Considering switching to lithium-ion batteries for your RV? They are an amazing power source, but you may need to consider making a few upgrades alongside the batteries to get the most out of your new power system. One of the most common questions we get asked about lithium is what do I need to upgrade in addition to the batteries?
As an Electrical Engineer and RV Tech, we could really get into the weeds on technicals, but we’re going to keep it high level enough for you to understand, but you’re still going to learn something! Let’s get into it.
Why Switch to Lithium-Ion Batteries?
Lithium batteries are becoming more and more popular for good reason. In energy storage applications, lithium-ion batteries provide more power than other battery types when taking weight and size into consideration.
They also last much longer and charge better. Lithium batteries can be installed in enclosed spaces because they do not emit any gasses. We did a deep dive on the cost of lithium and even found that over its life, it is the cheapest battery for power applications.
In addition to all the power benefits, lithium-ion RV batteries eliminate the dreaded “battery anxiety.” Meaning, you get overly obsessed and worried about your battery’s state of charge and health.
Lead-acid batteries require such specific charge parameters it’s easy to damage them by over-discharging or not properly charging them. With lithium-ion, you don’t have to think about your batteries all the time. They just work! Lithium-ion batteries also have such a long life, in most applications, they are lifetime batteries.
We personally recommend Battle Born Batteries as they are high-quality American-made and engineered, however, most lithium will get you these benefits.
Differences in Charging
Charging is what you need to consider most when making the switch to lithium-ion batteries in your RV. Most of the time, the switch is from lead-acid to lithium, and these batteries have significantly different charge profiles.
Lead-acid batteries have three different charging stages. Most lead-acid battery chargers will step through them based on the battery voltage and internal resistance. These charging stages are bulk, absorption, and float.
The absorption stage is a special phase where the voltage is held higher to force current into the battery as the resistance increases. In this phase, charging slows way down and is another big drawback to lead-acid batteries.
In lithium batteries, the absorption phase is not required. This is because the lower internal resistance of the batteries allows them to charge at full speed to almost completely full.
Because of this, lithium batteries can charge much faster than many other types of batteries. Additionally, they are a better choice for solar energy as they will not waste power due to a slowing charge. In fact when we switched from a set of lead acid batteries in our coach we already had 1200 watts of solar on the roof. Just by making the switch we saw a 30% improvement in solar production because we were able to store power more efficiently.
What Components Need to Be Upgraded With The Lithium Batteries?
This article is referring to drop-in lithium-ion RV batteries. These batteries have built-in BMS (battery management system) units and are designed to be used in place of traditional lead-acid batteries.
If you are considering building your own battery from cells or using batteries without a BMS, like electric car batteries, then you will require more equipment to make sure your batteries operate safely. Never connect any charger to lithium batteries without a BMS unless you have other safety measures in place.
Battery Chargers
Now that we have an understanding of the charge differences, it’s clear that a lithium-specific charger will be beneficial. The benefit is typically faster charging. Yet, this does not mean that a lead-acid battery charger will not work. In fact, we have installed lots of lithium batteries that have worked fine with existing chargers in the RV. Usually, the owner will eventually decide to upgrade the charger to get more benefit from the batteries however like faster charging and more full batteries.
Most of the time, drop-in lithium iron phosphate batteries will work with existing equipment as long as the charger does not have automatic equalization.
Usually, if the battery charger is programmable, you can reprogram it to work with lithium. However, sometimes a charger will only have different charge profile settings. If there is no lithium setting, AGM is usually the best choice.
Conversely, if the charger is fully programmable, it’s always best to get the proper voltage settings for bulk, absorption, and float from the manufacturer of your lithium-ion batteries.
Do Not Use Automatic Equalization With Lithium
Equalization is required in lead-acid batteries for longevity and health but not required in lithium. An equalization charge increases the voltage much higher than normal to “equalize the lead cells.”
If this is done on lithium batteries, it can damage their BMS. That’s why you should permanently disable automatic equalization. If you cannot disable automatic equalization on a lead-acid battery charger, replace it.
Solar Chargers
Along with the primary battery charger, any solar chargers also need to be compatible with lithium RV batteries. Most of the time, solar chargers will not have any equalization capabilities and will work with lithium. But they may charge a bit slow.
Some charge controllers are programmable and you can reprogram them to the appropriate voltages for the batteries. In this case, research the manufacturer of your batteries to get the proper voltage settings.
