Switching to Lithium Ion Battery Bank?

[adamis]

I'm toying around with replacing my current 300AH 6v Lifeline AGM batteries wired in series with a Lithium Ion Battery pack. The cost is certainly a lot higher and maybe I'm just looking for trouble but the idea is interesting to me. A bit of background...

The Lifeline AGMs came from another camper that I purchased used. That owner had pulled his genset out and replaced them with these two large batteries. They didn't fit in my new camper battery compartment so I have them sitting in the bed of my truck (one on each side and wired together in series with some 4AWG) wires before coming back into the camper. The setup works okay for the most part but I do have long wires to make it work and I think it's holding the batteries from charging fully. I've never had any issues with the batteries not being able to do the job for a couple of days but I think I'm only able to top them off to around 80 percent capacity.

I would like to go back to having the batteries in the camper to simplify my setup. I've done some research and it seems that a commercial RV 100AH Lithium Ion Battery will run about $1200. That of course leaves me 200AH less than what I had and the price can't be justified. I am considering building my own battery pack (seems like an interesting project that isn't beyond the reach of my abilities) but sourcing good cells for a good price appears to be hit and miss. The third route I am now exploring is reaching out to an EBike maker that cells battery packs. They have a 50v, 25AH battery pack but I've inquired if they could wire it to be a 12v (14.8v actually), 100AH battery pack. The cost for this pack is $719 which is about the same as replacing my two AGMs.

Now, I will loose 200AH of capacity by making the switch so I'm not really gaining on that end, however, do I really need 300AH of capacity in the first place? Looking at my camper, I don't see a lot of high drain devices so I'm thinking I might be able to get away with the smaller capacity.

So, my questions are:

1. Does anyone have any experience with Lithium Ion batteries in their camper?

2. What is the AH capacity of your camper and given your typical load, how long can you last comfortably if it was less than optimal for solar charging and you didn't want to charge via the truck or genset?

[3_tons]

Freep wrote:

egarant wrote:
I too am going to bit the bullet and go full lithium. Two group 31 drop in's.

I've researched and followed others on their blogs that have done the same. Each person said they would never go back to traditional batteries.

You do have to change the way you charge your batteries. I spoke to Progressive Dynamics, the folks that probably made your converter/charger. They make a lithium charger unit that replaces the traditional one that came in your OEM unit that meets the lithium charging profile.

They are also working with a company called Relion Batteries, a maker of drop in lithium batteries in designing the appropriate charging system.

I've spent a considerable time on the phone with Progressive Dynamics and the folks at Relion and will be making my swap to that setup later this year.

It's only money!

I've been looking into Lithium Iron quite a bit lately too. The dream is to be able to run the microwave without firing up the gen. I think I've settled on the batteries.

https://starkpower.com/product/stark-deep-cycle-12-volt-100ah/

I'm trying to decide if I should get an inverter wired up first to see what kind of hit I take on my batteries when I run the microwave.

I've been looking at the 2000 watt Xantrex Prowatt inverter and I'm trying to figure out where in my 2014 Lance 992 I should install it.

Not sure what to do, still doing research. Any advice is appreciated.

Not sure about Li batts, but my former Xantrex 2000 sinewave would run the MW, but to avoid a voltage bottleneck (inverter alarm), make sure that you upsize the battery cables...

[DieselBurps]

I predict in the future some in the industry will go to 24 volt and even 48 volt as better energy storage solutions become more mainstream like lithium, with the increase ability to run heavier loads.

[Jfet]

For A/C it is more about the solar portion. We regularly run our A/C during the day during the summer off of our solar/inverter/batteries.

With 1100 watts of nameplate solar, we usually see about 900 watts in full sun, which translates into about 75 amps going into a 12V bank (we use 24V). The 6000 BTU A/C pulls about 60 amps at 12V. It probably surges a lot higher when the compressor kicks on but our inverter is 4kW so it just pulls a touch from the batteries. But during the day the solar runs the A/C and recharges the battery bank (which is only 250AH at 12V, again we are 24V so it is 125AH).

I like lithium ion. When I can go to Costco and pick up 400AH lithium with a 3 year warranty, I am there!

[Freep]

thedavidzoo wrote:
No, we can't run the AC with the batteries, at least not how it is set up now with the wiring. We do have a lower BTU AC unit. I haven't done any calculations to see if it is even possible in terms of watts, load on the inverter, etc.

I have read that installing a larger starting capacitor on your AC unit can allow you to run in on battery, depending on the model of course. It's that initial startup that generally overwhelms the inverter.

These guys run an AC on their 400Ah batteries.

https://www.thefitrv.com/rv-tips/our-generator-free-rv-lithium-battery-solar-alternator-and-inverter/

[SidecarFlip]

Interesting. I'll still go with L-Iron, not L-Ion.

[thedavidzoo]

No, we can't run the AC with the batteries, at least not how it is set up now with the wiring. We do have a lower BTU AC unit. I haven't done any calculations to see if it is even possible in terms of watts, load on the inverter, etc.

[Freep]

thedavidzoo wrote:
...We also run a 12V DC compressor fridge.

We installed the system ourselves and thus learned a LOT and saved tons of money! It is an intricate setup, but once it is programmed you can pretty much forget about it. We use the MW with inverter all the time and hardly make a dent in the capacity.

Can you run your air conditioner on battery?

[thedavidzoo]

I typed up a long response, lost it all...

