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rsfm089

lithium ah vs agm ah

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18 hours ago, WalledSonic said:

1C is useless for car audio.

EDIT: also, blind estimation of 65%.  is there value to your guess when the previous post above was also a guess?

Please reference which part you think is a guess.  

Estimation and guess are two totally different meanings.

It's an estimation because not every AGM discharges the same rate to X voltage.  I hope you are well aware of this, hence the reasoning for the word estimation.
AGM is not a performance standard but rather a type of lead acid battery.
Like Lithium, there are differences in AGM batteries.
PS- it's been physically tested on good virgin lead AGMs that they can hold roughly 70A of current for 1hr before death.
This is physical test.  No guess work here.  Hence, estimation wording is used to differentiate virgin lead from recycled lead including other variables that differ AGM manufacturing.

Again, a 15ah lithium is NOT like a 150aH AGM when talking aH because you are referencing CAPACITY, not discharge performance.

The comparison you all are referencing is discharge performance so when using aH, you are comparing capacity.

Trust me, put xC rate on both a 15ah lithium and 150ah agm and see which one dies first.

A group 31 will drop to or even below 12.0v at only 1C (true 1C).

Another thing to consider too.. 
People talk about how long Lithium will last over AGM..  

Well, that's debatable too depending on what density you are purchasing.

Cycle life is based on DoD, charge/discharge rate, temperature and of course cycles.

The smaller aH lithium one uses, the more cycles you will go through.  Think about that for a while.. 

The only good Lithium for cycle life is LTO and the only company i know that manufactures those for car audio is the guys behind Juicebox battery.

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Your 65% value.  Thats the one I was referencing.

So my original comment "Its complicated" was quite accurate, bc estimations/guesses/etc are commonly used to try to draw a comparison to apples and oranges (lead  acid and lithium).  I think we can both agree that you cant draw a direct comparison between the two technologies when the dynamics of their usage alone cant be well plotted/interpretted for every person.  There's just too many variables. 

I respect your knowledge, sir, but 1C rate is absolutely useless for car audio when alternators are supplying hundreds of amps of current and speakers/amps are dumping hundreds of amps of current, all during a ~3 minute musically dynamic song.

Thank you for the information above.

By the way, Toshiba SCiB is LTO.  However, they wont sell direct to people like us lol, I tried.


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There are several LTO cells.  We have some that excel over many Lifepo4 cells. 

1C is a very good value to compare to because anything over 3C and AGMs do not do so well and some people like to skimp out on quality Lifepo4s and go to prismatics which 1C at that point would be worthwhile to start one's research knowledge.

We have some LifePO4s cells here that hold 12.0v (4s) at 16C in a controlled testing environment we have with Temp increase below 35F above ambient.
We will be testing these LTO cells against these when we have time.  We believe the LTOs aren't as strong as these LifePO4 but testing needs to be done regardless.

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3 minutes ago, shizzzon said:

We have some LifePO4s cells here that hold 12.0v (4s) at 16C in a controlled testing environment we have with Temp increase below 35F above ambient.
We will be testing these LTO cells against these when we have time.  We believe the LTOs aren't as strong as these LifePO4 but testing needs to be done regardless.

This is more realistic for car audio.  5C and up.


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17 hours ago, Mr DeeBeez said:

Well the emails sent out by SHCA do say that a 15ah lithium is comparable to 150 ah of agm. would support the statement that 10 ah of lithium is comparable to 100 ah of agm. Is it a 100% accurate comparison? no. but seems to be a good rule of thumb.

I too live in Wisconsin, and have talked to JY about using their lithiums in our winters. They said that there wouldnt be any damage done to the batteries, but performance would suffer in the cold. But I do agree with you with sticking to AGM's for now. I am in the same boat as you. Ill stick to agm's because of their durability and resilience to our application. 

For the Limitless vs AGM case, then sure. It may be a good rule of thumb in that situation. But keep in mind that not all Lithium is created equally. For example, we have JY with a 10C 12v discharge rating but we also have Winston with a high 11s 3C discharge rating. So to make a statement of 10A of lithium being comparable to 100A of AGM simply is not true in many (well, most) cases.

As far as cold temps... heres my input with my real world experiences. I live in Florida, which obviously is pretty warm. In the morning during the summer, 80deg is far from uncommon. After about 30 seconds of playing a bassheavy track, the internals of the battery heat up. While the ambient temp is already up there, I see almost a 1v difference in voltage drop once warm. JY batteries have a minimum temp rating of 40 degrees however. While they may not perform the best from the go, they will warm up. Whether or not you want to deal with that is up to you, but lets not forget that AGM technology isnt a fan of the cold either.

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On 5/8/2011 at 7:38 PM, Kranny said:
On 5/8/2011 at 7:35 PM, 'Maxim' said:

It hurts me inside when I read stuff like this and remember you're 15

LMFAO so true

:blush:

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37 minutes ago, WalledSonic said:

 

I respect your knowledge, sir, but 1C rate is absolutely useless for car audio

 

Question for you. What do you think an AGM's mid 11v discharge rate is?

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On 5/8/2011 at 7:38 PM, Kranny said:
On 5/8/2011 at 7:35 PM, 'Maxim' said:

It hurts me inside when I read stuff like this and remember you're 15

LMFAO so true

:blush:

Mitsubishi 3000GT (Old Build)

Headunit: Pioneer 80PRS

Frontstage: (2) McLaren Audio MLT-2 Tweeters & (4) PRV Audio MR Series Neo 6.5" Mids

Substage: 4 15" Hybrid Subs - Tantric Motors & Sundown Softies

Amps: Banda 2.4D Amp (Tweets), American Bass VFL 350.4 (Mids), and (2) Ampere 3800s

Electrical :Singer 260A Alt & JY Power Lithium

 

2005 Chevy Colorado Ext Cab

Headunit: Pioneer 80PRS

Frontstage: 4 PRV 700Ti Tweets & 6 10" Delta Mids on 3000wrms

Substage (In Progress): 4th Order 6 18" Walkthrough

Electrical: Singer "390" and JY Power

My Official Feedback Thread

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3 hours ago, hdorre said:

Question for you. What do you think an AGM's mid 11v discharge rate is?

Im assuming from your question that the C rate drops to a lower rate at lower voltage for typical lead acid cells?  Thats useful information, helping point out how the C rate varies within a particular chemistry based on demand or application.  I never play in the 11s in my daily so that doesnt even matter for my particular application.

Then we would need to throw in the application (burp, 3min run, hours long demos) to determine how realistic C rates are for whichever application.  My point is that only comparing two battery chemistries with a single 1C rate is not indicative of the performance in a real life application unless both chemistries react with the same rate in the real world under the same conditions.  Thats not the case.  Which is also why there is no direct comparison to be made.  Everyone that runs AGM, Lith, Caps, and various numbers of alternators with various impedance loads from their amps are going to see different results.  A single controlled experiment with 1C may help paint a picture or plot another point on a graph but it isnt the be-all-end-all comparison between the two technologies.


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i think people might get confused about the cold weather thing. Its not an issue to run the lithium in cold weather. The issue is charging in cold weather is not at all good for lithium. i made another post about running lithium in cold weather so don't want to post it again. 

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hoping someone responds to this, but for those of us who aren't as technically educated, I'd love if one of you can break down for your average joe, is running a 2000-3000W system on a stock alt with a lithium ion battery a better idea than spending 1K on 2-4 AGM batteries and hassling with upgrading the Alt.  

Edited by snb778
forgot something

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