Inverters
Typically, inverters do not mind running on lithium batteries. As long as they are in the right voltage range (12, 24, or 48 volts), they should work. However, you should change the low voltage cutout, if the inverter has one. Lithium battery manufacturers will provide a recommended low voltage cutout for inverters.
In general the best inverter for lithium batteries is one that is fully programmable. Our preference is the Victron line of inverters because they can be programmed for very specific voltage and charge profiles.
Other Considerations When Replacing Lithium-Ion Batteries
Usually, loads like lights, water pumps, and appliances will not even know they are running on a different type of battery. Therefore, you don’t need to change anything with them.
I always recommend installing a shunt-based battery monitoring system with lithium-ion batteries to accurately monitor the state of charge. My favorite monitor is the Victron BMV712.
- Victron Energy BMV-712 Smart Battery Monitor (Grey) is a high...
- Victron Energy BMV-712 features an additional input which can be...
- Built-in Bluetooth Communication – wirelessly monitor your...
Lithium-ion batteries are often replaced in vehicle house systems that are tied to an engine’s alternator system. A trailer charges through the tow vehicle, a motorhome charges off the engine, and the same with a boat. Because of the lower internal resistance of lithium, it is not uncommon to see lithium batteries burn up fuses or even the alternators themselves.
We wrote a blog all about how we set up alternator charging in one of our builds. I recommend if you want to charge lithium batteries off an alternator, to use a DC-DC converter that will keep the current at a safe level.
- For use in dual battery systems in vehicles or on boats where the...
- Screw terminals: The screw terminals give the advantage of not...
- Bluetooth Smart enabled: The unit can be monitored and programmed...
A DC-DC charge controller should be fully programmable so you can set the appropriate voltages and current limits.
In our motorhome we physically disabled the relay that connected the house and chassis batteries together so that the alternator would not get overloaded. When first connected we measured the current draw and it was around 250 amps!! This would quickly burn out the alternator so we shut it down and disconnected it. We run with no alternator charging because the solar and generator is more than enought, but if you want alternator charge, consider a DC-DC charger like mentioned above.
Lithium Upgrades Made Easy
Overall, what you need to change or replace is going to depend heavily on your current system. If you are running a basic charger without equalization, you can use a drop-in lithium RV battery without changing much else.
However, reprogramming or replacing the charger would be the best improvement you could make when switching to lithium as you will get faster charging. If you choose to switch out components, we highly recommend getting fully programmable equipment and programming your chargers and inverters to meet the manufactures recommendations.
An upgrade to lithium-ion RV batteries may seem daunting, but depending on your needs a simple drop-in replacement might suit your needs with minimal upgrades needed.
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John
Thursday 9th of February 2023
Tom,
Being a recent purchaser of a 200 AH lithium battery, I started researching if my current equipment is compatible, thus I just wanted to mention two points as there appear to be a few exceptions to the rule.
For instance, my progressive dynamics inteli-power converter equalizes at 14.4v for 15 minutes every 21 hours after it goes into storage mode, so I believe this particular product’s equalize mode, while not ideal, is probably safe with lithium.
The other thing is that Ray, from Love Your RV, did a test on his newer RAM truck, and the 12V power feed from his 7 pin connector never supplied more than the 30 Amps (from a 220A alternator) it was rated for to his fifth wheel, thus I believe some newer vehicles essentially have built in DC to DC converters/current limiters.
Would appreciate any feedback you have as I’m not an electrical engineer, but another discipline of engineer that watches a lot of RVer YouTube. While I generally agree that it’s best to install lithium designed equipment, especially for novice DIYers, those who are so inclined should investigate the specs of their equipment as there appear to some exceptions to the rule. I bring this up because as you stated, a lot of people are put off by lithium’s up front cost of entry, adding a new converter and DC/DC charger makes it worse. If those so inclined can use their existing equipment and/or gradually upgrade their equipment over time, we might start to see higher adoption rates for lithium, which I think most will say “why didn’t I do that a long time ago” after they enjoy the vastly improved user experience.
Thanks for all you do, you guys are an incredible resource!
Gregg
Monday 7th of August 2023
@Mortons on the Move,
I too would like to disconnect my house system from the alternator. I do not know the best or anyway to do this. I am working on a 2000 monaco monarch with a F53 chassis. My chassis disconnect has 5 wires attached. Not sure what powers what. There is a terminal post at the rear of RV with three wires attached. can you recommend a way to do the disconnect.
