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ThorTraveler · 05-23-2023, 05:40 PM

I have a 2021 Thor Tellaro 20LT that I am thinking of upgrading from AGM to Lithium batteries. Most of our camping has been in campgrounds that do not have electrical hookups so we are running lights, heater, etc off of batteries.

My dealer told me that I need 2 Lithium batteries, a new Lithium compatible AC-DC converter and a DC-DC charger.

The unit has a solar charging system that is compatible with Lithium batteries. So my question is do I really need the DC-DC charger to charge the batteries off the alternator as I drive? This is about 1/3 of the cost of the upgrade. If I really need to charge the batteries on a cloudy, cloudy day, I could do so with the generator.

Has anyone done this conversion? Any other thoughts?

2cyber71 · 05-23-2023, 06:00 PM

Don’t do it.
Keep what you have, maybe get a generator and put in another battery to run off the inverter you have.

Switching to Lithuim is just too expensive and might not work out well. If the install isn’t perfect you will have trouble.

Dry camping can’t use that much, maybe switch the AC to the new Truma AC that uses very little energy to run. Cheaper and you will be happy n

robertj1979 · 05-27-2023, 09:02 AM

Quote:

Originally Posted by 2cyber71

Don’t do it.
Keep what you have, maybe get a generator and put in another battery to run off the inverter you have.

Switching to Lithuim is just too expensive and might not work out well. If the install isn’t perfect you will have trouble.

Dry camping can’t use that much, maybe switch the AC to the new Truma AC that uses very little energy to run. Cheaper and you will be happy n

I would agree with this post! If your vehicle was not set up to use the lithium there are many ways this can cause problems. I have a lithium setup from the factory and have had some issues with mine even though it was set up by Thor that way. One thing Thor did not think through was the temperature requirements of the Lithium batteries. If you travel into or are in a cold weather area you will not be able to charge your batteries below 32 degrees F without some major modifications.

Persistent · 05-27-2023, 09:41 AM

Quote:

Originally Posted by ThorTraveler

I have a 2021 Thor Tellaro 20LT that I am thinking of upgrading from AGM to Lithium batteries. Most of our camping has been in campgrounds that do not have electrical hookups so we are running lights, heater, etc off of batteries.

My dealer told me that I need 2 Lithium batteries, a new Lithium compatible AC-DC converter and a DC-DC charger.

The unit has a solar charging system that is compatible with Lithium batteries. So my question is do I really need the DC-DC charger to charge the batteries off the alternator as I drive? This is about 1/3 of the cost of the upgrade. If I really need to charge the batteries on a cloudy, cloudy day, I could do so with the generator.

Has anyone done this conversion? Any other thoughts?

The advice you received sounds good.

Most likely, the AGM batteries currently charge from the engine alternator while you are driving. Possibly the engine start battery also charges when the RV is plugged into shore power.

Li batteries have a different charge and discharge voltage profile from AGM. They should not be charged or discharged on the same system except in an emergency. The B2B charger corrects the charging profiles and protects against overloading the alternator.

Ignore the B2B charger issue

You can ignore the requirement for B2B charger. Most likely problems will develop slowly or fast. It depends on many things.

The big one is that under some conditions the alternator will overheat and fry. One owner replaced two alternators on the same trip out before installing a B2B charger. Other owner's say they have no problems. It may work for a while. It may fail before you get out of the driveway.

The Li batteries may not balance properly when they charge. The immediate effect is you don't get full storage capacity. The long term effects are permanent loss of capacity.

Simply Disconnect the bridge between house battery bank and engine 12 volt system. This is the cheap way to safely manage. Lithium batteries will not charge from the engine. Chassis start battery will not charge from shore power or generator power.