Why so few LIFEPo4 batteries in RV?

[Loic]

Dear all,
I have been conducting researches for a project with a European company. They start thinking about developing a LIFEPO4 battery pack which would be used to replace lead acid batteries.

I tried to find more information about this kind of products here in the USA, but I haven't found many companies who offer this kind of product, at least assembled. I found company selling LiFePo4 cells, but you usually need some skills when it comes to connections.

All I can find are LIFEPO4 battery cells with adapters or batteries for bikes/scooters (10 or 20 AH).

It is much more expensive but has more capacity, is much more eco-friendly and has around 2000 charges cycles.

I saw that many members have trouble getting enough power to run all appliances and daily needs, especially with solar panels.

I was wondering why no one seems to be offering it for RV: is it something people would want? Apparently autonomy is not an issue since most of RVs are actually not really often out, would you say it’s true?
Someone did a cost analysis which put LIFEPO4 batteries ahead of classical lead acid ones.

Cost Analysis of Lithium Ion Battery Systems for RVs | Technomadia

I am not trying to sell those batteries, I was just wondering if the extra autonomy they provide is something RV owners do not really need, or if it’s just a cost issue.
I'll be happy to get your comments and insights!

I do not want to appear to advertise for that company so I do not enclose any names.

Loic

[cwsqbm]

The primary advantage a Li battery gets you over lead-acid is weight per Watt-Hr. However, it comes at a significant up front cost difference. It'd take a very expensive large battery bank to run the A/C systems of a motorhome just overnight. Unless prices come down, it won't become common.

The article you linked is seriously old, as comments go back to 2011. Read this blog instead.

[Scarab0088]

Li-ion IS less weight - and has a faster (more efficient) recharge time. But the cost is prohibitive at this time, and since weight is not often a concern in RV's


Best luck

[Loic]

Originally Posted by cwsqbm

The primary advantage a Li battery gets you over lead-acid is weight per Watt-Hr. However, it comes at a significant up front cost difference. It'd take a very expensive large battery bank to run the A/C systems of a motorhome just overnight. Unless prices come down, it won't become common.

The article you linked is seriously old, as comments go back to 2011. Read this blog instead.

Thank you for the article, i did not know this person and his blog is truly interesting.

From what I see the upfront cost of a LiFePO battery pack seems to be a real barrier for RV users.

i was wondering if class A RV could be interested, since cost is maybe less of a concern.

[MRUSA14]

I personally would be interested in a LIPO battery system. I would like it for the ability to add more battery capacity. I now have 8 6V golf cart sized batteries for a total of approximately 880 AH. I think that using LIPO batteries I could add 50-100% more capacity utilizing the same space and weight as the current batteries. This plus the ability to "dig deeper" into the LIPO batteries would make for a huge advantage when boondocking in my all-electric coach. It would be worth the added cost to me, but only if it were an established product with a trustworthy manufacturer and warranty.

[marcham]

Prices still have a long way to go before this will be affordable. I assume you'd be looking at 4 cells in series? No one is going to drop $4000 to $6000 on batteries, plus the cost of a new cell balancing charger plus the problem of linking the lifepo4 bank to the truck's alternator output (you'll need a dc-dc converter). I think Tesla is paying around $300 per kWh for their 18650 cells. (they pay about $3 a cell, whereas I pay about $8 a cell). Each cell is approx 11Wh. If you want them to last, you probably limit their discharge and ensure they never overcharge, so maybe they plan to get 8Wh out of a cell. Each cell is 3.2V nominal and 3100 mAh. Do some rough math and 300Ah costs about $1800 for Tesla to procure, add electronics, containment, testing, marketing, producer markup, distribution markup, retailer markup, etc...

For my motorcycle, the 6Ah lithium battery costs $120. Double the price compared to a flooded one but at half the weight it's worth it. On a larger scale it's not affordable yet for the recreation industry.


http://www.batteryspace.com/LiFePO4-...Balancing.aspx

[Duner]

I just did a comparison to my recent purchase to provide a capacity of 500 Ah.

