2015 Roadtrek Etrek convert AGM to lithium?

[Hugh M]

My AGM's are failing and I would like to replace them with lithium batteries. Has anyone attempted this? Complexity abounds in the 12v vs 24 banks with all the combiners and balancers. Hoping to use the existing cables. Any help is appreciated.
Thanks in advance!

[hbn7hj]

One course of action would be to get rid of all 24 volt stuff and start over with 12 volt lithium. I have never been around a 24 volt system so don’t know if that is reasonable.

You probably have a 24 volt alternator that would be expensive to replace.

You could charge at 24 volt and all loads be 12 volt, I think.

I would probably switch out the alternator. If I remember correctly it was almost impossible to install a battery monitor. I would solve that or install two of them.

[Arlo]

As the former owner of a 2013 E-Trek for 7 years and 105k miles, my advice is to replace the batteries with new AGMs unless you are interested in diving into a rebuild of the electrical system. There were many past posts in the forum focused on the E-Trek’s design, and how to improve upon it. The path that I considered was eliminating the 2 AGMs in the engine compartment and going with a 24v system using the 6 AGMs in the rear, which would have allowed installing a shunt-based SOC monitor. Alas, I decided I wanted a new Sprinter and sold the E-Trek in 2020 with the original 8 AGM batteries.

[booster]

Originally Posted by Arlo

As the former owner of a 2013 E-Trek for 7 years and 105k miles, my advice is to replace the batteries with new AGMs unless you are interested in diving into a rebuild of the electrical system. There were many past posts in the forum focused on the E-Trek’s design, and how to improve upon it. The path that I considered was eliminating the 2 AGMs in the engine compartment and going with a 24v system using the 6 AGMs in the rear, which would have allowed installing a shunt-based SOC monitor. Alas, I decided I wanted a new Sprinter and sold the E-Trek in 2020 with the original 8 AGM batteries.

I think this is very wise advice. You lose a bit of capacity but gain a whole bunch of reliability and monitoring quality things. Charging and discharging will get much more even between the batteries also. We have a 4 battery AGM setup in our 190P Roadtrek and it has been very reliable and easy to use. We have never been close to running out of power, but we do not try to use AC from batteries except as a test once in a while.

[andrewtschneider]

Having a 24 volt system allows thinner wires. So I would not change the voltage.
You can buy 24 volt LI batteries from RENOGY.
https://www.renogy.com/24v-50ah-lith...phate-battery/
Just need to find out if the lithium battery can be charged.
If not you might need to modify the charging system.
If you live in a cold area then you need to deal with battery heaters for winter.
Li batteries are nice but lots of implications to think through.
Some times the ‘better’ is the enemy of the ‘good’.

Have fun

[RossWilliams]

Originally Posted by Hugh M

My AGM's are failing and I would like to replace them with lithium batteries. Has anyone attempted this? Complexity abounds in the 12v vs 24 banks with all the combiners and balancers. Hoping to use the existing cables. Any help is appreciated.
Thanks in advance!

What do you hope to get from switching. As you note it is not a trivial process. As others have noted, unless you have some specific reasons for preferring lithium you may be better off just replacing the AGM's.

Not only did Roadtrek make a lot of changes on the fly as they rolled out their all-electric coaches but previous owners, if any, may have made changes to deal with some of the problems found in the process. So you may or may not have the same situation as others who have made the switch.

[avanti]

I would think that simply buying modern 24V lithium batteries would be the most straightforward approach. As @andrewtschneider said, you can get them from Renogy. Also Victron, which is what I am about to be using. I don't know anything about RT, but I assume you could just tear out all the balancing stuff. You do need a 24V to 12V converter for your 12V loads, but that is like $100. A big advantage is that the resulting 12V power is true 12V, not something that is constantly changing due to charging needs.

[hbn7hj]

What did you decide to do? The best advice is to stick with AGM but lithium is so superior I’d probably take on the hassle of switching.