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rsfm089

lithium ah vs agm ah

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Starting to look at lithium batteries but i am really confused. i have about 300 ah of agm batteries in my car at the cost of $300. (girlfriend works at auto zone). For the cost of what i payed for my batteries i could get one lithium battery that has 15ah. I guess what im trying to ask is why the price is so high and why is it more efficient to run lithium. Do they discharge different, charge faster, last longer? Thanks for the help in advance.

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2 minutes ago, rsfm089 said:

Starting to look at lithium batteries but i am really confused. i have about 300 ah of agm batteries in my car at the cost of $300. (girlfriend works at auto zone). For the cost of what i payed for my batteries i could get one lithium battery that has 15ah. I guess what im trying to ask is why the price is so high and why is it more efficient to run lithium. Do they discharge different, charge faster, last longer? Thanks for the help in advance.

http://batteryuniversity.com/learn/

Its complicated.  Get to reading.  

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I’ve always been told that 10ah of lithium is comparable to 100ah in agm. I don’t know a whole bunch about lithium, so I’ll let someone else chime in who is more knowledgable about the discharge rates etc. But I know the weight savings can be a big benefit. Much easier to have one 10 pound battery that can power your whole system, vs 6 huge 80+ pound batteries. Saves room and less strain on your car hauling around all that weight. 

I have 6 xp3000’s which weigh about 500 pounds. Would much prefer a  20 pound lithium than all the agm’s. 


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i've been reading like crazy and started to understand the efficiency and charge and discharge rate. Has anyone every used a StarkPower battery? trying to get ahold of them know to explain what i need and if there product will work in my application.

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Keep in mind how much amperage your alternator delivers since most "renewable-energy-marketed" lithium is not designed to take the high charge rates of a car audio application.  This will be an important factor to consider in your equation.

Take the recent email many of us received from SHCA this afternoon: 

"15ah: 3,000w RMS. 4.65”x3.75”x9” 7.50 pounds. 100a available charging. Equivalent (1.5) 100ah AGM batts"

100A available charging?  This battery is only suitable for a car with a small alternator or an application where the alternator-charge-amps are split up into other battery cells (like an AGM under the hood, for instance).

If, for instance, someone had a 240A alt and only (1) of these 15Ah Limitless Lithium batteries, the cell life would be shortened dramatically by overheating the cells from too high a charge rate.

High charge/discharge rates is one of the main limiting factors in using 'off-brand' lithium cells in a car audio application.  Some people that have had success with using 'off brand' lithium cells got a good deal on them and also did their homework to confirm that the charge rates weren't exceeded for their particular application.

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Whoever said 10ah is comparable to 100ah is 105% wrong.

I hope they do not sell batteries... 

Because the context in question is literally being asked what is the difference in aH between between the 2 vs what is the efficiency difference or C rate difference to X voltage, etc..  
Here is the difference in aH between AGM and Lithium-

AGM is 20Hr rate
Lithium is Variable rate based on KNOWN C rate

Examples-

AGM - 20Hr rate-
Divide the rated aH by 20hrs.

So, a 100AH AGM would mean it will discharge 5A for 20Hrs until dead.

Lithium- 
Manufacturer MUST present the known C rate to calculate discharge time by aH.

Examples-
10aH @1C
This means it will discharge 10A for 1 hour until dead

10aH @0.3C
This is more complicated.. and tricky sales tactic.

This means it will discharge 3.33A for 3 hrs until dead BUT-
Because it has bad voltage sag (probably high ESR), it can NOT discharge 10A in 1 hour.  It would be less than that.

An estimated conversion for AGM to Lithium aH is multiply the aH rating of AGM by ~65%.  
It's an estimate but doing that, you will get this-
100aH AGM = 65aH  

Use this to compare how long the battery would last at 1C (65A) until death.

Keep in mind the actual voltages between the 2 chemistries using this 65% formula will NOT be equally linear. 


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30 minutes ago, shizzzon said:

Whoever said 10ah is comparable to 100ah is 105% wrong.

I hope they do not sell batteries... 

Because the context in question is literally being asked what is the difference in aH between between the 2 vs what is the efficiency difference or C rate difference to X voltage, etc..  
Here is the difference in aH between AGM and Lithium-

AGM is 20Hr rate
Lithium is Variable rate based on KNOWN C rate

Examples-

AGM - 20Hr rate-
Divide the rated aH by 20hrs.

So, a 100AH AGM would mean it will discharge 5A for 20Hrs until dead.

Lithium- 
Manufacturer MUST present the known C rate to calculate discharge time by aH.

