AGM vs lithium house batteries

[Mat7783]

What is the technical difference in load discharge between these types of batteries? The lithium’s are more superior and of course expensive, so is it worth the cost. I haven’t done a detailed calculation yet, but plan to run 12v lites, water pumps,120v fridge 7.3cu’, 700w microwave,etc. thinking of 3kw inverter. So I am not sure about how many 200ah batteries to use? Is there a downside to using too many in a bank like 4 of them( 800ah)??😎

[Danjo]

Hey, I’m just now researching a solar design. I’ve run across this in the course of being here. Not sure who posted originally and I don’t quite get it yet, but it might be of interest to you

https://www.solarpaneltalk.com/forum...utorial-part-2

I just read through it again and maybe it’s not helpful. Good site though.

[Mat7783]

I meant to say 4 100ah batteries fir a total 400ah.

[Ronnie]

Interesting link. Must say I have to wonder about it though as most of us have inverters that are way more then solar panel wattage. For me 400 watts of solar panels, 1000 watt inverter, 220 amp of batteries. It all works well for me. Thing is my fridge has a high start load as would most any fridge, and I need the power from the inverter but for only a second, then after the compressor starts the load is minimal. If I had the size inverter as the article says I should it would never start the fridge.

I hope someone with experience other then me has something to say about AGM. I have used them for many years now in boats and campers and I get about twice the life of a FLA, flooded lead acid battery.

[john61ct]

Originally Posted by Mat7783

I haven’t done a detailed calculation yet, but plan to run 12v lites, water pumps,120v fridge 7.3cu’, 700w microwave,etc. thinking of 3kw inverter.

You need to learn more to ask the right Qs.

> What is the technical difference in load discharge between these types of batteries?

If you mean discharge C-rate, aka power density LFP is at least 10x better.

But do you need that?

> Is it worth the cost?

To many unknowns, really only you can answer after getting up to speed.

Probably not is my WAG.

> I am not sure about how many 200ah batteries to use. Is there a downside to using too many in a bank like 4 of them( 800ah)?

First get your target total Ah capacity, need an Ah per 24hr consumption budget, and description of your camping / usage off grid patterns, weather, driving etc etc.

Then decide on bank chemistry.

Only then start thinking brands models cell size etc.

[PNW_Steve]

Originally Posted by Danjo

Hey, I’m just now researching a solar design. I’ve run across this in the course of being here. Not sure who posted originally and I don’t quite get it yet, but it might be of interest to you

https://www.solarpaneltalk.com/forum...utorial-part-2

I just read through it again and maybe it’s not helpful. Good site though.

There is a TON of good battery and solar knowledge on that site. The stickies regarding batteries should be a "must read"

[enigmamdw]

Other than high C ratings, the only benefit of lipo is space/weight (power/weight ratio.) In our format unless you are building out a shorty bus those are not really an issue. These buses for the most part have a Governed load weight of ~36K lbs. Most builds don't get to that point.

Also lipo requires more expensive electronics for charging and using. they are less "flexible" with things like temperatures and over discharging, etc...

I'm personally going lipo because I'm familiar with it and i'm extra like that.

[john61ct]

FYI: The term "LiPo" has nothing to do with the LI chemistry LFP, which is what is used for non-propulsion storage banks.

LiPo is not even a chemistry really, more a materials & packaging technology to get even lower weight per kW and kWh.

Risk of thermal runaway is infinitesimal with LFP, while the other higher-density chemistries like LCO, LMO, NMC & NCA are very very dangerous.

[john61ct]

Originally Posted by Ronnie

I hope someone with experience other then me has something to say about AGM. I have used them for many years now in boats and campers and I get about twice the life of a FLA, flooded lead acid battery.

There are top-notch very expensive per Ah deep cycling AGM batteries that can last 8-10 years if coddled. EoL defined at say 75% SoH.

Mostly 5-7 years is considered good.

There are in the NA market very cheap FLA units, $1/Ah @12V, that can last even longer, and expensive ones that routinely go over a dozen.

In general FLA is much better value at least in NA. Not so much overseas, where everyone drank the AGM koolaid in the 90's and good FLA is a lot more expensive