My AGM to Lithium conversion

[Rbertalotto]

Here is a quick article I wrote on my adventure going from AGM batteries to Lithium.

http://rvbprecision.com/rv-projects/rv-lead-acid-agm-to-lithium.html

http://rvbprecision.com/rv-projects/rv-lead-acid-agm-to-lithium.html

[StirCrazy]

BFL13 wrote:

StirCrazy wrote:



considering a 80AH agm is over 450.00 bucks up here, and have been for over 4 yers now, I wouldnt say there was much of a cost risk. two of thoes in my camper would give me 160AH total for about 1K including taxes.. for 900 I did 300AH of LFP, droped from 130 to 49lbs, and was able to put it in the original battery space for the old camper freeing up my outside storage space which was taken up by the GC2's

Steve

Battery pricing varies but around here the 100AH AGM I got five years ago for $230 (Can) is now $330 and a T105 has gone up from about $155 to $255.

So 300AH of AGMs is now $990 before tax and core fee. Meanwhile a drop-in LFP price (not for sure typical as they vary) is about $1,500 for a 150AH so two would be $3,000

Somehow by rolling your own you got 300AH of LFP for $900 so that is quite a saving.

and if I would have ordered my cells today , for 267.00 I would have four 320AH grade A cells by the 30th of october.. add 100 bucks for the BMS and spare bits that 367.00 for a 12V 320AH battery. prices are realy droping now... might place and order for 12 so I can convert the 5th wheel........

Steve

[Rbertalotto]

StirCrazy wrote:

BFL13 wrote:
I used to say itinerant1 could have done equally well with 500 AH of AGMs by swapping them out as required. Now it is not so clear.

The difference now is that he is taking advantage of the LFP high draw ability to run his air conditioner.

It may be that the AGM option would only do that at higher SOCs while the LFP will at lower SOCs

That and the shifting money side where replacement AGMs are going up in price is tilting the balance for his scenario IMO.

How it plays out for recent RV LFPers will not be known for several years yet whether their LFPs were worth it vs another five years or so with another set of FLAs.

considering a 80AH agm is over 450.00 bucks up here, and have been for over 4 yers now, I wouldnt say there was much of a cost risk. two of thoes in my camper would give me 160AH total for about 1K including taxes.. for 900 I did 300AH of LFP, droped from 130 to 49lbs, and was able to put it in the original battery space for the old camper freeing up my outside storage space which was taken up by the GC2's

Steve

The quicker recharge is well worth the investment for how I use the trailer. Now that Li price s have dropped dramatically, it might just be a "no brainer"....

[Rbertalotto]

pianotuna wrote:
Itinerant1,

A bit off topic, but how often does the generator get used? Once a month? more? less?

My travel trailer is 99% used as a means c to an end. We almost never "camp"... we use it to attend events c where we are usually in a field or a parking lot with no shade. Having such great sun exposure I have not used a generator in four years! And we would be considered energy pigs. TVs on all the time. Computers running constantly. Charging cameras. Radios. Phones etc. Toast and Kureg coffee .....

[Rbertalotto]

pianotuna wrote:
Rbertalotto,

Very nice install.


How did you decide on 13.5 for absorb charging?

I called Renogy

[otrfun]

covered wagon wrote:
Should be required to have a sign on the side of the RV warning about Lithium batteries on board. Life has it's benefits and everything has a trade off. To me sometimes the trade off is too costly. Not talking about the initial cost, I'm talking about the danger involved with use and the eventual problems with recycling. I believe in keeping it simple, have a little more physical labor in life it's better for you.

Lead acid batteries off-gas highly toxic, extremely flammable hydrogen sulfide gas. The sulfuric acid inside a lead-cell battery (if splashed) can cause serious eye injuries. Lead used in lead-cell batteries is a known carcinogen that causes a number of very serious health issues. Put in this context, got to wonder why there isn't a warning sticker on the side of every internal-combustion vehicle on the road.

As for lifepo4's, they have zero off-gassing issues. To my knowledge (unlike lead-cell and some lithium-ion batteries) none of the materials used in lifepo4 cells are toxic. Also, all the *external* thermal runaway issues that exist with standard lithium-ion cells (i.e., fire/flames exiting the battery case) do not exist with lifepo4. A lifepo4 battery has superior chemical and thermal stability vs. a run-of-the-mill lithium-ion battery. Bottom line, lifepo4 can experience some small amounts of *internal* thermal runaway, but it won't exit the case.

