Does anyone use an IR gun to check battery temps when charging LI-ion cells? What are typical battery temps?, what is a “normal” rise in temp for safe charging?, should the rise in battery temperature be evenly distributed along the entire battery?, if the temp goes over XX* STOP THE CHARGING?
I am thinking that since we are creating a chemical change as long as the temperature of the chemical change is within some sort of “normal” limit then it should be ok. If the temperature goes outside of the “normal” limit something not good is happening internally and the rise in temperature of the battery would be a telltale sign.
I should would like to have some input on the idea of usign an IR gun to check proper charging temperature.
I dont use a thermometer, I might touch the cells once or twice just to check that things are ok. It depends on the charge current, but “warmer than ambient” is normal, “hot” is not good. Sorry I can’t give precise temps
I just touch the battery with my bare hands. If it’s the same temperature while charging as it was not charging, those are good batteries(at least you can say there’s low internal resistance). If it’s slightly warm, that’s still fine in my book. But if it’s getting hot, the battery has a decent amount of internal resistance. I still use a nicad airsoft battery in my airsoft gun that I got about 5 years ago and it gets HOT, though it’s a safer chemistry I would say. I wouldn’t do the same with lithiums.
Sad part is I have two IR non contact temperature devices(gun and keychain looking thing) and never thought to use either to check battery charging temps. Just checked with my hands.
The reason I am pursueing the IR gun temp thing is as internat resistance goes up the ability of the cell is going down. At some point when it is too “hot” in the charger you decide it is too much of a risk to recharge again.
There are a couple of good threads about measuring the Voc (open circuit voltage, Vload voltage under load for the cell, I discharge current, to get Rinternal resistance internal. Then compare that to a chart to see where the cell ranks excellant to fail.
I just think it might be a whole lot easier to use an IR gun and at temperature xxx* that correlates to internal resistance “250 –350 mOhm marginal” or “350 - 500 mOhm poor” or ” Above 500 mOhm fail”
Does anyone have a internal resistance meter AND an IR gun that would be willing to collect data over time and build a table that just an IR gun guy could use? I am willing to do the calculations and IR gun mine and help build the table. My guess of “too hot” and someone else’s “too hot” might be very different. However, xxx* is just that, xxx*.
The IR meters are fairly pricey and are single purpose. The IR gun can do a lot of temp checks on a lot of areas (A/C being one of the biggest - time to change the filter - is the evaporator clogged? are the RV brakes all stopping equally? can I turn the water heater cooler and save a few bucks - how hot is the water) and are a lot easier to choose one that fits your budget.
The main source of cell heating when charging LiIons is heat transfer from the charger. Think about it - at a 1A charge rate, 100 milliohms of IR will result in heat dissipation of 100mW, which is not a lot for something the size of an 18650 cell.
I have a Fluke temperature gun, and an ESR meter, the main use for using the temp gun with batteries is to check the cells temp when I measure the ESR, as it is very temperature dependant.
A li-ion is stressed when dwelling anything over 86° F. Battery University says that anything between 32° F and 113° F is acceptable for charging temps. But does also conclude that its best to limit to 86° F. When the internal resistance has risen the cell will show higher charging temps. If the temps are getting high I would consider the battery shot. Even if they are some usable life left in the battery it will be at a reduced capacity and lower current capability. When the heat builds to a certain point in a li-ion cell it can go into thermal run away and vent, this is much more likely with a fully charged cell. Basically if the cell temps are getting high when charging its time to toss it, not worth the risk with the prices that new quality cells are now. Especially when stuck in a flashlight that you carry in your pocket. Venting is very uncommon but it does and can happen. Learning li-ions do’s and don’ts is the key to safety.