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The datasheet for a power/battery management module that I am interested in mentions that:

The rated voltage of the PSU(Power Supply Unit) must be at least 1V above the maximum charging voltage requested by the battery.

My AC/DC power supply outputs 12V, and the maximum charging voltage requested by my 10.8V 3S2P Lithium-Ion rechargeable battery is 12.6V. Based on the quoted block, my power supply and rechargeable battery would not work with the power management module.

Is there any reason behind the quoted statement? Trying to make a purchasing decision regarding the PM module...

Any input is greatly appreciated @.@

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  • \$\begingroup\$ Yes there is, and the conclusion will be that your PSU cannot fully charge the battery. Probably not dangerous but certainly not optimal. \$\endgroup\$ Sep 2 '20 at 12:11
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I could not find that statement in the datasheet you linked. However, take note of this on the input voltage specification:

Datasheet excerpt

What this means is that if you want to charge a battery which requires 12.6V, you must provide 13.6V to the unit in order for it to maintain the 12.6V output.

It's a little confusing, because it reads Input (Power Supply Output) but what this section is trying to tell you is that the power management module (PMM) unit's input requirements are dependent on the output voltage desired.

(Put another way, the power supply unit (PSU) must provide 1V more than the battery charging value, so that the PMM can regulate to that voltage.)

This is common for voltage regulators as well. In order to guarantee a stable output voltage, the input voltage must be higher by some amount.

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  • \$\begingroup\$ Thank you @JYelton so much for your detailed explanation! The quoted statement is in the application note that is only available upon request. Now it makes sense :) \$\endgroup\$ Sep 1 '20 at 22:35

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