Yes, there is a YT video showing a lifepo4 experiencing arcs and flames when pierced with a metal spear. Any battery will experience this if internally short circuited using conductive metal. The same effect, externally generated, can be experienced by simply shorting the neg and pos terminals of any battery.

[covered_wagon]

Thank you all for the update and link about latest tech on lithium batteries. I will do some reading on it for sure especially since I am skeptical about their safety.

[3_tons]

covered wagon wrote:
Should be required to have a sign on the side of the RV warning about Lithium batteries on board. Life has it's benefits and everything has a trade off. To me sometimes the trade off is too costly. Not talking about the initial cost, I'm talking about the danger involved with use and the eventual problems with recycling. I believe in keeping it simple, have a little more physical labor in life it's better for you.

Present day reality is that LiFePO4 (or LFP) chemistry is in fact very safe, and with a sealed casing, is not even considered a hazardous material….However, your concerns are duly noted :), just be sure not to short out the - & + terminals..

3 tons

[pianotuna]

covered wagon wrote:
Not talking about the initial cost, I'm talking about the danger involved with use and the eventual problems with recycling.

Up until recently I would have agreed with you. However, that is no longer the case:

"The lithium solution was heated to 70–80?, and Na2CO3 solution was added to the reaction dropwise to produce sediments of Li. This precipitate was vacuum filtered, washed with high purity water several times, and dried under vacuum to obtain high purity battery grade Li2CO3."

From: https://www.degruyter.com/document/doi/10.1515/ntrev-2020-0119/html?lang=en

[StirCrazy]

covered wagon wrote:
Should be required to have a sign on the side of the RV warning about Lithium batteries on board. Life has it's benefits and everything has a trade off. To me sometimes the trade off is too costly. Not talking about the initial cost, I'm talking about the danger involved with use and the eventual problems with recycling. I believe in keeping it simple, have a little more physical labor in life it's better for you.

this is a case of taking facts from older Li technology and trying to say its true to LiFeP04. this in fact is not true at all. here is a quote.

"With electrodes made of non-toxic materials, LiFePO4 batteries pose far less risk to the environment than lead-acid batteries. They can also be recycled to recover the materials used in their electrodes, wiring, and casings to be used in new lithium batteries."

Steve

[Cptnvideo]

A little off topic. We are fulltimers that prefer to boondock. Bought our current RV (5th wheel) 6 weeks ago and the solar-LFP system 4 weeks ago. We have had issues with the RV fridge maintaining even 45° while running on propane (18 cf fridge in slide), so elected to replace it with a 20 cf res fridge. So far, so good, with our 1200 watts of solar and 618 ah of LFP batteries. However, since we can afford it, we might add 400 watts of solar and another 206 ah battery in the fall. I would rather have peace of mind than worrying about whether we can run the A/C or not.
IMO, solar and LFP batteries make boondocking a joy. Love being independent of the electric grid.

[BFL13]

2oldman reduced his bank from 6 to 4 back when because solar did not have time to get 6 done in his situation and 4 were enough

Also you can have too many batts for 50-80s and be in higher SOC slower recharge zone


So many scenarios!

[Itinerant1]

BFL13 wrote:

Itinerant1 wrote:
StirCrazy brings up a fair point that the agm pack has to made larger to equal the lfp pack. I think but could be wrong that 800ah lead would be equal 500ah lfp, it's been along time ago researching this so I could be mistaken.

Over the past 6 years with my lfp and using it in whatever SOC with high draw items for long periods of time and not needing to get them back to full like a lead pack should be also be thought about when comparing "price". With lead how often is a rv park needed or home needed to full charge on occasion to get longest life. Or long generator time to get back to full. How often is the equalization charge needed for long life.

All good points for that scenario.

You could do your daily 200AH with 500 of AGMs ok but as noted need to keep getting them to full. Having more than 500 of AGMs would just make it harder to get to full

To meet the 20% charging rate spec means 100a charger and big enough gen for it

It depends on scenario for each RVer if any advantage with LFPs. No use for me where 4 sixes are just right

I forgot about the proper % for charging lead whereas lfp can be done with hammering it if you have the ability or just give it a trickle.

So biggier with lead is not always better or atleast in a camper situation?

[covered_wagon]

Should be required to have a sign on the side of the RV warning about Lithium batteries on board. Life has it's benefits and everything has a trade off. To me sometimes the trade off is too costly. Not talking about the initial cost, I'm talking about the danger involved with use and the eventual problems with recycling. I believe in keeping it simple, have a little more physical labor in life it's better for you.

[pianotuna]

Of course there are lead acid formulations that do not require 100% recharging, except once in 30 days.