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?

[theoldwizard1]

adamis wrote:

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.

Be careful what you are doing !

There are 2 basic chemistries used in Li-Ion cells, lithium iron phosphate and lithium cobalt oxide (there are DOZENS of variation on both). LiFe cell is what is used in most heavy duty application (except Tesla) because they are INHERENTLY SAFER ! Their capacity and voltage is lower but they can NOT be overcharged or over discharged to a catastrophe. LiCo cell will EXPLODE AND BURN if over charged or over discharged.

The only way to obtain "inexpensive" batteries is from a wrecked Tesla or a lot used laptop battery packs.

The BEST Li-Ion cells are made by Panasonic/Sano/Tesla, LG or Sony. If you want to "roll your own" you have a lot to learn about charging, discharging, cooling balancing and battery capacity. I am not saying it can't be done, but it will take time testing cells.

[egarant]

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!

[covered_wagon]

I wouldn't do it. I would rather keep it simple keeping the old charging system and able to replace wet cells/ AGMs just about anywhere on the cheap. Not having to drive to any place special for replacement is a big plus. I would not have to worry about ruining them either like special treatment battery babysitting.

[trail-explorer]

adamis wrote:
2. What is the AH capacity of your camper

ZERO.

My camper doesn't have an amp hour capacity

[Flapper]

Without getting too long, please do a lot of research into Lithiums before trying to do it on the cheap! There are several different chemistries, some fairly safe, some very unsafe (think Samsung, Hoverboards, etc.). Packs do not come in "12v" configurations, but around 11.1 to 14.8, with variations due to specific chemistry. You must have a charger specifically for them, that can balance each cell in a pack (3-4 per pack). You cannot run them down to 0, that kills them right away. If not used for a moderate length of time, they must be partially discharged to a storage voltage, or you greatly shorten their life. They do not tolerate cold at all. There is a lot of babysitting involved in owning them, and if you neglect them, there is a moderate to good chance of burning up your RV with some of them. The old Spiderman saying holds true here also: "With great power comes great responsibility".

[GordonThree]

Caps won't help in an RV at least not the current technology. Maybe in 30 years when graphene based hybrid batteries come around and we see energy density come up.

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

[Camp_woof]

Looks like some kind of super capacitor technology, just a completely different animal and not needed/suited for RV. The Maxwell datasheet shows this is basically a short term energy storage device (supercap!) that works with your existing batteries. The use case is that supercaps have extremely low ESR and use that technology difference to deliver very high cranking amps over a wide temperature. Great for a big diesel engine, not needed at all for RV.

To be more clear, the datasheet I read says this device takes 25A max to charge, and charges for 15 minutes. That's about 6 amp-hour of capacity. What this technology does is give you ALL that power in 10-15 seconds of cranking, very high cold cranking amps. Again, this is opposite of the the long and relatively lighter load we put on RV batteries where we look for high amp-hour capacity.

[Scalcote]

I've just started seeing/reading up on these type of batteries. I'd be interested to see how they would work for our type of application.

http://www.maxwell.com/esm/

Yes fast discharge but equally fast recharge....would solar panels keep up with extended drain/usage?

While they can discharge really fast will they on a slow drain?

May be one traditional battery and one capacitor style battery.

http://www.lightav.com/car/batcap/batcap.html

[sbryan]

Have a look here. Lots of good information.

http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28937969.cfm

[adamis]

That's a pretty good read though I think his pockets are a bit deeper than most thus giving him some additional options.

In his blog he linked to this company for his battery source:

http://lithionicsbattery.com/product-category/12-16-volt/

They don't have any pricing that I can see so difficult to tell if they are an affordable option or not at this time.

[Camp_woof]

Check out the sprinter van sources, Roadtrek offers Lithium ion as a factory option. (like with all things Roadtrek, just bring $$$).

Here's some good info as well, discusses Amperage used and went with Lithionics battery packs:
https://www.thefitrv.com/rv-tips/our-generator-free-rv-lithium-battery-solar-alternator-and-inverter/

[GordonThree]

Your amp hour loss is not an apples to apples comparison.

Lithium ion pack you can actually use almost 100% of the rated capacity, versus at most 50% from the AGM. So you're only loosing 50ah by my optimistic math.

That up front cost is a rough pill to swallow I'll give you that. I guess the bright size double the usable capacity and half the weight, the value really adds up for larger banks.

[fpoole]

Kewl, glad it was helpful..

I too, have what sounds like your setup... 2x6vt in camper and then 2 sets of 6vt boxed next to headboard (flat bed) long wired to the camper.

It's not the perfect solution but the only one that can be used with the rig scenario. The guy at Starlight didn't recommend it at all, but couldn't think of another scenario, so it is what it is..

Starlight has an excellent reputation down there, but me thinks he wants the "Perfect" solution and sometimes that just won't work.

I would like to get rid of the "External" batteries, thus the smaller lithium ones.

Here's what I have now and it's a PITA when I want to off load the camper (rarely). I was thinking of just getting longer cables, 10' to keep the boxes at the headboard and run the 10' to connect to camper. and yes, I know loosing power/charging etc..

Anyway, looking forward to see what you find...
thanks..

[adamis]

Nice link, I had not come across that company before. Their prices are high but then they do include the entire package for install which certainly adds to the value.

I've been looking at something like this:

https://nexgenbattery.com/rv-lithium-batteries/

But that is just for the battery hence why I started looking at other options.

[fpoole]

Subscribed - Yah, I was looking at the Lithium option too... apparently, from what I was looking at, you can just ADD the battery packs as needed, build to your requirement.

http://www.starlightsolar.com/RV_Lithium_Battery.html

so following.
thanks...