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snb778

Anyone know of Nexgen lithium batteries?

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1 hour ago, Wishuponasub said:

I think they are just called CMax because they came out of a Ford Cmax. Supposedly these brand new Toyota cells are the best available.

I'm not to sure on all the chemistry questions you have. I don't dig that deep to learn it and I have no reason to do so. If ford thought it was safe enough then I'm good with it.

As far as BMS any bms would do. I choose not to run them because they are not required and imo not needed. I mean every cell in the pack is connected. Positive on one end negative on the other. So how is one gonna be missed?

C rating is the rate of discharge/charge I believe. Cells we use must have a higher C rating due to the large amounts of amperage we provide for charge/ and the discharge demands that we ask of them. It is one of the most important factors in determining which batteries we can use or not.

As far as connecting them it has to do with series/parallel. For example you will see it as 4s9p or whatever. The series would be combining the voltage and the parallel is for the ah. <I believe, I may be mistaken but i don't believe so.

 

1 hour ago, Wishuponasub said:

Just for the record, I'm just a dumb redneck and anything I say should be taken with a grain of salt.

LOL, i respect a man who can admit he doesnt know what he's doing, but still giving it a try.

 

What are the power ratings per cell on those Cmax? Voltage and amps? I'm curious why so many only gets you 12 volts OR 45ah?

I have put in about 20hrs of research in the last few days on cells and lithium.  The BMS is to keep each individual cell from getting to a volatile state.  If the voltage drops to low (under 2V) or to high (above 5V depending on the cells starting voltage of course) they can become volatile.  The better cells are less like to explode due to their construction and safeguards.  I've read anything under 32deg. lithium cells WILL NOT charge at all.  Take this info for a grain of salt, as i'm by no means and expert, but quickly getting eddumacated

Edited by snb778
misspelled word

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https://www.batterystuff.com/kb/articles/battery-articles/battery-bank-tutorial.html

Give this a once over.

Or just look at the 3 pictures. They explain it.

Edited by Wishuponasub

Sitting around waiting to be installed:

  4 FI X 10

 270 CES alt

D3400/73ah lithium

 AA 3800.1

  (2) AA 75.4

     

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I would message the owner or whoever you talked to and ask him what the C rate of the battery you're interested in is.  This will tell you whether or not its going to be a good battery for our hobby.  You want a high C rate.  I sourced a custom 70aH LiPo bank with a 10C Max discharge rate (10s), meaning it can supply 700 amps for 10 seconds at full discharge.  Now, my equipment isn't pulling 700 amps even at max discharge (full volume, on tuning, bass notes) so it allows me to show near full voltage during music, and when it does pull down a little, my 270a alternator is right there to supply it with what it lost, giving me a near instant snap back to 14.4v-14.6v.

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15 hours ago, bmwking said:

I would message the owner or whoever you talked to and ask him what the C rate of the battery you're interested in is.  This will tell you whether or not its going to be a good battery for our hobby.  You want a high C rate.  I sourced a custom 70aH LiPo bank with a 10C Max discharge rate (10s), meaning it can supply 700 amps for 10 seconds at full discharge.  Now, my equipment isn't pulling 700 amps even at max discharge (full volume, on tuning, bass notes) so it allows me to show near full voltage during music, and when it does pull down a little, my 270a alternator is right there to supply it with what it lost, giving me a near instant snap back to 14.4v-14.6v.

What characteristic of the battery controls how long it can take that amperage draw?  Is that the C-rating?  

The reason I ask is because I see so many people making 12V batteries with the 18650 cells that are like 4-5Amps each, and 3.2v....why are those not as desirable vs the 38120's with the same ratings?

How do you get to 700 amps for 10 seconds? What calculation do you use to determine that?

Thanks for the help.

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Hi.  I posted a good example outlining how to size/choose a battery here:

 


Chevy Sonic Wall (4) 15's on 10k Build Log

https://www.stevemeadedesigns.com/board/topic/209412-2015-chevy-sonicwall4-15s10klithiumlarge-case-hairpin-us-alts/

(4) Fi SP4 15's | (2) Ampere 5Ks | Active! | Arc KS600.2 & KS125.2mini | CDT Silk Domes | Silver Flute 8s | 240Ah JY | US Alts

Jeep Wrangler JK (4) 8's in a 4th Order Build Log

https://www.stevemeadedesigns.com/board/topic/209841-shadow-2016-jeep-wrangler-jk4th-order4-8sdc-35klarge-case-hairpin-us-alts/

IG @walledsonic

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47 minutes ago, WalledSonic said:

Hi.  I posted a good example outlining how to size/choose a battery here:

 

Thanks for pointing me there.  I'm hung up on this part, i don't quite understand "The specs say the maximum charge current is less than 3C (48A x 3 = 144A).  Lets assume you have a 300A alternator, which is an acceptable size for a 5K.  300A is 6.25C.".   Which specs say the max charge current is less than 3c? Is that saying the cells shouldn't be charge at a higher rate than 3c? Where did that number come from?  How does 300A = 6.25c?  

Thanks,

Steve B

 

 

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5 hours ago, snb778 said:

What characteristic of the battery controls how long it can take that amperage draw?  Is that the C-rating?  

The reason I ask is because I see so many people making 12V batteries with the 18650 cells that are like 4-5Amps each, and 3.2v....why are those not as desirable vs the 38120's with the same ratings?

How do you get to 700 amps for 10 seconds? What calculation do you use to determine that?

Thanks for the help.

yes that is the C rating

the 18650 cells are small batteries, like AA size, and in no way adequate for our application. the 38120s have more material inside (hence larger) and can handle more current for more time.  this is why people can use 38120s in large banks to provide a voltage stiffener, but not replace an actual full size battery.

my total bank is a 4 x 3.2v cells (12.8v total) each cell has a 70aH rating and a 10C rating.  it's my (albeit basic) understanding that the C rate is the number preceding the C (ie 10C) multiplied by the aH, giving my a max discharge current of 10C or 700 amps, for short 10 second (max, before the C rate lowers) bursts when needed.

Edited by bmwking

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4 hours ago, bmwking said:

yes that is the C rating

the 18650 cells are small batteries, like AA size, and in no way adequate for our application. the 38120s have more material inside (hence larger) and can handle more current for more time.  this is why people can use 38120s in large banks to provide a voltage stiffener, but not replace an actual full size battery.

my total bank is a 4 x 3.2v cells (12.8v total) each cell has a 70aH rating and a 10C rating.  it's my (albeit basic) understanding that the C rate is the number preceding the C (ie 10C) multiplied by the aH, giving my a max discharge current of 10C or 700 amps, for short 10 second (max, before the C rate lowers) bursts when needed.

1. So the AH x C rating = max amps? What exactly does that mean "Max" amps? until what happens?  

2. Each CELL has 70ah? wtf kind of cells are you using? lol.  

3. I guess what im struggling with is despite the size, if a smaller cell has 3.2v, and 8ah and so does a bigger one...whats the difference?  Can't just be the fact that they're bigger.

4. I see a lot of these lithium batteries say 100 amps or 200 amps (not amp hours)....what is that stating?  Will an amp that pulls 300-400amps not work with these? 

Thanks for the help

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