Mortons on the Move
Saturday 11th of February 2023
Great points, and I should probably update the article to state "within limits". Sounds like your equalization would be ok if thats all it does. A true equalization usually pushed the voltage to 15-18V. As for the truck charging, your again correct, if your amperage is within limits of your alternator (30amp continuous is fine) and wiring (you need 10Awg) then your fine. In my case with my motorhome and 0awg wires, it was pulling over 200A! no good. If the wire size is small enough and long enough it will lower the current, in fact we talked about that in our video about alternator charging a while ago. Thanks for your comment and enjoy your lithium!!
Jon Campbell
Thursday 3rd of February 2022
The question I have is, if your Li Battery has an onboard BMS, why would you need a separate battery monitor? We are looking at Renogy 12V/100A Smart Batteries with bult in Blue Tooth BMS. Thoughts?
Mortons on the Move
Tuesday 8th of March 2022
In that case you shouldn't need a separate monitor as its basically built in. You just need to monitor state of charge and current flow.
Tony
Sunday 16th of May 2021
Hi Tom, I’ve read your blog twice and all the info on the Battle Born (BB) website. Wonder if you can confirm my understanding? Our 2016 Entegra Aspire (43’ diesel) currently has 4 AGM’s that are pooping out after just 3 years, so we want to replace with 4 100 BB10012 batteries. Our current Magnum energy controller doesn’t have a lithium setting, but we can set custom parameters.
To keep the conversion to Li as simple, safe and cost effective, can we simply add a battery isolation manager to protect the engine’s alternator and use the custom programming on the Magnum? BB’s website recommends the DC-DC charger for systems of 1 or 2 batteries, and the BIM for systems >3 batteries. You recommend the DC-DC charger. If I understand correctly, the choice is between either of these devices, but not both. Time is of the essence, as our motorhome is in the shop this week and the batteries should arrive by Tuesday. I did order a BIM, but not a DC-DC charger. I want to make sure that the technicians doing the work truly understand what needs to be done for correct installation. Your input is appreciated.
Mortons on the Move
Sunday 20th of June 2021
Yes that will work fine using the Magnum with custom parameters. BB should have the charge settings on their site. As for the alternator protection, the BIM will work well. It basically cuts out the current on and off for a 50% load to prevent overheating. A DC-DC converter will usually net a better charge because it regulates a constant current of your choosing. If you know your alternator is good for 30amps continuous you can set it as such. Either way will work well, however. The BIM is a little more complicated to wire because it needs an ignition wire to know the engine is running , while the DC-DC is voltage-based and will only charge when there is a higher voltage.
One last thing to consider is that you may not need alternator charging at all. If you have onboard gen and or solar, they will both provide much better and faster charging than the alternator. Many installs I have done we just disconnect the house system from the alternator altogether.
Tony
Sunday 16th of May 2021
An update: I did also order the Victron BMV 712 and a newer version of the Magnum controller ARC50
Tim
Sunday 24th of January 2021
Maybe making the switch to Lithium this year??? I am curious on the wire size you are using on your system going to the inverter. I have looked at charts and seems like every chart is a bit different. 1/0, 2/0, ??? Most RV toyhaulers like mine usually come with two LeadA batteries, so probably switching them out for two Lithium. Do you have a video about this?
Mortons on the Move
Sunday 24th of January 2021
Wire Sizing? I dont but plan to write a blog post about it soon. Since I am an electrical engineer I always go by NEC for wire sizing.https://www.cerrowire.com/products/resources/tables-calculators/ampacity-charts/ Its all going to come down to the ampacity. @ 12V - 3000W inverter = 4/0 2000W=2/0 We run various sizes in our system because its 24V. This video shows our wire sizing. https://www.youtube.com/watch?v=wDRDWryBP1A
Greg Brown
Sunday 24th of January 2021
It would be great if we could see a comparison between the many other LiFePO batteries that are out there. The BattleBorn are great compared to AGM and flooded cell batteries, lots of others are coming on line. Will these all become interchangeable with updated systems? Thanks Greg
Mortons on the Move
Sunday 24th of January 2021
Its on my long list of things to do :) I would love to do some physical comparisons but I plan to write a blog post about the different cell types soon. As far as interchangeable, most of the equipment will work with lithium of all types but mixing batteries would not be advised. Like lead-acid lithium has slightly different characteristics between brands and you may drain or damage one type over time.