$1150 for 4 x 250 Full River AGM (304 lbs)

$7830 for 5 x 100 Ah Super B Li (120 lbs) LINK for specs & price

And I had to swallow hard to fork out the extra $500 over Trojan T-125 wet cells. Plus you run the risk of something going wrong and having to replace almost $8k prematurely.

[phranc]

Cost

[nebster]

Lithium also needs much more aggressive thermal management to perform well and last.

[Loic]

Hello,

By thermal management you mean a BMS? Some battery packs already come with an integrated solution to protect the cells.

Marcham, i did not know for Tesla, it's definitively interesting. It seems logical that given the economy of scales they can get the prices down, especially when you sell more than 11,000 cars per year.

I am still astonished by the total price of the battery system though

[Technomadia]

There actually are some companies in the US offering LFP battery installations and pre-built kits.

We recently published a 3.5 year in review of our LFP setup (you linked to our cost analysis done when we first installed the system):

Living the Lithium Lifestyle – 3.5 Year Lithium RV Battery Update | Technomadia

The article gives an update to the industry and companies we know of who are providing products and services. We also speculated on why our system isn't living completely up to the theoretical advantages.

With the higher cost of acquisition, and the battery technology not being fully proven in an RV house system application over the long term - it's no wonder it's not yet mainstream.

- Cherie

[nebster]

Originally Posted by Loic

By thermal management you mean a BMS? Some battery packs already come with an integrated solution to protect the cells.

Temperature-sensitive management is also important, but no. I meant that, for large packs, we see active thermal management of the pack for example in automotive applications. The packs are heated or cooled (using energy from the pack, when necessary) to keep the cells within the safe band. Liquid or electric heat and cooling is circulated within the pack as needed.

Obviously this only makes financial sense once the pack is sufficiently large. Those of who use lithium in, for example, electric bikes or laptops, face some of the same problems Technomadia discusses: if used (and especially charged) in temperature ranges much outside comfortable ones, the cells degrade much faster than they do in the lab at ambient temps.

So, for a big expensive pack, ideally the RV would have a dedicated bay with insulation and some form of local heating and cooling to keep the the pack happy. Otherwise it ends up yielding half the benefit after half the expected charge cycles, or something similarly sucky.

[ahicks]

I haven't dealt with the bigger batteries that would be used in something like an RV, but if they behave anything like the smaller systems I am familiar with (in Radio Control where they are fast becoming very popular), a conversion to LiFe is a much bigger deal than just installing a different battery.

On the plus side, one of the battery's big advantages is it maintains an almost flat voltage/discharge curve through the majority of it's discharge. BUT, when the voltage finally drops, it's goes to near nothing very quickly - and monitoring the point that happens is difficult/impossible to do by monitoring voltage.

Running an LiFe down below about half it's capacity is hard on it. Running one down completely will usually destroy it, affecting future full capacity at minimum and that's if you are able to revive it at all. .

My biggest concern is regarding charging with existing systems. The LiFe charging is generally done while carefully monitoring max. voltage - without exceeding it- using a specially programmed digital charging system. The cells are very voltage sensitive, and max voltage is achieved WAY before the battery is fully charged. When charging, amperage starts out with about whatever you have available (very high capacity there), but amperage is then adjusted/tapered to nothing as the battery approaches 100% charge, then the charge is shut off. There's no "float" charge on LiFe. They hold their charge for months without. A "float" charge to maintain full charge isn't necessary, and will actually cook the battery.

I'm not sure, but thinking this process isn't going to be compatible with the engine alternator or power convertor systems we have on the typical RV. They're going to need much more refined voltage and amperage regulation than what we have now.

[rtz]

Some charge equipment is coming online:

PDI Lithium Battery Charger

9100L Series Lithium ion