Lithium battery charging

vince56 · Senior Member

Lithium battery charging

Peter_n_Margaret · Senior Member

Some people like to make Li harder than it really is.
Let's start with "Why is your solar controller NOT "Li capable"?"

I solar charge my Li battery at 14.0V. That is LESS than that typically used for AGM and is the maximum that the rest of the system will generally see.
I then float the Li at 13.5V. They don't ever "punch out" "14+ volts".
In emergencies I also direct charge it from the alternator which runs at 14.2V. No DC-DC required.
Cheers,
Peter

vince56 · Senior Member

Hi Peter and thanks for your reply.
I was under the impression that solar controllers needed to be designated as Lithium capable for proper use with those batteries.
The reason I say 14+ is that I have seen many Li chargers advertised at 14.6V

I take it from your reply that any charger lead acid or not will do the job but not charge the Li batteries to their max??

Peter_n_Margaret · Senior Member

Li has a range of voltages that they can be charged at. What does your battery manufacturer state as appropriate.
Provided the charger does not EXCEED the recommended voltages it will probably be quite satisfactory. A little low won't hurt the battery but you may not get to quite 100% SOC. - So what? - It is probably better for the battery to be a tad low. Anything over 13.5 is probably OK.

Of course, everyone who sells chargers will tell you that you need a new one.
Cheers,
Peter

Jaahn · Guru

Vince I have two 40Ahr lithium batteries which I fitted into a battery box and made some external terminals and a ciggy socket (similar to ones you can buy now). I have used it as a portable power source eg for use outside the camper/home for lights or TV or what ever, it has powered a 12V tv while staying away for a year in a house, and I use it as a jumpstarter for (other peoples) cars, and have used it as an emergency car battery to drive a dead car home a couple of times.

I do not own a "lithium charger" and I use the car or camper if necessary or my solar on the camper, set for LA charging and even a small old 4A simple car battery charger if it needs some extra charging. Mostly I just put some leads to the camper LA batteries outputs or the car battery. Now people have said they will never last by treating them casually like that ! But they are now over 10 years old and I do not notice any reduction in capacity.

When I bought them the vendor told me charging them with a car or a car type charger was a suitable voltage and it has worked OK for me. I do not worry if the voltage falls a bit as Lithium do like that. You might loose a tiny bit of capacity but so what.

Some solar battery chargers for flooded LA batteries do have a extra higher voltage that is applied occasionally to stir the acid in the flooded cells. That should be set to off or to the same voltage as the normal charging voltage like you do for sealed LA batteries.

Cheers Jaahn

PS what is your car and does it have a smart alternator ?

-- Edited by Jaahn on Friday 13th of December 2024 05:34:12 PM

vince56 · Senior Member

Hi Jaahn,
Car is a 200 LC, I have a diode fitted to boost alternator output so should be thought of as a "normal" alternator.

TimTim · Guru

RE: Lithium battery chargingt

67HR · Senior Member

Lithium battery charging

67HR · Senior Member

67HR wrote:
Query for Tim,
I have a 4ah cetex charger that I've used for the last 8 years to charge my wifes car, the AGM 680CC in my jeep and ride on batteries.
If I want to charge my new LiFePO4 12.8 v 100ah battery what battery select do I use.?
I also have an older Electro charger that I can select votages up to 13.8v
Just wondering what would be best to use as I obviously don't need to float the lithium battery.
Cheers trev.

-- Edited by 67HR on Tuesday 17th of December 2024 02:21:56 PM

Here's a pic of the old electro unit.

vince56 · Senior Member

Hi Tim,
I will have a Renogy 40amp DCDC charger MPPT.
Cheers Vince

TimTim · Guru

67HR wrote:
Query for Tim,
I have a 4ah cetex charger that I've used for the last 8 years to charge my wifes car, the AGM 680CC in my jeep and ride on batteries.
If I want to charge my new LiFePO4 12.8 v 100ah battery what battery select do I use.?
I also have an older Electro charger that I can select votages up to 13.8v
Just wondering what would be best to use as I obviously don't need to float the lithium battery.
Cheers trev.

-- Edited by 67HR on Tuesday 17th of December 2024 02:21:56 PM

Hi Trev,

No idea about your CteK unless you have a model number and many are multi stage chargers.

Your Electro is a 15A charger so it will charge much faster than your 4A Ctek. Here is the manual for it if you dont have one.

https://catalogue.electroparts.com.au/manuals/BC-1210%2C1215%2C1220.pdf?_ga=2.205896276.699246294.1734495891-1316888989.1734495891

I would set it on charger, Gel and Float at 13.5V. Do not use the Calcium setting under any circumstances.

With Gel setting it should take it up to about 14.2V so if you have a multimeter you can charge it up to see what voltage it reaches, disconnect and let it rest for a couple of hours and see if it settles at about 13.4V to 13.3V.

Good luck

Tim

-- Edited by TimTim on Wednesday 18th of December 2024 04:11:45 PM

vince56 · Senior Member

BTW Tim, what's your take on storage of Lithium batteries? I have been told best to store at a lower voltage in battery, ie, not fully charged.

Are We Lost · Guru

The VoltX manual says to discharge down to 80% state of charge for best longevity when storing. I imagine it would not make a lot of difference but they are the ones who should know.

Peter_n_Margaret · Senior Member

Are We Lost wrote:
The VoltX manual says to discharge down to 80% state of charge for best longevity when storing.

But they never actually tell you WHY.

Cheers,

Peter

Are We Lost · Guru

Advice on storing at 80% SOC is fairly common. Are you saying the manufacturers are wrong about their own products? Renogy goes into a bit more detail and proposes a lower storage value than VoltX.

