Lithium battery configuration

As I understand it, sulphation occurs in lead acid batteries any time they are not fully charged. Sulphation is what kills lead acid batteries. The deeper the discharge, the greater the rate of sulphation. Charging reverses the sulphation but not completely. The deeper the discharge, the less reversible is the sulphation. The longer the battery is discharged, the less reversible is the sulphation.
Thus for maximum battery life, both the depth of discharge and the period of discharge should be minimised.

LiFePO4 cells do not have this problem, and thus can be more deeply discharged without reducing their life as much as with lead-acid.

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Originally Posted by Silenceisgolden

The deeper the discharge, the greater the rate of sulphation.

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This statement is not correct.

You can discharge any deep cycle battery down to the manufacturers stated limit and recharge the battery to its fully charged state.

Many batteries are used this way, for example, those used in golf buggies and electric folk lifts, and they do not loose capacity just because they have been deeply discharged.

Theoretically, if you discharge any battery below 75% SoC and LEAVE IT FOR SOME TIME, then sulphation will occur, but only if you leave the battery in a discharged state for more than 24 hours.

While a battery is under load or being charged, there is a chemical reaction occuring in the battery.

While this chemical reaction is occurring, no sulphation will occur, and the chemical reaction in a battery can take up to 24 hour to stop, after charging or discharging has been removed.

Also, leaving a battery in a fully charged state for long periods of time between charges will also allow a battery to slowly sulphate, because all lead acid batteries SLOWLY self discharge.

Sulphation can only occur if a battery is allowed to settle and then left for some time, it does not occur in batteries that are continually cycled.

Earlier it was mentioned running a CPAP. I have a portable CPAP which came with a lithium battery with enough capacity to power it for 2 nights. I recharge it during the day when the house is making plenty of solar. Being portable I can take it everywhere, even on planes. This might be a way to cut your usage.

Tim, I would like to hear your thoughts more deeply on this discussion and also that of others, with knowledge of the topic.

Whilst we embrace this new technology and can get swept up in the hype, what are we really getting for our $$$ and sales hype ?
As I understand it, the Lithiums do have definite advantages in (generally) being able to run down to extremely low levels and be fully recovered which is great.
Certainly in uses like torches etc and other rechargeable batteries where we can avoid having to throw away used product after its limited life, it's good.

But let's stick to what I want to know is fact from sales hype and the new you-beaut follow the mob toy. It's, to me, about the battery construction and ability to survive the purpose for which it's manufactured.
A battery in hard working machinery like a tractor, truck etc exposed to continuous jarring and hard movement, corrugations etc has to be internally stronger than one used in more passive conditions.
Why is a marine battery different to a family car battery, for instance.

So, how is a 12v lithium battery constructed and is it internally more stable than other lead acids, calcium or what ever they claim it is. Being cynical, I see a lot of batteries that look to have the same case construction
with just a different label slapped on the outside.

JohnC

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Originally Posted by Salt grinder

Tim, I would like to hear your thoughts more deeply on this discussion and also that of others, with knowledge of the topic.

Whilst we embrace this new technology and can get swept up in the hype, what are we really getting for our $$$ and sales hype ?
As I understand it, the Lithiums do have definite advantages in (generally) being able to run down to extremely low levels and be fully recovered which is great.
Certainly in uses like torches etc and other rechargeable batteries where we can avoid having to throw away used product after its limited life, it's good.

But let's stick to what I want to know is fact from sales hype and the new you-beaut follow the mob toy. It's, to me, about the battery construction and ability to survive the purpose for which it's manufactured.
A battery in hard working machinery like a tractor, truck etc exposed to continuous jarring and hard movement, corrugations etc has to be internally stronger than one used in more passive conditions.
Why is a marine battery different to a family car battery, for instance.

So, how is a 12v lithium battery constructed and is it internally more stable than other lead acids, calcium or what ever they claim it is. Being cynical, I see a lot of batteries that look to have the same case construction
with just a different label slapped on the outside.

JohnC

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When we choose to upgrade I didn’t think there was any sales hype or felt the need to follow the mob. There is enough solid info out there along with thousands of installations that are working fine for what the end user wants. Go with the ‘brand’ name batteries and it’s a pretty safe bet.

