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26650 LiFePo and DNA75.


Akima
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Hi,
Can someone help me and explain what the setting for use in Escribe for DNA75 LiFePo using battery voltage of 3.3 V? In the case of DNA 200 I noticed that there are some settings while the DNA75 no. I tried to adjust the characteristics of the battery based on the Data Sheet of the battery, the analyzer also applied, however, does not give the desired results. Electricity is cut off at about 2.75 V despite the fact that the battery has a current cutoff at about 2.2 Volt. 

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  • 2 weeks later...
kristian jose said:

Hi Guys is there a .csv file for Lifepo 26650 batteries please? I went and brought these especially for my DNA75 and there not cheap. Thanks in advance.

welcome to the forum kristian jose. as vapingbad stated above the dna 75 was not designed to run with lifepo batteries. you could run them in the mod but i would charge them externally. the onboard charger will charge your lifepo past 3.65 volts to 4.20. i'm not sure lifepo batteries like that. you will not need a battery csv file for dna 75. the battery meter works off of straight battery voltage. battery analyzer is only there to test your battery's capacity. it's curve is not used by the 75.
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if you set the cell soft cut off to anything 2.55v and below (max allowable limit is 2.5v, the board can't function below that voltage) the dna 75 gets screwy and starts spitting out all kinds of error messages. this mainly happens when your battery is at 3.6v and below, when firing the device. i have my cell soft cut off set to 2.66v. that way i get the most out of my batteries without bouncing off the dna 75 hard limit. some will say "that's too low, you'll damage your batteries." when in fact most manufacturers test their batts down to 2.5v. also that 2.66v cut off is when under load not a resting voltage cut off.  to each his own, i say. this setup works great for my needs.

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  • 2 weeks later...

I posted in a wrong spot, when I should have posted here. I think, you'll be interested to know, that I'm successfully using A123 LiFePo4 in my DNA75 and loving it :)
There are some limitations, due to the fact that DNA75 only supports Li-Ion and LiPo type batteries:
1. Do not charge LiFePo4 batteries via USB, because it will try to charge it to 4.2V, which is NOT safe for LiFePo4. IMHO
2. Apply correct settings to your battery discharge profile, otherwise the battery indicator will be showing wrong values. You can use my CSV fine in the link below.
3. Even though, my LiFePo4 is working better then any Li-Ion batteries that I've tried (I tried many :D) the Hard Cutoff limit, of the DNA75 board, is set to 2.5V and it doesn't allow the battery to be used to it's full potential. It will be nice to see LiFePo4 support implemented in the next revision of the DNA75 firmware. But that's up to EVOLV do decide. I think that LiFePo4 is the answer to all DNA75 power issues due to the lack of powerful enough 26650 Li-Ion batteries on the market. But that's my opinion. :) 

Link: https://forum.evolvapor.com/topic/65832-topic/?do=findComment&comment=891150

A
nd the answer is NO. Here is the letter, I received from Evolv:

Hi Michael,

The DNA75's charging system works independently from the board controls unfortunately.

On the DNA200/250 we use a charging IC controlled by the onboard processor. This allows us to program a charging profile for batteries like LiFePo4 into the 200 and 250. It is also the same reason we have feedback like charge current, cell balance, etc.

On the DNA75 the charging system is independent and not microprocessor controlled, we can read things like charge status, but do not have complete granular control over the charging system like the DNA 250. This is also the same reason you don't see things like Charge Current on the DNA75 as well. Because the charging IC is a fixed max voltage we sadly cannot add LiFePo4 support. We can limit the cutoff though by simply not allowing the board to operate below a certain voltage, but not stop the charging IC from going over 3.6v, I hope this makes sense. This means we can support LiPo and Li-Ion batteries because we can limit how far they discharge, but not LiFePo4 because we cannot limit the charging cutoff.

We made the choice to not have LiFePo4 support on the DNA75 for a number of reasons. Mainly because the demand for LiFePo4 support and capabilities was never large at all. In the time since the DNA200 was released this is maybe the second or third ticket we have received regarding LiFePo4 usage. Second, was that the DNA75 was meant to be positioned in the middle of Evolv's product offerings, and is priced much much lower than something like a 200. The charging was only one of a few areas where we saw the ability to reduce costs on the board in order to reach the target price, while retaining the functionality our customers wanted and were accustomed to. 

My apologies that the DNA75 did not meet your desired functionality in this case, and we will continue to keep LiFePo4 support in mind going forward.

Thanks,
Evolv, Inc

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AMDtrucking said:

I posted in a wrong spot, when I should have posted here. I think, you'll be interested to know, that I'm successfully using A123 LiFePo4 in my DNA75 and loving it :)
There are some limitations, due to the fact that DNA75 only supports Li-Ion and LiPo type batteries:
1. Do not charge LiFePo4 batteries via USB, because it will try to charge it to 4.2V, which is NOT safe for LiFePo4. IMHO
2. Apply correct settings to your battery discharge profile, otherwise the battery indicator will be showing wrong values. You can use my CSV fine in the link below.
3. Even though, my LiFePo4 is working better then any Li-Ion batteries that I've tried (I tried many :D) the Hard Cutoff limit, of the DNA75 board, is set to 2.5V and it doesn't allow the battery to be used to it's full potential. It will be nice to see LiFePo4 support implemented in the next revision of the DNA75 firmware. But that's up to EVOLV do decide. I think that LiFePo4 is the answer to all DNA75 power issues due to the lack of powerful enough 26650 Li-Ion batteries on the market. But that's my opinion. :) 

Link: https://forum.evolvapor.com/topic/65832-topic/?do=findComment&comment=891150

A
nd the answer is NO. Here is the letter, I received from Evolv:

Hi Michael,

The DNA75's charging system works independently from the board controls unfortunately.

On the DNA200/250 we use a charging IC controlled by the onboard processor. This allows us to program a charging profile for batteries like LiFePo4 into the 200 and 250. It is also the same reason we have feedback like charge current, cell balance, etc.

On the DNA75 the charging system is independent and not microprocessor controlled, we can read things like charge status, but do not have complete granular control over the charging system like the DNA 250. This is also the same reason you don't see things like Charge Current on the DNA75 as well. Because the charging IC is a fixed max voltage we sadly cannot add LiFePo4 support. We can limit the cutoff though by simply not allowing the board to operate below a certain voltage, but not stop the charging IC from going over 3.6v, I hope this makes sense. This means we can support LiPo and Li-Ion batteries because we can limit how far they discharge, but not LiFePo4 because we cannot limit the charging cutoff.

We made the choice to not have LiFePo4 support on the DNA75 for a number of reasons. Mainly because the demand for LiFePo4 support and capabilities was never large at all. In the time since the DNA200 was released this is maybe the second or third ticket we have received regarding LiFePo4 usage. Second, was that the DNA75 was meant to be positioned in the middle of Evolv's product offerings, and is priced much much lower than something like a 200. The charging was only one of a few areas where we saw the ability to reduce costs on the board in order to reach the target price, while retaining the functionality our customers wanted and were accustomed to. 

My apologies that the DNA75 did not meet your desired functionality in this case, and we will continue to keep LiFePo4 support in mind going forward.

Thanks,
Evolv, Inc

the minimum voltage the dna 75 will operate at is 2.5v. i'm almost positive this is hardware limitation. isn't 2.5v the lowest you can safely take a lifepo4 battery anyways?
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