Renogy: How to store Lithium Batteries

Charge Level
The state of charge is a often-overlooked yet critical factor in lithium battery storage, especially for long-term storage. Unlike some other battery types, lithium-ion batteries should neither be stored fully charged nor completely discharged. The ideal charge level for storing lithium batteries is around 40-50% of their capacity.

Storing a lithium-ion battery at full charge puts stress on its components, potentially leading to a faster loss of capacity over time. Conversely, allowing a battery to discharge completely before storage can cause irreversible damage. If you're planning long-term storage of lithium batteries, periodically check and adjust their charge levels to maintain this optimal range.

Just about any lithium product you buy now comes out of the factory only partly charged.

-- Edited by Are We Lost on Wednesday 18th of December 2024 06:42:30 PM

Radar · Guru

My question is.

What is termed as storage of a battery.

At present the caravan is parked up for 2 months, I do not think this is a long time but is it.

Peter_n_Margaret · Senior Member

Being common does not mean credible any more than having to have a special charger.
Tell us WHY. If they can not or will not, I choose to view it with suspicion.
Cheers,
Peter

Are We Lost · Guru

Radar, I agree that 2 months hardly seems an issue.

Peter, I do not claim to be any sort of expert on batteries. If the manufacturers commonly recommend something I would pay more heed to that advice than random people on the internet. So what is it that you think is wrong with their advice? And as per your earlier comment ....

But they never actually tell you WHY.

Cheers,

Peter

Peter_n_Margaret · Senior Member

For a start, I can not find any evidence that Renogy actually manufactures LiFePO4 batteries.
Can you?
Cheers,
Peter

Are We Lost · Guru

No, and you may well be correct that they are not the manufacturer. But would you agree that Renogy would have in depth knowledge on battery technology that far exceeds yours or mine?

I asked Copilot (AI). Copilot said 50-60% state of charge was best. When asked why the answer was ...
Batteries degrade over time due to chemical reactions within the cells. These reactions are accelerated when the battery is at a high or very low SOC.

Storing at 50% to 60% SOC reduces the rate of these reactions, thereby prolonging the battery's life.

Of course, the wisdom of AI is not absolute (garbage in, garbage out), but the answers align with most of the manufacturer/supplier advice and make logical sense to me.

Anyway, I think it is becoming unnnecessarily pedantic over an issue where the advice is widespread. It may make little difference, although some sites say it is very important. But it seems the common expert advice is that storing LiFePO4 at 80% or lower state of charge is recommended.

Over and out.

Peter_n_Margaret · Senior Member

Renogy sell batteries. There is no way they would want their advice to be the opposite to everyone else's, so they may just choose to follow the flock?
Why then is the advice for Li different to that of any LA battery?
Cheers,
Peter

TimTim · Guru

vince56 wrote:
BTW Tim, what's your take on storage of Lithium batteries? I have been told best to store at a lower voltage in battery, ie, not fully charged.

Hi Vince,

Well I go against the grain on this one.

It is the cell manufacturers that are the ones that state that the cells should not be stored at 100%. The battery manufacturers and battery sellers then repeat that information and of course things get altered a little as you move down the line.

I did read the reasons why some time back but my brain can only hold so much information and I cannot remember the scientific reasons why but it is supposed to maximise the life of the battery. The same is stated about compression of the cells but I have only ever seen one battery where the cells were restrained against expansion.

My last batch of EVE cells arrived at 70% SOC so that would give you an indication of what the manufacturer considers to be storage SOC given that they take about 2 months to get to me.

With a specified lifespan of 5000 cycles (3000 for some batteries) until they drop to 80% capacity, my belief is that my travelling days will be over well and truely before they reach that level of capacity. I dont bother with worrying about storage SOC levels or length of time before it is considered storage. i just charge them up and let them sit there and just turn off the solar. I have two seperate banks and sometimes I just leave the solar charging one on float even though it is not needed.

These batteries are more robust than many will believe so whether you leave at 80%, 70% or 60% they are not going to suddenly die on you or even lose capacity at a rate that is noticeable. I will leave mine fully charged and maybe do a capacity test every few years just to check how they are going.

I wouldnt suggest or expect anyone to follow my lead but just to do what they feel comfortable with.

Good luck

Tim

Scubadoo · Veteran Member

TimTim wrote:

...
These batteries are more robust than many will believe so whether you leave at 80%, 70% or 60% they are not going to suddenly die on you or even lose capacity at a rate that is noticeable. I will leave mine fully charged and maybe do a capacity test every few years just to check how they are going.

I agree 100%.

Charge within parameters, store at 10 or 100% SOC and they are likely outlast the average RV anyway.

Far too much scaremongering from sellers and dare I say it the occasional forum poster.

Our Sinopoly 300Ah 4 cell LiFePO4 battery has survived 10 years of full-time travel powering both the motorhome and starting the 3.9l turbo diesel Canter truck engine.

At the last 5 November annual capacitity test and converted to Ah we have crashed from the original 315 to just 299. A whopping c5% loss!

At that rate I'm guessing at least another 20 years of capacity life but fully expect them to die of old age long before that but probably after me. hmm

We have never "stored" the battery. Our aim is 100% SOC every day but that only exists while the sun shines or driving.

Dick0 · Guru

I for one don't concern myself about storage recommendations. My batteries are always connected to solar whether travelling or in storage and set to "float" at 90%. If I get approx. 3000 cycles out of the batteries, I probably won't see the day when the batteries will need replacing. If you are worried about battery storage charge the batteries then isolate them from charge and loads and they will sit there happily until your next travels.