June 15, 2024, 10:38:01 AM

PIC32-HMZ144 and LIPO6600

Started by rzur2004, March 07, 2016, 07:28:16 PM

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Is this lipo compatible with the board ? Isn't it to big for the build in charger ?


Check the data sheet but I expect you'll find it just charges at a max current so would take a while to charge.



Thanks, You are right, there is a current limit due to thermal constraints (MCP73812T-420I/OT is configured via R11,15k to limit at about 70mA)



In the past I had some trouble with the LIPO6600. I did not notice that the battery have only:
"the battery has overcharge and short circuit protection."
But there is no mention about a deep discharge protection.

So I hooked the battery on a PIC32 board and just left it there. Some weeks (or months) later I just wanted to use the board again and noticed that the battery is empty and dead. :(

Then started to look on the internet and found that LiPo batteries are categorized in two categories. One is for high current use, where there is usually less protection (no deep discharge). The other is for handheld devices which does not need so much current, usually with more protection, overcharge, short circuit and deep discharge.

So for the PIC32 I would not recommend to use directly the LiPo6600. Because if you forget to disconnect the battery, it will be deep discharged and finally become dead. Unless you add there additional protection. Or you must buy somewhere LiPo battery with deep discharge protection. I think Olimex do not have any in the WebShop :( Maybe a point where they could do some improvement.

One final word: MCP73812T: When I got my PIC32-OTG (not HMZ but does not matter) board I was just curios about the charge current. So I just measured the LiPo charge current by shorting the output with the multimeter (of course with no LiPo connected at all). I was expecting that the MCP73812T will limit the output current to the maximum charge current. No. The IC was blown. :( So do not do that. I think the IC was maybe limiting the current, but due to the voltage drop on the IC it was just overheated.
MCP73833 (USB-uLiPo): Here i think I did not have any problems, since the IC have a precondition phase, where the LiPo voltage is expected to be smaller than a value.
This means that the PIC32-HMZ144 LiPo connector is not protected against shortcut to ground :( Also a point for improvement.