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Hardware support => Low Power Techniques => Topic started by: vk3jap on March 30, 2017, 10:01:30 AM

Title: What about when LiPo goes very low
Post by: vk3jap on March 30, 2017, 10:01:30 AM
I'm still a relative newbie to Moteino but I have a few and some small 1 cell (37Vdc, 110mAh LiPo) batteries. I want to run them in a very power efficient way but I am wondering about the space when they go VERY low Voltage wise. I just want to be sure that the Arduino will not work (assuming BOD will stop it from doing anything meaningful as the vBattt is too low (which is good) .. but there will still be some current draw on the battery I'm thinking.. albeit small. So it is going to pull my little LiPo cell down down down to the point of ruin..?

What happens.. if you discharge a LiPo cell heaps - can you damage it permanently..? Will it become dangerous, overheat etc.?

am I correct in saying (or assuming) that when the vBatt gets too low that the arduino will not actually practically do anything - as the BOD will be active etc..?

The example is that I put a Moteino in my letterbox to monitor it for mail etc.. lets say I go away for 1 month, or 12 months, or whatever.. I don't want to have to worry about these things going so low and causing problems. I'm fine with them just getting a point where they no longer 'work' as such and when I get back I just recharge the LiPo etc.  so just trying to understand who this part all works.
Title: Re: What about when LiPo goes very low
Post by: Felix on March 30, 2017, 01:28:17 PM
I assume this is a question about Moteino more than about battery chemistry and complete discharge effects.
RE depleted batteries - just recharge them when you get a chance. If you plan to be away a very long time after they are dead, then increase capacity - what use is a moteino that does nothing?
If your batteries are built and used properly, they will not overheat or anything like that.
Depending if the BOD is active or not, the moteino will stop working when entering the BOD threshold. From other tests performed by myself and others, if you disable BOD, then the atmega328p will stop working around 1.6v (moteino without the LDO, run at 8mhz). LiPo cells are considered depleted around 3V.
Title: Re: What about when LiPo goes very low
Post by: vk3jap on March 31, 2017, 08:39:41 AM
Perfect..Thanks Felix!