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I have a couple of questions about a new build I'm putting together. I'm switching to my system to all lithium and will be eliminating my agm. I see everyone say that if you put lithium and agm together it will blow your alternator. Is this true? Also is it safe to start your car with lithium batteries? And is it recommended to purchase a bms for these deafbonce lithiums I got? 

https://alphardaudio.us/products/lithium-battery-lt-lfp-300p

 

My system will be at around 9k watts powering 2 custom made 18 inch pierce audio 4k 12 magnet neo subs. My alternator is a 240 amp mechman, will 240 be enough to charge up my system I've heard that lithium is a lot of strain on alternators. 

 

If I'm driving my car just about every other day will I have to hook my batteries up to a lithium charger every other night or will they be fine to start my car every day and just wait a couple min for the alt to charge them?

 

Sorry for all the questions but thank you for the help!! 

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Mixing AGM and lithium is a bad idea. Not because it'll blow your alternator though. The resting voltage of lithium is different than an AGM. So while the car is off, the batteries will begin to leach off each other trying to test at the same voltage. Over time that will greatly reduce the lifespan of the batteries. 

Lithium actually does the opposite of stressing out your alternator. The charge rate and discharge rate makes it perfect for car audio. You just have to do a little homework on the lithium you're using and make sure you're not exceeding the charge rate. That won't damage the alternator, but can damage the battery. Along with the charge and discharge rate, it makes it easier to have a lower amperage alternator and still maintain good voltage. 

It's also perfectly fine to start your car on lithium. I do it. 

Last, I'm sorry, I don't know what a BMS is. Is that a balancer of some sort? 

 

Edited by Dafaseles

2011 Chevy Silverado under construction

My build log here. Check it out! 

 

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15 hours ago, JMAGG said:

I have a couple of questions about a new build I'm putting together. I'm switching to my system to all lithium and will be eliminating my agm. I see everyone say that if you put lithium and agm together it will blow your alternator. Is this true? Also is it safe to start your car with lithium batteries? And is it recommended to purchase a bms for these deafbonce lithiums I got? 

https://alphardaudio.us/products/lithium-battery-lt-lfp-300p

 

My system will be at around 9k watts powering 2 custom made 18 inch pierce audio 4k 12 magnet neo subs. My alternator is a 240 amp mechman, will 240 be enough to charge up my system I've heard that lithium is a lot of strain on alternators. 

 

If I'm driving my car just about every other day will I have to hook my batteries up to a lithium charger every other night or will they be fine to start my car every day and just wait a couple min for the alt to charge them?

 

Sorry for all the questions but thank you for the help!! 

 

Hey dude,

 

quick answers

 

1 - Mixing LiFePo4 and AGM is a really bad idea, as charging and resting voltage are different, I'd say the risk is to damage every component (Lithium battery and/or AGM battery and/or alternator).

 

2 - You NEED a BMS, as you charge between the first (0V) and last plug (+12v) the cells can loose their balance, so the BMS is here to keep everything controled (about 3.4V resting voltage for each cells).

If you don't use the BMS, you will use prematurely the cells, have lower voltages and so on.

 

3 - Starting your car with lithium is not a problem, I'd say it's better as the voltage is usually higher and voltage drops less :) I'm currently doing it

 

4 - 240A of charge is enought, LiFePo4 demands half the capacity in terms of charge (300Ah of battery will not charge with over 150A, 600Ah -> 300A, etc....) I have 600Ah with a mechman 370A on my side it's cool).

 

4 - LiFePo4 do not need specific chargers as they don't have "memory" like AGM and low self discharge, a simple Alternator is enough (if it can supply enough amps of course), so you don't need a charger, you can really run those batteries as AGM (start the car, run the car, no needs to wait if the car hasn't been sitting for month).

 

If I can resume :

LiFePo4 are OEM friendly batteries, with the Lithium advantages, they run at about the same charging voltage (14.4-14.6V), just need a bit more current to charge, and can be installed simply, and use a BMS :)

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On 6/10/2021 at 2:47 AM, Car Audio 83 said:

 

Hey dude,

 

quick answers

 

1 - Mixing LiFePo4 and AGM is a really bad idea, as charging and resting voltage are different, I'd say the risk is to damage every component (Lithium battery and/or AGM battery and/or alternator).

 

2 - You NEED a BMS, as you charge between the first (0V) and last plug (+12v) the cells can loose their balance, so the BMS is here to keep everything controled (about 3.4V resting voltage for each cells).

If you don't use the BMS, you will use prematurely the cells, have lower voltages and so on.

 

3 - Starting your car with lithium is not a problem, I'd say it's better as the voltage is usually higher and voltage drops less :) I'm currently doing it

 

4 - 240A of charge is enought, LiFePo4 demands half the capacity in terms of charge (300Ah of battery will not charge with over 150A, 600Ah -> 300A, etc....) I have 600Ah with a mechman 370A on my side it's cool).

 

4 - LiFePo4 do not need specific chargers as they don't have "memory" like AGM and low self discharge, a simple Alternator is enough (if it can supply enough amps of course), so you don't need a charger, you can really run those batteries as AGM (start the car, run the car, no needs to wait if the car hasn't been sitting for month).

 

If I can resume :

LiFePo4 are OEM friendly batteries, with the Lithium advantages, they run at about the same charging voltage (14.4-14.6V), just need a bit more current to charge, and can be installed simply, and use a BMS :)

you have answered very well. Thankx for such beautiful explanation about lithuim usage in car audio speakers

Edited by james deen
  • Haha (+1 Rep) 1
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