Lithium for dummies: need advice in simple terms

[profdant139]

I have been torturing myself, trying to develop some sort of a decision tree to see if I should convert to lithium batteries. I have searched the archive for a "lithium for dummies" thread and have come up empty. (If I'm wrong, I am sure someone will let me know! 😉 )

So that is what I am humbly asking for -- is there a really easy to understand site or article that explains or compares lithium batteries to lead/acid batteries for RV use and then guides the shopper through the steps needed to come to a conclusion?

Or maybe this thread can serve as a resource for those of us (like me) who do not have technical backgrounds?

In any event, here are my particular questions:

Aside from the obvious cost difference (which may or may not be a deal killer), my three biggest concerns are weight, capacity, and cold weather charging.

Weight: I am in my eighth decade (!) and am having trouble lifting a group 31 lead acid battery without hurting my back. It looks like lithium is a clear winner on that issue.

Capacity: I'm satisfied with the capacity of a group 31 -- it's nominally at 110 amp/hours, which means I can get about 55 amp/hours from the battery without risk of damage to the battery. Am I correct in concluding that if I were to get a lithium battery with 100 amp/hour capacity, I could use almost all of that capacity?

Cold weather: What does one do about charging a lithium battery when camping in sub-freezing weather? We really like snow camping -- is that a deal killer? We are almost never subjected to temps below ten degrees. And the daytime usually warms up to around 30 or so.

Thanks in advance for your help and advice -- and on behalf of all of us dummies, thanks for keeping it as simple as you can!

[PerryB67]

TechWriter wrote:
Did you get the SOKs with heaters?

The following is from SOK's web site:

SK12V206H designed for cold weather using! Can safely charge at temperatures down to -20°C (-4°F) by a standard charger or solar charger. The heater pads which draws power from the charger itself,battery cells no power lost.

The Sok heater only works when you are connected to a power source, i.e. plugged in at a campground, or during the day when you have adequate solar. If you're boondocking, when we would want a heater, they don't heat at night when it gets cold.

Enjoy,

Perry

[3_tons]

profdant139 wrote:
This post describes a DIY battery heater -- it is a little too sophisticated (well, actually a lot) for my skills or lack therof. But it looks to be a doable deal for technically-minded folks:

Li Battery Heater DIY

Well, if not so DIY inclined, a drop-in battery might be a far better option…

3 tons

[profdant139]

This post describes a DIY battery heater -- it is a little too sophisticated (well, actually a lot) for my skills or lack therof. But it looks to be a doable deal for technically-minded folks:

Li Battery Heater DIY

[theoldwizard1]

Cptnvideo wrote:
I don't know for sure but I would expect it would take a few hours below ambient freezing for the cells to get to freezing temperature. Therefore, I don't see the need for a heater.

Charging and discharging will produce some heat.

[Cptnvideo]

TechWriter, I guess I should explain what I meant about waiting for warmer weather.
We are currently NW of Phoenix with the highs currently reaching the upper 50s and the lows going to upper 30s-lower 40s. I'm a wuss and waiting for temps above 60° before I do the install.
Per SOK, the BMS will shut down charging at 0°C BATTERY temp (not ambient temp), but will allow discharge to a lower temp. Charging would be turned back on at 5°C. I don't know for sure but I would expect it would take a few hours below ambient freezing for the cells to get to freezing temperature. Therefore, I don't see the need for a heater.

[StirCrazy]

S Davis wrote:

StirCrazy wrote:

otrfun wrote:

StirCrazy wrote:

otrfun wrote:

theoldwizard1 wrote:
. . . What I don't know is if below freezing will affect the battery life while discharging or storing.

Specs vary from manufacturer to manufacturer, but generally speaking, maximum recommended discharge current tapers downward as temps drop below 32f or so. Probably wouldn't want to do more than a .10c - .15c discharge at temps below, say, -10c (14f).

