Destructive Lithium Battery Testing — I guess I run with a pretty rough crowd, a friend of mine deliberately destroyed two lithium batteries while testing. He tested them to the point of failure.
In the Navy, we used to call an electronic device that failed — smoke checking. If you hit a device with too much current (or sometimes too high a voltage) it destroys the device. Yes, smoke comes out when it fails. In the past, I have smoked checked a battery in my Honda, because the voltage regulator on the alternator failed. Thus, the battery was supplied with too high a voltage and boiled to the point of leaking the acid solution. I have also smoke checked switches and other devices, intentionally and unintentionally. When you smoke check a device, it never works again. I have never smoke checked a lithium battery.
I have been gathering lots of data during my testing, including testing high current flow. My testing included overcurrent all the way to inverter shutdown. I even run my air conditioner using my battery and inverter as the energy source. Nothing I have done matches the testing Scott Helmann has performed.
I explained this issue in my 2019 post here — RV Solar Series: Lithium/Lead Acid Final Analysis look for the section called No Cold Charging. Here is a summary of the problem. If you charge (or discharge) your lithium batteries when they are too cold, you will damage them permanently.
You may remember that I have a combination of both lithium and lead-acid batteries on my RV. My lead-acid batteries power the direct current (DC) side of the house and the lithium batteries power the alternating current (AC). Here is a link to the description of my battery layout. Hybrid Mongrel Battery
I installed my lithium batteries in an area that I expect to stay warm. Or at least warmer than my lead-acid batteries. My lithium batteries are installed near the inverter. The inverter creates waste heat as a by-product of converting DC electricity to AC electricity.
Waste Heat to the Rescue
Nearly 10 percent of the watts used by the inverter — are wasted. When boondocking I use my battery bank to run my refrigerator. This requires me to change the DC electricity in the battery to AC power to run the fridge. In the summer this creates a problem because the compartment gets too hot when recharging the batteries. In the winter the heat helps keep the batteries warm. (Testing this winter how effective this is or whether or not I need to supplement with extra heat.)
Now that I am getting some cold temperatures outside, I am getting some cold temperature readings. If necessary I will be installing some extra heat in the battery compartment. A simple light-bulb would be enough. I only need to keep the temperature above freezing.
Also to protect them from the cold, my batteries sit on rigid foam insulation rather than the un-insulated compartment floor. This creates a thermal break between the battery case and the steel floor.
Battery Management System
All good lithium batteries, including my Lion Energy UT 1300 and Battle Born batteries have a built-in Battery Management System. (BMS) The job of the BMS is to control the charging and discharging of the battery. One of these functions is to make sure the battery is not charged or discharged at low temperatures.
You Only Know if you Measure.
I have done this and so has Scott Helmann. Scott is kind of a pioneer in the RV battery world. In 2018 he was experimenting with Valence LiFePo4 U1 batteries commonly used in medical devices. Scott’s goal was to get a big increase in available energy and a decrease in weight as compared to lead-acid batteries. It worked. In 2018 I was only dreaming of lithium batteries, Scott was working with them.
In the fall of 2018, Scott, anticipating cold weather camping decided to test the battery. (Note: It doesn’t really matter that the tested battery was a Valence, but rather than that it matters that the battery was a lithium-iron-phosphate-battery. To be clear, the lithium battery didn’t fail, instead, the computer controlling the battery failed. The battery however suffered the consequences of the failure.)
As a side note, I discussed the effect of temperature on lithium batteries in this post. Ten Lithium Battery Myths and Answers look at myth #10
To test the batteries, Scott put two of these fully charged batteries in the freezer for two days and then used them. The batteries had low-temperature protection in the BMS. (Let’s just say that the low-temperature protection didn’t work.) If the low-temperature protection worked, then the BMS would have refused to allow discharge of the battery.
Destructive Lithium Battery Testing — Results
The pre-test capacity of each battery was measured by creating a slow full discharge, measuring the actual amps delivered, and measured during a discharge. After the discharge test, Scott recharged the battery to full. The capacity of the batteries before testing was 460 watt-hours. The batteries were slightly used and did not have full capacity at the start of the test. New the batteries would hold 512 watt-hours.
Then Scott put the batteries into a freezer for two days at minus two degrees Fahrenheit. The battery was estimated to be at zero degrees Fahrenheit (internal temperature). Then he again performed a discharge test. Unfortunately, the BMS allowed the electricity from the battery to be used when the battery was cold. This was a complete failure of the BMS. “After about 15-20 minutes I discontinued the test. I then charged one battery while it was still cold and it charged just fine but later I found I damaged the battery resulting in additional lost capacity.” — Scott Helmann
The current available from the damaged battery was 341 watt-hours. This represents a 26% loss in capacity. The test resulted in a huge loss in only 15 – 20 minutes. Scott didn’t do a full discharge when the batteries were cold… If that was done the batteries would have been totally ruined. Scott found that both batteries that were discharged had suffered damage even only after a limited test. Scott’s destructive lithium battery testing included five batteries only two were damaged during the cold discharge test. Only one was recharged when cold — also damaged.
I’m going to discuss some of Scott’s further exploratory surgery on the damaged batteries in a separate post.
On Good Batteries
The BMS on good batteries will not allow them to be charged or discharged when the battery temperature is too low.
On a good battery, discharging when cold isn’t a problem because the BMS shuts down discharging before damage can occur. In Scott’s Valence batteries this low temperature shut off didn’t work.
On a good battery, charging when cold isn’t a problem because the BMS won’t allow charging when the battery is too cold.
Here are the Options:
- Keep the batteries warm so you can charge and discharge as needed. (my choice)
- Re-warm cold batteries so that you can charge them when energy is available.
Battle Born has introduced new batteries that have built-in heaters. If an energy source is available, these batteries will use the heaters to re-warm the batteries up to a temperature that would allow charging.
My non-destructive lithium battery testing this year
My testing this year will determine how much heat I will need to apply to keep my batteries warm. At sunrise today, the outside temperature is 30 degrees and the batteries are at 53 degrees. The condition of this “test” is multiple cold nights with 65-degree daytime temperatures. Starting at sunset my battery was at 66 degrees.
Obviously, a 65-degree daytime temperature isn’t a cold, long, hard freeze. If I get my way, we are not going to ever camp in a cold, long, hard freeze. I hope that I don’t have to heat my batteries to keep them at a temperature that they will need additional heat. They only have to stay above freezing.
Please subscribe and join us on our journey
We will add you to our email list and send you updates about once a week. Here is a link. Subscribe
About the links
Links on our website are freely provided. We do not get income or commissions. No, we don’t make paid endorsements. We don’t make recommendations but instead, we will tell you what we like (or dislike).
Just like the rest of the stuff on our blog, we hope that it helps you. We are so happy you find these articles worth your time.
This is what we used to create our RV Hybrid Mongeral Battery system. We do not get commissions on the links and are provided only to help our friends.