MP2636 Power Booster & Charger Module (DFR0446)

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This is a placeholder topic for “MP2636 Power Booster & Charger Module” comments.

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In many applications, we will use lithium batteries as our power solutions. In this kind of application, the most two important things are the power boost and battery … read more

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Hi. Still learning about power management with lithium batteries.

Does this module provide protection from over-discharging the battery? I know it doesn’t explicitly say it does, but it’s claimed that it works like a USB powerbank, and I think all (OK maybe not ALL, but all reasonable quality) USB powerbanks provide this feature.

Thanks!

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Hi Alex,

I’ve taken a look through the datasheet, and unfortunately can’t find anything mentioning undervoltage protection.

Generally though, these protections (such as the ones built into our LiPo cells) let the battery discharge too much for regular use anyway.

What I’d suggest is having your host microcontroller measure the battery voltage with a voltage divider and ADC, possibly incorporating a follower op-amp circuit if your ADC doesn’t have a high-impedance frontend. More on all that here: https://e2e.ti.com/blogs_/archives/b/precisionhub/posts/how-to-design-cost-sensitive-battery-monitoring-circuits

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Hi James, Alex
I think a lot of these cells have this over discharge cut out built in at the top or nipple end. Beware though this adds a little bit to the length and causes a VERY tight fit in most cell holders.
The cell must recover a bit after cutting out as once activated the cut out would prevent access to the cell for charging if cut off circuitry remained OFF. For this reason it would not be a good idea to “coax” a bit more out of the cell because if it went so far down so as to not recover you would never charge it. I am not aware of any provision to allow a charge if the cut off circuit is off but there may be.
Cheers Bob

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Just adding to this old thread as I’ve been doing some testing of this module and low battery behavior, which might be useful for potential purchasers on the product page in the shop.

Basically, when the battery drops to about 2.6V, the “Boost” light goes out and the output voltage drops to about 0.25V. If there’s any reasonable load on the battery at the time it drops to that voltage, it will most likely “rebound” (in my particular test case, to just above 2.9V) which caused the “Boost” to reactivate, providing about 4.5V on the output again. This of course caused the battery voltage to quickly drop to about 2.6V again, which dropped the voltage on the output to 0.25V again and this “reboot cycle” continued until I unplugged the device that was on the output.

So, while there is no specific battery undervoltage protection, the “Boost” function will only operate if the battery voltage is above certain thresholds. This is actually listed on the data sheet (now that I’ve seen the behavior) - see Page 8 under “Weak Battery Threshold”.
That section of the data sheet says Boost will cease at 2.5V and will only restart when the battery is > 2.9V (typical, 3.05V max)

Those values align with my testing.

I didn’t measure the current consumption of the board while in that “Weak Battery” state but given there was 0.25V on the USB port, it won’t be zero.

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Hey @Russell,

Thanks for sharing your testing results! This would be super useful information for anyone planning on setting up a long-term project with this module.