Long-term storage recommendations are not too stringent. If you follow the temp recommendations for charging (typically 0-40c; 32-104f) that should be acceptable. If you want the absolute best for your cells, strive for 25c (77f) and 30-50% SOC.

the specs for the new cells I ordered are pretty good that way, 0.5C discharge down to -30C short term storage of a month -40C/F long term storage -25C and charger from -5C to +60C. but it totaly does depend on the manufacture and for premades, they tend to add a little more of a buffer so they have less warenty clames they have to pay.

Very impressive. As far as advertised specs, it can work both ways. Make them conservative so they can reduce warranty claims, or make it look like their cells walk on water to sell more cells/batteries. Me, I tend to give the research and testing produced by independent labs the most creedence.

these are the new K cells from EVE and the specs are from eve's testing sheets not a salesman 😉 . now am I going to set them to charge ar -5C, naa I'll keep it at +1 as my batteries are inside the living space so will never get that cold anyways, I may test the cold discharge though... well then again naa, I aint going camping at -30C haha, but the thing of interest to me was you can short term store much colder than long term (short term they describe as 30 days or less) and the fact that they seam to be a significantly more robust than the normal 280AH cells rated at 5000 cycles (100% to 0%) instead of 3500and I realy like the new double tapped termanals on them two bolts for power path instead of one skinny post.

Steve

They are not much more robust, they changed the testing specifications. The older LF280N that I have are rated at double the amp draw, 1c for 3500 cycles with a compression fixture. The new LF280K are rated at half that at .5c for 6000 cycles with a compression fixture.

Hmm, I just checked that out again and yes there was a cycle test chang, but eve actualy weighed in on it and they are a more robust construction and will still have more cycle life than the normal 280 which is why there being discontinued and the N and K will be the only two but the N are for local chinese sale only. but thats not the reason I am getting thoes ones, its the termanal blocks they have.

new bocks

Steve

[Cptnvideo]

No, I did not. And I don't plan to be in 32° weather either. LOL

[TechWriter]

Cptnvideo wrote:
I like the SOK 206ah LFPs so much that I just bought 2 more. Haven't installed them yet as I'm waiting for the weather to warm up a little. That will bring my total capacity to 1030 ah.

Did you get the SOKs with heaters?

[Cptnvideo]

I like the SOK 206ah LFPs so much that I just bought 2 more. Haven't installed them yet as I'm waiting for the weather to warm up a little. That will bring my total capacity to 1030 ah.

[S_Davis]

StirCrazy wrote:

otrfun wrote:

StirCrazy wrote:

otrfun wrote:

theoldwizard1 wrote:
. . . What I don't know is if below freezing will affect the battery life while discharging or storing.

Specs vary from manufacturer to manufacturer, but generally speaking, maximum recommended discharge current tapers downward as temps drop below 32f or so. Probably wouldn't want to do more than a .10c - .15c discharge at temps below, say, -10c (14f).

Long-term storage recommendations are not too stringent. If you follow the temp recommendations for charging (typically 0-40c; 32-104f) that should be acceptable. If you want the absolute best for your cells, strive for 25c (77f) and 30-50% SOC.

the specs for the new cells I ordered are pretty good that way, 0.5C discharge down to -30C short term storage of a month -40C/F long term storage -25C and charger from -5C to +60C. but it totaly does depend on the manufacture and for premades, they tend to add a little more of a buffer so they have less warenty clames they have to pay.

Very impressive. As far as advertised specs, it can work both ways. Make them conservative so they can reduce warranty claims, or make it look like their cells walk on water to sell more cells/batteries. Me, I tend to give the research and testing produced by independent labs the most creedence.

these are the new K cells from EVE and the specs are from eve's testing sheets not a salesman 😉 . now am I going to set them to charge ar -5C, naa I'll keep it at +1 as my batteries are inside the living space so will never get that cold anyways, I may test the cold discharge though... well then again naa, I aint going camping at -30C haha, but the thing of interest to me was you can short term store much colder than long term (short term they describe as 30 days or less) and the fact that they seam to be a significantly more robust than the normal 280AH cells rated at 5000 cycles (100% to 0%) instead of 3500and I realy like the new double tapped termanals on them two bolts for power path instead of one skinny post.

