.7 V here refer to different characteristics.

  • 3.7 V is the nominal voltage (average voltage during a complete discharge) of a "traditional" LiCoO 2 -based lithium ion cell. Such a cell typically has a minimum voltage around 3.0 V, a maximum voltage around 4.2 V and a nominal voltage between 3.6 and 3.7 V.

  • 4.4 V refers to the maximum voltage of cells with an improved anode that can endure higher voltages. These cells tend to have a similar minimum voltage, but the maximum voltage is between 4.35 V and 4.4 V. Since they can be charged further, the nominal voltage is also increased to around 3.8 V. This improvement is achieved with silicon and graphene -containing additives

In the radio control world these are explicitly marketed as "LiHV" etc, but they are increasingly common in all sorts of products like mobile phones.

There are several research papers on the subject, e.g. http://m.jes.ecsdl.org/content/164/1/A6075.abstract

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