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Does anybody have any experience with running their vehicle on CMAX? The reason I ask is I see alot of people having better results on CMAX but they're usually running separate alts. I'm currently running LifePo4 JY charging at 14.8 and I only have room for ONE alternator as it is one of the smallest cars around with a super small engine compartment, absolutely no room for a bracket. Any issues with running cars on 15.7-16 volts? Starting? OEM electronics not running right? etc... Personal experiences only please.

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You know it really depends on the car, anything beyond 16v+ and it's usually problematic,light bulbs pop, pcm/ecu's freak out, even some aftermarket head units & amps wont go beyond 16v +/-, one time i got stuck at 18v and my trans wouldn't shift past 1st lol.

 

If you really want to use li-ion chemistry, you'll make things easier on yourself with a 200a stepdown or secondary alt, i myself would rather cop another JY LFE, li-ion is more energy dense and your also forced to use it at a higher voltage over LFE, which is why people have better results.

 

Another thing, 16v/4 = 4v, yes your cycle life will be higher but you won't really have full capacity, which is why it might be better to stick with another jy lfe.

 

Hope this helps.

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5 hours ago, slowfkncar said:

You know it really depends on the car, anything beyond 16v+ and it's usually problematic,light bulbs pop, pcm/ecu's freak out, even some aftermarket head units & amps wont go beyond 16v +/-, one time i got stuck at 18v and my trans wouldn't shift past 1st lol.

 

If you really want to use li-ion chemistry, you'll make things easier on yourself with a 200a stepdown or secondary alt, i myself would rather cop another JY LFE, li-ion is more energy dense and your also forced to use it at a higher voltage over LFE, which is why people have better results.

 

Another thing, 16v/4 = 4v, yes your cycle life will be higher but you won't really have full capacity, which is why it might be better to stick with another jy lfe.

 

Hope this helps.

Yes, this does help quite a bit. You basically confirmed some things that I had already heard, but gave me more details and also why and when these shortfalls may happen (occasionally, usually above 16v). I haven't really heard of the step ups you are referring to but after doing some research I don't see anything above a 5-20 amp input current. Obviously we use much more, do they make those catered to the car audio community? But it sounds like what your saying is even if I could make that work I wouldn't be able to use my cmax to full capacity.. Which is a show stopper for me. I've been leaning toward getting another JY bank, it would be my cheapest option at about $500 per 80aH. Thanks for the help! On another note I replaced a worn serpentine belt yesterday and put one on 1/2" shorter and I'm noticing some positive results already but I will have to amp clamp my alt to see for sure. Still needing more power though.

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14 hours ago, markcrnll said:

Yes, this does help quite a bit. You basically confirmed some things that I had already heard, but gave me more details and also why and when these shortfalls may happen (occasionally, usually above 16v). I haven't really heard of the step ups you are referring to but after doing some research I don't see anything above a 5-20 amp input current. Obviously we use much more, do they make those catered to the car audio community? But it sounds like what your saying is even if I could make that work I wouldn't be able to use my cmax to full capacity.. Which is a show stopper for me. I've been leaning toward getting another JY bank, it would be my cheapest option at about $500 per 80aH. Thanks for the help! On another note I replaced a worn serpentine belt yesterday and put one on 1/2" shorter and I'm noticing some positive results already but I will have to amp clamp my alt to see for sure. Still needing more power though.

If you charge to 16.8v then you can get full capacity out of those cells, at 16v you'll have less which defeats the purpose of going li-ion over LFE.

 

You can use multiple isolated 16v to 12v stepdowns in parallel, high current low voltage is hard to find due to low demand but you might find a few shops that can make a custom design.

 

Every single time i have used an overdrive pully with the same belt, it always slipped or slipped enough to stall the alternator, I always look up the oem belt size and go down by 1/3 or 1/2 an inch.

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Also, XS power makes a 16v agm that has a 12v post, I've never tried them myself due to fear of uneven internal voltage but you could always convert your entire system to 16.8v and use the 12v post off a 16v xs battery for your car electronics, then hook your cmax 4s pack with an isolator between both batteries.

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