Anyway, short version: we have the 400Ah lithium system mentioned above from Starlight Solar in Yuma. Also 640W solar. After some initial kinks due to defective parts (replaced under warranty), we really like our system. Might be overkill, but hey, zombie apocalypse...We also run a 12V DC compressor fridge.

We installed the system ourselves and thus learned a LOT and saved tons of money! It is an intricate setup, but once it is programmed you can pretty much forget about it. We use the MW with inverter all the time and hardly make a dent in the capacity. Check out Elitepowersolutions.com in AZ (supplier to Starlight) for loads of info.

I think you can discharge in freezing temps, but CHARGING the batteries when frozen is a no-go. Ours are inside, so no concerns. We just disconnect the panels during storage in winter. Technically you don't need the fancy BMS, however, you'd really have to be on top of your cell voltages and temps so you don't go out of bounds.

Oh, the 30% federal tax CREDIT (not deduction) is still in effect. That also helped with the cost. 😉

[Freep]

egarant wrote:
I too am going to bit the bullet and go full lithium. Two group 31 drop in's.

I've researched and followed others on their blogs that have done the same. Each person said they would never go back to traditional batteries.

You do have to change the way you charge your batteries. I spoke to Progressive Dynamics, the folks that probably made your converter/charger. They make a lithium charger unit that replaces the traditional one that came in your OEM unit that meets the lithium charging profile.

They are also working with a company called Relion Batteries, a maker of drop in lithium batteries in designing the appropriate charging system.

I've spent a considerable time on the phone with Progressive Dynamics and the folks at Relion and will be making my swap to that setup later this year.

It's only money!

I've been looking into Lithium Iron quite a bit lately too. The dream is to be able to run the microwave without firing up the gen. I think I've settled on the batteries.

https://starkpower.com/product/stark-deep-cycle-12-volt-100ah/

I'm trying to decide if I should get an inverter wired up first to see what kind of hit I take on my batteries when I run the microwave.

I've been looking at the 2000 watt Xantrex Prowatt inverter and I'm trying to figure out where in my 2014 Lance 992 I should install it.

Not sure what to do, still doing research. Any advice is appreciated.

[GordonThree]

happycamper002 wrote:

GordonThree wrote:


. . . I guess you could do regen braking on your RV, the cap soaking up the burst of energy and transferring it to a battery.

Regenerative braking can only be achieved if your MH is totally designed to operate on battery (an all electric) vehicle.

OP's plan is to replace generic batteries with Lithium-Ion, while keeping the old fossil-fueled engine and transmission. There is no mention of converting the rig to operate like a Tesla.

When someone says that one can achieve a regenerative braking to recharge batteries, it makes my training and brain go on a feeding frenzy.

Regenerative power comes from electric motor/s that make the vehicle move. No internal combustion engine, or separate gear variation in the drive train.

As you decelerate the energy of the drive motors (they act like generators) is fed back to recharge the batteries. . . hence the regenerative braking.

If I'm wrong I'll dig up my old notes.

Exactly. The conventional shoe/drum brake and axle hub would be replaced by a wheel-motor (generator). When braking is called for by the tow vehicle, a controller would load the motors via battery or just a dump load to resist rotation, applying braking force and recovering a small amount of energy. the recovery isn't huge, I think a lot of it gets lost in heat.

not saying it's likely, just could be if you want to throw enough money at it 🙂

[SidecarFlip]

When my Trojan's get pooped out, I'm going with 2 L-Iron batteries (not Lithium Ion. Same great attributes without the chance of fire or explosion in a short circuit scenario

[Camp_woof]

I assume you would buy an existing battery monitoring system and just hook it up yourself to the cells ... yes, that's within range of some people.

JimH, one nice advantage of Liion is that their capacity stays up in cold. So, you can run the furnace and not kill the batteries, of course wanting to keep the batteries themselves above freezing. (which you can do when a battery provides decent amp-hour capacity in cold!

OP, If you want to geek out on some of the actual IC technology used in the BMS ... simply google "lithium ion battery monitor ic" and look for trusted IC manufacturers like TI, Maxim, Analog devices, Intersil. Plenty of white papers and interesting info. Poke around and you'll find datasheets, application notes, white papers, etc. You can even order demo boards of some parts and play around with smaller cells.

http://www.intersil.com/content/dam/Intersil/documents/isl9/isl94203.pdf
http://www.ti.com/lit/an/slaa478/slaa478.pdf

[jimh406]

I think I'd update the charging system or existing batteries first. I can't think of any reason why 4 gauge wouldn't be enough to charge the batteries. $1200 buys a lot of both.

[happycamper002]

GordonThree wrote:


. . . I guess you could do regen braking on your RV, the cap soaking up the burst of energy and transferring it to a battery.

Regenerative braking can only be achieved if your MH is totally designed to operate on battery (an all electric) vehicle.

OP's plan is to replace generic batteries with Lithium-Ion, while keeping the old fossil-fueled engine and transmission. There is no mention of converting the rig to operate like a Tesla.

When someone says that one can achieve a regenerative braking to recharge batteries, it makes my training and brain go on a feeding frenzy.

Regenerative power comes from electric motor/s that make the vehicle move. No internal combustion engine, or separate gear variation in the drive train.

As you decelerate the energy of the drive motors (they act like generators) is fed back to recharge the batteries. . . hence the regenerative braking.

If I'm wrong I'll dig up my old notes.