Steve

They are not much more robust, they changed the testing specifications. The older LF280N that I have are rated at double the amp draw, 1c for 3500 cycles with a compression fixture. The new LF280K are rated at half that at .5c for 6000 cycles with a compression fixture.

[profdant139]

OK, Steve, I'll continue to display my ignorance -- what are double tapped terminals, and why are two terminals better than one? And why a fat terminal vs a skinny one?

The more I know, the more I realize how much I don't know.

[StirCrazy]

otrfun wrote:

StirCrazy wrote:

otrfun wrote:

theoldwizard1 wrote:
. . . What I don't know is if below freezing will affect the battery life while discharging or storing.

Specs vary from manufacturer to manufacturer, but generally speaking, maximum recommended discharge current tapers downward as temps drop below 32f or so. Probably wouldn't want to do more than a .10c - .15c discharge at temps below, say, -10c (14f).

Long-term storage recommendations are not too stringent. If you follow the temp recommendations for charging (typically 0-40c; 32-104f) that should be acceptable. If you want the absolute best for your cells, strive for 25c (77f) and 30-50% SOC.

the specs for the new cells I ordered are pretty good that way, 0.5C discharge down to -30C short term storage of a month -40C/F long term storage -25C and charger from -5C to +60C. but it totaly does depend on the manufacture and for premades, they tend to add a little more of a buffer so they have less warenty clames they have to pay.

Very impressive. As far as advertised specs, it can work both ways. Make them conservative so they can reduce warranty claims, or make it look like their cells walk on water to sell more cells/batteries. Me, I tend to give the research and testing produced by independent labs the most creedence.

these are the new K cells from EVE and the specs are from eve's testing sheets not a salesman 😉 . now am I going to set them to charge ar -5C, naa I'll keep it at +1 as my batteries are inside the living space so will never get that cold anyways, I may test the cold discharge though... well then again naa, I aint going camping at -30C haha, but the thing of interest to me was you can short term store much colder than long term (short term they describe as 30 days or less) and the fact that they seam to be a significantly more robust than the normal 280AH cells rated at 5000 cycles (100% to 0%) instead of 3500and I realy like the new double tapped termanals on them two bolts for power path instead of one skinny post.

Steve

[otrfun]

StirCrazy wrote:

otrfun wrote:

theoldwizard1 wrote:
. . . What I don't know is if below freezing will affect the battery life while discharging or storing.

Specs vary from manufacturer to manufacturer, but generally speaking, maximum recommended discharge current tapers downward as temps drop below 32f or so. Probably wouldn't want to do more than a .10c - .15c discharge at temps below, say, -10c (14f).

Long-term storage recommendations are not too stringent. If you follow the temp recommendations for charging (typically 0-40c; 32-104f) that should be acceptable. If you want the absolute best for your cells, strive for 25c (77f) and 30-50% SOC.

the specs for the new cells I ordered are pretty good that way, 0.5C discharge down to -30C short term storage of a month -40C/F long term storage -25C and charger from -5C to +60C. but it totaly does depend on the manufacture and for premades, they tend to add a little more of a buffer so they have less warenty clames they have to pay.

Very impressive. As far as advertised specs, it can work both ways. Make them conservative so they can reduce warranty claims, or make it look like their cells walk on water to sell more cells/batteries. Me, I tend to give the research and testing produced by independent labs the most creedence.

[StirCrazy]

3 tons wrote:
“And by "storage," I mean "whenever I'm not actually on a camping trip, the batteries go onto the trickle charger."

LFP’s Uber low self-discharge rate makes the solution to this quandary easy…I simply added a battery ‘side’ post knife switch disconnect from Amazon which isolates the battery whenever camper is not in use…No need to keep on a trickle charger….In this way shore power (if available?) can continue to be used to operate the 12v systems via the onboard converter-charger…

I just don't plug in at home anymore and shut off my solar. no parasitic draws in my 32 yeear old camper... as long as I am under 90% I am happy for winter storage.

in the summer I turn the solar the morning before we are going camper so it is full when I leave and it can do its top ballance then I change the profile to run from 10% to 90%. I figure one top ballance for eaxh camping trip is enough.

when we upgrade I'll probably have to add somthing like that to my battery.