this post was submitted on 30 Jan 2025
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AGM are absolutely awful compared to even the absolute worst lithium batteries, and won't last long at all if regularly cycled below even 50% SoC. LFP chemistries are a bit worse for energy density compared to NCA/NCM chemistries, but they don't contain any nickel or cobalt, and won't autoignite in the same way other chemistries will. Absolutely ridiculous they're suggesting lead batteries over better lithium options.
I thought AGM were considered "deep cycle", as in designed for their full capacity to be used between charges.
There are some possibly inaccurate and definitely confusing statements in the reply you got, but the first part, that agm is a physical structure of the lead acid battery that can be tipped over without making a giant mess and that deep cycle is another function of design as opposed to a function of the lead acid chemistry is correct.
What’s left unsaid is that lead acid batteries which are damaged and not working right anymore have a much safer and lower tech recycling process than lithium ones do and that’s saying something because one of the parts is lead!
Thanks! The other reply obviously meant well but was a bit mansplainey !
My situation is, I've recently purchased a camper trailer. It's wired up but needs a battery. I haven't had time to "research" other than seeing what batteries people are selling second hand. It seemed to me that everyone was using AGM batteries for this purpose and while I knew that AGM referred to the physical structure of glass mesh I had assumed it was synonymous with deep cycle batteries.
Now I've read about it a bit more I realise that LiFePO4 batteries are superior but more costly.
I guess, the reason why I was seeing AGM batteries everywhere is because everyone's buys them because they're cheap and then realises they really needed LiFePO4 so they try to sell the AGM and upgrade.
I’m a wet cell lead acid man myself.
There’s the monthly battery fluid level check to contend with but if you can make sure it doesn’t tip over too often or too long and you can bank on being able to get to civilization once every six or ten years then you’re in the low total cost of ownership ecosystem.
Of course, they’re not as good in the cold and if you screw up and let all the water leak out then you gotta fill it back up and hope it’s not too messed up.
Whatever you pick will be fine. Tbh if you’re not gonna have the trailer for longer than the life of the battery, pick the one that’s got more curb appeal or resale value!
Fair enough.
It seems like on an e-bike Lithium would be the go due to it's higher energy density.
On a trailer you can house it in something appropriate and the size and weight requirements aren't as restrictive.
It seems like keeping the battery is a common practice when selling a trailer. That's why mine doesn't have one. A lot of people would never use one if they're always parked in someone's yard or in a powered site.
I doubt we will really need a battery at all over the next 6 months with the trips we have planned. Probably better to hold off until we have a few trips under our belt to determine exactly what appliances we're really going to need.
AGM just means the acid is held inside a glass mat, like fibreglass structure so instead of liquid it's like a sponge. This gives it less maintenance and more shock absorption, can also be turned or tipped over without issue. It's still lead acid just not held in liquid form.
A lead acid based battery can be deep cycle or starter or both. Being deep cycle basically means the plates inside the are battery thicker, which allows it more tolerance for being depleted as well as generally more reserve.
A real easy way to understand it that I found (when explaining it to customers without a technical background.)
Imagine instead of electricity it's water. A deep cycle battery is simply a larger tank of water with a regular size pipe to get the water out. A starter battery is a regular size tank with a large pipe to get the water out.
So if you need to start a engine that needs a chunk of water(electricity) all at once to start it , a starter battery can provide it but doesn't have alot of reserve behind it so the pipe cant stay open very long.
The deep cycle can't provide the large rush of water at once(cca) but does have lots of reserve so the pipe runs longer.
Both suffer from reduced flow(voltage drop) as the tank empties. Imagine the pipe not able to be completely filled as the tank drained, you still get water but the rate is reduced as the pressure behind drops. Both suffer damage if left too empty or are drawn too low, a deep cycles design just gives it far more tolerance to that depleted state, allow it to be cycled more( charged from empty) more times before the battery fails.
Dual purpose batteries are basically large tank, large pipe.
It's worth noting that DC voltage only draws what it needs, you can hook up the largest battery bank to the smallest load with no issue as far as the size of the bank etc if everything is setup and function correctly.
Lithium suffers from none of these drawbacks. (As well as many more advantages) Gotta use the newer tech that is far safer though. Early Lithium and most cheap none reputable stuff is using the riskier tech with substandard QC.
Do we have enough mineral resources for all the batterie needs to be to fulfilled with lithium only?
I guess china needs lithium in other places more and cheap. Therefore made this initiative. Makes sense for china to protect their lithium stack. International trade in near future gonna be a mess.
And even if you only cycle lead batteries above 50% SOC, they will still last a significantly shorter amount of time, especially compared to LiFePo4 batteries.