Litium car audio batteries

[KilluminatiDre 10+ year member]

Someone send me a battery to test, i live in a warm dry climate lol

 

[Papermaker85 5,000+ posts]

Someone send me a battery to test, i live in a warm dry climate lol

they have a video on YouTube I don't see no benefit except the weight

 

[kr15 5,000+ posts]

JY claims their 45ah can provide a 2500a burst for 3 seconds. But the math tells me their battery can only sustain about 3-400a with minimal drop, and 8-1000a on burst.

I think the issue is they advertise that, and in real world application, theres no way it will discharge 2500a. So the guy clamping 25k thinks all he needs is 1 jy 45ah.

This is where I get confused. Where should that battery be truly rated? Conservative 400a rating? Appearant 800a burst rating? Or pixie dust 2500a rating?

 

[shizzzon 10+ year member]

Yes? I don't see what's so hard...

A single G31 has over 2000 cranking amps.. I don't see anyone trying to size their system off that...

Lithium terminology is literally the easiest method for sizing calculations. Agm is all guess work and from experience only.

 

[shizzzon 10+ year member]

Have you done any testing with these in parallel with other types of batteries, and caps?
I'd imagine with other things in parallel I could get away with excess charging capability because it'd be split between other things but you're doing a lot of testing so maybe you have some insight.

No. These are the kind of cells to work best probably with a single alternator.

If running duals, you'd just need more ah but these hold voltage under load so well, adding more ah just for the fact you already have large charging system will not increase voltage as much as increase reserve capacity.

 

[hispls 5,000+ posts]

Agm is all guess work and from experience only.

Of course the fact that thousands of people have been using them for the last couple decades rather provides enough data that there is zero guesswork. In fact any of us with a few builds under our belts has a very good idea of how many AH worth of AGM batteries hangs with how much power.

What nobody is delivering is, for example, saying "I replaced 5 group 31 AGMs with one 80AH lithium and do the exact same numbers on bass race and burp". It is implied that you "need" less amp hours with lithium but nobody is actually offering up a ratio or any hard testing data.... which just seems pretty shady.

 

[shizzzon 10+ year member]

Lol. no you have it backwards.

Provide any model AGM battery and try to estimate what it's voltage drop and time to depletion is with just the specifications given..

I guarantee you cannot.(besides just the ah and cranking amp rating which is common sense).

You can with lithium most of the time.

This is why C rate is given. Provide several C rates and a graph.. Which most all AGM companies do NOT do.. and you can estimate very close precisely how much ah in lithium you need.

The only reason why people know how much AGM they need now is what i said earlier.. from experience.

I have provided enough C rates AND capacity shifting difference in a 15C bandwidth to know exactly how long these cells work at practically any C rate and holding voltage.

For those that still do not understand that, lithium is not for you yet as that's just scratching the surface of the information that one should know about lithium.

 

[JohnKuthe]

Anyone have any real world experience with lithium car audio batteries? Theres a new company out thats selling these with claims that their 40 ah will sustain 4500 rms on a stock alternator. Only videos i can find so far are theirs.

Lithium batteries/cells have a DIFFERENT VOLTAGE than to lead-acid cells/batteries. It's called "electronegativity", an inherent property of comparison of electromagnetic properties of the elements involved! Learn about electrochemistry and you MAY understand.

John Kuthe,...

 

[wew lad 5,000+ posts]

No. These are the kind of cells to work best probably with a single alternator.
If running duals, you'd just need more ah but these hold voltage under load so well, adding more ah just for the fact you already have large charging system will not increase voltage as much as increase reserve capacity.

Thanks, better off with more caps at this point then considering I have 320dca at idle, about 280dca surplus for the system

 

[Boominburban 10+ year member]

Its not letting me get to the last page again ....

