Lithium or sodium for replacement

No balancing at all with lithium ion cells is a disaster waiting to happen.
Not measuring intermediate cell voltages is scary, too.

I agree, but it does need at least passive balancing, which it sounds like your product doesn't have.

click the "Post New Thread" button in the top right corner of any forum section.

No, but I will reply to the thread once you create it.

I would only need QTY1 module for a review, but QTY2 is better because I can test in parallel.
Note that based on the information you've provided so far, I can almost certainly assure you my review would identify several safety issues with your product.

 

There are various Li-ion chemistries. I was curious which you have chosen.

 

Venceder created a new thread like you requested,
My version of Li-ion modules for Toyota/Prius NiMH

Please use that new thread to discuss his battery project.

 

Just think of how much time and money Toyota would have not spent, and could still not spend,
if they knew you didn't need to balance the battery and maintain it to just a few tenths of each other.
No one would get that P08080 or whatever that number is....

And you don't have to worry about it freezing either....

 

I read somewhere that a lithium battery will be permanently damaged by freezing temperatures. My car has been parked outside for the last 2 winters, and temps have gone as low as -30. No damage has been detected. I know for a fact that no battery heating was used. So who is wrong?

My Gen 3 plug-in had a 4.4 kWh lithium battery and sat outside for 10 years. No damage beyond normal aging, as far as I could tell; 15% loss of capacity in all that time.

 

Okay, there is one...... tell that to the thousands of cars sitting, waiting to charge there batteries,
and they wouldn't....

Just remember, even a broken clock is correct twice a day....

 

If I read you correctly, you think that a battery that needs charging is damaged?
Please set me straight if so,

 

You're not reading correctly...

 

A more correct statement:
Charging a frozen lithium battery too quickly can cause permanent damage. When the normally liquid solvent between the anode and cathode is frozen, lithium migration into the crystal structure is more difficult (this process is known an 'intercalation'). If you charge too fast below freezing, then instead of weaving through the crystalline matrix (i.e. intercalating), metallic lithium plates the anode's outermost surface. This process is irreversible, and can lead to dendrite formation (!!!), drastic capacity loss (!), and increased internal resistance (because the lithium plating blocks the chemical interface between the electrolyte and anode).

Note that most lithium batteries allow charging at a reduced rate down to at least -20 degC.
For example, the 5AhG3 cells I use in my Honda Insight product are rated for (worst case):
-charging at 2000 W/kg at 25 degC, and;
-charging at 500 W/kg at -20 degC.

...

Discharging lithium cells below freezing isn't as problematic in most use cases. Frozen cells have higher internal resistance (because the electrolyte is frozen), but this is actually advantageous because it helps heat up the cells faster. Some lithium BMS systems will run a current limited AC signal into lithium batteries to heat them up. However, note that discharging frozen cells at high C rates can cause internal hot spots to form inside a frozen cell, which can lead to accelerated cell degradation. For this reason, most lithium cell manufactures will also limit discharge below freezing (e.g. to 20C, instead of 50C).

Before anyone jumps in and claims that sodium cells aren't affected by freezing temperatures, I'll remind this community that in my testing at -20 degC, NexPower's V3 sodium pack delivered just 1 Wh (for the entire pack), which is several hundred times less capacity than it delivered at room temperature.

...

Full disclosure: According to NexPower's FAQ, I am "not a battery expert".
Therefore, I defer to any actual battery expert(s) who opt to flesh out my high level explanation.

 

There’s lithium ion and lithium ion phosphate. Huge difference between the chemistry when it comes to below freezing the temps. Deterioration is what happens, not instant failure at below freezing with lifepo4

 

Huh? The people here who had the lifepo4 battery from jerk the ripper said that turd gen has a great bms that’s built in the ecu.

 

Well there ya go, you heard it here first "A properly made battery does not need active balancing" at least that will save me from reading any more, with genius comments like that, I'll save what remaining brain cells I have from rolling over and dying and my eyes from rolling so far back in my head I'll never be able to see again .....

T1 Terry