Lithium to me is just another option depending on ones needs. Will suit some but not others.

For us it was the only way to go.......it’s factored into our budget for our two year trip and the install only needs to last 4 years and it’s done it’s job....although fully expect it to be powering on well after.

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Originally Posted by Salt grinder

Tim, I would like to hear your thoughts more deeply on this discussion and also that of others, with knowledge of the topic.

Whilst we embrace this new technology and can get swept up in the hype, what are we really getting for our $$$ and sales hype ?
As I understand it, the Lithiums do have definite advantages in (generally) being able to run down to extremely low levels and be fully recovered which is great.
Certainly in uses like torches etc and other rechargeable batteries where we can avoid having to throw away used product after its limited life, it's good.

But let's stick to what I want to know is fact from sales hype and the new you-beaut follow the mob toy. It's, to me, about the battery construction and ability to survive the purpose for which it's manufactured.
A battery in hard working machinery like a tractor, truck etc exposed to continuous jarring and hard movement, corrugations etc has to be internally stronger than one used in more passive conditions.
Why is a marine battery different to a family car battery, for instance.

So, how is a 12v lithium battery constructed and is it internally more stable than other lead acids, calcium or what ever they claim it is. Being cynical, I see a lot of batteries that look to have the same case construction
with just a different label slapped on the outside.

JohnC

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Hi John, I am flat out but will give you a reply in the next few days.

Your questions are important ones to answer, as the lithium battery market is a mine field and you do need some basics to protect your pocket.

one of the hardest things to get right when installing a lithium setup is dealing with charging them.

They dont like being hard charged, if youve got a discharged lithium (not to the point its cut out) and try charging it straight off a large alternator the alternator will deliver too much current and cook up the lithium battery.


one thing I have always wanted to experiment with is to match the alternator to the peak charge rating of a lithium bank and let that provide source current. its not quite as simple as putting a 35a alternator onto a bank that can handle a 35a charge because as you load up an alternator as it struggles to make voltage the amps go up to maintain maximum rated watts...

but back of the napkin maths suggests that if you have a lithium pack rated to 40a charge peak you should be ok to directly run that off of a 30a alternator thats been tweaked to peak at 14.2v (or whatever your flavor of lithium likes for a peak charge voltage)

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Originally Posted by Blknight.aus

one of the hardest things to get right when installing a lithium setup is dealing with charging them.
)

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For the majority of lithium battery users (caravan, touring) charging is straight forward.......between a DC-DC and the batteries BMS it all looks after itself.

Unless off course you have a unique setup or need....than it’s easy peezy, install, set, forget.

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Originally Posted by W&KO

For the majority of lithium battery users (caravan, touring) charging is straight forward.......between a DC-DC and the batteries BMS it all looks after itself.

Unless off course you have a unique setup or need....than it’s easy peezy, install, set, forget.

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IF you're buying a complete ready to go system that comes prematched from the one supplier yes, but once you're out of that environment it can get "sketchy" It is getting a lot easier now with many reputable suppliers providing a lithium setting on their chargers and DC/DC systems, hell I even got a tip from my local jaycar guy to check out the website of the company that provides their older chargers for a bulletin that describes what settings to use if you want to use their older non lithium compatible regulators on a lithium bank (which is loosely translated, "Dont unless the charge capacity of the bank is higher than the rated output of the regulator" and then some maths on how to set the float, bulk and absorbsion charge voltage limits)

I'm waiting on the newer format of batteries to come out at a reasonable price which perform similarly to normal led batteries as far as hooking them up is concerned as all of the management is built into the battery.
similar to this one in the lnk below but with the ports on the top of the battery that allow BMS linking for when you connect them in series and a trickle charge jack that allow you to charge them very slowly if you over discharge them

reBel Batteries - 12V 100A LiFePO4 Tear Down - Inside a Lithium Iron Phosphate Battery - YouTube

A video from Stephan who used to frequent this site with a good rundown on how he is using lithium.

https://www.youtube.com/watch?v=FbStDC-7Q9E&t=10s