 

[shizzzon 10+ year member]

Of course the fact that thousands of people have been using them for the last couple decades rather provides enough data that there is zero guesswork. In fact any of us with a few builds under our belts has a very good idea of how many AH worth of AGM batteries hangs with how much power.
What nobody is delivering is, for example, saying "I replaced 5 group 31 AGMs with one 80AH lithium and do the exact same numbers on bass race and burp". It is implied that you "need" less amp hours with lithium but nobody is actually offering up a ratio or any hard testing data.... which just seems pretty shady.

I have time now to answer this directly.

We mentioned earlier AGM offers NO formula for providing how many you need for any given install..

You even said it yourself-

" In fact any of us with a few builds under our belts has a very good idea of how many AH worth of AGM batteries hangs with how much power."

Like i've said over and over.. ONLY those with experience know how many batts they would need. Poor way of manufacturing batteries.

Now, you want to know this-

""I replaced 5 group 31 AGMs with one 80AH lithium and do the exact same numbers on bass race and burp". It is implied that you "need" less amp hours with lithium but nobody is actually offering up a ratio or any hard testing data...."

Let me break this down because I am.. others are, etc.. I just think many people in this thread just have not done any lithium research on terminology..

For one, let me tackle this statement-

"I replaced 5 group 31 AGMs with one 80AH lithium and do the exact same numbers on bass race and burp"

For one, what if you said i replaced 5 G31 XS Powers with X amount of G31 Duracells and do the same number..

Where is the formula or ratio for that? There isn't going to be one answer at all. Why?

Because this question doesn't provide the DATA required to do so such as -

Static current draw, starting and ending voltage, duration of test.

SPL replication in itself can have other variables at play. It's best to leave that out of it because this will create false projections.

IE- what if battery replacement allowed user to use custom buss bars that netted better SPL? Others reading that only the SPL got higher will miss some of the variables WHY and conclude it will always NET a higher SPL when in fact it may have only done so because of added electrical conductivity that some users may NOT be using persay which voids that result.

Going back to the original question-

Lithium terminology actually provides a simple formula for calculating what you will need BEFORE purchasing anything!

C rate- Multiplier to it's aH

50aH rated at 1C means- 50A for 1 hour to death.

How does AGM do it?

aH over 20hr period.

So 50aH AGM would be 2.5A over 20hrs to death.

What is a true 1C performance rating for AGM?

I do not know.. because AGM ratings are kept hidden from the public.

What is a fact is it wont do 100A for 1hr, lol.. That's far from possible.

This right there is why lithium aH is always less than AGM for equal performance(however you are comparing).

Now, you want a ratio or something.. well, guess what, speaking of only LiFePO4, there are MANY variants of performance products out there..

Luckily, they all share the same terminology so it's very easy to find what you need..

So lets say you have 5 G31s.

A G31 is typically good for about 100A per batt dropping to 11.9v

So 5 would be 5,950w ACTUAL power.

Let's say you have 2 270A alts and they are revved for a burp providing 252A per alt to the rear at 11.9v.

That's 5,998w ACTUAL power.

So far, we are at 11,948w.

Let's multiply this number by 80% efficiency = 9,558w.

So, we want to replicate this on lithium eye to eye with voltage drop..

Well, lets round up 11.9v to 12v.

11,948w - 5,998w (from alts) is 5,950w.

5,950w / 12v = ~500A.

So we need to create a lithium bank in 4S to supply 500A at 12v.

All you do is this-

When researching lithium, look at the discharge graphs-

Look at the C rates that fall NO lower than 3.0v (per cell).

Whatever that C rate is, divide it by 500A to get the required aH for that pack.

Cheap *** prismatics typically do 3C to 12.0v (or the even worse ones at 2C to 12.0v, lol)

So, like the Winstons.. the yellow prismatics. They do 3C to 12.0v. (but they are also not lifepo4, they are Lithium Ytrium Phosphate)

Anyways, if you used those, you'd need-167aH to equal the performance BASED ON 1 Burp comparison.

The cells we have here.. you only need 34aH, //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif See what i mean.. Beast cells (minus the limitation of charging extremely fast)

JY has a 10C rating to 12v so you'd want 50aH of theirs.