Examples-
10aH @1C
This means it will discharge 10A for 1 hour until dead

10aH @0.3C
This is more complicated.. and tricky sales tactic.

This means it will discharge 3.33A for 3 hrs until dead BUT-
Because it has bad voltage sag (probably high ESR), it can NOT discharge 10A in 1 hour.  It would be less than that.

An estimated conversion for AGM to Lithium aH is multiply the aH rating of AGM by ~65%.  
It's an estimate but doing that, you will get this-
100aH AGM = 65aH  

Use this to compare how long the battery would last at 1C (65A) until death.

Keep in mind the actual voltages between the 2 chemistries using this 65% formula will NOT be equally linear. 

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?

Edited by WalledSonic

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25 minutes ago, shizzzon said:

Whoever said 10ah is comparable to 100ah is 105% wrong.

I hope they do not sell batteries... 

Because the context in question is literally being asked what is the difference in aH between between the 2 vs what is the efficiency difference or C rate difference to X voltage, etc..  
Here is the difference in aH between AGM and Lithium-

AGM is 20Hr rate
Lithium is Variable rate based on KNOWN C rate

Examples-

AGM - 20Hr rate-
Divide the rated aH by 20hrs.

So, a 100AH AGM would mean it will discharge 5A for 20Hrs until dead.

Lithium- 
Manufacturer MUST present the known C rate to calculate discharge time by aH.

Examples-
10aH @1C
This means it will discharge 10A for 1 hour until dead

10aH @0.3C
This is more complicated.. and tricky sales tactic.

This means it will discharge 3.33A for 3 hrs until dead BUT-
Because it has bad voltage sag (probably high ESR), it can NOT discharge 10A in 1 hour.  It would be less than that.

An estimated conversion for AGM to Lithium aH is multiply the aH rating of AGM by ~65%.  
It's an estimate but doing that, you will get this-
100aH AGM = 65aH  

Use this to compare how long the battery would last at 1C (65A) until death.

Keep in mind the actual voltages between the 2 chemistries using this 65% formula will NOT be equally linear. 

learning a lot about this now the company i was talking to said at a 327amp draw 4 12v100ah lithium would last for three hours on continuous play. they also explained to me that if i had a 320ho alt i would more then likely damage the battery over time. the other bad thing is that a lithium battery should not be charged at 0 degrees C or 32 degrees F, the only safe way to charge is with a 1amp charger. It takes about 15 hours to charge 10ah lithium. i live in wisconsin its cold. until new tech comes out and some way to properly charge in cold weather other then removing my batteries i will stick to agm for now. If i was in warm weather and could get the right chargers i would be all over lithium. 

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2 hours ago, shizzzon said:

Whoever said 10ah is comparable to 100ah is 105% wrong.

I hope they do not sell batteries... 

Because the context in question is literally being asked what is the difference in aH between between the 2 vs what is the efficiency difference or C rate difference to X voltage, etc..  
Here is the difference in aH between AGM and Lithium-

AGM is 20Hr rate
Lithium is Variable rate based on KNOWN C rate

Examples-

AGM - 20Hr rate-
Divide the rated aH by 20hrs.

So, a 100AH AGM would mean it will discharge 5A for 20Hrs until dead.

Lithium- 
Manufacturer MUST present the known C rate to calculate discharge time by aH.

Examples-
10aH @1C
This means it will discharge 10A for 1 hour until dead

10aH @0.3C
This is more complicated.. and tricky sales tactic.

This means it will discharge 3.33A for 3 hrs until dead BUT-
Because it has bad voltage sag (probably high ESR), it can NOT discharge 10A in 1 hour.  It would be less than that.

An estimated conversion for AGM to Lithium aH is multiply the aH rating of AGM by ~65%.  
It's an estimate but doing that, you will get this-
100aH AGM = 65aH  

Use this to compare how long the battery would last at 1C (65A) until death.

Keep in mind the actual voltages between the 2 chemistries using this 65% formula will NOT be equally linear. 

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.

2 hours ago, rsfm089 said:

learning a lot about this now the company i was talking to said at a 327amp draw 4 12v100ah lithium would last for three hours on continuous play. they also explained to me that if i had a 320ho alt i would more then likely damage the battery over time. the other bad thing is that a lithium battery should not be charged at 0 degrees C or 32 degrees F, the only safe way to charge is with a 1amp charger. It takes about 15 hours to charge 10ah lithium. i live in wisconsin its cold. until new tech comes out and some way to properly charge in cold weather other then removing my batteries i will stick to agm for now. If i was in warm weather and could get the right chargers i would be all over lithium. 

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. 

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