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If you follow my writings here on 4WDTalk, you might know that I recently upgraded the batteries in my Turtleback Expedition Trailer from AGM to lithium.
In that article, which you can read here, I explain the differences between AGM and lithium batteries from the standpoints of performance, durability, price and so forth.
There are a lot of considerations to make when upgrading your batteries beyond the factors I just listed. In today’s article, we’ll go over some of these additional factors for an AGM to lithium upgrade.
AGM to Lithium Upgrade: Understand the Charge/Discharge Rate
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As I discuss in my other article, lithium batteries have a much better depth of discharge (DoD) than AGM batteries. It works out to about 50 percent for AGMs and 80-90 percent for lithium batteries.
Apart from that, you also need to think about how fast you would drain the batteries.
So, for example, if you have a 100Ah battery and a 10 amp load, the battery would be drained in 10 hours. This is what is known as a C/10 rate. If you have the same 100Ah battery but a 50 amp load, the battery will last two hours. This is a C/2 rate. Typically, batteries are rated for their C/20 rate, or the load that would result in a 20 hour battery life.
Naturally, if you’re running a high load (or if you charge your batteries with high current) you need to think about the batteries’ charge and discharge rates.
So, for example, if you need a higher rate than what the batteries can accommodate, you would need to add additional batteries in parallel. In AGM batteries, charging them too slowly can cause premature sulphation, which drastically shortens their lifespans. This, however, is not a problem with lithium batteries.
Where most AGM batteries do their best at a rate of C/8 to C/12, some lithium batteries can go all the way to C/1 or even higher, provided the period of use is short. In other words, a 100Ah lithium battery (like mine, shown above) could handle currents over 100A if need be.
Of course, running that much power will not get you the best battery life. Instead, battery manufacturers usually recommend working at a C/2 rate or less to ensure longevity of the lithium battery.
Voltage Sag is a Thing of the Past With Lithium Batteries
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When you’re running thirsty accessories like your winch off of your AGM batteries, you might notice what’s called voltage sag. This is exactly what you think it would be – the voltage drops from 12V to 11V or less.
If you’re running an inverter, a heavy load could mean that the voltage drops below the inverter’s cutoff, which results in the inverter shutting down. Additionally, if you need to run a heavy DC load, you need the batteries to maintain a high voltage to carry the load.
But since lithium batteries can handle high currents, you don’t have to worry about voltage sag. Run your winch or the air conditioner in your trailer all you want – the voltage will not significantly drop with lithium batteries.
Get a Battery Management System for Your AGM to Lithium Upgrade
One of the best things you can do to update your battery system (aside from the AGM to lithium upgrade itself) is to invest in a battery management system.
These systems, like the Manager30 from REDARC shown above, are designed to charge and maintain your batteries, making them the ideal solution for your overlanding rig.
This battery management system works with lithium batteries, lead acid, gel, AGM, calcium, or lithium iron phosphate batteries while incorporating solar inputs, AC, and DC as well. See the Manager30 in action in the video below:
By ensuring that your batteries are always fully charged, a system like this gives you the peace of mind you need as you head out on long overlanding trips. It charges auxiliary batteries from your vehicle’s alternator as you drive and serves as a 110 volt AC shore mains power charger as well.
In addition, this thing is a battery isolator, an MPPT solar regulator, a load disconnect controller, and it has a remote battery monitor.
In other words, the Manager30 is a six-in-one operation that takes the worry out of your power system by charging and maintaining your batteries for you. If you want to get the most out of your batteries, I highly recommend getting one of these bad boys!
So, are you ready to make an AGM to lithium upgrade? I have, and I can’t wait to get out and test out my new batteries and my Manager30!