Again, that is just ONE single test comparison to equal performance.

Do NOT EVER EVER EVER size your lithium bank based on 1 single comparison like this.

You should also do durational tests (perferably with car off so it's better comparison) so you can see how your AGMs handle X load when your alts are maxed out.

Find this out, then add it to your alts output performance to know how to size lithium based on that.

One thing to note too-

With any battery tech, the higher the discharge, the Lower the capacity becomes.

Meaning..

If i take an AGM of 100ah and discharge it at 5A.. after 20hrs, when it dies, it would have shown it was 100aH worth of capacity after recharging.

However, if i discharge it at 40A til death, it may only show it was 92ah of capacity (i have no idea what the capacity shift difference would be for AGM)

On lithium- depending on graphs (not all brands will give you this info but we have it for ours, //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif )

Going from 1C to their MAX continuous discharge rating can shorten it's capacity by 5-20%!

That means the cheaper lithium cells, lets say you went with prismatics. 200aH worth.

Prismatics actually only carry their aH spec TRUE discharging at 0.3C (lol).. which in this case would be 67A for little over 3hrs to maintain 200aH..

But if you take the same 200aH pack and discharged 400A (2C) to death, it may have shortened it's total capacity to about 180aH after recharge.

Our cells capacity shift up to 15C has a shift NO greater than 130mah.. That means it went from 4.3xx ah to 4.2xx ah. That's virtually undetected without measuring it.

That means the cells do not degrade that easily with abuse.

When i say shorten it's total capacity above, it only does it during that cycle. Of course cycle life can shorten if abused all the time like that.. same way DoD use alters cycle life but i'm sure we all know this.

 

[hispls 5,000+ posts]

I have time now to answer this directly.

Thanks. That is very useful info that I don't think anybody is really trying to share or explain.

 

[ChaseinBass]

Very educational , Thank you for taking the time to explain this.

 

[Papermaker85 5,000+ posts]

bump. i'm indecisive. i could build one but i just don't know enough to do it(which cells are best etc...) and i really don't wanna spend more time. any recommendations?

 

[Papermaker85 5,000+ posts]

I have time now to answer this directly.
We mentioned earlier AGM offers NO formula for providing how many you need for any given install..

You even said it yourself-

" In fact any of us with a few builds under our belts has a very good idea of how many AH worth of AGM batteries hangs with how much power."

Like i've said over and over.. ONLY those with experience know how many batts they would need. Poor way of manufacturing batteries.

Now, you want to know this-

""I replaced 5 group 31 AGMs with one 80AH lithium and do the exact same numbers on bass race and burp". It is implied that you "need" less amp hours with lithium but nobody is actually offering up a ratio or any hard testing data...."

Let me break this down because I am.. others are, etc.. I just think many people in this thread just have not done any lithium research on terminology..

For one, let me tackle this statement-

"I replaced 5 group 31 AGMs with one 80AH lithium and do the exact same numbers on bass race and burp"

For one, what if you said i replaced 5 G31 XS Powers with X amount of G31 Duracells and do the same number..

Where is the formula or ratio for that? There isn't going to be one answer at all. Why?

Because this question doesn't provide the DATA required to do so such as -

Static current draw, starting and ending voltage, duration of test.

SPL replication in itself can have other variables at play. It's best to leave that out of it because this will create false projections.

IE- what if battery replacement allowed user to use custom buss bars that netted better SPL? Others reading that only the SPL got higher will miss some of the variables WHY and conclude it will always NET a higher SPL when in fact it may have only done so because of added electrical conductivity that some users may NOT be using persay which voids that result.

Going back to the original question-

Lithium terminology actually provides a simple formula for calculating what you will need BEFORE purchasing anything!

C rate- Multiplier to it's aH

50aH rated at 1C means- 50A for 1 hour to death.

How does AGM do it?

aH over 20hr period.

So 50aH AGM would be 2.5A over 20hrs to death.

