Initial thoughts on LifePO4 (Lithium) battery conversion in my 2017 Newmar Ventana

[Neal]

I've been thinking through Lithium, if my house batteries are due for a change out which I'm not sure they are yet, but the gears are turning as to what I'd do. After seeing a recent YouTube video from RVing with Tito on his comment of having too much battery but also that he chose the Battleborn 270 aH GC3's. Very interesting idea in seeing his setup.

First off, sizing Lithium batteries. The common item mentioned by those with Lithium's is they installed too much. I believe this is due to the fact you can use 100% of your Lithium battery available and if you're using FLA or AGM then you're stopped at 50%. So for me in my current setup I have 8 batteries with 900 aH. That puts me at 450 aH if I understand this correct. So when buying LifePO4's buying the necessary aH's based on 100% availability needs to be sized in. Obviously your use and desired duration on battery plays in as well, I'm just comparing a replacement of existing aH's.

With that said I can see converting my battery bay into a typical basement with only a portion of it being batteries (and solar) now and getting more space if designed properly for other storage (DI rinse, air compressor, 120V cord reel, whatever).

My thoughts are installing 2 x Battleborn GC3's which would give me 540 usable aH's. More than I have now. Plenty of space to add capacity if needed. But my plan would be to stack the two, assuming I have the space for them to fit which I believe I do, in the aft part of the compartment to keep weight aft. Before I go buying too much Lithium I would want to see how this aH works. Yeah, I'm a man of excess with everything, being responsible on this design is key.

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Sticking with the Magnum inverter and solar components, may improve some Victron items as needed for LifePO4 but trying to keep this simple. With only two batteries I "assume" the wiring of the two in series would be straight-forward.

For the battery guru's, let me know your thoughts.

 

[Rich W.]

Unless you want to run an AC off the system, with your solar, theres really no reason to exceed 500-600ah. I’ve put the whole idea on hold until my house batteries need replacement and then I’ll have to make a decision.

 

[Jim]

Sticking with the Magnum inverter and solar components, may improve some Victron items as needed for LifePO4 but trying to keep this simple. With only two batteries I "assume" the wiring of the two in series would be straight-forward.

For the battery guru's, let me know your thoughts.

Not a battery guru, but wouldn't wiring them in series double the voltage, and not the AH storage? And I don't think you really want to change your 12v system to run on 24v.

Or have I missed something?

 

[Neal]

I may be calling it wrong. Don't want to double the voltage. Definitely will consult battleborn on wiring.

 

[Neal]

You are correct @Jim parallel is the correct term.

How to Wire Batteries in Parallel or Series - Dakota Lithium Batteries

Here at Dakota Lithium we pride ourselves on the domestic manufacturing of robust and reliable LiFePO4 batteries. It probably comes as no surprise that we get a lot of battery-related questions. One of the most common queries is “I need more power! Do you have a battery that can give me more...

dakotalithium.com

 

[Neal]

Started reading the docs on the GC3's, excellent documentation.

 

[MemoriesByTheMile]

We have 1000ah of lithium phosphate batteries from Lithionics ( they are based in Tampa).
We also have 300watts of solar panels.

Having more battery capacity opens up more possibilities. If the system (this includes not only the battery but also inverters and wiring sizes) is built for higher discharge rates you can run A/C unit or units.

More capacity allows for no charging from solar and still able to run for 4 days on battery alone (assuming no A/C). This is great when the coach is in a service bay and they forget to plug the coach in. Keeps all systems running and no loss of food.

More capacity allows for use of the microwave, coffee maker, refrigerator, hair dryer without having to run the generator (when in areas where we might disturb others).

If the extra battery capacity isn't used, then I can see where someone would regret the extra expense.

Neal, you don't see like someone who regrets trying out new things. Just think through if the extra benefits are something you would enjoy.

Dave

 

[Neal]

Thanks Dave, but what is the correct sizing of LifePO4? I have 900 aH now of 8 x FLA batteries. Sure, I can throw 4 of these GC3's in with no problem, but is it a waste?

So let's talk first, what is the equivalent of my current capacity translated to LifePO4?

I have 1800W solar and a Victron 150/100 Tr solar charge controller.

What is an ideal aH i.e. number of GC3's someone would use?

 

[Neal]

https://battlebornbatteries.com/wp-content/uploads/2022/10/BBGC3_Manual-Edition.PIM_BBGC3Rev014_09062022.pdf

https://battlebornbatteries.com/wp-content/uploads/2022/10/BBGC3-Product-Cutsheet-9-12-22-RGB-1.pdf

https://battlebornbatteries.com/wp-content/uploads/2022/10/BBGC3-Datasheet-5-31-222-Web-2.pdf

 

[MemoriesByTheMile]

Neal, your initial thoughts of taking your current FLA batteries and cutting it in half is the normal rule of thumb. That would give you roughly the same usable capacity you currently have usable with FLA.

So 2 of the BB units you mentioned appears to give you slightly more than your current FLA capacity.

Look into the battery management system and charging system. When our coach was converted to Lithium it needed a new battery charging system and needed a new BIM.

This is a link to Lithionics:

Lithionics Battery

lithionicsbattery.com

Dave