a great comparison of LI vs AGM jars

Mexican Wanderer

Our LFP battery suite has about 9 kW-hrs and a 4.0 kW PSWI. Son trailed system running microwave, air conditioner and a few other things just to see what would happen. We were drawing 3.5 kW through inverter from battery..

At this moment we are on beach about 20 km north of Tulum and we are running the Dometic energy hog air conditioner from battery suite and we are drawing 2200 W. We will recover tomorrow from solar - or we might plug into the shore power to recharge if it is overcast. We have done such 4 times in last two weeks since it rained all day on those occasions. Need to remove the Dometic and put in 48 V mini-splits. Battery suite is 48 V nominal and this would mitigate the energy loss of running power through the inverter.

Switching over to mini-splits would open space for two or more 235 W panels. But probably not need them since they are supposedly one heck of a lot more efficient.

Live on RV.net indeed

Reed and Elaine

atreis wrote:

MEXICOWANDERER wrote:
I'll be feeding a tree before lithium goes discount. A rechargeable AA lthium battery costs upwards of Twenty Dollars EACH.

Not a reasonable comparison for technical reasons.

Rechargeable Lithium batteries are natively 3.7V per cell. Getting one down to 1.5V requires some electronics inline that also results in them being a lot less efficient than competing technologies, such as NiMH. (BTW - not sure what the difference is with the non-rechargeable ones, which are relatively affordable.)

Disposable deep cycle house batteries?

MEXICOWANDERER wrote:
I'll be feeding a tree before lithium goes discount. A rechargeable AA lthium battery costs upwards of Twenty Dollars EACH.

Not a reasonable comparison for technical reasons.

Rechargeable Lithium batteries are natively 3.7V per cell. Getting one down to 1.5V requires some electronics inline that also results in them being a lot less efficient than competing technologies, such as NiMH. (BTW - not sure what the difference is with the non-rechargeable ones, which are relatively affordable.)

Another considerable source may be used electric car banks. Plenty of power left over for an RV but no good for motive power.

I'll be feeding a tree before lithium goes discount. A rechargeable AA lthium battery costs upwards of Twenty Dollars EACH. Like space flight photovoltaic in the sixties waiting until the seventies did not bring that much relief. Anyway I might end up shovelling coal.

brulaz wrote:
Besides the huge weight advantage, LiFePO4 batteries (the safe Li-Ion batteries) can be left partially charged indefinitely. In fact IIRC they prefer to be stored at around 50% SOC. For those of us with just solar, no generator, that's quite an advantage over AGM when boondocking with uncertain levels of sunshine. As long as you don't drop below 10% or over 90% SOC you are good.

However the cost is still prohibitive for me. Maybe next year?

There's many more yacht owners successfully running LiPO4. But maybe they have more money than most of us ...

All of the common Lithium chemistries do better if left at 40-50% SOC for long-term storage, not just LiFePO4. There are specialty chargers available that will put them into that state if you're preparing them for long term storage.

Cost: It's come down some. Hopefully it will come down more, just like other technologies. Batteries are slower to do that though.

MEXICOWANDERER wrote:
HERE'S THE FIRST AND MOST IMPORTANT COMPARISON!


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Versus

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Only if volume and weight are are of no concern

Hi Grizman,

One word. WOW!

grizzzman wrote:

Huntindog wrote:
What exactly is the problem with low tempertures for these batteries?
That is a serious shortcoming for my usage... A dealbreaker even if they were free.

Any chance that the technology may improve in that area?

Will -49 F work ? Look here

I really wonder if those Yttrium doped batteries can be charged at -45C like they claim. Know of no other LiFeP type battery that can be charged when below freezing.

In my pre-depression boat work, we all watched AGMs for a long time. They were the province of aircraft for a long time. Then when USPs became essential, the volume went up and the price came down. To date, I have fit no less than 4 performance cruisers and 8 competition keel boats with them and there is one more this spring. I am sure that when LiPos get closer to being cost effective, they will be in demand. Today, the ROI just is not there.

If it were a new build and you could do a 240V split stack and then chop that for AC power, we could do away with all the 12V power. That could well be nearly cost effective.

Matt