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 > Lithium for dummies: need advice in simple terms

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profdant139

Southern California

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Posted: 12/05/22 05:36pm Link  |  Quote  |  Print  |  Notify Moderator

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! [emoticon] )

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!


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mordecai81

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Posted: 12/05/22 06:31pm Link  |  Quote  |  Print  |  Notify Moderator

I went from an 83lb 150 a/h lead acid battery to a 33lb 125 a/h lithium in large part because of the weight. My battery lives on the tongue wrapped in a battery heater wrap that is powered by the battery itself, so I can charge in below freezing temps. There are now many batts with internal heaters that would be an easy solution to low temp charging.
Besides the weight savings, the other main reason for us going to lithium was the faster generator charging to full on low solar days. I've cut my genny running time by 2/3 when parked in the shade, which is typical for us on days we aren't traveling. I do have a good stand-alone 60 amp charger with a lithium setting.
You can use almost all the available a/h in a lithium. If you don't have a good battery monitor and are just guesstimating the amps in and out you'll have to be conservative and leave a decent buffer on the bottom end to ensure the fridge and furnace keep running through the night.

StirCrazy

Kamloops, BC, Canada

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Posted: 12/05/22 07:30pm Link  |  Quote  |  Print  |  Notify Moderator

profdant139 wrote:

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! [emoticon] )

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.

yes aproximatly 1/2 the weight. I replaed two 79 lb 6V batteries that gave me 104 usable AH with one 300AH LifePo4 that weighs 48lbs.

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?

yes, but with a condition. you will only get the minimum rated cycles , but if you stay a little off the top and bottom, and keep to deciently shallow discharges, you can greatly improve the cycle life. so instead of 3000 cycles you could get as high as 7000 depending how you set it up and what kind of cells they used.

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.

there is no off hasing with these batteries so you can move them into the living space. got a cabnet you never use or a space some where else. you can dischare to -20C or -30C if they use the K varent of cell so once you get the furnace going and the space warmed up there is no issue. or some people just use a heating pad and some insulation around the battery to keep it warm. lots of ways to get around this.

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!



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OkieGene

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Posted: 12/05/22 07:49pm Link  |  Quote  |  Print  |  Notify Moderator

A new feature now is a Lithium battery with a self-heating feature. It uses a small portion of it's stored power to heat itself up.

You should be able to google that, lithium iron phosphate battery with self heating.

And as noted above, you can keep them inside the coach, or in a heated bay, and all will be fine.

TechWriter

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Posted: 12/05/22 09:48pm Link  |  Quote  |  Print  |  Notify Moderator

profdant139 wrote:

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.

Lithium batteries should not be charged when temps drop below freezing. Doing so could damage the battery.

At the very least, buy lithium batteries that have a built-in BMS (Battery Management System) that also have low temp sensors which will turn the batteries off when they get too cold. Getting batteries with internal heaters is also a possibility.

If you like snow camping, then make sure you at least have lithium batteries with low-temp sensors. Relying on "warm" battery compartments is foolish.

However, be advised that many (most?) inexpensive lithium batteries do NOT have low temp sensors or heaters. Make sure before you buy.


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pianotuna

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Posted: 12/05/22 09:50pm Link  |  Quote  |  Print  |  Notify Moderator

profundant,

20% to 85% for Li, so the 100 amp-hour has 75 amp-hours that are usable.

charge them to 100% once every 30 days to reset the battery management system.

Use a dc to DC charger for alternator protection, if planning to charge from the engine.

I can't use LI where I live. Too cold for them. For those that can avoid cold LiFeP04 are the cat's meow.

I would go for SiO2 myself.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

profdant139

Southern California

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Posted: 12/05/22 09:52pm Link  |  Quote  |  Print  |  Notify Moderator

Great point about the absence of out-gassing -- I did not know that, and it would make it possible to bring the battery inside.

If only I had some extra room! Very tiny trailer -- 12 foot box, believe it or not.

Keep those comments coming -- thanks to all of you!

Tom/Barb

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Posted: 12/05/22 09:56pm Link  |  Quote  |  Print  |  Notify Moderator

I converted to lithium batteries 4 years ago, Our battery compartment is not heated.
We have seen temps as low as 19 degrees f.

no issues


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theoldwizard1

SE MI

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Posted: 12/06/22 02:28am Link  |  Quote  |  Print  |  Notify Moderator

profdant139 wrote:


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?

I would say you are optimistic about the capacity of your lead acid batteries if you want the maximum life.
"Almost all" is a good way to say what the maximum capacity of lithium batteries are.

profdant139 wrote:


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.

So if your cold weather camping and concerned about battery charging, then you are getting your power from the sun or a generator. If power from your source is not an issue they sell heaters you install under the battery. You can also install the batteries inside a heated RV as they do NOT let off any gases.
Discharging does generate some heat but if you stored them "outside", I would want a well insulated box with heaters. Heaters usually draw power from the battery so you will lose a fair amount of capacity.

Unless you are DIYing your own battery pack, make certain that the internal charge controller will shut down charging during cold operation. Not all have this feature.

wa8yxm

Davison Michigan (East of Flint)

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Posted: 12/06/22 04:11am Link  |  Quote  |  Print  |  Notify Moderator

profdant139 wrote:


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?

There are several differences The biggest ones are as follows.

First there are multiple types of Lithium batteries the one you want is LiFePO4 (Lithium Iron Phosphate).

Now. These batteries have a slightly higher voltage so you really need a converter/charger set for them Progressive Dynamics makes one and sells it through Battle Born Batteries (BB also sells very good LiFePO4 batteries)

You would have to talk to BB about engine charging on a motor home or tow vehicle charging on a trailer (GM alternators I believe WILL charge LI's don't know about Found On Road Dead (FORD) alternators)

The batteries have a very "Tight" discharge curve.. Where with Lead Acid (LA) batteries they start FULL then go FULl FUll. Full full dowN doWN doWN dOWN DOWN LiFePO5 basically go FULL FULl FULl FULL FULl Dead. (The voltage does not drop much till the very end)

Where as LA battereies need to be 50 or 75% full or more.. Li 5% won't kill 'em so you can use most all the stored energy.

Finally Where as you can charge LA batteries from like -30 or lower to hotter than hadies.. LiFePO4 do not like to be charged below Freezing.. Some have temp sensors and heaters.. Some CLAIM they do but don't.. Some simply do not. Again I beileve BB does have heaters and will heat up first. then charge.

All in all... I plan on changing my house 12 volt system to LI. it will only require new batteries and a slight re-progam on the programmable charger.


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