Lithium Batteries: What You Need To Know

Intro

LiFePO (Lithium Iron Phosphate) batteries are often misunderstood. The battery chemistry is different from what many of us are used to working with. When we try to apply best practices and previous knowledge of other battery chemistries to a LiFePO battery it leads to damaged LiFePO batteries and disappointment. I hope this article helps you understand some of the differences and  clears up any confusion you may have had about LiFePO batteries.

Chemistry

The LiFePO chemistry is more stable than Lithium Ion batteries. As such, the LiFePO batteries will not burn and catch on fire like the Lithium Ion battery chemistry. An overcharge situation can cook a LiFePO battery and they can smoke, but will not burn. I can give a firsthand account on this. My voltage regulator failed and cooked my brand new LiFePO battery. The case started to melt and deform, but no fire!

Since the LiFePO battery is not based on a lead chemistry there is a lot of weight savings.

Charging

The LiFePO battery is best charged at 13.6 - 14.4 volts. Much more than 14.4 and you will cook the battery. Most auto and motorcycle charging systems easily fall into this range, but I did install a volt meter when I put my battery in so I could monitor the charging system.

The LiFePO batteries will charge a lot faster than an AGM or lead acid battery. With a 10-15 AMP charger designed for the LiFePO batteries you can get a full charge in as little as 15 minutes!

The LiFePO batteries are made up of individual cells wired in series in the case. These cells will have minor differences in electrical attributes and will become unbalanced over time. It is good practice to put your LiFePO battery on a balance charger after each oil change. Balance chargers aren’t very expensive and it will even up all your battery cells to get a good service life and performance out of it.

You can use a trickle charger if you need to, as long as there is no desulfation mode. Battery Tender brand chargers will work, but the ideal charger for this type of battery is a balance charger.

It is not good practice to keep a LiFePO battery on a trickle charger like many people do with traditional batteries. The LiFePO battery has a very slow self-discharge rate. They can sit all winter and be ready to go as long as nothing is draining the battery while it sits.

Discharge

One advantage of LiFePO batteries over traditional batteries is the discharge curve. A LiFePO battery will put out a steady voltage without dropping output almost to the end of full discharge. You have to keep the discharge curve in mind. Traditional batteries give you a bit of warning when they are getting weak. The LiFePO will go from full power to low power quickly when you discharge it too far.

Traditional batteries can be discharged all the way and can often be charged back up. With a LiFePO battery a 100% discharge will likely ruin your battery. It is best to not discharge below 10 volts.

People often notice that the cranking power seems to stay very strong compared to traditional batteries and it has to do with the discharge curve. They really are full strength for longer. 

With that being said, I have had two of my batteries discharged to 1.5 volts. Most chargers will not start a cycle if the battery is below 3 volts. I took a car battery charger on a 2 amp charge setting and brought the batteries up to about 8 volts in a matter of seconds. Then I was able to use my balance charger to bring the battery back to full voltage. This type of situation is not ideal and I am sure that I shortened the service life of my battery by allowing it to discharge so far, but it illustrates the resiliency of the LiFePO chemistry.

One downside to LiFePO batteries compared to other chemistries is in amp hours. Amp hours is how long a battery can last with a smaller output for a longer period of time. Traditional chemistries usually have more amp hours than a LiFePO battery.

Environment and Use

When temperatures approach freezing it is hard on all batteries. However, LiFePO batteries get weak in cold weather, but there is an easy fix. Just turn your switch on and when the battery starts to discharge the chemical reaction will warm the battery internally. I have experienced this first hand in the winter. I have tried to start the bike when its very cold and I thought I had a dead battery. Then I remembered I switched to LiFePO. I let my headlight burn for about 1 minute and it fired right up.

I had a problem with a lead acid battery in my KLR during offroad rides. I fall a lot and acid can leak out. With a LiFePO battery all the cells are separate and protected in a ballistic case. They are more tolerant to rugged use.

Creative Uses

The LiFePO batteries are a lot smaller and they are very powerful for their size. The 8 cell version is what most motorcycles use and they save a lot of weight and space in a battery box. However, a 4 cell is enough to crank many motorcycles. I have seen people replace their traditional batteries with an 8 cell LiFePO battery and add another 4 cell emergency battery in the same battery box. They have a spare emergency battery in the same space and still have a weight savings. This could be a huge deal in building a RTW adventure bike or for any ride where you will be on your own and far away.

Popular Brands

• Shorai - Probably the most well known brand.
• Alien Motion - These are the batteries I have used and I have been satisfied
• Antigravity - Probably the second biggest brand.
• Ballistic Performance - They are manufactured in Plymouth, Wisconsin and they have more case size options than other manufacturers. If it is important to you to match the OEM battery size, this is the brand to look at.
• EarthX - This brand is expensive, but it has built in electronics to protect the battery and balance the cells. No special charger is needed. 

If you have any questions or you if you have some information to add please post it in the comments below.