BLOG Should I only charge lithium batteries to 80 percent? What is the 20-80 rule?

[Neal]

https://www.rvtravel.com/should-i-only-charge-lithium-batteries-to-80-percent-what-is-the-20-80-rule/

 

[TheLooks]

Yes and no. For longevity charge to 80%. But Lithium needs to be charged fully and balanced on a schedule as they "drift" and are not equal in final charge. The Beard, Todd Henson, just did a video on this. I cannot find it however. They being each cell in the battery.

 

[Phillbo]

Mine charge to 100%.

 

[d23haynes57]

My rig plugged in at home, power on. A lot of 12 volt loads including air compressor for the slides and leveling, fridge is almost always on ready for another trip. Batteries at 13.6 float, 100% and usually in standby. 2.5 years no effect that I can see. At this point my set of batteries costs about the same as full tank of fuel. Should they fail in less than 10 years, so what?

 

[Kevin D Pem]

I had a rack mount with a Daley BMS. That is where the state of charge was done on that battery. The builder set it at 90 10. I got a year and a half out of it.

So I ask. Why would you buy a battery capable of 70% discharge capability, and cripple it to lead acid capabilities/capacity? If it made any kind of sense why not start with North Star Blue+ batteries and boost cycle life to 5000 cycles?

 

[TheLooks]

There are many other factors in charging Lifepo4 then just that. How aggressive or not the charge voltage and current are and float voltage and when it drops slightly and kicks back into charge mode. Plus the temperature environment. I looked into your favorites and choked on the cost compared to Lifepo4. But time will tell....

 

[Kevin D Pem]

There are many other factors in charging Lifepo4 then just that. How aggressive or not the charge voltage and current are and float voltage and when it drops slightly and kicks back into charge mode. Plus the temperature environment. I looked into your favorites and choked on the cost compared to Lifepo4. But time will tell....

And I agree completely! I too was shocked with the price, I was when I bought them. I agree with the many ways to destroy a battery no matter the chemistry.

Here is the argument in a nutshell! Honest weight. That principal will never change. I am starting to see people get their buyers remorse as the false perimeter promises have the cracks widen with stop gaps that may prove useful like the one this OP brought up. But the result is a far cry From what I expect From My purchase. And honestly? Equal to a standard consumer Walmart everstart minus the cycle life unproven claims. But hay they save a 100 or so pounds.

It's kind of like wanting a mil spec computer and the price brings you to a standard grade laptop. Your new computer won't hold up to the expected environment even if the salesman made the promise.

 

[TheLooks]

I bought 2 Walmart batteries before coming West and meeting you...both failed and I nearly came to blows with a young idiot that tried to tell me about battery voltage etc....as in 12v is a good battery. I bought into the you can find a Walmart anywhere to get a replacement....never again. My cheap watt cycle batteries are doing great and I am out in the wild now testing them further. I could not buy one of your super carbon batteries for what I have in 3 if these at 514ah. Time will tell

 

[Kevin D Pem]

The float-and-recharge cycling point is what I keep coming back to. I'm setting up a small solar shed in Boise with a 12V LiFePO4 bank, and the 80% cap only makes sense to me if the controller's absorption and float aren't constantly nudging it back up. Temperature is my bigger worry — a cold garage in January versus a 95°F July afternoon is a wide spread. I was comparing the ECO-WORTHY 12V 280Ah LiFePO4 Battery Review against cheaper options, and honestly the price gap is hard to justify without knowing how the BMS handles low-temp cutoff. Has anyone run one of these through a full Idaho winter?

What you need to know. All lithium batteries can not be charged below freezing.

There are heated batteries out there, and the safest way to deal with the issue.

Remember that although many BMSs have charge cut off so they will not charge below the freezing set point. Although they have the feature, thermal sensors can and do fail. Mainly because the circuit is analog, and throughout electronic control history, analog has always been problematic requiring constant attention.

So! A heated battery is your best bet.