I have a project utilizing E-Series in outdoors environments with below-freezing temperatures.
I had not considered the limitations of LiPo batteries in these temperatures, so am now looking into alternatives.
Does anyone have any recommendations for battery tech I could look into? It’s worth noting that these are powered by an external car battery/alternator arrangement so the battery is more used for brown-out situations rather than extended use.
I already have hardware manufactured for field trials so I would prefer plug and play options if they happen to exist!
I was thinking another option could be to temporarily disable battery use, based on ambient temperature? (Or temperature of the battery ideally if this is supported). Disable PMIC
This has come up before and if you have external power such as a car battery or alternator, you should look into battery warmers for the LiPo cell. That plus an insulated case is likely to be the cheapest answer.
I’m not sure how applicable this advice is to you, but for any long-term deployment which doesn’t specifically need a battery, I would advise against including one at all. They are a source of complexity and likely source of failure. The fact that you are doing outdoor deployments, with associated temperature swings, make it even more likely to be a principle failure mode.
We have a solar-powered application using SLA batteries which feed into a 12V regulated power stage. The 12V stage can provide >2A, so there is no concern about delivering the peak power. This worked fine through a very hard Boston winter (we had over a week where the high didn’t go above -8 degrees).
Only in the worst case do you need the full 10W anyway, because that’s when the radio is using the most power to reach distant cell towers. So you might be able to get away with cheating here a bit, depending on if you are installing in the countryside or the city.
I’m going to run some tests sans-batteries, but it looks like with my particular power circuit I’m good down to 5.5V or so. There’s a chance I’ll see instantaneous dips below that during crank cycle - but we’ll just have to see.
I might look into a more robust capacitance on the input for future design revs. It would be great to do away with the LiPo for multiple reasons, not the least of which being safety.