What is a true 1C performance rating for AGM?

I do not know.. because AGM ratings are kept hidden from the public.

What is a fact is it wont do 100A for 1hr, lol.. That's far from possible.

This right there is why lithium aH is always less than AGM for equal performance(however you are comparing).

Now, you want a ratio or something.. well, guess what, speaking of only LiFePO4, there are MANY variants of performance products out there..

Luckily, they all share the same terminology so it's very easy to find what you need..

So lets say you have 5 G31s.

A G31 is typically good for about 100A per batt dropping to 11.9v

So 5 would be 5,950w ACTUAL power.

Let's say you have 2 270A alts and they are revved for a burp providing 252A per alt to the rear at 11.9v.

That's 5,998w ACTUAL power.

So far, we are at 11,948w.

Let's multiply this number by 80% efficiency = 9,558w.

So, we want to replicate this on lithium eye to eye with voltage drop..

Well, lets round up 11.9v to 12v.

11,948w - 5,998w (from alts) is 5,950w.

5,950w / 12v = ~500A.

So we need to create a lithium bank in 4S to supply 500A at 12v.

All you do is this-

When researching lithium, look at the discharge graphs-

Look at the C rates that fall NO lower than 3.0v (per cell).

Whatever that C rate is, divide it by 500A to get the required aH for that pack.

Cheap *** prismatics typically do 3C to 12.0v (or the even worse ones at 2C to 12.0v, lol)

So, like the Winstons.. the yellow prismatics. They do 3C to 12.0v. (but they are also not lifepo4, they are Lithium Ytrium Phosphate)

Anyways, if you used those, you'd need-167aH to equal the performance BASED ON 1 Burp comparison.

The cells we have here.. you only need 34aH, //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif See what i mean.. Beast cells (minus the limitation of charging extremely fast)

JY has a 10C rating to 12v so you'd want 50aH of theirs.

Again, that is just ONE single test comparison to equal performance.

Do NOT EVER EVER EVER size your lithium bank based on 1 single comparison like this.

You should also do durational tests (perferably with car off so it's better comparison) so you can see how your AGMs handle X load when your alts are maxed out.

Find this out, then add it to your alts output performance to know how to size lithium based on that.

One thing to note too-

With any battery tech, the higher the discharge, the Lower the capacity becomes.

Meaning..

If i take an AGM of 100ah and discharge it at 5A.. after 20hrs, when it dies, it would have shown it was 100aH worth of capacity after recharging.

However, if i discharge it at 40A til death, it may only show it was 92ah of capacity (i have no idea what the capacity shift difference would be for AGM)

On lithium- depending on graphs (not all brands will give you this info but we have it for ours, //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif )

Going from 1C to their MAX continuous discharge rating can shorten it's capacity by 5-20%!

That means the cheaper lithium cells, lets say you went with prismatics. 200aH worth.

Prismatics actually only carry their aH spec TRUE discharging at 0.3C (lol).. which in this case would be 67A for little over 3hrs to maintain 200aH..

But if you take the same 200aH pack and discharged 400A (2C) to death, it may have shortened it's total capacity to about 180aH after recharge.

Our cells capacity shift up to 15C has a shift NO greater than 130mah.. That means it went from 4.3xx ah to 4.2xx ah. That's virtually undetected without measuring it.

That means the cells do not degrade that easily with abuse.

When i say shorten it's total capacity above, it only does it during that cycle. Of course cycle life can shorten if abused all the time like that.. same way DoD use alters cycle life but i'm sure we all know this.

i really don't now why they make the **** so confusing. there is no need for any ratings except time over voltage at a given discharge rate. typical rates should be established and specs coule then be incremental calculations.

battery storage potential DO NOT TELL the output potential discharge rate and recharge rate. take that AH and throw it out. its pointless.

you want to know starting voltage. resistance(lower it is the faster the discharge and recharge) and the discharge amperage at a given voltage drop over time. its really that easy!

thanks for the info though man. you the man!