Great Video the only thing to add is after this bottom balance method, the first charge is very important. You need to make note of the first cell to reach full SOC. This would be the weakest cell. Then base all other charging off of this charge. Usually 10% to 20% less than full. This might make understanding why a BMS is not needed. But with the cells you have there; you are running a greater risk then if using the Lifepo4 cells. Those do look like the Leaf Cells. A bit more dangerous.
100 percent truth in your explanation Tom ! I do the same with R/C car batteries , I like the bottom balance better than Charge balance , Because it is safer for the cells and makes them last longer on a charge and live longer over the life of the cell . Great info man !!
+ShawnMrFixit Lee I agree..........I think balancing at the top can be dangerous. I think bottom balancing the cells and then slightly under charging will give the cells the longest life.
Very good Tom, thanks. Now maybe explain what to do on the other side, I mean under charging the pack a little and why ;) I have been watching EVtv since 2011 and learned all this from Jack too, and I am very thankful
+Christophe HUBERT Thanks very much for watching and commenting Christophe.......I plan to explain the "other side" of things when I charge the cells for the first time.
Great video. I understand for hobbyists making EV conversions and building your own battery pack. But I'm curious in the new shiny Gigafactory or other carmaker facilities how do they do it? There must be an automated process that is part of production.
Have you tracked the actual discharge curve for the Nissan/Renault cells? As I mentioned in one of your previous videos I don't think they have the same flat discharge curve as LiFePO4 cells, but are more linear similar to LiCo and LiNiCoAl. I would also think that these cells are much more closely matched than what we get from CALB, and if so they would be fine if top balanced, since that would also be effectively bottom balancing them.
As per the Data Sheet these cells End of Discharge is listed as 2.5v. Most every Li cells I've ever dealt with state 3.0V. Only LiFePo4 type go below 3.0V. Usually 2.7 - 2.5V. How far down are you taking these ?
Hey Tom, working on a prius gen 2 with NIHM cells. I have a bunch that are like .2v after sitting for two years. Are those dangerous to try to charge back up?
+Robert Orr Id say its between .3 and 1C Robert. I am not an artist......It didn't need to be exact, my main focus was to emphasis how flat the curve is and to show how steep it turns at the knee.
Fantastic explanation. I appreciate it because I was wondering as well. Will the car have some sort of dash monitor for the voltage level that you can see when it's being depleted?
+Dan Frederiksen I am going to assume your assumption is correct Dan......But no electric car maker will let you use much more then 70% of the battery packs energy either. The only exception would be Tesla.
+Dan Frederiksen you do need balancing if you have a BMS that monitors all of the cells. even if its 50s that is worth using a BMS and running the leads to each cell. initial Bottom balancing would only be good for possibly the first 100 cycles and each cell will start to drift because they all age differently.
+Cutler Cycles for DIY I would generally avoid BMS to avoid the danger of it going wrong which is far greater than without it. For a commercial car I would use a full BMS, likely optical so there is no mess of wires spanning high voltage. A BMS is something that really needs to work well or you are better off without it.
Great Video the only thing to add is after this bottom balance method, the first charge is very important. You need to make note of the first cell to reach full SOC. This would be the weakest cell. Then base all other charging off of this charge. Usually 10% to 20% less than full. This might make understanding why a BMS is not needed. But with the cells you have there; you are running a greater risk then if using the Lifepo4 cells. Those do look like the Leaf Cells. A bit more dangerous.
100 percent truth in your explanation Tom ! I do the same with R/C car batteries , I like the bottom balance better than Charge balance , Because it is safer for the cells and makes them last longer on a charge and live longer over the life of the cell . Great info man !!
+ShawnMrFixit Lee I agree..........I think balancing at the top can be dangerous. I think bottom balancing the cells and then slightly under charging will give the cells the longest life.
Very well explained Tom... I'll be watching along the whole build.
+snocrushr Glad your hooked Greg!
Very good Tom, thanks. Now maybe explain what to do on the other side, I mean under charging the pack a little and why ;)
I have been watching EVtv since 2011 and learned all this from Jack too, and I am very thankful
+Christophe HUBERT Thanks very much for watching and commenting Christophe.......I plan to explain the "other side" of things when I charge the cells for the first time.
Very well explained Tom. I understand it now.
+Cheator40 Thanks Jerry
Interesting info Tom
+TheWreckingYard Thanks Ron
I understood 100% thanks Tom.
+ZIGgassedUP Thanks Zig
Great video. I understand for hobbyists making EV conversions and building your own battery pack. But I'm curious in the new shiny Gigafactory or other carmaker facilities how do they do it? There must be an automated process that is part of production.
thanks for explaining why its necessary to balance at low volts -
Awesome explanation Tom.
+Greg's Garage Thanks Greg!
Have you tracked the actual discharge curve for the Nissan/Renault cells? As I mentioned in one of your previous videos I don't think they have the same flat discharge curve as LiFePO4 cells, but are more linear similar to LiCo and LiNiCoAl. I would also think that these cells are much more closely matched than what we get from CALB, and if so they would be fine if top balanced, since that would also be effectively bottom balancing them.
As per the Data Sheet these cells End of Discharge is listed as 2.5v. Most every Li cells I've ever dealt with state 3.0V. Only LiFePo4 type go below 3.0V. Usually 2.7 - 2.5V. How far down are you taking these ?
why you aren't using top ballancing with bms, that shut power off when any cell is empty (2.5V)?
+Volodumur Kalunyak Exactly individual cell monitor and top charge balance.
Bms have their own issues.
Hey Tom, working on a prius gen 2 with NIHM cells. I have a bunch that are like .2v after sitting for two years. Are those dangerous to try to charge back up?
Explain bottom balancing please?
After bottom balancing why i see many people bring the batteries up to 3.5V per cell? Why not higher?
Nice explanation Tom. I assume this is a discharge curve at 1C?
+Robert Orr Id say its between .3 and 1C Robert. I am not an artist......It didn't need to be exact, my main focus was to emphasis how flat the curve is and to show how steep it turns at the knee.
Could i use a 0.2 ohm 300 watt resistor, will it hurt anything? what would be the difference?
Cool
Fantastic explanation. I appreciate it because I was wondering as well. Will the car have some sort of dash monitor for the voltage level that you can see when it's being depleted?
+rindress Absolutely......I am alittle unsure exactly what ill be using but I will make a video when I get to that point. Thanks for watching!
Makes more sense now
+Buckswoodshop Its alittle different then your electric razor.
Yes it is. Lol
awesome
+RobsPackanShine Thanks Robbie
Video Resolution. Are terrible ... can not see the numbers!
Please Record with higher resolution?
thx
+Александр ztx Your welcome
Video Resolution. Years Terrible can not see the numbers!
Please Record with higher resolution?
Why not simply but BMW to do This?
I assume that no electric car maker uses bottom balancing.
+Dan Frederiksen I am going to assume your assumption is correct Dan......But no electric car maker will let you use much more then 70% of the battery packs energy either. The only exception would be Tesla.
+Dan Frederiksen you do need balancing if you have a BMS that monitors all of the cells. even if its 50s that is worth using a BMS and running the leads to each cell. initial Bottom balancing would only be good for possibly the first 100 cycles and each cell will start to drift because they all age differently.
+Cutler Cycles for DIY I would generally avoid BMS to avoid the danger of it going wrong which is far greater than without it.
For a commercial car I would use a full BMS, likely optical so there is no mess of wires spanning high voltage. A BMS is something that really needs to work well or you are better off without it.