Batteries: AGM vs LiFePO4

[Bailey'sMom]

LiFePO4 = Lithium Phosphate

First off....I realize how expensive LiFePO4 batteries are. Yikes. Like super duper expensive. But they weigh like 28 lbs for a 12volt 100Ah battery. And supposed to have super long life. And can safely be discharged 80 to 90%.

See this Q&A From Amazon....

Question: Compared to regular deep cycle batteries, approximately how many years should this last during regular daily use on an off-grip property?

Answer: Thanks for the question. The LiFePO4 battery has the potential to last 3x-10x longer than a traditional lead acid battery. With any battery, it's cycle life all depends on how you treat it. Many lead acid batteries are rated at around 1000 cycles when you discharge it 50% on a consistent basis (50% DOD). For a Battle Born LiFePO4 Battery, you can discharge the battery 80%-90% and it will still last 3000-5000 cycles. Even after the 3000-5000 cycles, the LiFePO4 battery should still have 70%-80% capacity. Lighter weight, longer life and more usable Ah (ampere-hours). see less
By Continuous Resources, LLC SELLER on November 16, 2017


So I am wondering if any TM owner has tried the lithium batteries and if so what are their thoughts?

I dry camp with no hookups so I rely on my battery and solar to keep me going for two week stints. Currently I only do two 2 week trips a year, but hope to retire in 3 or 4 years at which time I will plan to have 6 or 7 two week trips. I don’t use a lot of power but would run fan more if my batteries were better.

BIGGEST CONCERN: if i am reading all the research correctly and I can pretty much get the same amp hours from one 12v lithium battery as I get from two 6v batteries. Do you think this is accurate? Because the weight is only 28 lbs vs about 140 lbs, and if it has longer life span than AGM, then it might be worth the high cost of the lithium battery. They have excellent warranty. 3 years, 5 years pro-rated.

Thoughts? It would cost a little more than double what 2 AGMs run.

[Bailey'sMom]

Here is an excellent chart showing comparison of Ah, size, and cycles. Found this on amazon

[BrucePerens]

Sara,

With most electronics, if you can wait, you can be assured that you will be able to buy something much better performing, at a much better price. So, if you are 3-4 years out from retirement, you should look at lithium again then.

There really isn't any reason for lithium batteries to be more expensive than lead-acid. They use plentiful natural materials that aren't toxic or dangerous like lead and acid. They are light to ship. They require some management electronics, but there's no reason for those to be expensive. The cost will change as more electric cars use the cells and they are fabricated at greater scale.

Right now I use two GC2 batteries with 400 watts of panels on the rear of the Trailmanor. I could fit another pair of GC2 in the back if I had a reason, but I've not run the first pair dry anywhere that I actually had sun to charge. The solar arrangement was easy to build using only drills and a metal saw, and almost exactly covers the available space in the rear with the shells closed. The panels themselves cost about $500. This keeps the compressor 'fridge running full time and the MaxxFan on its thermostat, various devices on USB chargers, the Riobi drill battery charger, and the trailer's lights and built-in loads.

The batteries have lots of capacity left at sun-up. But the panels are really sensitive to shade and will not work if you park under a tree canopy. I think any solar arrangement will have the same problem

So, I would still carry a lightweight 4-cycle generator to run sometimes during the day when I'm parked in shade. Even lithium won't save you from that.

A good small generator, more panels, and 2 new GC2s will cost less than the lithium batteries alone, at this point.

Make sure to have a battery saver.

[Bailey'sMom]

Hi Bruce

Unfortunately my need is immediate as my existing batteries are well past their lifespan and don’t really hold much of a charge. I think they maybe the original batteries from 2010. I know for sure that they are at very least five years old. This will be my sixth summer on these batteries (I purchased camper used in 2013 and doubt the dealer installed new batteries). I noticed significant drop off 2summers ago and should have swapped them out last summer, but I must do it this summer.

So I would rather spend a bit more now and have less weight and easier for me to handle.

What are your thoughts on how much Amp hours I would get from one 12v 100Ah LiThium vs two 6v AGM 225Ah batteries?

[BrucePerens]

Well, you'd spend about $1000 for a Lithium 12 Volt 100 Amp battery, not counting tax and shipping, and that would be for a no-name brand. If this runs at 80% total capacity in practice (because deeper discharge shortens the battery life), that is 12 * 80 or 960 watt-hour.

Some of these batteries are guaranteed for as long as 5 years, but a 5-year guarantee on a company that can't be reached or is out of business is worth nothing. I am dubious that a lithium battery would last much longer than 5 years. These companies don't actually have enough batteries in use yet to back up any claims of longevity.

Batteries Plus wants $130 per GC2 and they want your old batteries, or there's a $27 core charge. There's a 10% online discount coupon, and you pick the battery up at their store so no shipping. So, 260 * 0.9 (discount) is 234, and then you'll have tax that bumps that up a bit so figure $250. Let's say we never discharge these below 50% of capacity, so 235 AH / 2 = 117.5 * 12 = 1410 watt-hours over 20 hours.

So, the lead acid cost 1/4 as much and have 40% more capacity. So, I would suggest that you deal with the weight. At this time, lithium batteries are simply not economically practical for RV use.

[Bailey'sMom]

Thanks Bruce. If I don’t try the lithium, then I plan to get AGM batteries not flooded, for a couple reasons.

1. Less maintenance
2. Supposed to recharge faster

Still researching and waiting to hear more opinions. But will have to decide in the next week or two.

[BrucePerens]

AGMs are a bad choice for deep discharge use. They are the same as flooded batteries but with a fiberglass envelope around the plates, a catalyst to hopefully recover some water from oxygen and hydrogen gas, and the caps are glued shut. They cost more and don't last as long.

AGM is designed for shipping automobiles standing on their tails on rail cars, so the acid doesn't leak out.

There is not really any chemical reason they would charge faster. And they are less robust - overcharge once and they are ruined, while with a flooded battery you just put the water that boiled off back. Adding water once in 6 months seems such a low cost for a much better battery.

[Bailey'sMom]

I thought someone on the forum had posted a list of power consumption of the various items in a TrailManor such as lights, fridg, fantastic fan, heater fan, flushing toilet, etc which would allow a person to calculate how many amp hours or watts needed.

I can’t seem to find it.

Does anyone have a link?

[Bill]

http://www.trailmanorowners.com/foru...ead.php?t=7876

Bill

[J_Norris]

I'd love to see you try just so I can learn from your experience. I'm getting a LiFePO4 battery for my e-bike after lots of research into their safety and longevity (both much better than the LiIon batteries in phones).

I also still occasionally do backpacking and I think the tradeoff between cost and something being lightweight is personal and I really value quality lightweight gear of any kind.

In the interest of encouraging you, I found this that you may have already seen.

http://www.jenericramblings.com/2017...ng-to-lithium/

BTW, just because I want them to be a good idea doesn't mean they necessarily are I'll be considering them when we replace our batteries. So please report back on how you decided and why.